Model simulation is an important way to study the effects of climate change on agriculture.Such assessment is subject to a range of uncertainties because of either incomplete knowledge or model technical uncertainties,impeding effective decision-making to climate change.On the basis of uncertainties in the impact assessment at different levels,this article systematically summarizes the sources and propagation of uncertainty in the assessment of the effect of climate change on agriculture in terms of the climate projection,the assessment process,and the crop models linking to climate models.Meanwhile,techniques and methods focusing on different levels and sources of uncertainty and uncertainty propagation are introduced,and shortcomings and insufficiencies in uncertainty processing are pointed out.Finally,in terms of how to accurately assess the effect of climate change on agriculture,improvements to further decrease potential uncertainty are suggested.
YAO FengMeiQIN PengChengZHANG JiaHuaLIN ErDaBOKEN Vijendra
Quantitative estimation of vegetation water content(VWC) using optical remote sensing techniques is helpful in forest fire as-sessment,agricultural drought monitoring and crop yield estimation.This paper reviews the research advances of VWC retrieval using spectral reflectance,spectral water index and radiative transfer model(RTM) methods.It also evaluates the reli-ability of VWC estimation using spectral water index from the observation data and the RTM.Focusing on two main definitions of VWC-the fuel moisture content(FMC) and the equivalent water thickness(EWT),the retrieval accuracies of FMC and EWT using vegetation water indices are analyzed.Moreover,the measured information and the dataset are used to estimate VWC,the results show there are significant correlations among three kinds of vegetation water indices(i.e.,WSI,NDⅡ,NDWI1640,WI/NDVI) and canopy FMC of winter wheat(n=45).Finally,the future development directions of VWC detection based on optical remote sensing techniques are also summarized.
ZHANG JiaHua1,XU Yun1,YAO FengMei2,WANG PeiJuan1,GUO WenJuan1,LI Li1 & YANG LiMin3 1 Chinese Academy of Meteorological Sciences,Beijing 100081,China
The occurrence of rice high-temperature damage (HTD) has increased with global warming. Cultivation of rice is seriously affected by the HTD in the middle and lower reaches of the Yangtze River, which directly affects food security in this region and in the whole of China. It is important to monitor and assess crop HTD using satellite remote sensing information. This paper reviews the recent development of monitoring rice HTD using optical remote sensing information. It includes the use of optical remote sensing information to obtain the regional spatial distribution of high temperatures, mixed-surface temperature retrieval for rice fields based on mixed decomposition information, the development of field and thermal infrared testing and modeling, and the satellite/ground-based remote sensing coupled method for monitoring rice HTD. Finally, the prospects for monitoring crop HTD based on remote sensing information are summarized.
ZHANG JiaHuaYAO FengMeiLI BingBaiYAN HaoHOU YingYuCHENG GaoFengVijendra BOKEN
