| 1. |
- Arndt, D. S., et al.
(författare)
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STATE OF THE CLIMATE IN 2017
- 2018
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 99:8, s. S1-S310
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Forskningsöversikt (refereegranskat)
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| 2. |
- Arndt, D. S., et al.
(författare)
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State of the Climate in 2016
- 2017
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 98:8, s. S1-S280
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Tidskriftsartikel (refereegranskat)abstract
- In 2016, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-continued to increase and reach new record highs. The 3.5 +/- 0.1 ppm rise in global annual mean carbon dioxide from 2015 to 2016 was the largest annual increase observed in the 58-year measurement record. The annual global average carbon dioxide concentration at Earth's surface surpassed 400 ppm (402.9 +/- 0.1 ppm) for the first time in the modern atmospheric measurement record and in ice core records dating back as far as 800000 years. One of the strongest El Nino events since at least 1950 dissipated in spring, and a weak La Nina evolved later in the year. Owing at least in part to the combination of El Nino conditions early in the year and a long-term upward trend, Earth's surface observed record warmth for a third consecutive year, albeit by a much slimmer margin than by which that record was set in 2015. Above Earth's surface, the annual lower troposphere temperature was record high according to all datasets analyzed, while the lower stratospheric temperature was record low according to most of the in situ and satellite datasets. Several countries, including Mexico and India, reported record high annual temperatures while many others observed near-record highs. A week-long heat wave at the end of April over the northern and eastern Indian peninsula, with temperatures surpassing 44 degrees C, contributed to a water crisis for 330 million people and to 300 fatalities. In the Arctic the 2016 land surface temperature was 2.0 degrees C above the 1981-2010 average, breaking the previous record of 2007, 2011, and 2015 by 0.8 degrees C, representing a 3.5 degrees C increase since the record began in 1900. The increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 24 March, the sea ice extent at the end of the growth season saw its lowest maximum in the 37-year satellite record, tying with 2015 at 7.2% below the 1981-2010 average. The September 2016 Arctic sea ice minimum extent tied with 2007 for the second lowest value on record, 33% lower than the 1981-2010 average. Arctic sea ice cover remains relatively young and thin, making it vulnerable to continued extensive melt. The mass of the Greenland Ice Sheet, which has the capacity to contribute similar to 7 m to sea level rise, reached a record low value. The onset of its surface melt was the second earliest, after 2012, in the 37-year satellite record. Sea surface temperature was record high at the global scale, surpassing the previous record of 2015 by about 0.01 degrees C. The global sea surface temperature trend for the 21st century-to-date of +0.162 degrees C decade(-1) is much higher than the longer term 1950-2016 trend of +0.100 degrees C decade(-1). Global annual mean sea level also reached a new record high, marking the sixth consecutive year of increase. Global annual ocean heat content saw a slight drop compared to the record high in 2015. Alpine glacier retreat continued around the globe, and preliminary data indicate that 2016 is the 37th consecutive year of negative annual mass balance. Across the Northern Hemisphere, snow cover for each month from February to June was among its four least extensive in the 47-year satellite record. Continuing a pattern below the surface, record high temperatures at 20-m depth were measured at all permafrost observatories on the North Slope of Alaska and at the Canadian observatory on northernmost Ellesmere Island. In the Antarctic, record low monthly surface pressures were broken at many stations, with the southern annular mode setting record high index values in March and June. Monthly high surface pressure records for August and November were set at several stations. During this period, record low daily and monthly sea ice extents were observed, with the November mean sea ice extent more than 5 standard deviations below the 1981-2010 average. These record low sea ice values contrast sharply with the record high values observed during 2012-14. Over the region, springtime Antarctic stratospheric ozone depletion was less severe relative to the 1991-2006 average, but ozone levels were still low compared to pre-1990 levels. Closer to the equator, 93 named tropical storms were observed during 2016, above the 1981-2010 average of 82, but fewer than the 101 storms recorded in 2015. Three basins-the North Atlantic, and eastern and western North Pacific-experienced above-normal activity in 2016. The Australian basin recorded its least active season since the beginning of the satellite era in 1970. Overall, four tropical cyclones reached the Saffir-Simpson category 5 intensity level. The strong El Nino at the beginning of the year that transitioned to a weak La Nina contributed to enhanced precipitation variability around the world. Wet conditions were observed throughout the year across southern South America, causing repeated heavy flooding in Argentina, Paraguay, and Uruguay. Wetter-than-usual conditions were also observed for eastern Europe and central Asia, alleviating the drought conditions of 2014 and 2015 in southern Russia. In the United States, California had its first wetter-than-average year since 2012, after being plagued by drought for several years. Even so, the area covered by drought in 2016 at the global scale was among the largest in the post-1950 record. For each month, at least 12% of land surfaces experienced severe drought conditions or worse, the longest such stretch in the record. In northeastern Brazil, drought conditions were observed for the fifth consecutive year, making this the longest drought on record in the region. Dry conditions were also observed in western Bolivia and Peru; it was Bolivia's worst drought in the past 25 years. In May, with abnormally warm and dry conditions already prevailing over western Canada for about a year, the human-induced Fort McMurray wildfire burned nearly 590000 hectares and became the costliest disaster in Canadian history, with $3 billion (U.S. dollars) in insured losses.
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| 3. |
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| 4. |
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| 5. |
- Dunn, R. J. H., et al.
(författare)
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GLOBAL CLIMATE : State of the Climate in 2020
- 2021
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Ingår i: Bulletin of the American Meteorological Society. - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 102:8
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Ades, M., et al.
