Size segregated aerosol mass concentration measurements over the Arabian Sea during ICARB

Journal of Earth system science

R Ramakrishna Reddy2¹  L Siva Sankara Reddy2¹  S Suresh Babu1²  K Niranjan3³  K Rama Gopal2¹  Vijayakumar S Nair1²  K Narasimhulu2¹  K Krishna Moorthy1²  V Sreekanth3³  B L Madhavan3³ 

[1] Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, India.$$;Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum 695 022, India.$$;Department of Physics, Andhra University, Visakhapatnam 530 003, India.$$

关键词: Aerosol mass concentration;    Arabian Sea;    ICARB.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Mass concentration and mass size distribution of total (composite) aerosols near the surface are essential inputs needed in developing aerosol models for radiative forcing estimation as well as to infer the environment and air quality. Using extensive measurements onboard the oceanographic research vessel, Sagar Kanya, during its cruise SK223B in the second phase of the ocean segment of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), the spatial distribution of the mass concentration and mass size distribution of near-surface aerosols are examined for the first time over the entire Arabian Sea, going as far as 58°E and 22°N, within a span of 26 days. In general, the mass concentrations (𝑀𝑇) were found to be low with the mean value for the entire Arabian Sea being 16.7 ± 7 𝜇 g m−3; almost 1/2 of the values reported in some of the earlier campaigns. Coarse mode aerosols contributed, on an average, 58% to the total mass, even though at a few pockets accumulation mode contribution dominated. Spatially, significant variations were observed over central and northern Arabian Sea as well as close to the west coast of India. In central Arabian Sea, even though the 𝑀𝑇 was quite low, contribution of accumulation aerosols to the total mass concentration was greater than 50%. Effective radius, a parameter important in determining scattering properties of aerosol size distribution, varied between 0.07 and 0.4 𝜇 m with a mean value of 0.2 𝜇 m. Number size distributions, deduced from the mass size distributions, were approximated to inverse power-law form and the size indices (𝜐) were estimated. It was found to vary in the range 3.9 to 4.2 with a mean value of 4.0 for the entire oceanic region. Extinction coefficients, estimated using the number-size distributions, were well-correlated with the accumulation mode mass concentration with a correlation coefficient of 0.82.

【 授权许可】

Unknown