Role of fine mode aerosols in modulating cloud properties over industrial locations in north India

Abstract

Abstract. The influence of aerosols on cloud properties over North India which includes the Indo-Gangetic Plain has been investigated for the years 2000 to 2010. During the years 2004, 2009 and 2010 there has been an abrupt increase in fine mode aerosol optical depth (AOD) inducing a sharp decline in cloud effective radius (CER) in the month of January. The following monsoon during these years was a failure in the region considered for the study. In the year 2010, a highest AOD value of 0.35 was recorded in the month of January. In accordance with the aerosol indirect effect, this large increase in AOD resulted in a significant reduction in CER. The monsoon season in that year was deficient in the study region even though the rest of the country received above normal rainfall. For the years when CER diminished below 12 microns in the month of May, a delay in the advancement of monsoon towards North India is noted even after a normal or early onset in southern peninsula. Meanwhile, a rapid progression took place when it was 12 microns or above. During non-monsoon months an inverse relationship existed between cloud effective radius and liquid water path and a strong positive association occurred in the monsoon months. Present analysis suggests that the excessive aerosol loading and the associated aerosol indirect effects in the months prior to the monsoon season has an effect on the propagation and onset of the south west monsoon over the region.

Global observations of aerosol-cloud-precipitation-climate interactions

“…The aerosol indirect effect on the monsoon water cycle is still in an early stage of research. Evidence of reduction in cloud effective radius as a function of increasing AOD in northern India, consistent with the albedo effect [ Twomey , ], has been found from MODIS and Aerosol Robotic Network (AERONET) data [ Abish and Mohanakumar , ; Tripathi et al, ; Panicker et al, ; Cherian et al, ]. Analysis of the microphysical structure of deep convective clouds over the Indian Peninsular region observed during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) showed that polluted clouds had larger concentrations of smaller drops.…”

Absorbing aerosol variability over the Indian subcontinent and its increasing dependence on ENSO

“…The proliferation of the absorbing aerosols during the pre-monsoon season is shown to have modulated the cloud properties and on the overall performance of the Indian summer monsoon (Menon et al, 2002;Lau et al, 2006;Meehl et al, 2008;Gautam et al, 2009;Abish and Mohanakumar, 2011). Such an alteration in the normal weather pattern demands attention in a meteorologically sensitive region because of the location of Monsoon Trough and the apparent position of inter tropical convergence zone (ITCZ) during the summer monsoon season (June to September).…”

Investigation of the aerosol–cloud–rainfall association over the Indian summer monsoon region

“…These studies suggested that aerosolinduced changes in cloud dynamics and microphysics are the potential causal mechanism for the aerosol-cloud-rainfall linear dependence. Over the Indian region, previous studies have compared MODIS-observed cloud microphysical properties between low-and high-aerosol loading to demonstrate the aerosol microphysical effect and its linkage to interannual variations in seasonal rainfall (Abish and Mohanakumar, 2011;Panicker et al, 2010;Ramachandran and Kedia, 2013). Aerosol impacts on cloud microphysics over central India based on ground-based measurements are also evident (Harikishan et al, 2016;Tripathi et al, 2007).…”