Altitude variation of aerosol properties over the Himalayan range inferred from spatial measurements

作者：Dumka U C^*; Moorthy K Krishna; Tripathi S N; Hegde P; Sagar Ram

来源：Journal of Atmospheric and Solar-Terrestrial Physics, 2011, 73(13): 1747-1761.

DOI：10.1016/j.jastp.2011.04.002

• Altitude profile
• Mixing height
• Heating rate
• Central Himalayas
• Absorption aerosol optical depth
• Absorption Angstrom exponent

Altitude variations of the mass concentration of black carbon, number concentration of composite aerosols are examined along with the columnar spectral aerosol optical depths using state of the art instruments and the Angstrom parameters are inferred from the ground based measurements at several altitude levels, en route from Manora Peak, Nainital (similar to 1950 m above mean sea level) to a low altitude station Haldwani (similar to 330 m above mean sea level) at its foothill within an aerial distance of <10,000 m. The measurements were done during the winter months (November-February) of 2005, 2006 and 2007 under fair weather conditions. The results show a rapid decrease in all the measured parameters with increase in altitude, with >60% contribution to the AOD coming from the regions below 1000 m. The Angstrom wavelength exponent remained high in the well mixed region, and decreased above. The normalized AOD gradient was used to estimate aerosol mixing height, which was found to be in the altitude range 1000-1500 m, above which the particle concentrations are slowly varying as a function of altitude. The heating rate at the surface is found to be maximum but decreases sharply with increase in altitude. Analysis of the wavelength dependence of absorption aerosol optical depth (AAOD) showed that the aerosol absorption over the site is generally due to mixed aerosols.

• 出版日期2011-8