| 1. |
- Achberger, C, et al.
(författare)
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Performance of the Rossby Centre regional atmospheric model in Southern Sweden: comparison of simulated and observed precipitation
- 2003
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Ingår i: Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 1434-4483 .- 0177-798X. ; 76:3-4, s. 219-234
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Tidskriftsartikel (refereegranskat)abstract
- Two climate model simulations made with the Rossby Centre regional Atmospheric model version I (RCA1) are evaluated for the precipitation climate in Scania, southern-most Sweden. These simulations are driven by the HadCM2 and the ECHAM4/OPYC3 global circulation models (GCMs) for 10 years. Output from the global and the regional simulations are compared with an observational data set, constructed from a dense precipitation gauge network in Scania. Area-averaged time series corresponding to the size and location of the RCA1 grid points in Scania have been created (the Scanian Data Set). This data set was compared to a commonly used gridded surface climatology provided by the Climatic Research Unit (CRU). Relatively large differences were found, mainly due to the fact that the CRU-climatology uses fewer stations and lacks a correction for rain-gauge under-catch. This underlines the importance of the data set chosen for model evaluations. The validation is carried out at a large scale including the whole area of Scania and at the finest resolution of RCA1 (the grid point level). When integrated over the whole area of Scania, RCA1 improves the shape of the annual precipitation cycle and the inter-annual variability compared to output from the GCMs. The RCA1 control climate is generally too wet compared to the observations. At the grid point level, RCA1 improves the simulation of the variability compared to the GCMs. There is a strong positive correlation between precipitation and altitude in all seasons in the observations. This relationship is, however, much weaker and even reversed in the RCA1 simulations. Analysis of the dense rain gauge network reveals features of spatial variability at around 20-35 km in the area and indicates that a finer resolution is needed if the spatial variability in the area is to be better captured by RCA1.
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| 2. |
- An, Dong, et al.
(författare)
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Evidence of climate shift for temperature and precipitation extremes across Gansu Province in China
- 2020
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Ingår i: Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 1434-4483 .- 0177-798X. ; 139:3-4, s. 1137-1149
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Tidskriftsartikel (refereegranskat)abstract
- Temperature and precipitation extremes are the dominant causes of natural disasters. In this study, seven indices of extreme temperature and precipitation events in Gansu Province, China, were analysed for the period 1961–2017. An abrupt climate shift was recorded during 1980–1981. Thus, the study period was divided into a preshift (before the climate shift) period 1961–1980 and an aftshift (after the climate shift) period 1981–2017. Comparison of mean extreme indices for preshift and aftshift periods was performed for the purpose of exploring possible increasing/decreasing patterns. Generalized extreme value (GEV) distribution was applied spatially to fit the extreme indices with return periods up to 100 years for preshift/aftshift periods. Singular value decomposition (SVD) was adopted to investigate possible correlation between the extreme climate events and indices of large-scale atmospheric circulation. The results indicate that changes in mean and return levels between the preshift and aftshift periods vary significantly in time and space for different extreme indices. Increase in extreme temperature regarding magnitude and frequency for the aftshift period as compared with the preshift period suggests a change to a warmer and more extreme climate during recent years. Changes in precipitation extremes were different in southern and northern parts of Gansu. The precipitation extremes in the north have increased that can result in more serious floods and droughts in the future. SVD analyses revealed a complex pattern of correlation between climate extremes and indices of large-scale atmospheric circulation. Strengthening of westerlies and weakening of the south summer monsoon contribute to the complex changing patterns of precipitation extremes. Results in this study will contribute to disaster risk prevention and better water management in this area.
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| 3. |
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| 4. |
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| 5. |
- Bey, Ergün, et al.
(författare)
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Long-term air temperature trends in North Cyprus
- 2024
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer. - 0177-798X .- 1434-4483. ; 155, s. 1113-1122
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Tidskriftsartikel (refereegranskat)abstract
- The Eastern Mediterranean region is a major climate change hotspot. The island of Cyprus is likely to face increases in the frequency and intensity of hotter weather conditions and heatwaves in the near future. Studies conducted on the long-term temperature changes in Cyprus are very limited. Here, we present an updated and most detailed assessment of the maximum, minimum, mean and diurnal temperature series in North Cyprus for the period 1975–2021. Data obtained from the meterological stations of North Cyprus have been analysed using Mann–Kendal (MK) test and Theil–Sen slope estimator. Overall the mean minimum temperature trend (Tmin) showed the highest warming rate 0.61 (0.24 ≤ Tmin ≤ 0.99)°C decade−1 followed by the mean temperature trend (Tmean) 0.38 (0.29 ≤ Tmean ≤ 0.50) °C decade−1 and the mean maximum temperature trend (Tmax) 0.28 (0 ≤ Tmax ≤ 0.50) °C decade−1. The magnitude of the warming trend observed in the overall mean minimum temperature of North Cyprus 0.61 °C decade−1, is one of the fastest warming trends reported in the literature. A negative association was detected between the direction of prevailing winds of North Cyprus and the magnitude of increase in the mean temperature trends of the locations with coastal Mediterranean climate, which has pointed out the importance of prevailing winds regarding their cooling effect in coastal areas. The diurnal temperature range trend of North Cyprus indicates an apparent decrease (− 0.33 °C decade−1). The warming impact of urban heat island effect was detected in temperature trends of Nicosia in the Mesaoria plain. The information provided here is invaluable to consider in any climate assessment and adaptation plan in Cyprus. If the current warming trend persists into the future, it will devastatingly impact all sectors and natural systems in the region.
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| 6. |
- Björklund, Jesper, 1979, et al.