(författare)
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Global Climate : in State of the climate in 2019
- 2020
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 101:8, s. S17-S127
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Ades, M., et al.
(författare)
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GLOBAL CLIMATE
- 2020
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Ingår i: BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY. - 0003-0007 .- 1520-0477. ; 101:8
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Aaron-Morrison, Arlene P., et al.
(författare)
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State of the climate in 2014
- 2015
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Ingår i: Bulletin of the American Meteorological Society. - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 96
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Tidskriftsartikel (refereegranskat)abstract
- Most of the dozens of essential climate variables monitored each year in this report continued to follow their long-term trends in 2014, with several setting new records. Carbon dioxide, methane, and nitrous oxide-the major greenhouse gases released into Earth's atmosphere-once again all reached record high average atmospheric concentrations for the year. Carbon dioxide increased by 1.9 ppm to reach a globally averaged value of 397.2 ppm for 2014. Altogether, 5 major and 15 minor greenhouse gases contributed 2.94 W m-2 of direct radiative forcing, which is 36% greater than their contributions just a quarter century ago. Accompanying the record-high greenhouse gas concentrations was nominally the highest annual global surface temperature in at least 135 years of modern record keeping, according to four independent observational analyses. The warmth was distributed widely around the globe's land areas, Europe observed its warmest year on record by a large margin, with close to two dozen countries breaking their previous national temperature records; many countries in Asia had annual temperatures among their 10 warmest on record; Africa reported above-average temperatures across most of the continent throughout 2014; Australia saw its third warmest year on record, following record heat there in 2013; Mexico had its warmest year on record; and Argentina and Uruguay each had their second warmest year on record. Eastern North America was the only major region to observe a below-average annual temperature. But it was the oceans that drove the record global surface temperature in 2014. Although 2014 was largely ENSO-neutral, the globally averaged sea surface temperature (SST) was the highest on record. The warmth was particularly notable in the North Pacific Ocean where SST anomalies signaled a transition from a negative to positive phase of the Pacific decadal oscillation. In the winter of 2013/14, unusually warm water in the northeast Pacific was associated with elevated ocean heat content anomalies and elevated sea level in the region. Globally, upper ocean heat content was record high for the year, reflecting the continued increase of thermal energy in the oceans, which absorb over 90% of Earth's excess heat from greenhouse gas forcing. Owing to both ocean warming and land ice melt contributions, global mean sea level in 2014 was also record high and 67 mm greater than the 1993 annual mean, when satellite altimetry measurements began. Sea surface salinity trends over the past decade indicate that salty regions grew saltier while fresh regions became fresher, suggestive of an increased hydrological cycle over the ocean expected with global warming. As in previous years, these patterns are reflected in 2014 subsurface salinity anomalies as well. With a now decade-long trans-basin instrument array along 26°N, the Atlantic meridional overturning circulation shows a decrease in transport of-4.2 ± 2.5 Sv decade-1. Precipitation was quite variable across the globe. On balance, precipitation over the world's oceans was above average, while below average across land surfaces. Drought continued in southeastern Brazil and the western United States. Heavy rain during April-June led to devastating floods in Canada's Eastern Prairies. Above-normal summer monsoon rainfall was observed over the southern coast of West Africa, while drier conditions prevailed over the eastern Sahel. Generally, summer monsoon rainfall over eastern Africa was above normal, except in parts of western South Sudan and Ethiopia. The south Asian summer monsoon in India was below normal, with June record dry. Across the major tropical cyclone basins, 91 named storms were observed during 2014, above the 1981-2010 global average of 82. The Eastern/Central Pacific and South Indian Ocean basins experienced significantly above-normal activity in 2014; all other basins were either at or below normal. The 22 named storms in the Eastern/Central Pacific was the basin's most since 1992. Similar to 2013, the North Atlantic season was quieter than most years of the last two decades with respect to the number of storms, despite the absence of El Niño conditions during both years. In higher latitudes and at higher elevations, increased warming continued to be visible in the decline of glacier mass balance, increasing permafrost temperatures, and a deeper thawing layer in seasonally frozen soil. In the Arctic, the 2014 temperature over land areas was the fourth highest in the 115-year period of record and snow melt occurred 20-30 days earlier than the 1998-2010 average. The Greenland Ice Sheet experienced extensive melting in summer 2014. The extent of melting was above the 1981-2010 average for 90% of the melt season, contributing to the second lowest average summer albedo over Greenland since observations began in 2000 and a record-low albedo across the ice sheet for August. On the North Slope of Alaska, new record high temperatures at 20-m depth were measured at four of five permafrost observatories. In September, Arctic minimum sea ice extent was the sixth lowest since satellite records began in 1979. The eight lowest sea ice extents during this period have occurred in the last eight years. Conversely, in the Antarctic, sea ice extent countered its declining trend and set several new records in 2014, including record high monthly mean sea ice extent each month from April to November. On 20 September, a record large daily Antarctic sea ice extent of 20.14 × 106 km2 occurred. The 2014 Antarctic stratospheric ozone hole was 20.9 million km2 when averaged from 7 September to 13 October, the sixth smallest on record and continuing a decrease, albeit statistically insignificant, in area since 1998.
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| 9. |
- Fountoulakis, K.N., et al.
