Vertical Profiling of Radio Refractivity and Associated Parameters Using Tethered Balloon Over New Delhi

Abstract

Atmospheric radio refractivity and its vertical gradient affect electromagnetic (EM) wave propagation mostly in the lower troposphere. The vertical profiles of the radio refractivity over New Delhi are very limited that inspired us to study the same using tethered balloon facility. Here, we investigated radio refractivity and its gradient over New Delhi (28°38′10″N, 77°10′17″E) using radiosonde balloon observation for one week (February 21–27, 2014). Vaisala RS 80 radiosonde device used during this experiment comprised of the individually factory-calibrated temperature, pressure and humidity sensors. The resolution of temperature sensor, pressure sensor and humidity sensor is 0.1 °C, 0.1 hpa and 1% RH, respectively. The refractivity measured using radiosonde has been observed to be reduced by 8.6% at 930 masl (mean above sea level) relative to that of ground level (i.e., 230 masl) during up-leg observation (7:00–7:30 PM), while the same has been found to be increased by 10.8% at ground level relative to that of 930 masl during down-leg observation (3:30–4:00 AM). Though it is a small set of information pertaining to refractivity observations using tethered balloon, certainly it can provide micro-insights of the meteorological effects on radio wave propagation better than that of routine experiments. The present study could be crucial for understanding the probable effects on radio wave propagations within atmospheric boundary layer over the study region and would reduce the underlying uncertainties associated with such measurements.