K. Krishna Reddy

A Comparison Study of Summer Season Raindrop Size Distribution Between Palau and Taiwan, Two Islands in Western Pacific

Raindrop size distribution (RSD) characteristics in summer season rainfall of two observational sites [Taiwan (24o 58’ N, 121o 10’ E) and Palau (7o 20’ N, 134o 28’ E)] in western Pacific are studied by using five years of impact type disdrometer data. In addition to disdrometer data, TRMM, MODIS, and ERA-Interim data sets are used to illustrate the dynamical and microphysical characteristics associated with summer season rainfall of Taiwan and Palau. Taiwan and Palaus raindrop spectra showed a significant difference, with a higher concentration of mid and large drops in Taiwan than Palau rainfall. RSD stratified on the basis of rain rate showed a higher mass-weighted mean diameter (Dm) and a lower normalized intercept parameter (log10Nw) in Taiwan than Palau rainfall. Precipitation classification into stratiform and convective regimes showed higher Dm values in Taiwan than Palau. Furthermore, for both the locations, the convective precipitation has a higher Dm value than stratiform precipitation. The radar reflectivity - rain rate relations (Z= A*Rb) of Taiwan and Palau showed a clear variation in the coefficient and a less variation in exponent values. Terrain-influenced clouds extended to higher altitudes over Taiwan resulted with higher Dm and lower log10Nw values as compared to Palau.

Observation of Precipitation and Drop-Size Distribution Associated with a Typhoon using VHF Radar

This paper describes some of the microphysical and kinematic properties of precipitating systems associated with a typhoon using Chug-Li VHF radar. In order to gain a better understanding of these mechanisms and the vertical structure of the precipitation associated with a typhoon at different stages of development, an analysis has been carried out of the radar back-scattered signal in order to obtain the power, velocity and velocity width of the Doppler spectrum of clear air and hydrometeors. The vertical profiles of raindrop size distribution (DSD) parameters are estimated through model-based regression analysis. The study reveals that during a typhoon, different convective and stratiform types of precipitation occur at different times with varying intensities. This study also reports on some of the characteristic features of the convective systems observed during the typhoon.

Sensitivity Study on 2013: Tropical Cyclones Using Different Cloud Microphysical and Planetary Boundary Layer Parameterisation Schemes in WRF Model

The Indian subcontinent is the worst affected part of the world due to tropical cyclones (TCs). This region account for ~7 % 0.of the total number of global TCs (Gray 1968). The formation of TCs is more pronounced over Bay of Bengal (BOB) compared to Arabian Sea. A large number of TCs form over the BOB region generally move in the north and north-west directions and make landfall along the coastal regions of India, Bangladesh, and Myanmar (Tyagi et al. 2010; Mohapatra et al. 2012, 2015). These TCs have been responsible for the damage of property, loss of agriculture crops, and thousands of human lives (Paul 2010). In the BOB, TC genesis is highly seasonal with primary maximum in the post-monsoon season (October to December) and secondary maximum during pre-monsoon season (April and May). Hence, there is a need to improve the understanding and the forecast of TC over the Indian Ocean region. Several dynamic models have been used for the forecasting of the track and intensity of TC over specific regions. There has been significant improvement in recent years in terms of track, intensity and landfall forecasts (Mohapatra et al. 2013a,b,c). However, the accurate track and intensity predictions of TCs remain a challenging task for atmospheric scientists and the research community.

Precipitation and cloud microstructure variations between two southern Indian stations

Raindrop size distribution (RSD) characteristic variations between two southern Indian stations [Gadanki (13.5° N, 79.2° E) Kadapa (14.47° N, 78.82° E)] using ground based parsivel disdrometer data are studied. Number concentration of mid and large drops is more over Gadanki when compared to Kadapa precipitation. The mean value of mass weighted mean diameter (Dm) is higher in Gadanki than Kadapa precipitation. Both monthly and diurnal variations of Dm show higher values of Dm over Gadanki than Kadapa. After classifying the precipitations systems into stratiform and convective, Gadanki has higher (lower) Dm than Kadapa in stratiform (convective).