(författare)
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Modeling psychological function in patients with schizophrenia with the PANSS : An international multi-center study
- 2021
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Ingår i: CNS Spectrums. - : Cambridge University Press. - 1092-8529 .- 2165-6509. ; 26:3, s. 290-298
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Tidskriftsartikel (refereegranskat)abstract
- Background.The aim of the current study was to explore the changing interrelationships among clinical variables through the stages of schizophrenia in order to assemble a comprehensive and meaningful disease model.Methods.Twenty-nine centers from 25 countries participated and included 2358 patients aged 37.21 ± 11.87 years with schizophrenia. Multiple linear regression analysis and visual inspection of plots were performed.Results.The results suggest that with progression stages, there are changing correlations among Positive and Negative Syndrome Scale factors at each stage and each factor correlates with all the others in that particular stage, in which this factor is dominant. This internal structure further supports the validity of an already proposed four stages model, with positive symptoms dominating the first stage, excitement/hostility the second, depression the third, and neurocognitive decline the last stage.Conclusions.The current study investigated the mental organization and functioning in patients with schizophrenia in relation to different stages of illness progression. It revealed two distinct “cores” of schizophrenia, the “Positive” and the “Negative,” while neurocognitive decline escalates during the later stages. Future research should focus on the therapeutic implications of such a model. Stopping the progress of the illness could demand to stop the succession of stages. This could be achieved not only by both halting the triggering effect of positive and negative symptoms, but also by stopping the sensitization effect on the neural pathways responsible for the development of hostility, excitement, anxiety, and depression as well as the deleterious effect on neural networks responsible for neurocognition.
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| 10. |
- Fountoulakis, KN, et al.
(författare)
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Relationship of suicide rates to economic variables in Europe: 2000-2011
- 2014
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Ingår i: The British journal of psychiatry : the journal of mental science. - : Royal College of Psychiatrists. - 1472-1465. ; 205:6, s. 486-496
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Tidskriftsartikel (refereegranskat)abstract
- It is unclear whether there is a direct link between economic crises and changes in suicide rates.AimsThe Lopez-Ibor Foundation launched an initiative to study the possible impact of the economic crisis on European suicide rates.MethodData was gathered and analysed from 29 European countries and included the number of deaths by suicide in men and women, the unemployment rate, the gross domestic product (GDP) per capita, the annual economic growth rate and inflation.ResultsThere was a strong correlation between suicide rates and all economic indices except GPD per capita in men but only a correlation with unemployment in women. However, the increase in suicide rates occurred several months before the economic crisis emerged.ConclusionsOverall, this study confirms a general relationship between the economic environment and suicide rates; however, it does not support there being a clear causal relationship between the current economic crisis and an increase in the suicide rate.
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| 11. |
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| 12. |
- Vicente-Serrano, S. M., et al.
(författare)
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Diverse relationships between forest growth and the Normalized Difference Vegetation Index at a global scale
- 2016
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 187, s. 14-29
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Tidskriftsartikel (refereegranskat)abstract
- This study compared the densest available database of tree-ring growth with the longest Normalized Difference Vegetation Index (NDVI) information available at the global scale to quantify the relationship between annual forest growth and the NDVI across different forest types and regions and to characterize the patterns of response of forest growth to NDVI values at different temporal scales. We found a general positive relationship between the inter-annual NDVI variability and the annual tree growth in most of the analyzed forests. Nevertheless, there were strong differences in the tree growth responses to NDVI, given that the annual tree-ring records in each forest responded in a different way to the magnitude, seasonality and accumulation period of the NDVI values. Thus, we found eight main patterns of tree-ring response to the NDVI, which were related to the forest type and climate conditions of each corresponding site. The identified patterns may be useful for determining early-warning signals of changes in forest growth over large areas based on remote sensing information.
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| 13. |
- Dominguez-Castro, F., et al.
(författare)
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Mapping seasonal and annual extreme precipitation over the Peruvian Andes
- 2018
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418. ; 38:15, s. 5459-5475
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Tidskriftsartikel (refereegranskat)abstract
- Seasonal and annual extreme precipitation over the Peruvian Andes have been mapped for the first time. Maps were developed using the most complete, quality-controlled and homogenous daily precipitation records in Peru from 1973 to 2016. For each observed rain gauge series, we defined parameters as the de-clustered daily intensity, total precipitation duration, total magnitude and dry-spell length. Then, we fitted the seasonal and annual series of these variables to a Generalized-Pareto distribution using a peak-over-threshold approach. We estimated the distribution parameters and validated the performance of different thresholds to obtain the best estimation of precipitation probability. We also mapped the distribution parameters obtained for the different meteorological stations using the universal kriging algorithm, accounting for elevation and the distance to the Pacific Ocean as co-variables. The accuracy of the extreme precipitation maps for a period of 25 and 50 years were validated using a jack-knife approach. Some of the maps show strong uncertainty given the random spatial distribution of the variables as a consequence of the complex topography and climate of the region. Nevertheless, the maps show a useful general assessment of the spatial distribution of the precipitation hazard probability over the region, providing a good agreement with the estimations obtained in the meteorological stations for some variables and time periods analysed. Extreme precipitation maps over this high-complex terrain of Peru are of key importance for flood risk assessment, water resources management, crop yield, soil conservation and human settlements.
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| 14. |
- Lopez-Moreno, J. I., et al.
