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The cloud aerosol interaction and precipitation enhancement experiment (CAIPEEX): Overview and preliminary results

Kulkarni, JR and Maheskumar, RS and Morwal, SB and Padma Kumari, B and Konwar, M and Deshpande, CG and Joshi, RR and Bhalwankar, RV and Pandithurai, G and Safai, PD and Narkhedkar, SG and Dani, KK and Nath, A and Nair, S and Sapre, VV and Puranik, PV and Kandalgaonkar, SS and Mujumdar, VR and Khaladkar, RM and Vijayakumar, R and Prabha, TV and Goswami, BN (2012) The cloud aerosol interaction and precipitation enhancement experiment (CAIPEEX): Overview and preliminary results. Current Science, 102 (3). pp. 413-425.

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While the demand for enhancing rainfall through cloud seeding is strong and persistent in the country, considerable uncertainty exists on the success of such an endeavour at a given location. To understand the pathways of aerosol-cloud interaction through which this might be achieved, a national experiment named Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) in two phases, was carried out. The rationale of CAIPEEX, the strategy for conducting the experiment, data quality and potential for path-breaking science are described in this article. Pending completion of quality control and calibration of the CAIPEEX phase-II data, here we present some initial results of CAIPEEX phase-I aimed at documenting the prevailing microphysical characteristics of aerosols and clouds and associated environmental conditions over different regions of the country and under different monsoon conditions with the help of an instrumented research aircraft. First-time simultaneous observations of aerosol, cloud condensation nuclei (CCN) and cloud droplet number concentration (CDNC) over the Ganges Valley during monsoon season show very high concentrations (> 1000 cm-3) of CCN at elevated layers. Observations of elevated layers with high aerosol concentration over the Gangetic valley extending up to 6 km and relatively less aerosol concentration in the boundary layer are also documented. We also present evidence of strong cloud- aerosol interaction in the moist environments with an increase in the cloud droplet effective radius. Our observations also show that pollution increases CDNC and the warm rain depth, and delays its initiation. The critical effective radius for warm rain initiation is found to be between 10 and 12 μm in the polluted clouds and it is between 12 and 14 μm in cleaner monsoon clouds.

Item Type: Article
Additional Information: Copyright of this article belongs to Indian Academy of Science
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 28 Dec 2013 19:47
Last Modified: 28 Dec 2013 19:47

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