Based on daily meteorological data of 18 observations from 1961 to 2001 within Guizhou Province, ... more Based on daily meteorological data of 18 observations from 1961 to 2001 within Guizhou Province, Mann-Kendall trend test, correlation analysis and principal component analysis were applied to determine trend of pan evaporation and its relation with meteorological factors (net solar radiation, temperature, relative humid, wind speed etc.). Analysis results demonstrate: pan evaporation presents a significant decrease trend in the 41 years (99% confidence level). This decrease trend is especially more significant in winter, spring and summer seasons. Spatially, significant decrease of pan evaporation occurs in the east area and part of the west area, and seldom occurs in the other areas. The pan evaporation decrease is primarily resulted from reduction of net solar radiation.
The objective of this study is to quantitatively evaluate the successive Tropical Rainfall Measur... more The objective of this study is to quantitatively evaluate the successive Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) products and further to explore the improvements and error propagation of the latest 3B42V7 algorithm relative to its predecessor 3B42V6 using the Coupled Routing and Excess Storage (CREST) hydrologic model in the mountainous Wangchu Basin of Bhutan. First, the comparison to a decade-long (2001-2010) daily rain gauge dataset reveals that: (1) 3B42V7 generally improves upon 3B42V6's underestimation both for the whole basin (bias from À41.15% to À8.38%) and for a 0.25°Â 0.25°grid cell with high-density gauges (bias from À40.25% to 0.04%), though with modest enhancement of correlation coefficients (CC) (from 0.36 to 0.40 for basinwide and from 0.37 to 0.41 for grid); and (2) 3B42V7 also improves its occurrence frequency across the rain intensity spectrum. Using the CREST model that has been calibrated with rain gauge inputs, the 3B42V6-based simulation shows limited hydrologic prediction NSCE skill (0.23 in daily scale and 0.25 in monthly scale) while 3B42V7 performs fairly well (0.66 in daily scale and 0.77 in monthly scale), a comparable skill score with the gauge rainfall simulations. After recalibrating the model with the respective TMPA data, significant improvements are observed for 3B42V6 across all categories, but not as much enhancement for the already-well-performing 3B42V7 except for a reduction in bias (from À26.98% to À4.81%). In summary, the latest 3B42V7 algorithm reveals a significant upgrade from 3B42V6 both in precipitation accuracy (i.e., correcting the underestimation) thus improving its potential hydrological utility. Forcing the model with 3B42V7 rainfall yields comparable skill scores with in situ gauges even without recalibration of the hydrological model by the satellite precipitation, a compensating approach often used but not favored by the hydrology community, particularly in ungauged basins.
Based on daily meteorological data of 18 observations from 1961 to 2001 within Guizhou Province, ... more Based on daily meteorological data of 18 observations from 1961 to 2001 within Guizhou Province, Mann-Kendall trend test, correlation analysis and principal component analysis were applied to determine trend of pan evaporation and its relation with meteorological factors (net solar radiation, temperature, relative humid, wind speed etc.). Analysis results demonstrate: pan evaporation presents a significant decrease trend in the 41 years (99% confidence level). This decrease trend is especially more significant in winter, spring and summer seasons. Spatially, significant decrease of pan evaporation occurs in the east area and part of the west area, and seldom occurs in the other areas. The pan evaporation decrease is primarily resulted from reduction of net solar radiation.
The objective of this study is to quantitatively evaluate the successive Tropical Rainfall Measur... more The objective of this study is to quantitatively evaluate the successive Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) products and further to explore the improvements and error propagation of the latest 3B42V7 algorithm relative to its predecessor 3B42V6 using the Coupled Routing and Excess Storage (CREST) hydrologic model in the mountainous Wangchu Basin of Bhutan. First, the comparison to a decade-long (2001-2010) daily rain gauge dataset reveals that: (1) 3B42V7 generally improves upon 3B42V6's underestimation both for the whole basin (bias from À41.15% to À8.38%) and for a 0.25°Â 0.25°grid cell with high-density gauges (bias from À40.25% to 0.04%), though with modest enhancement of correlation coefficients (CC) (from 0.36 to 0.40 for basinwide and from 0.37 to 0.41 for grid); and (2) 3B42V7 also improves its occurrence frequency across the rain intensity spectrum. Using the CREST model that has been calibrated with rain gauge inputs, the 3B42V6-based simulation shows limited hydrologic prediction NSCE skill (0.23 in daily scale and 0.25 in monthly scale) while 3B42V7 performs fairly well (0.66 in daily scale and 0.77 in monthly scale), a comparable skill score with the gauge rainfall simulations. After recalibrating the model with the respective TMPA data, significant improvements are observed for 3B42V6 across all categories, but not as much enhancement for the already-well-performing 3B42V7 except for a reduction in bias (from À26.98% to À4.81%). In summary, the latest 3B42V7 algorithm reveals a significant upgrade from 3B42V6 both in precipitation accuracy (i.e., correcting the underestimation) thus improving its potential hydrological utility. Forcing the model with 3B42V7 rainfall yields comparable skill scores with in situ gauges even without recalibration of the hydrological model by the satellite precipitation, a compensating approach often used but not favored by the hydrology community, particularly in ungauged basins.
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