Comparison of atmospheric profiles between microwave radiometer retrievals and radiosonde soundings

Abstract

Atmospheric profiles of temperature (T), vapor density (ρv), and relative humidity (RH) retrieved from ground‐based microwave radiometer (MWR) measurements are compared with radiosonde soundings at Wuhan, China. The MWR retrievals were averaged in the ±30 min period centered at sounding times of 00 and 12 UTC. A total of 403 and 760 profiles under clear and cloudy skies were selected. Based on the comparisons, temperature profiles have better consistency than the ρv and RH profiles, lower levels are better than upper levels, and the cloudy are better than the clear‐sky profiles. Three cloud types (low, middle, and high) were identified by matching the infrared radiation thermometer‐detected cloud base temperature to the MWR‐retrieved temperature‐height profiles. Temperature profile under high cloud has the highest correlation coefficient (R) and the lowest bias and RMS, but under low cloud is in the opposite direction. The ρv profile under middle cloud has the highest R and the lowest bias but under high cloud has the lowest R, the largest bias, and RMS. Based on the radiosonde soundings, both clear and cloudy wind speeds and drifting distances increase with height but increase much faster under clear than cloudy above 4 km. The increased wind speeds and drifting distances with height have resulted in decreased correlation coefficient and increased temperature biases and RMSs with height for both clear and cloudy skies. The differences in R, bias, and RMS between clear and cloudy skies are primarily resulted from their wind speeds and drifting distances.

Quantifying the relationship between PM<sub>2.5</sub> concentration, visibility and planetary boundary layer height for long-lasting haze and fog–haze mixed events in Beijing

“…Many studies demonstrated that PMWR is a useful tool to sense the thermodynamic structure of the lower troposphere continuously by providing profiles of temperature and humidity with reasonable accuracy and height resolution (Ware et al, 2003(Ware et al, , 2013Xu et al, 2015). The intercomparison with the radiosonde data demonstrated the good correlation of temperature and vapour density retrievals Xu et al, 2015). The biases of temperature retrieved by PMWR against radiosondes increased with height, and the maximum bias is 4 • under 2000 m; the bias of water vapour profile was smaller than 1 g m −3 .…”

Thermal Structure of a Coastal–Urban Boundary Layer

“…where T is the temperature measured by the microwave radiometer in K, p 0 is the reference pressure of 1013 hPa, and p is the pressure derived from the heights of a standard atmosphere (Wallace and Hobbs 2006). The pressure information is then used to estimate the mixing ratio at each level using (Stull 1988)…”

“…Here, we investigate the variability of the urban boundary layer in New York City using vertical profiles from three local airports, and profiles derived from a microwave radiometer within the urban centre to investigate the seasonal variabilities in the thermal and moisture boundary-layer structure. Microwave radiometers have the advantage of being robust instruments (Xu et al 2015), with a recent, extensive study judging them to be very good at estimating temperature profiles, particularly in the lower boundary layer (Lundquist et al 2017). While microwaveradiometer observations have been used to determine the mixed-layer height (Cimini et al 2013), the vertical extent of the urban heat island (Khaikine et al 2006), and for estimating stability conditions for wind-energy applications (Friedrich et al 2012), our main objectives here are to analyze the spatial variability in the thermal structure of the boundary layer over the highly dense area of New York City, and to quantify the diurnal and seasonal variabilities of the urban thermal and moisture profiles.…”

Uncertainties of ground-based microwave radiometer retrievals in zenith and off-zenith observations under snow conditions

“…Moreover, the MWR is equipped with an infrared radiation thermometer (IRT), which measures sky infrared temperature at one zenith infrared (9.6-10.5 µm) channel and gives information on cloud-base temperature (Ware et al, 2013;Cimini et al, 2015;Xu et al, 2015). Meteorological sensors attached to the MWR can obtain ambient temperature, pressure, and relative humidity at the instrument level.…”

“…Meteorological sensors attached to the MWR can obtain ambient temperature, pressure, and relative humidity at the instrument level. The retrieval algorithm developed by the factory can automatically convert the microwave, infrared, and surface meteorological measurements into temperature, humidity, and liquid profiles with the aid of neural networks (Xu et al, 2015). Longtime radiosondes and liquid water content profiles generated from radiosondes were processed within a radiative transfer model and used as the neural network training set (Ware et al, 2013).…”