Tropospheric Zenith Delay (TZD) for Microwaves During Severe Weather Events Over a Few Indian Stations

Abstract

To have an accurate signal in navigational systems such as GPS, it must be known how much the radio signal gets delayed when it propagates from the satellite to the receiver. In general, the delay is mostly caused by refractivity of the troposphere when a radio signal propagates in the neutral atmosphere and such refractivity is primarily due to the presence of dry gases and water vapor present over there. Though the troposphere delay or troposphere zenith delay (TZD) can be expected based on the earlier datasets, however, during severe weather events (heavy rainfalls and hail storms), the temporal and spatial variability of water vapor distribution is so dynamic that it is impossible to predict. Therefore, further case studies are needed to assess TZD under various severe weather events over tropical stations where the water vapor distribution is highly dynamic. This study presents tropospheric delay (both wet and dry) calculated during severe weather events over three Indian cities. A comparison of troposphere delay during severe weather conditions with normal days is made. Diurnal variation of ZHD and ZWD using ECMWF data is also presented.