A new static microwave sounding unit （MSU） channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 （CMIP5） historical multimodel simulations as inputs into the fast Radi...A new static microwave sounding unit （MSU） channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 （CMIP5） historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS （RTTOV v10）. For the same CMIP5 model simulations, it is demonstrated that the computed MSU channel 4 brightness temperature （T4） trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV, but show more cooling than those computed using the traditional UAH （University of Alabama at Huntsville） or RSS （Remote Sensing Systems in Santa Rosa, California） static weighting functions. The new static weighting function not only reduces the computational cost, but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function. This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics. Although not completely removed, this difference can be reduced using the proposed weighting function to some extent, especially over the tropics. This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions. This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere.展开更多
The Loess Plateau(LP)is an ecologically fragile region due to its sensitivities to climate variations and anthropogenic influences[1].The Chinese government recognized the ecological significance of the LP and impleme...The Loess Plateau(LP)is an ecologically fragile region due to its sensitivities to climate variations and anthropogenic influences[1].The Chinese government recognized the ecological significance of the LP and implemented a series of ecological restoration and conservation policies since 1999.Revegetation of degraded ecosystems of the LP is mainly attributed to the environmental protection policies.These policies are led by Grain for Green(GFG)project,supported by some vegetation conservation programs.The GFG project,also known as the Conversion of Cropland to Forest and Grassland Program,was launched in 1999,and the LP is one of the pilot regions of this project.The first phase of GFG was implemented between 1999 and 2014,and the second phase started in 2015.The local farmers were accommodated by providing grain and cash subsidies for converting their agriculture land into forests and/or grasslands[2].The GFG program has converted approximately 16,000 km^(2)of rain-fed agriculture land to grassland and forests,resulting in a 25%increase in vegetation cover of the LP during 1999 and 2010[3].展开更多
基金supported by the National Program on Key Basic Research Projects of China(Grant Nos.2010CB951604 and 2010CB28402)
文摘A new static microwave sounding unit （MSU） channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 （CMIP5） historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS （RTTOV v10）. For the same CMIP5 model simulations, it is demonstrated that the computed MSU channel 4 brightness temperature （T4） trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV, but show more cooling than those computed using the traditional UAH （University of Alabama at Huntsville） or RSS （Remote Sensing Systems in Santa Rosa, California） static weighting functions. The new static weighting function not only reduces the computational cost, but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function. This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics. Although not completely removed, this difference can be reduced using the proposed weighting function to some extent, especially over the tropics. This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions. This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere.
基金supported by the Pioneer Talents Program of the Chinese Academy of Sciences and the National Natural Science Foundation of China(41971032)the support of the President’s International Fellowship Initiative Program of the Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences。
文摘The Loess Plateau(LP)is an ecologically fragile region due to its sensitivities to climate variations and anthropogenic influences[1].The Chinese government recognized the ecological significance of the LP and implemented a series of ecological restoration and conservation policies since 1999.Revegetation of degraded ecosystems of the LP is mainly attributed to the environmental protection policies.These policies are led by Grain for Green(GFG)project,supported by some vegetation conservation programs.The GFG project,also known as the Conversion of Cropland to Forest and Grassland Program,was launched in 1999,and the LP is one of the pilot regions of this project.The first phase of GFG was implemented between 1999 and 2014,and the second phase started in 2015.The local farmers were accommodated by providing grain and cash subsidies for converting their agriculture land into forests and/or grasslands[2].The GFG program has converted approximately 16,000 km^(2)of rain-fed agriculture land to grassland and forests,resulting in a 25%increase in vegetation cover of the LP during 1999 and 2010[3].
