12-14 September, 2011, Lucknow - Earth Science India

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National Conference on Science of Climate Change and Earth’s Sustainability: Issues and Challenges ‘A Scientist-People Partnership’ 12-14 September, 2011, Lucknow Ozone Column Contents have shown an overall declining trend of total ozone contends (TOC) over northern high, mid and low latitude stations. They interpreted their results based on popular hypothesis of atmospheric dynamics and chemistry coupled processes. In the present investigation, an attempt has been made to study the long term changes in TOC over tropical station like Udaipur (Geo. Lat. 24.6° N, Geo. Long. 74° E, Altitude 580 meter) to find out the basic causes of observed declining trend of TOC in the present study of the order of .5 t0 .9 Dobson Unit per year over tropical latitude. More details of the results would be discussed during the presentation. In the present study, the daily value of TOC at these station collected by TOMS during the period 2002 to 2010 are used and the monthly median values and its standard error bars are computed for plotting the variations between their TOC values of particular months with different years for the two stations. In addition to this, variations of monthly mean values of contents of other atmospheric parameters like Aerosols Index at 330 nm, Stratospheric height Zonal Wind, Meridional Wind and Air Temperature at 10 mbar for the same low latitude as well as same period of study are also plotted along with monthly TOC variation and are also shown in the same figure to correlate the long term declining trend of the TOC with these parameters. It is found that among all the parameters, air temperature at 10 mbar showed the highest positive correlation coefficient of the order of .76 and lowest for Zonal Wind velocity and least for AI index at 330 nm and Meridional Wind at 10 mbar. ANTHROPOGENIC CONTRIBUTION TO THE COMPOSITE AEROSOL OPTICAL AND RADIATIVE PROPERTIES OVER DELHI IN THE GANGA BASIN A.K. Srivastava 1* , Sachchidanand Singh 2 , S. Tiwari 1 and D.S. Bisht 1 1 Indian Institute of Tropical Meteorology (Branch), Prof Ranmath Vij Marg, New Delhi 2 National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi *email: atul@tropmet.res.in An optically equivalent model has been formulated on the basis of surface measured aerosol chemical compositions and the retrieved optical aerosol properties (during the year 2007) over Delhi- a typical urban station in the western part of the Ganga basin. The measured water-soluble and black carbon (BC) concentrations are considered to be the main anthropogenic components over the station on the basis of aerosol chemical compositions; however, the concentrations of insoluble and mineral dust were decided by varying their concentrations iteratively in the model while maintaining the mass fraction of BC, so that the model-derived optical properties for composite aerosols match with the measured one. Further, a different approach in the 28
National Conference on Science of Climate Change and Earth’s Sustainability: Issues and Challenges ‘A Scientist-People Partnership’ 12-14 September, 2011, Lucknow optical model was used to quantify the contribution of anduopogenic aerosols in the composite aerosol properties by assuming water-soluble and BC as the major contributors in anduopogenic aerosols over the station. Model estimated various aerosol parameters such as aerosol optical depth (AOD), single scattering albedo (SSA) and asymmetry parameter (AP) for composite and anthropogenic aerosols were estimated independently, which shows significantly different features on monthly and seasonal basis. The anduopogenic components measured at Delhi were found to be contributing - 72% to the annual composite A0130.5 (-0.84±0.19), which was found to be more during the winter (84%) and post monsoon (-78%) periods and less during the summer (-58%). Results are highly associated with the surface meteorological conditions including the nature of boundary layer. The derived optical properties for composite and anduopogenic aerosols were used in a radiative transfer model for estimating the direct radiative forcing and the atmospheric heating rate due to these aerosols over the station. Also, the contribution of anthropogenic fraction to the total atmospheric forcing (due to composite aerosols) was estimated and discussed. STUDY OF CHARACTERISTICS OF ATMOSPHERIC AEROSOLS DURING DUST STORMS IN INDO- GANGETIC BASIN Sarvan Kumar, Sanjay Kumar and A.K. Singh Atmospheric Research Lab., Department of Physics, Banaras Hindu University, Varanasi 221 005 Dust storms are normally occurring event that take place in arid and semi-arid region of earth, temperate, tropical and sub-tropical latitude characterized by dry soil/sand. Arid regions around the Arabian Sea like Iran, Afghanistan, India and Pakistan usually experience a high frequency of dust storms per years. The Kanpur AERONET (Aerosol Robotic Network) station and Moderate Resolution Imaging Spectro-radiometer (MODIS) data show pronounced effect on the aerosol optical properties and aerosol size distribution during major dust storm events over the IG plains that have significant effect on the aerosol radiative forcing (ARF). The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging Spectro Radiometer (MISR) on board terra/aqua platform can be used for aerosol measurements. In the present study the AOD derived from ground measurements (AERONET) as well as satellites measurements (MODIS, MISR) are utilized to study the effects of dust storms over the IG-basin. The back-trajectory analyses of storm 29
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12-14 September, 2011, Lucknow - Earth Science India

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