Radiative implication of a haze event over Eastern India

AbstractAerosol haze degrades visibility by the process of absorption and scattering of aerosols. In the present study an attempt has been made to characterize the physical and optical properties of aerosols during a haze event on 29 March 2012 and assess its implication on radiative forcing. In this context representative clear (2 March 2012) and normal (19 March 2012) days were identified in terms of their Aerosol Optical Depth (AOD) loading over Hyderabad. On the hazy day, a huge spread of haze was observed over the eastern part of India by MODerate resolution Imaging Spectroradiometer (MODIS) on board Terra satellite which is represented by high Aerosol Optical Depth at 550nm. In-situ observations on hazy day showed an enhancement of columnar AOD500 respectively by 4.5 and 1.8 fold in comparison to clear and normal days. Significant increase in the scattering coefficient and a moderate enhancement of Single Scattering Albedo (SSA) are observed on hazy day compared to normal day. Study also showed that Diffuse-to-Direct- beam irradiance Ratio (DDR) had increased 4.5 times at 496.6nm spectral band on hazy day. LIDAR (LIght Detection And Ranging) observations on hazy night showed a threefold increase in aerosol backscattering below the Atmospheric Boundary Layer (ABL) compared to normal representative night. The hazy day is characterized by large negative surface forcing (−87.82W m−2) when compared to normal day (−53.90W m−2). A large positive enhancement of atmospheric forcing of 30.56W m−2 is observed on hazy day compared to normal day

Influence of meteorological parameters on atmospheric CO2 at Bharati, the Indian Antarctic research station

During the 35th Indian Scientific Expedition to Antarctica, measurements of atmospheric carbon dioxide (CO2) were carried out using a Li-Cor CO2/H2O analyser at Bharati, the Indian Antarctic research station. This study examines the short-term variability of atmospheric CO2 during the austral summer (January–February) of 2016. An average of 396.25 ± 4.20 ppm was observed during the study period. Meteorological parameters such as relative humidity, precipitation, wind speed, air temperature and atmospheric boundary layer height in conjunction with photosynthetically active radiation, the biological activity indicator which modulates atmospheric CO2 concentration have been investigated. High wind speed (>20 m s−1) combined with precipitation scavenges CO2 in the atmosphere, resulting in low concentrations at the study site. The lowest CO2 concentration of 385 ppm coincided with heavy precipitation of 15 mm during study period. Statistical analysis of the data shows that precipitation and relative humidity independently correlated 55% (r = −0.55) and 32% (r = −0.32), respectively, with the variability of CO2 mixing in the atmosphere at the study site. Atmospheric CO2 was significantly correlated with precipitation alone with a p value of 0.003. Further, multiple regression analysis was performed to test the significant relation between variability of atmospheric CO2 and meteorological parameters. Long-range air-mass transport analysis depicted that the majority of the air masses are reaching the study site through the oceanic region