(författare)
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Air and wet bulb temperature lapse rates and their impact on snowmaking in a Pyrenean ski resort
- 2019
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Ingår i: Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 135:3-4, s. 1361-1373
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Tidskriftsartikel (refereegranskat)abstract
- A set of 17 air temperature and relative humidity sensors were used to analyze the temporal variability of surface air temperature (Tair), wet bulb temperature (Twb), and daily snowmaking hours (SM, number of hours per day with Twb<-2 degrees C), lapse rates, and the occurrence of thermal inversions at the Formigal ski resort (Spanish Pyrenees) from December to March during three consecutive ski seasons (2012-2013, 2013-2014, and 2014-2015). The Tair and Twb lapse rates showed strong hourly and daily variability, with both exhibiting almost identical temporal fluctuations.The Twb exhibited average lapse rates that were slightly steeper (-5.2 degrees C/km) than those observed for Tair (-4.9 degrees C/km). The less steep lapse rates and most thermal inversions were observed in December. Days having less (more) steep Tair and Twb lapse rates were observed under low (high) wind speeds and high (low) relative humidity and air pressure. The temporal dynamics of the SM lapse rates was more complex, as this involved consideration of the average Tair in the ski resort, in addition to the driving factors of the spatio-temporal variability of Twb. Thus, on a number of cold (warm) days, snowmaking was feasible at all elevations at the ski resort, independently of the slopes of the lapse rates. The SM exhibited an average daily lapse rate of 8.2h/km, with a progressive trend of increase from December to March.Weather types over the Iberian Peninsula tightly control the driving factors of the Tair, Twb, and SM lapse rates (wind speed, relative humidity, and Tair), so the slopes of the lapse rates and the frequency of inversions in relation to elevation for the three variables are very dependent on the occurrence of specific weather types. The less steep lapse rates occurred associated with advections from the southeast, although low lapse rates also occurred during advections from the east and south, and under anticyclonic conditions. The steepest Tair and Twb lapse rates were observed during north and northwest advections, while the steepest rates for SM were observed during days of cyclonic circulation and advections from the northeast.
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| 15. |
- Navarro-Serrano, F., et al.
(författare)
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Estimation of near-surface air temperature lapse rates over continental Spain and its mountain areas
- 2018
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418. ; 38:8, s. 3233-3249
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Tidskriftsartikel (refereegranskat)abstract
- Although the mean environmental lapse rate (MELR) value (a linear decrease of -6.5 degrees C/km) is the most widely used, near-surface (i.e., non-free atmosphere) air temperature lapse rates (NSLRs; measured at 1.5 m height) are variable in space and time because of their dependence on topography and meteorological conditions. In this study we conducted the first analysis of the spatial and temporal variability of NSLRs for continental Spain and their relationship to synoptic atmospheric circulation (circulation weather types [CWTs]), focusing on major mountain areas including the Pyrenees, Cantabrian, Central, Baetic, and Iberian ranges. The results showed that the NSLR varied markedly at spatial and seasonal scales and depended on the dominant atmospheric conditions. The median NSLR values were weaker (less negative) than the MELR for the mountain areas (Pyrenees -5.17 degrees C/km; Cantabrian range -5.22 degrees C/km; Central range -5.78 degrees C/km; Baetic range -4.83 degrees C/km; Iberian range -5.79 degrees C/km) and for the entire continental Spain (-5.28 degrees C/km). For the entire continental Spain the steepest NSLR values were found in April (-5.80 degrees C/km), May (-5.58 degrees C/km), and October (-5.54 degrees C/km) because of the dominance of northerly and westerly advections of cold air. The weakest NSLR values were found in July (-4.67 degrees C/km) and August (-4.78 degrees C/km) because of the inland heating, and in winter because of the occurrence of thermal inversions. As the use of the MELR involves the assumption of large errors, we propose 1 zonal, 12 monthly, 11 CWTs, and 132 hybrid monthly-CWTs NSLRs for each of the mountain ranges and for the entire continental Spain. More regional studies are urgently needed to accurately assess the NSLR as a function of atmospheric circulation conditions.
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| 16. |
- Vicente-Serrano, S. M., et al.
(författare)
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A comparison of temporal variability of observed and model-based pan evaporation over Uruguay (1973-2014)
- 2018
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418. ; 38:1, s. 337-350
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Tidskriftsartikel (refereegranskat)abstract
- This study analyses variability and trends of atmospheric evaporative demand (AED) across Uruguay in the past four decades. Changes were assessed using pan evaporation measurements from 10 meteorological stations and compared to PenPan model calculations, which is a physically based model that employs meteorological data as input. Results demonstrate a high agreement between the observed AED and those estimated from the PenPan model. Both observations and model estimations agree on a high interannual variability in AED, though being statistically insignificant (p>0.05) at seasonal and annual scales. Given that AED shows high sensitivity to changes in relative humidity and sunshine duration, as a surrogate of solar radiation, the lack of significant trends in the AED observations and estimations over Uruguay can be linked to the insignificant trend found for these climate variables for the period from 1973 to 2014. This is the first study that reports Pan evaporation trends for this part of the world, helping to infill gaps for mid-latitude Southern Hemisphere areas, which are poorly represented in Pan evaporation trends.
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| 17. |
- Vicente-Serrano, S. M., et al.