(författare)
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Advances towards improved low-frequency tree-ring reconstructions, using an updated Pinus sylvestris L. MXD network from the Scandinavian Mountains
- 2013
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 113:3-4, s. 697-710
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Tidskriftsartikel (refereegranskat)abstract
- The dendrochronological use of the parameter maximum density (MXD) in Pinus Sylvestris L., at high latitudes, has provided valuable insights into past summer temperature variations. Few long MXD chronologies, from climatically coherent regions, exist today, with the exception being in northern Europe. Five, 500-year-long, Fennoscandian, MXD chronologies were compared with regard to their common variability and climate sensitivity. They were used to test Signal-free standardization techniques, to improve inferences of low-frequency temperature variations. Climate analysis showed that, in accordance with previous studies on MXD in Fennoscandia, the summer temperature signal is robust (R (2) > 50 %) and reliable over this climatically coherent region. A combination of Individual standardization and regional curve standardization is recommended to refine long-term variability from these MXD chronologies and relieve problems arising from low replication and standardization end-effects.
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| 7. |
- Burauskaite-Harju, Agne, et al.
(författare)
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Characterizing and visualizing spatio-temporal patterns in hourly precipitation records
- 2012
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer. - 0177-798X .- 1434-4483. ; 109:3-4, s. 333-343
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Tidskriftsartikel (refereegranskat)abstract
- We develop new techniques to summarize and visualize spatial patterns of coincidence in weather events such as more or less heavy precipitation at a network of meteorological stations. The cosine similarity measure, which has a simple probabilistic interpretation for vectors of binary data, is generalized to characterize spatial dependencies of events that may reach different stations with a variable time lag. More specifically, we reduce such patterns into three parameters (dominant time lag, maximum cross-similarity, and window-maximum similarity) that can easily be computed for each pair of stations in a network. Furthermore, we visualize such threeparameter summaries by using colour-coded maps of dependencies to a given reference station and distance-decay plots for the entire network. Applications to hourly precipitation data from a network of 93 stations in Sweden illustrate how this method can be used to explore spatial patterns in the temporal synchrony of precipitation events.
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| 8. |
- Burauskaite-Harju, Agne, et al.
(författare)
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Diagnostics for tail dependence in time-lagged random fields of precipitation
- 2013
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 112:3-4, s. 629-636
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Tidskriftsartikel (refereegranskat)abstract
- Weather extremes often occur along fronts passing different sites with some time lag. Here, we show how such temporal patterns can be taken into account when exploring inter-site dependence of extremes. We incorporate time lags into existing models and into measures of extremal associations and their relation to the distance between the investigated sites. Furthermore, we define summarizing parameters that can be used to explore tail dependence for a whole network of stations in the presence of fixed or stochastic time lags. Analysis of hourly precipitation data from Sweden showed that our methods can prevent underestimation of the strength and spatial extent of tail dependencies.
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| 9. |
- Chu, T, et al.
(författare)
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Statistical downscaling of daily mean temperature, pan evaporation and precipitation for climate change scenarios in Haihe River, China
- 2010
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 99:1-2, s. 149-161
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Tidskriftsartikel (refereegranskat)abstract
- A statistical downscaling method (SDSM) was evaluated by simultaneously downscaling air temperature, evaporation, and precipitation in Haihe River basin, China. The data used for evaluation were large-scale atmospheric data encompassing daily NCEP/NCAR reanalysis data and the daily mean climate model results for scenarios A2 and B2 of the HadCM3 model. Selected as climate variables for downscaling were measured daily mean air temperature, pan evaporation, and precipitation data (1961-2000) from 11 weather stations in the Haihe River basin. The results obtained from SDSM showed that: (1) the pattern of change in and numerical values of the climate variables can be reasonably simulated, with the coefficients of determination between observed and downscaled mean temperature, pan evaporation, and precipitation being 99%, 93%, and 73%, respectively; (2) systematic errors existed in simulating extreme events, but the results were acceptable for practical applications; and (3) the mean air temperature would increase by about 0.7A degrees C during 2011 similar to 2040; the total annual precipitation would decrease by about 7% in A2 scenario but increase by about 4% in B2 scenario; and there were no apparent changes in pan evaporation. It was concluded that in the next 30 years, climate would be warmer and drier, extreme events could be more intense, and autumn might be the most distinct season among all the changes.
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| 10. |
- Coelho, C.A.S., et al.
(författare)
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Exploring the impacts of the tropical Pacific SST on the precipitation patterns over South America during ENSO periods
- 2002
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Ingår i: Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 1434-4483 .- 0177-798X. ; 71:3-4, s. 185-197
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Tidskriftsartikel (refereegranskat)abstract
- Summary Previous studies on precipitation over South America that strongly support the existence of links between precipitation and SST anomalies in the Pacific Ocean have identified specific regions where the ENSO signal is particularly stronger. Northeast of Brazil and some parts of southern South America are examples of these regions. However, the same attention was not taken to identify which regions in the Central and East Pacific ocean are better correlated with the South America precipitation during extreme ENSO events, and also which are the transition regions of the precipitation signal over South America during these events. Coincident periods of ENSO events for both SST over the tropical Pacific ocean and monthly precipitation sums from many observational stations over South America were selected and analyzed. Two statistical methods were used for the data analysis: Singular Value Decomposition (SVD) and Simple Linear Correlation (SLC). The SVD results for warmer events in the Pacific corroborate previous ones and also clearly identified a transition region between the drier conditions in the Northeast of Brazil and the wetter conditions in the Southeast/South of Brazil. Transition regions were also determined over Peru and central Amazon. The SLC results indicated that the SST anomalies in the tropical east Pacific ocean has the strongest influence in the South American precipitation during El Niño events. During La Niña events the central area of the Pacific, around 180°, has shown a more significant influence.
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