Climate change is expected to have long-term impacts on drought and wildfire risks in Oregon as summers continue to become warmer and drier. This paper investigates the projected changes in drought characteristics and...Climate change is expected to have long-term impacts on drought and wildfire risks in Oregon as summers continue to become warmer and drier. This paper investigates the projected changes in drought characteristics and drought propagation in the Umatilla River Basin in northeastern Oregon for mid-century(2030–2059) and late-century(2070–2099) climate scenarios. Drought characteristics for projected climates were determined using downscaled CMIP5 climate datasets from ten climate models and Soil and Water Assessment Tool to simulate effects on hydrologic processes. Short-term(three months) drought characteristics(frequency, duration, and severity) were analyzed using four drought indices, including the Standardized Precipitation Index(SPI-3), Standardized Precipitation-Evapotranspiration Index(SPEI-3), Standardized Streamflow Index(SSI-3), and the Standardized Soil Moisture Index(SSMI-3). Results indicate that short-term meteorological droughts are projected to become more prevalent, with up to a 20% increase in the frequency of SPI-3drought events. Short-term hydrological droughts are projected to become more frequent(average increase of 11% in frequency of SSI-3 drought events), more severe, and longer in duration(average increase of 8% for short-term droughts).Similarly, short-term agricultural droughts are projected to become more frequent(average increase of 28% in frequency of SSMI-3 drought events) but slightly shorter in duration(average decrease of 4%) in the future. Historically, drought propagation time from meteorological to hydrological drought is shorter than from meteorological to agricultural drought in most sub-basins. For the projected climate scenarios, the decrease in drought propagation time will likely stress the timing and capacity of water supply in the basin for irrigation and other uses.展开更多
An enhanced ARTSIST Sea Ice(ASI)algorithm is presented based on a data fusion method of calculating total sea ice concentration from high-frequency microwave data.Algorithms that use low-frequency data to calculate to...An enhanced ARTSIST Sea Ice(ASI)algorithm is presented based on a data fusion method of calculating total sea ice concentration from high-frequency microwave data.Algorithms that use low-frequency data to calculate total sea ice concentration are less affected by atmosphere,but their spatial resolutions tend to be lower.In contrast,algorithms using high-frequency data have higher spatial resolution but are significantly influenced by atmosphere.Although errors can be eliminated using weather filters,the concentration of mixed pixels cannot be modified.Here,an enhanced ASI algorithm uses the 19 GHz polarization difference to modify the 91 GHz polarization difference,which is substituted into the ASI algorithm to calculate total sea ice concentration.Arctic total sea ice concentration results are obtained based on Special Sensor Microwave Imager Sounder(SSMIS)data on January 3,from 2008 to 2017.Total sea ice area and average concentration using the enhanced ASI algorithm are compared to traditional ASI and NASA Team results.In the Marginal Ice Zone,there is a considerable difference between the enhanced and traditional ASI algorithm results,with the former much closer to the NASA Team results.The proposed algorithm effectively modifies the concentration of the mixed pixels in the marginal zone.展开更多
基金the financial support received from the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA), USA (Grant No.2017-67003-26057) via an interagency partnership between USDA-NIFAthe National Science Foundation (NSF) on the research program Innovations at the Nexus of Food, Energy and Water Systemsfunded by the Ministry of Education, Government of India through the Scheme for Promotion of Academic and Research Collaboration (SPARC) project grant (SPARC/2018-2019/P1080/SL)。
文摘Climate change is expected to have long-term impacts on drought and wildfire risks in Oregon as summers continue to become warmer and drier. This paper investigates the projected changes in drought characteristics and drought propagation in the Umatilla River Basin in northeastern Oregon for mid-century(2030–2059) and late-century(2070–2099) climate scenarios. Drought characteristics for projected climates were determined using downscaled CMIP5 climate datasets from ten climate models and Soil and Water Assessment Tool to simulate effects on hydrologic processes. Short-term(three months) drought characteristics(frequency, duration, and severity) were analyzed using four drought indices, including the Standardized Precipitation Index(SPI-3), Standardized Precipitation-Evapotranspiration Index(SPEI-3), Standardized Streamflow Index(SSI-3), and the Standardized Soil Moisture Index(SSMI-3). Results indicate that short-term meteorological droughts are projected to become more prevalent, with up to a 20% increase in the frequency of SPI-3drought events. Short-term hydrological droughts are projected to become more frequent(average increase of 11% in frequency of SSI-3 drought events), more severe, and longer in duration(average increase of 8% for short-term droughts).Similarly, short-term agricultural droughts are projected to become more frequent(average increase of 28% in frequency of SSMI-3 drought events) but slightly shorter in duration(average decrease of 4%) in the future. Historically, drought propagation time from meteorological to hydrological drought is shorter than from meteorological to agricultural drought in most sub-basins. For the projected climate scenarios, the decrease in drought propagation time will likely stress the timing and capacity of water supply in the basin for irrigation and other uses.
基金The National Natural Science Foundation of China under contract No.41606209the Open Fund from Key Laboratory of Global Change and Marine-Atmospheric Chemistry under contract No.GCMAC1605+1 种基金the Natural Science Project of Henan Education Department under contract No.15A120007the Key Laboratory of Ocean Circulation and Waves,Institute of Oceanology,Chinese Academy of Sciences under contract No.KLOCW1805
文摘An enhanced ARTSIST Sea Ice(ASI)algorithm is presented based on a data fusion method of calculating total sea ice concentration from high-frequency microwave data.Algorithms that use low-frequency data to calculate total sea ice concentration are less affected by atmosphere,but their spatial resolutions tend to be lower.In contrast,algorithms using high-frequency data have higher spatial resolution but are significantly influenced by atmosphere.Although errors can be eliminated using weather filters,the concentration of mixed pixels cannot be modified.Here,an enhanced ASI algorithm uses the 19 GHz polarization difference to modify the 91 GHz polarization difference,which is substituted into the ASI algorithm to calculate total sea ice concentration.Arctic total sea ice concentration results are obtained based on Special Sensor Microwave Imager Sounder(SSMIS)data on January 3,from 2008 to 2017.Total sea ice area and average concentration using the enhanced ASI algorithm are compared to traditional ASI and NASA Team results.In the Marginal Ice Zone,there is a considerable difference between the enhanced and traditional ASI algorithm results,with the former much closer to the NASA Team results.The proposed algorithm effectively modifies the concentration of the mixed pixels in the marginal zone.
