Wind profiler observations of a monsoon low-level jet over a tropical Indian station

Abstract

Abstract. Three-year high-resolution wind observations of the wind profiler have been utilized to characterize the diurnal and seasonal features of the monsoon Low-Level Jet (LLJ) over a tropical station, Gadanki (13.5 • N, 79.2 • E), with a focus on the diurnal variability of low-level winds. The Boreal summer monsoon winds show a conspicuously strong westerly LLJ with average wind speed exceeding 20 m s −1 . The L-band wind profiler measurements have shown an advantage of better height and time resolutions over the conventional radiosonde method for diurnal wind measurements. An interesting diurnal oscillation of LLJ core has been observed. It is varying in the height range of 1.8±0.6 km with the maximum and minimum intensity noticed during the early morning and afternoon hours, respectively. The jet core (wind maxima) height is observed to coincide with the inversion height. Strong wind shears are normally located beneath the LLJ core. The sole wind profiler observations are capable of identifying the monsoon phases, such as onset, break and active spells, etc. The mutual influence between the LLJ and the boundary layer has been discussed. One notices that the observed LLJ diurnal structures depend on the local convective activity, wind shears and turbulence activity associated with boundary layer winds. The day-to-day change in the LLJ structure depends on the latitudinal position of the LLJ core.

Comparison of low‐level jets along the north coast of China in summer

“…Overall, the occurrence distribution of LLJ shows a diurnal change, and the similar results have been indicated in Kalapureddy et al . []. Both Tianjin and Shanghai display a similar pattern.…”

Time evolution of monsoon low-level jet observed over an Indian tropical station during the peak monsoon period from high-resolution Doppler wind lidar measurements

“…Using lower atmospheric wind profiler (LAWP) data over Gadanki, India, Kalapureddy et al . [] showed that the MLLJ core lies at a height of 1.8 + 0.6 km with a mean jet intensity of about 20 m/s. Using measurements from a UHF radar/wind profiler (404 MHz) over Pune (18.38°N, 73.58°E), India, Joshi et al .…”

Intriguing Aspects of the Monsoon Low-Level Jet over Peninsular India Revealed by High-Resolution GPS Radiosonde Observations

“…Before going into further detail, it is worthwhile to see how much diurnal variation exists in the MLLJ intensity and height. Although the diurnal variation of the MLLJ is least explored, by considering the diurnal cycle measured with UHF radar over Gadanki Kalapureddy et al (2007) showed that the MLLJ exhibits strong diurnal variability in intensity and height of the jet core, with its core peaking up to 3 km during 0900-2200 LT. In the present study, the GPS radiosonde measurements and other reanalysis datasets over Gadanki have been considered to study the diurnal variation of MLLJ.…”

“…Using Lower Atmospheric Wind Profiler (LAWP) data over Gadanki, Kalapureddy et al (2007) showed that the MLLJ core lies at a height of 1.8 6 0.6 km and found the mean jet intensity to be 20 m s 21 . Using a similar instrument over Pune (18.38N, 73.58E), Joshi et al (2006) found that the jet core height varies between 1.6 and 3 km.…”