资源环境科技发展态势分析平台

Aerosol characteristics and climatic implications derived for selected locations of the north-eastern region of India and adjoining locations Thimphu (THM), Dhaka (DAC) and Banmauk between 22-30 degrees N and 88-98 degrees E are reported. The region is found to reveal a distinct spatio-temporal variability in aerosol distribution, with highest climatological mean aerosol optical depth at 550 nm (AOD(550)) at DAC (0.65 +/- 0.07) and lowest at the high altitude location THM (0.19 +/- 0.02). Seasonally the maximum AOD(550) is observed in the pre-monsoon season. Moderate resolution imaging spectroradiometer Level-3 Collection 6 AOD(550) and angstrom ngstrom exponent (AE) exhibit a significant and simultaneous increasing trend in the range of approximate to 0.003 year(-1) to 0.012 year(-1) and approximate to-0.001 year(-1) to 0.020 year(-1), respectively, during the period 2001-2014. Together with AE, increasing trend of total ozone mapping spectrometer and ozone monitoring instrument-retrieved aerosol index (approximate to 0.001 year(-1) to 0.007 year(-1) during 1979-2014) signifies an increase in anthropogenic aerosol loading, leading to an increase in number density of cloud condensation nuclei and decrease/increase of cloud effective radius /cloud optical depth (COD). This is further associated with overall decreasing trends of rainfall rate over this complex monsoon region. A slow increase in maximum temperature (T-max) (approximate to 0.008 degrees C year(-1) to 0.049 degrees C year(-1)) compared to that in minimum temperature (T-min) (approximate to 0.007 degrees C year(-1) to 0.068 degrees C year(-1)) is attributed to solar dimming due to increasing aerosol loading and COD (approximate to 0.056 year(-1) to 0.15 year(-1)). A decrease in high-level cloud (CODhigh) counteracts decreasing trends of ground reaching solar radiation over a few locations, including Dibrugarh. This study is important from an aerosol radiation interaction and aerosol cloud interaction viewpoint, which facilitates in reaching a closure of model simulated present day climate change and future climate projections.