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In this study, we have examined the impact of droughts on the atmospheric CO 2 spatial variability and changes its emission scenario over India. Surface monitoring over India is very sparse and have started recently. Satellite retrievals from AIRS/Aqua during 2004–2011 are used here to understand CO 2 variability over India. During recent decade, Indian region witnessed two drought years 2004 and 2009 and no flood. Year 2009 was mega drought for India ever seen, when actual rainfall was approx −23% below the mean rainfall over most part of India. Satellite retrieved mid-tropospheric CO 2 indicates increase of about 3 ppm during summer monsoon drought. Enhanced impact of drought conditions is also seen on subsequent seasons, winter (JF) and hot pre-monsoon season (MAM). Post-monsoon season (OND) does not show any clear impact, as rainfall during this season has its own variability quite different than summer monsoon (JJAS) may be compensating changes in CO 2 values. Decrease in vegetation and weak circulation patterns during drought conditions may have influences on distribution of CO 2 over Indian region. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we have studied variability and growth rate of surface observed atmospheric Carbon Dioxide (CO2) concentrations over Cape Rama, west coast of India and its association with rainfall and vegetation over this region. Cape Rama is a maritime site which experiences a seasonal reversal wind pattern receiving air masses having marine (continental) signatures during summer (winter) monsoon season. This study reveals that summer monsoon (JJAS) precipitation and monthly values of atmospheric CO2 concentration during the season are well correlated. Negative correlations are seen with CO2 concentrations of concurrent months of the season as well as subsequent months. However the magnitudes of correlation coefficients are decreased till hot pre-monsoon season (MAM). Annual cycle and interannual variability show negative relationship between CO2 concentration and vegetation over the region. CO2 concentration shows increasing trend and NDVI shows decreasing trend. However, the magnitude of increasing trend of CO2 concentration is higher. Amplitude of decreasing phase of vegetation is higher than the amplitude of increasing phase. Though the results show certain link between CO2 and climate variability, further examination with dense and longer data may be needed to confirm the result. [Copyright &y& Elsevier]

Abstract: Atmospheric Infrared Sounder (AIRS) retrieved mid-tropospheric Carbon Dioxide (CO2) have been used to study the variability and its association with the climatic parameters over India during 2004 to 2011. The study also aims in understanding transport of CO2 from surface to mid-troposphere over India. The annual cycle of mid-tropospheric CO2 shows gradual increase in concentration from January till the month of May at the rate ~0.6ppm/month. It decreases continuously in summer monsoon (JJAS) at the same rate during which strong westerlies persists over the region. A slight increase is seen during winter monsoon (DJF). Being a greenhouse gas, annual cycle of CO2 show good resemblance with annual cycle of surface air temperature with correlation coefficient (CC) of +0.8. Annual cycle of vertical velocity indicate inverse pattern compared to annual cycle of CO2. High values of mid-tropospheric CO2 correspond to upward wind, while low values of mid-tropospheric CO2 correspond to downward wind. In addition to vertical motion, zonal winds are also contributing towards the transport of CO2 from surface to mid-troposphere. Vegetation as it absorbs CO2 at surface level, show inverse annual cycle to that of annual cycle of CO2 (CC-0.64). Seasonal variation of rainfall-CO2 shows similarities with seasonal variation of NDVI-CO2. However, the use of long period data sets for CO2 at the surface and at the mid-troposphere will be an advantage to confirm these results. [Copyright &y& Elsevier]