(författare)
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Vegetation greening in Spain detected from long term data (1981-2015)
- 2020
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Ingår i: International Journal of Remote Sensing. - : Informa UK Limited. - 0143-1161 .- 1366-5901. ; 41:5, s. 1709-1740
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Tidskriftsartikel (refereegranskat)abstract
- This study describes a newly developed high-resolution (1.1 km) Normalized Difference Vegetation Index dataset for the peninsular Spain and the Balearic Islands (Sp_1km_NDVI). This dataset is developed based on National Oceanic and Atmospheric Administration–Advanced Very High Resolution Radiometer (NOAA–AVHRR) afternoon images, spanning the past three decades (1981–2015). After a careful pre-processing procedure, including calibration with post-launch calibration coefficients, geometric and topographic corrections, cloud removal, temporal filtering, and bi-weekly composites by maximum NDVI-value, we assessed changes in vegetation greening over the study domain using Mann-Kendall and Theil-Sen statistics. Our trend results were compared with those derived from some widely recognized global NDVI datasets [e.g. the Global Inventory Modelling and Mapping Studies 3rd generation (GIMMS3g), Smoothed NDVI (SMN) and Moderate-Resolution Imaging Spectroradiometer (MODIS)]. Results demonstrate that there is a good agreement between the annual trends based on Sp_1km_NDVI product and other datasets. Nonetheless, we found some differences in the spatial patterns of the NDVI trends at the seasonal scale. Overall, in comparison to the available global NDVI datasets, Sp_1km_NDVI allows for characterizing changes in vegetation greening at a more-detailed spatial and temporal scale. In specific, our dataset provides relatively long-term corrected satellite time series (>30 years), which are crucial to understand the response of vegetation to climate change and human-induced activities. Also, given the complex spatial structure of NDVI changes over the study domain, particularly due to the rapid land intensification processes, the spatial resolution (1.1 km) of our dataset can provide detailed spatial information on the inter-annual variability of vegetation greening in this Mediterranean region and assess its links to climate change and variability.
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| 18. |
- Zha, J. L., et al.
(författare)
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Projected changes in global terrestrial near-surface wind speed in 1.5 degrees C-4.0 degrees C global warming levels
- 2021
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 16:11
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Tidskriftsartikel (refereegranskat)abstract
- Understanding future changes in global terrestrial near-surface wind speed (NSWS) in specific global warming level (GWL) is crucial for climate change adaption. Previous studies have projected the NSWS changes; however, the changes of NSWS with different GWLs have yet to be studied. In this paper, we employ the Max Planck Institute Earth System Model large ensembles to evaluate the contributions of different GWLs to the NSWS changes. The results show that the NSWS decreases over the Northern Hemisphere (NH) mid-to-high latitudes and increases over the Southern Hemisphere (SH) as the GWL increases by 1.5 degrees C-4.0 degrees C relative to the preindustrial period, and that these characteristics are more significant with the stronger GWL. The probability density of the NSWS shifts toward weak winds over NH and strong winds over SH between the current climate and the 4.0 degrees C GWL. Compared to 1.5 degrees C GWL, the NSWS decreases -0.066 m s(-1) over NH and increases +0.065 m s(-1) over SH with 4.0 degrees C GWL, especially for East Asia and South America, the decrease and increase are most significant, which reach -0.21 and +0.093 m s(-1), respectively. Changes in the temperature gradient induced by global warming could be the primary factor causing the interhemispheric asymmetry of future NSWS changes. Intensified global warming induces the reduction in Hadley, Ferrell, and Polar cells over NH and the strengthening of the Hadley cell over SH could be another determinant of asymmetry changes in NSWS between two hemispheres.
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| 19. |
- Azorin-Molina, C., et al.
(författare)
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AVHRR warm-season cloud climatologies under various synoptic regimes across the Iberian peninsula and the Balearic islands
- 2015
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 35:8, s. 1984-2002
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Tidskriftsartikel (refereegranskat)abstract
- In this study we retrieved the spatial distribution of mid-afternoon clouds under various synoptic regimes across the Iberian Peninsula and the Balearic Islands for the warm/convective-season, from May to October. Accurate daily cloud masks were derived by applying a daytime over land multispectral convective cloud detection algorithm spanning 15 years (1997–2011) of Advanced Very High Resolution Radiometer (AVHRR) HRPT data. We processed a total of 2094 afternoon overpasses (between 1230 and 1720 UTC) corresponding to the NOAA-14, NOAA-16 and NOAA-18 spacecrafts, and stratified daily cloud masks as a function of: (1) the automated circulation-typing scheme of Jenkinson and Collinson and (2) the prevailing wind field at 850 hPa. The AVHRR warm-season cloud climatology with high spatial resolution (1.1-km) identified six representative areas (regions of interest; ROIs) with intensified cloud activity (hot spots). The results also revealed the typical spatial distribution of clouds for each synoptic regime across the whole region, identified the synoptic patterns and wind regimes under which high amounts of clouds occur for each ROIs, and showed that strong boundary layer winds in general increase the frequency of clouds. The regional cloud climatology presented here could be useful, e.g. to improve convective short-term forecasting by identifying active cloud areas for each atmospheric type.
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| 20. |
- Azorin-Molina, Cesar, et al.
(författare)
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Evaluating anemometer drift: A statistical approach to correct biases in wind speed measurement
- 2018
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Ingår i: Atmospheric research. - : Elsevier BV. - 0169-8095. ; 203, s. 175-188
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies on observed wind variability have revealed a decline (termed “stilling”) of near-surface wind speed during the last 30–50 years over many mid-latitude terrestrial regions, particularly in the Northern Hemisphere. The well-known impact of cup anemometer drift (i.e., wear on the bearings) on the observed weakening of wind speed has been mentioned as a potential contributor to the declining trend. However, to date, no research has quantified its contribution to stilling based on measurements, which is most likely due to lack of quantification of the ageing effect. In this study, a 3-year field experiment (2014–2016) with 10-minute paired wind speed measurements from one new and one malfunctioned (i.e., old bearings) SEAC SV5 cup anemometer which has been used by the Spanish Meteorological Agency in automatic weather stations since mid-1980s, was developed for assessing for the first time the role of anemometer drift on wind speed measurement. The results showed a statistical significant impact of anemometer drift on wind speed measurements, with the old anemometer measuring lower wind speeds than the new one. Biases show a marked temporal pattern and clear dependency on wind speed, with both weak and strong winds causing significant biases. This pioneering quantification of biases has allowed us to define two regression models that correct up to 37% of the artificial bias in wind speed due to measurement with an old anemometer.
