| 11. |
- Chen, Deliang, 1961, et al.
(författare)
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Spatial Interpolation of Daily Precipitation in China : 1951-2005
- 2010
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Ingår i: Advances in Atmospheric Sciences. - : Springer Science and Business Media LLC. - 0256-1530 .- 1861-9533. ; 27:6, s. 1221-1232
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Tidskriftsartikel (refereegranskat)abstract
- Climate research relies heavily on good quality instrumental data; for modeling efforts gridded data are needed. So far, relatively little effort has been made to create gridded climate data for China. This is especially true for high-resolution daily data. This work, focuses on identifying an accurate method to produce gridded daily precipitation in China based on the observed data at 753 stations for the period 1951-2005. Five interpolation methods, including ordinary nearest neighbor, local polynomial, radial basis function, inverse distance weighting, and ordinary kriging, have been used and compared. Cross-validation shows that the ordinary kriging based on seasonal semi-variograms gives the best performance, closely followed by the inverse distance weighting with a power of 2. Finally the ordinary kriging is chosen to interpolate the station data to a 18 kmx 18 km grid system covering the whole country. Precipitation for each 0.5A degrees x 0.5A degrees latitude-longitude block is then obtained by averaging the values at the grid nodes within the block. Owing to the higher station density in the eastern part of the country, the interpolation errors are much smaller than those in the west (west of 100A degrees E). Excluding 145 stations in the western region, the daily, monthly, and annual relative mean absolute errors of the interpolation for the remaining 608 stations are 74%, 29%, and 16%, respectively. The interpolated daily precipitation has been made available on the internet for the scientific community.
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| 12. |
- Cubasch, U., et al.
(författare)
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Introduction
- 2013
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Ingår i: Climate Change 2013: The Physical Science Basis. - Cambridge, United Kingdom and New York, NY, USA : Cambridge University Press. - 9781107661820 ; , s. 119-158
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Bokkapitel (refereegranskat)
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| 13. |
- Cubasch, U., et al.
(författare)
-
Introduction
- 2013
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Ingår i: Climate Change 2013: The Physical Science Basis. - 9781107661820 ; , s. 119-158
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 14. |
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| 15. |
- Fan, Lijun, et al.
(författare)
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Statistical downscaling of summer temperature extremes in northern China
- 2013
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Ingår i: Advances in Atmospheric Sciences. - : Springer Science and Business Media LLC. - 0256-1530 .- 1861-9533. ; 30:4, s. 1085-1095
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Tidskriftsartikel (refereegranskat)abstract
- Two approaches of statistical downscaling were applied to indices of temperature extremes based on percentiles of daily maximum and minimum temperature observations at Beijing station in summer during 1960-2008. One was to downscale daily maximum and minimum temperatures by using EOF analysis and stepwise linear regression at first, then to calculate the indices of extremes; the other was to directly downscale the percentile-based indices by using seasonal large-scale temperature and geo-potential height records. The cross-validation results showed that the latter approach has a better performance than the former. Then, the latter approach was applied to 48 meteorological stations in northern China. The cross-validation results for all 48 stations showed close correlation between the percentile-based indices and the seasonal large-scale variables. Finally, future scenarios of indices of temperature extremes in northern China were projected by applying the statistical downscaling to Hadley Centre Coupled Model Version 3 (HadCM3) simulations under the Representative Concentration Pathways 4.5 (RCP 4.5) scenario of the Fifth Coupled Model Inter-comparison Project (CMIP5). The results showed that the 90th percentile of daily maximum temperatures will increase by about 1.5A degrees C, and the 10th of daily minimum temperatures will increase by about 2A degrees C during the period 2011-35 relative to 1980-99.
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| 16. |
- Fang, K. Y., et al.
