The Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX): overview and preliminary results

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

mRNA Secondary Structures Fold Sequentially But Exchange Rapidly In Vivo

Self-cleavage assays of RNA folding reveal that mRNA structures fold sequentially in vitro and in vivo, but exchange between adjacent structures is much faster in vivo than it is in vitro

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

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

Oceansat-1 derived met-ocean parameters during various stages of monsoon depression of June 1999, along Orissa coastline, east coast of India

113-121After the launch of Oceansat-1 (IRS-P4) on May 26, 1999, weather scientists got the opportunity to study some of the meteorological and oceanographic (met-ocean) parameters associated with the weather systems formed over the oceanic regions around India, even under cloudy conditions. Oceansat-1 carries multifrequency scanning microwave radiometer (MSMR) which has a capability to provide information of certain parameters viz. sea surface wind speeds (SSW), sea surface temperature (SST), integrated water vapour (IWV) and cloud liquid water content (CLW). A monsoon depression was formed over the Bay of Bengal on 17 June 1999 causing widespread rainfall over Orissa coast and the adjoining regions. Oceansat-1 derived met-ocean parameters were studied during various stages of this depression. The maximum values of these parameters during the life cycle of the depression over the Bay of Bengal were SST : 30º - 31º C, SSW : 16-18 m/s, IWV : 7.0 g/cm², CLW : 90-100 mg/cm². It was observed that SSW, IWV and CLW show high values one to three days before the formation of the depression. High values, shape and steep gradients of the met-ocean parameters give prior indication of formation/intensification of the weather system and its probable location. SST reduced by about 1º-2º after the passage of the low pressure system over the region

Orissa super cyclone of October 1999 as revealed by IRS-P4 satellite data

35-42A super cyclone hit Orissa coast during 24-31 Oct. 1999 causing vast damage to property and life. Life cycle of this super cyclonic storm from its genesis to landfall is studied using IRS-P4 satellite derived parameters over the oceanic region. The parameters, viz. sea surface temperature, sea surface wind, integrated water vapour, cloud liquid water content are studied over the region 5-25° N and 70-100°E. Synoptic surface pressure charts were compared with INSAT imagery. The IRS-P4 satellite data supplemented the data from INSAT in studying various characteristics associated with the super cyclone