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| 21. |
- Corell, D., et al.
(författare)
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Influences of synoptic situation and teleconnections on fog-water collection in the Mediterranean Iberian Peninsula, 2003-2012
- 2020
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 40:7, s. 3297-3317
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Tidskriftsartikel (refereegranskat)abstract
- Fog-water collection has been widely analysed for its quantification and potential uses; however, there are few studies assessing the synoptic conditions and large-scale teleconnection patterns that affect its occurrence. Focusing on the Mediterranean Iberian Peninsula, this work aims to analyse the synoptic patterns, both at surface level and 850 hPa geopotential height, that most likely to favour fog-water collection, and to quantify the relationship between fog-water collection and the NAOi (North Atlantic Oscillation index), MOi (Mediterranean Oscillation index) as well as WeMOi (Western Mediterranean Oscillation index) teleconnection patterns. For this purpose, daily fog-water observations from a dense network of 23 fog-water collectors located along the Mediterranean Iberian Peninsula for 2003-2012 were analysed in relation to synoptic patterns and the three-teleconnection indices. The major findings are: (a) The most favourable synoptic patterns for fog-water collection are maritime advections carrying humidity from the Mediterranean basin, and cyclonic circulations, whereas anti-cyclonic situations generally led to large number of foggy days with low fog-collection rates. (b) In terms of winds at 850 hPa, the most favourable low-level flows for fog-water collection are associated with strong winds (>5.1 m s(-1)) from the Mediterranean. Atlantic winds generally cause a greater number of fog days than Mediterranean winds, with less fog-water collection rates. (c) WeMOi has the greatest influence on fog-water collection, mainly during winter and spring months, with statistically significant negative relationships for most of the stations. MOi also shows a great influence, with a large number of statistically significant negative correlations, mainly during the same months as WeMOi. Lastly, NAOi presented the lowest and no significant negative correlations with fog-water collection.
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| 22. |
- Estrela, M. J., et al.
(författare)
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Spatio-temporal variability of fog-water collection in the eastern Iberian Peninsula: 2003–2012
- 2019
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Ingår i: Atmospheric Research. - : Elsevier BV. - 0169-8095. ; 226, s. 87-101
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Tidskriftsartikel (refereegranskat)abstract
- Among the different inputs involved in the hydrological system, fog water measured by man-made passive devices is one of the most unknown components, although it could be an additional water resource for specific environmental applications (forest restoration, forest firefighting, etc.). Focusing on the Mediterranean Iberian Peninsula, the aim of this work is to quantify fog-water collected by a 24-fog-stations network spread across three latitudinal sectors with different locations (coastal, pre-littoral and inland), and to determine the most productive sites. Measurements from the network show that distance-to-sea, latitude or elevation differences between stations are factors affecting fog-water collection potential. The network, based on passive cylindrical omnidirectional fog-water collectors, was active during the period 2003–2012. In addition to fog collection, other environmental variables such as rainfall, wind speed and wind direction, air temperature and relative humidity were measured. These ancillary data were used in a specific data reduction technique to eliminate the simultaneous rainwater component from the fog water measurements, and in the retrieval of the optimum mean wind directions to harvest fog-water efficiently. It was concluded that (i) positive differences in elevation allow greater collection rates, even under 100 m differences; (ii) optimum harvesting wind directions for inland locations are in line with the orientation of the existent valley coupled with the shortest path to the coastline, their collected fog-water volumes being generally smaller than those near the coast; (iii) fog-water collection at coastal locations present more dispersed optimal wind directions, ranging from north to the direction of the most immediate coastline; and (iv) there is a practically null dependence of the optimum mean wind direction on seasonality, but a strong dependence of fog-water captured volumes, however. © 2019 Elsevier B.V.
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| 23. |
- Fang, K., et al.
(författare)
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Wind speed reconstruction from a tree-ring difference index in northeastern Inner Mongolia
- 2022
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Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865. ; 72
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Tidskriftsartikel (refereegranskat)abstract
- The lack of instrumental wind speed data beyond the industrial era limits our ability to evaluate the contributions of natural versus anthropogenic processes on long-term changes in wind speed. It is thus desirable to find proxies for historical changes in wind speed. Persistent and strong winds can cause compression wood composed of wider and denser rings in conifer trees at leeward sides. This work hypothesizes that the asymmetric wind impact on tree radial growth provides information about wind speed changes. To test the hypothesis, we developed a Tree-Ring Difference Index (TRDI) representing the differences between tree ring widths at the windward and leeward sides. Thirty-four trees subjected to strong and persistent winds in a Picea mongolica forest in northeastern Inner Mongolia were analyzed. The TRDI based on 124 cores correlates significantly with the maximum wind speeds recorded from May to August, indicating that this proxy can be used for wind speed reconstruction. Our reconstruction reveals long-term changes in wind speed including an upward trend from 1940 to 1954, followed by continually decreasing wind speeds from 1955 to 1990 and increasing values from 1991 to 2010. The reconstructed wind speeds include strong multi-decadal variability and significant correlations with the Pacific Decadal Oscillation (PDO). © 2022 Elsevier GmbH
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| 24. |
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| 25. |
- Vicente-Serrano, S. M., et al.
