Indian Institute of Tropical Meteorology, NCL P O, Pashan, Pune 411008, India.
Indian Institute of Tropical Meteorology, NCL P O, Pashan, Pune 411008, India; DASS, Savitribai Phule Pune University, Pune 411007, India.
J Environ Manage. 2018 Jan 15;206:1224-1232. doi: 10.1016/j.jenvman.2017.09.047. Epub 2017 Oct 20.
Importance of atmospheric aerosols through direct and indirect effects on hydrological cycle is highlighted through multiple studies. This study tries to find how much the aerosols can affect evapo-transpiration (ET), a key component of the hydrological cycle over high NDVI (normalized difference vegetation index)/dense canopy, over Dibrugarh, known for vast tea plantation. The radiative effects of aerosols are calculated using satellite (Terra-MODIS) and reanalysis data on daily and monthly scales. Aerosol optical depth (AOD) obtained from satellite and ground observations compares well. Aerosol radiative forcing (ARF), calculated using MERRA data sets of 'clean-clear radiation' and 'clear-radiation' at the surface, shows a lower forcing efficiency, 35 Wm, that is about half of that of ground observations. As vegetation controls ET over high NDVI area to the maximum and that gets modified through ARF, a regression equation is fitted between ET, AOD and NDVI for this station as ET = 0.25 + (-84.27) × AOD + (131.51) × NDVI that explains 82% of 'daily' ET variation using easily available satellite data. ET is found to follow net radiation closely and the direct relation between soil moisture and ET is weak on daily scale over this station as it may be acting through NDVI.
大气气溶胶通过直接和间接影响水文循环的重要性已在多项研究中得到强调。本研究试图找出气溶胶对蒸发蒸腾（ET）的影响有多大，ET 是水文循环的一个关键组成部分，在高 NDVI（归一化差异植被指数）/茂密树冠下，这种情况在迪布鲁加尔很常见，那里有大片的茶园。气溶胶的辐射效应是使用卫星（Terra-MODIS）和再分析数据在日和月尺度上计算的。从卫星和地面观测获得的气溶胶光学深度（AOD）很好地吻合。利用 MERRA 数据集在地表上的“清洁辐射”和“清洁辐射”计算出的气溶胶辐射强迫（ARF）显示出较低的强迫效率，为 35 Wm，约为地面观测值的一半。由于植被对高 NDVI 区域的 ET 控制达到最大，并通过 ARF 进行了修正，因此为该站拟合了一个 ET、AOD 和 NDVI 之间的回归方程，即 ET=0.25+（-84.27）×AOD+（131.51）×NDVI，该方程使用易于获取的卫星数据解释了 82%的“日”ET 变化。研究发现，在该站，ET 与净辐射密切相关，并且在日尺度上，土壤湿度与 ET 之间的直接关系较弱，因为它可能通过 NDVI 起作用。
