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Aerosols characteristics, trends and their climatic implications over Northeast India and adjoining South Asia
Author(s) -
Dahutia Papori,
Pathak Binita,
Bhuyan Pradip Kumar
Publication year - 2017
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.5240
Subject(s) - aerosol , moderate resolution imaging spectroradiometer , environmental science , climatology , atmospheric sciences , angstrom exponent , altitude (triangle) , precipitation , monsoon , ozone , spectroradiometer , meteorology , geography , satellite , geology , reflectivity , physics , geometry , mathematics , astronomy , optics
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°N and 88–98°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 Ångström exponent (AE) exhibit a significant and simultaneous increasing trend in the range of ∼0.003 year −1 to 0.012 year −1 and ∼−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 (∼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 ) (∼0.008 °C year −1 to 0.049 °C year −1 ) compared to that in minimum temperature ( T min ) (∼0.007 °C year −1 to 0.068 °C year −1 ) is attributed to solar dimming due to increasing aerosol loading and COD (∼0.056 year −1 to 0.15 year −1 ). A decrease in high‐level cloud (COD high ) 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.