(författare)
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Increased Vegetation in Mountainous Headwaters Amplifies Water Stress During Dry Periods
- 2021
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Ingår i: Geophysical Research Letters. - 0094-8276. ; 48:18
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of blue and green water partitioning under vegetation and climate change, as well as their different interactions during wet and dry periods, are poorly understood in the literature. We analyzed the impact of vegetation changes on blue water generation in a central Spanish Pyrenees basin undergoing intense afforestation. We found that vegetation change is a key driver of large decreases in blue water availability. The effect of vegetation increase is amplified during dry years, and mainly during the dry season, with streamflow reductions of more than 50%. This pattern can be attributed primarily to increased plant water consumption. Our findings highlight the importance of vegetation changes in reinforcing the decrease in water resource availability. With aridity expected to rise in southern Europe over the next few decades, interactions between climate and land management practices appear to be amplifying future hydrological drought risk in the region.
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| 26. |
- Vicente-Serrano, S. M., et al.
(författare)
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Recent changes in monthly surface air temperature over Peru, 1964-2014
- 2018
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418. ; 38:1, s. 283-306
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Tidskriftsartikel (refereegranskat)abstract
- This study assessed changes in the maximum and minimum surface air temperatures across Peru during the period 1964-2014. For this purpose, we employed the most complete records of air temperature series that were also subjected to a rigorous quality control and homogenization protocol. Based on the homogenized series, we created a monthly gridded data set of maximum and minimum air temperatures at a 5x5km grid spacing. The results suggest a general warming trend in surface air temperature across Peru, albeit with clear spatial and seasonal variation. Our results also reveal some differences in the detectable trends between maximum and minimum air temperatures. Maximum air temperature trends mainly increased during the austral summer (DJF), but cold season minimum air temperature trends showed an opposite pattern, with the strongest warming being recorded in the austral winter (JJA). In addition, maximum air temperature trends exhibited a clear elevation-warming dependency, with the strongest warming recorded at highly elevated sites. On the contrary, this dependency is weakened for minimum air temperature trends, as lower magnitudes of change and even a cooling trend were observed at high elevations during most months of the year. For mean air temperature trends, there are no clear spatial and temporal seasonal differences across Peru.
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| 27. |
- Azorin-Molina, Cesar, et al.
(författare)
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Biases in wind speed measurements due to anemometer changes
- 2023
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Ingår i: Atmospheric Research. - 0169-8095. ; 289
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Tidskriftsartikel (refereegranskat)abstract
- This research presents a case study of the biases and discontinuities that were introduced in observed long-term mean wind-speed and gust data-series due to anemometer changes in a meteorological station in northern Spain, operated by the Spanish State Meteorological Agency: San Sebastian-Igueldo. Field and wind-tunnel experiments with predefined conditions have been presented in the literature, however this research uses a real case study to assess the impact of anemometer changes on wind speed measurements due to three factors being: (i) the 3-cup anemometer model (SEAC vs. THIES companies); (ii) sensor height (∼19.95 m vs. ∼20.45 m) and (iii) sensor age (20-years old vs. new). Our results show (a) substantial biases in the measured wind speed and daily peak wind gusts, with the new THIES anemometer reporting stronger surface winds than the old SEAC anemometer; (b) opposing biases under weak (negative) and moderate-strong (positive) winds; and (c) significant breakpoints in the long-term wind data-series, which highlight the importance of data homogenization. National Weather Services and climate assessment groups will benefit from these findings since errors in wind speed and gust measurements can be minimized by implementing systematic observation protocols. Robust anemometer observations provide a basis for accurate quantification of the magnitude of changes and the variability of surface winds.
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| 28. |
- Azorin-Molina, Cesar, et al.
(författare)
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Recent trends in wind speed across Saudi Arabia, 1978-2013: a break in the stilling
- 2018
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418. ; 38
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Tidskriftsartikel (refereegranskat)abstract
- We analyse recent trends and variability of observed near-surface wind speed from 19 stations across Saudi Arabia (SA) for 1978-2013. The raw wind speed data set was subject to a robust homogenization protocol, and the stations were then classified under three categories: (1) coast, (2) inland and (3) mountain stations. The results reveal a statistically significant (p<0.05) reduction of wind speed of -0.058m s(-1) dec(-1) at annual scale across SA, with decreases in winter (-0.100m s(-1) dec(-1)) and spring (-0.066m s(-1) dec(-1)) also detected, being non-significant in summer and autumn. The coast, inland and mountain series showed similar magnitude and significance of the declining trends across all SA series, except for summer when a decoupled variability and opposite trends of wind speed between the coast and inland series (significant declines: -0.101m s(-1) dec(-1) and -0.065m s(-1) dec(-1), respectively) and the high-elevation mountain series (significant increase: +0.041m s(-1) dec(-1)) were observed. Even though wind speed declines dominated across much of the country throughout the year, only a small number of stations showed statistically significant negative trends in summer and autumn. Most interestingly, a break in the stilling was observed in the last 12-year (2002-2013) period (+0.057m s(-1) dec(-1); not significant) compared to the significant slowdown detected in the previous 24-year (1978-2001) period (-0.089m s(-1) dec(-1)). This break in the slowdown of winds, even followed by a non-significant recovery trend, occurred in all seasons (and months) except for some winter months. Atmospheric circulation plays a key role in explaining the variability of winds, with the North Atlantic Oscillation positively affecting the annual wind speed, the Southern Oscillation displaying a significant negative relationship with winds in winter, spring and autumn, and the Eastern Atlantic negatively modulating winds in summer.
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| 29. |
- Azorin-Molina, C., et al.