(författare)
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Covarying Hydroclimate Patterns between Monsoonal Asia and North America over the Past 600 Years
- 2014
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Ingår i: Journal of Climate. - : American Meteorological Society. - 0894-8755 .- 1520-0442. ; 27:21, s. 8017-8033
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Tidskriftsartikel (refereegranskat)abstract
- Proxy data with large spatial coverage spanning to the preindustrial era not only provide invaluable material to investigate hydroclimate changes in different regions but also enable studies on temporal changes in the teleconnections between these regions. Applying the singular value decomposition (SVD) method to tree-ring-based field reconstructions of the Palmer drought severity index (PDSI) over monsoonal Asia (MA) and North America (NA) from 1404 to 2005, the dominant covarying pattern between the two regions is identified. This pattern is represented by the teleconnection between the dipole pattern of southern-northern latitudinal MA and the dipole of southwest NA (SWNA)-northwest NA (NWNA), which accounts for 59.6% of the total covariance. Its dominated by an antiphase low MA and SWNA teleconnection, driven by the El Nino-Southern Oscillation (ENSO), and is most significant at an interannual time scale. This teleconnection is strengthened (weakened) in periods of increased (decreased) solar forcing and high (low) temperature, which is associated with intensified (weakened) ENSO variability. Additional forcing by SST anomalies in the Indian and western Pacific Oceans appears to be important too.
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| 17. |
- Gao, Ge, 1972, et al.
(författare)
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Spatial and temporal characteristics of actual evapotranspiration over Haihe River basin in China
- 2012
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Ingår i: Stochastic Environmental Research and Risk Assessment. - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 26:5, s. 655-669
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Tidskriftsartikel (refereegranskat)abstract
- Spatial and temporal characteristics of actualevapotranspiration over the Haihe River basin in Chinaduring 1960–2002 are estimated using the complementaryrelationship and the Thornthwaite water balance (WB)approaches. Firstly, the long-term water balance equation isused to validate and select the most suitable long-termaverage annual actual evapotranspiration equations for ninesubbasins. Then, the most suitable method, the Pike equation,is used to calibrate parameters of the complementaryrelationship models and the WB model at each station. Theresults show that the advection aridity (AA) model moreclosely estimates actual evapotranspiration than does theGranger and Gray (GG) model especially considering theannual and summer evapotranspiration when compared withtheWBmodel estimates. The results from theAA model andthe WB model are then used to analyze spatial and temporalchanging characteristics of the actual evapotranspirationover the basin. The analysis shows that the annual actualevapotranspirations during 1960–2002 exhibit similardecreasing trends in most parts of the Haihe River basin forthe AA and WB models. Decreasing trends in annual precipitationand potential evapotranspiration, which directlyaffect water supply and the energy available for actualevapotranspiration respectively, jointly lead to the decreasein actual evapotranspiration in the basin. A weakening of thewater cycle seems to have appeared, and as a consequence,the water supply capacity has been on the decrease, aggravatingwater shortage and restricting sustainable social andeconomic development in the region.
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| 18. |
- Gustafsson, Malin, et al.
(författare)
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Extreme rainfall events in Southern Sweden: Where does the moisture come from?
- 2010
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Ingår i: Tellus A. - : Stockholm University Press. - 0280-6495. ; 62:5, s. 605-616
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Tidskriftsartikel (refereegranskat)abstract
- The atmospheric transport of moisture leading to extreme summer precipitation events in southern Sweden was investigated using a Lagrangian trajectory model. Surprisingly, we found that the trajectories crossed continental Europe and the Baltic Sea before arriving over Sweden; they did not arrive directly from the North Sea. Such transport pathways were not seen for a control sample of non-extreme rainfall events. We then used a new source region identification technique to investigate the hypothesis that Europe and the Baltic are important sources of the moisture that is rained out in the extreme events. Although the results varied between events, we found that this is indeed the case. Our results establish the atmospheric transport patterns that are apparently a pre-requisite for extreme rainfall events to occur in southern Sweden, and further suggest regional moisture availability may also play a key role.
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| 19. |
- Hansson, Daniel, 1980, et al.
(författare)
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Reconstruction of river runoff to the Baltic Sea, AD1500-1995
- 2011
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418. ; 31, s. 696-703
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we reconstructed river runoff to the Baltic Sea since 1500 using temperature and atmospheric circulation indices, showing the important atmospheric processes for river runoff in different regions. Runoff appears to be strongly linked to temperature, wind and rotational circulation components in the northern region and Gulf of Finland, but more associated with rotational and deformation circulation components in the south. No significant long-term change has been detected in total river runoff to the Baltic Sea for 500 years, although decadal and regional variability is large. Analysis of runoff sensitivity to temperature shows that the south region may become drier with rising air temperatures. This is in contrast to the north region and Gulf of Finland where warmer temperatures are associated with more river runoff. Over the past 500 years the total river runoff to the Baltic Sea has decreased by 3% (450 m3/s) per degree Celsius increase.
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| 20. |
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