Showing papers by "Animesh Maitra published in 2020"

Multitechnique Rain Classification From Ground-Based Measurements Over a Tropical Location

Abstract: This article aims to classify precipitation into two categories, namely stratiform and convective. Multiple techniques, such as utilizing the micro rain radar (MRR), electric field monitor (EFM), radiometer, and disdrometer measurements, have been deployed for this purpose, at a tropical location Kolkata, India. A new rain classification technique, using logistic regression modeling of the sixth to third moment ratio ${(M6/M3)}$ , has been proposed. Classification of rain types based on the new technique shows high consistency with that based on radar reflectivity ( ${Z}$ ) values obtained from disdrometer measurements. This article also distinguishes mixed rain from stratiform and convective rain. The observations on the bright band structure by MRR and on differential brightness temperature at 31.4 and 22.23 GHz by a radiometer are utilized to classify mixed rain types. Although the EFM measurements do not classify rain types directly, they give a distinct signature of the impending stratiform/convective rain events. A comparative analysis between the percentage of stratiform and convective rain durations shows significant dominance of stratiform rain over convective rain. At the present location, the convective phenomenon shows higher occurrences during the pre-monsoon period compared to the monsoon period.

Analysis of an Aerosol Environment in an Urban Region and Its Impact on Regional Meteorology

Abstract: The aerosol environment over a region is a potential parameter to perturb the regional meteorology and it remains as a large source of uncertainties. This chapter presents an analysis of the aerosol environment over Kolkata, a densely-populated metropolitan area in the Eastern India, near to the land-ocean boundary of Bay of Bengal. Along with the natural sources of aerosols, anthropogenic aerosols constantly contribute to the total aerosol loading in this region. This analysis shows how the spectral dependence pattern of aerosol optical parameters estimates the dominant type of aerosols over a region. Furthermore, the investigation shows the impact of the dominant type of aerosols on the boundary layer meteorology utilizing ground based observations. In the course of this discussion, the role of atmospheric black carbon (BC) aerosols in controlling the aerosol environment is focused. This urban region experiences much high BC concentrations mostly originating from incomplete combustion of fossil fuel used in vehicles. The chapter also includes a discussion on back trajectory analysis showing the influence of transported air masses on the regional aerosol environment. The investigation presented in this chapter depicts significant perturbation in the boundary layer temperature profile in association with the abundance of pollutant aerosols which in turn can affect the normal atmospheric convective processes over a region. This chapter contributes to a better understanding of impact of pollutant aerosols on the regional meteorology and thermodynamic processes.