(författare)
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Trends of daily peak wind gusts in Spain and Portugal, 1961-2014
- 2016
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Ingår i: Journal of Geophysical Research-Atmospheres. - : American Geophysical Union (AGU). - 2169-897X. ; 121:3, s. 1059-1078
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Tidskriftsartikel (refereegranskat)abstract
- Given the inconsistencies of wind gust trends under the widespread decline in near-surface wind speed (stilling), our study aimed to assess trends of observed daily peak wind gusts (DPWG) across Spain and Portugal for 1961-2014 by analyzing trends of (i) the frequency (90th percentile) and (ii) the magnitude (wind speed maxima) of DPWG. Wind gust series were homogenized on a daily basis, using MM5-simulated series as reference, resulting in 80 suitable station-based data sets. The average DPWG 90th percentile frequency declined by -1.49ddecade(-1) (p<0.05) annually. This showed marked seasonal differences: decreasing in winter (-0.75ddecade(-1); p<0.05) and increasing in summer (+0.18ddecade(-1); p>0.10). A negligible trend was calculated for the annual magnitude of DPWG (-0.005ms(-1) decade(-1); p>0.10), with distinct seasonality: declining in winter (-0.168ms(-1) decade(-1); p<0.10) and increasing in summer (+0.130ms(-1) decade(-1); p<0.05). Combined, these results reveal less frequent and declining DPWG during the cold semester (November-April) and more frequent and increasing DPWG during the warm semester (May-October). Large-scale atmospheric changes such as the North Atlantic Oscillation Index (negative correlations similar to-0.4--0.6; p<0.05) and the Jenkinson and Collison scheme (positive correlations mainly with Westerly regime: similar to+0.5-0.6; p<0.05) partly account for the decadal fluctuations of both frequency and magnitude of DPWG, particularly in winter. However, the North Atlantic Oscillation index-DPWG relationships are smaller in spring, summer, and autumn (similar to-0.1--0.2; p>0.10), especially for the frequency, suggesting the role of local-to-mesoscale drivers.
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| 30. |
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| 31. |
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| 32. |
- Navarro-Serrano, F., et al.
(författare)
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Air temperature measurements using autonomous self-recording dataloggers in mountainous and snow covered areas
- 2019
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Ingår i: Atmospheric Research. - : Elsevier BV. - 0169-8095. ; 224, s. 168-179
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Tidskriftsartikel (refereegranskat)abstract
- High mountain areas are poorly represented by official weather observatories. It implies that new instruments must be evaluated over snow-covered and strongly insolated environments (i.e. mid-latitude mountain areas). We analyzed uncertainty sources over snow covered areas including: 1) temperature logger accuracy and bias of two widely used temperature sensors (Tinytag and iButton); 2) radiation shield performance under various radiation, snow, and wind conditions; 3) appropriate measurement height over snow covered ground; and 4) differences in air temperature measured among nearby devices over a horizontal band. The major results showed the following. 1) Tinytag performance device (mean absolute error: MAE approximate to 0.1-0.2 degrees C in relation to the reference thermistor) was superior to the iButton (MAE approximate to 0.7 degrees C), which was subject to operating errors. 2) Multi-plate radiation shield showed the best performance under all conditions ( > 90% samples has bias between +/- 0.5 degrees C). The tube shield required wind ( > 2.5 m s(-1)) for adequate performance, while the funnel shield required limited radiation ( < 400 W m(-2)). Snow cover causes certain overheating. 3) Air temperatures were found to stabilize at 75-100 cm above the snow surface. Air temperature profile was more constant at night, showing a considerable cooling on near surface at midday. 4) Horizontal air temperature differences were larger at midday (0.5 degrees C). These findings indicate that to minimize errors air temperature measurements over snow surfaces should be carried out using multi-plate radiation shields with high-end thermistors such as Tinytags, and be made at a minimum height above the snow covered ground.
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| 33. |
- Navarro-Serrano, F., et al.
(författare)
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Maximum and minimum air temperature lapse rates in the Andean region of Ecuador and Peru
- 2020
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 40:4, s. 6150-68
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Tidskriftsartikel (refereegranskat)abstract
- To know the vertical distribution of air temperature is complex, and this is necessary for different applications. The main explanatory variable of air temperature is elevation above sea level, whose relationship with air temperature is measured by air temperature lapse rates (LRs). LRs can vary considerably spatiotemporally due to a wide spectrum of geographical, environmental, and other atmospheric factors. Our study presents the first comprehensive assessment of spatiotemporal changes of LRs over the Tropical Andes. Our study is focused on the Peruvian and Ecuadorian Andes, divided in two subregions by the parallel 9.5 degrees (i.e., north and south). Maximum and minimum air temperatures were employed from 115 quality checked weather stations, for the period 1994-2011. Maximum (LRmax) and minimum (LRmin) air temperature lapse rates have been calculated for the whole study period. The effects of seasonality, humidity content and ENSO on the variability of LRs have been analysed. Results show that LRs have large spatiotemporal variability, since references values of LRmax range from -3.57 (South, dry season) to -4.77 (North, wet season), and LRmin range from -3.78 (North, dry season) to -4.93 degrees C center dot km(-1) (South, dry season), in function of season and subregion. Results indicate that the ENSO phases contribute significantly to the variability of southern subregion LRs. This study also presents that minimum air temperatures were more unpredictable than maximum air temperatures in terms of error and uncertainty, as a consequence of the larger spatial variability of nocturnal air temperatures, mainly influenced by local topography. In conclusion, this work goes deeper into the need to obtain precise LRs adapted to the study region, and shows that the use of standard LR values can cause significant failures in modelling air temperature in regions of complex terrain, such as the Andes.
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