Estimation of Humidity Profiles with the L-Band Boundary Layer Radar-RASS Measurements

Abstract

A radar remote-sensing technique of humidity profiles, which was originally developed for the middle and upper atmosphere radar (the MU radar), is applied to the lower troposphere radar (LTR) with Radio Acoustic Sounding System (RASS) operated on L-band (1357.5 MHz) in order to expand the height range into the atmospheric boundary layer. Radar volume reflectivity and turbulence energy dissipation rate are derived from LTR observations of turbulence echoes. Virtual temperature profiles are simulta- A kytoon was moored at about 160 m during the radar operation, and monitored temperature, pressure and humidity, though not continuously, which are used for defining the lower boundary values in retrieving q profiles. By using the RASS temperature, and kytoon data, we could successfully estimate continuous q profiles. The radar-derived q profiles generally agreed with radiosonde data. This study successfully demonstrated a potential of the humidity estimation with the LTR in the atmospheric boundary layer. Future long-term observation is expected to investigate the precision under various meteorological conditions.

Estimation of Humidity Profiles by Combining Co-Located VHF and UHF Wind-Profiling Radar Observation

“…R range is interpolated to the temporal resolution of GPS observations, assuming that rapid temporal variations in R range are minor in scale. Furumoto et al (2003Furumoto et al ( , 2005 estimated humidity profiles using the MU radar and LTR at 1.5-7.5 km and 0.2-2.2 km height, respectively, over a period when short-term variations in R range appeared to be small; however, during strongly disturbed conditions, such short-term variations may not be negligible. When the estimation range is expanded, R range becomes larger, and the error involved in estimating IWV G that is related to short-term variations in R range decreases.…”

“…The humidity retrieval algorithm using windprofiling radars is widely described in detail in the literature Furumoto et al 2003Furumoto et al , 2005Furumoto et al , 2006. The method is briefly outlined here.…”

“…We cannot use the time-interpolation of radiosonde results as boundary values for the humidity estimation from LTR, because rapid humidity fluctuations are very large in the observation height range of LTR. Furumoto et al (2005) used humidity data from a kytoon moored at the observation site to obtain the lower boundary values of the estimation using LTR data. Unfortunately, the present campaign did not operate a kytoon or other instruments to obtain boundary values of q 0 and y 0 for the LTR estimation with high temporal resolution.…”

“…The results of this method are in good agreement with C-band meteorological radar data and GMS satellite observations. This method has also been applied to wind-profiling L-band Lower Troposphere Radar (LTR) and Equatorial Atmosphere Radar (EAR) (Furumoto et al 2005(Furumoto et al , 2006a). …”

“…In previous studies, humidity profiles have been successfully determined, using the MU radar, at heights between 1.5 km and 7.5 km Furumoto et al 2003). Humidity profiles have also been estimated from L-band wind-profiling radar at heights between 0.3 km and 2.2 km (Furumoto et al 2005). In this study we expand on the earlier work of the Kyoto University research group by using radar from two radars, aiming at the expansion of the estimation height range.…”