Assimilation of humidity and temperature observations retrieved from ground‐based microwave radiometers into a convective‐scale NWP model

Abstract

Temperature and humidity retrievals from an international network of ground-based microwave radiometers (MWRs) have been collected to assess the potential of their assimilation into a convective-scale numerical weather prediction (NWP) system. Thirteen stations over a domain encompassing the western Mediterranean basin were considered for a time period of 41 days in autumn, when heavy precipitation events most often plague this area.Prior to their assimilation, MWR data were compared to very-short-term forecasts. Observation-minus-background statistics revealed some biases, but standard deviations were comparable to that obtained with radiosondes. The MWR data were then assimilated in a three-dimensional variational data assimilation system through the use of a rapid update cycle. A first set of four different experiments were designed to assess the impact of the assimilation of temperature and humidity profiles, both separately and jointly. This assessment was done through the use of a comprehensive dataset of upper-air and surface observations collected in the framework of the HyMeX programme.The results showed that the impact was generally very limited on all verified parameters, except for precipitation. The impact was found to be generally beneficial in terms of most verification metrics for about 18 h, especially for larger accumulations. Two additional data-denial experiments showed that even more positive impact could be obtained when MWR data were assimilated without other redundant observations. The conclusion of the study points to possible ways of enhancing the impact of the assimilation of MWR data in convective-scale NWP systems.

Combining ground-based microwave radiometer and the AROME convective scale model through 1DVAR retrievals in complex terrain: an Alpine valley case study

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Hygroscopic growth study in the framework of EARLINET during the SLOPE I campaign: synergy of remote sensing and in situ instrumentation

“…The ground-based MWR (RPG-HATPRO G2, Radiometer physics GmbH), which is also located at IISTA-CEAMA station and belongs to MWRnet (Rose et al, 2005;Caumont et al, 2016), is used here for retrieving temperature profiles. The MWR is a passive remote sensor that performs automatic measurements of sky brightness temperature at two bands: the oxygen V band (51-58 GHz) and water vapor K band (22-31 GHz) associated with temperature and water vapor and liquid water, respectively.…”

Long-term observations minus background monitoring of ground-based brightness temperatures from a microwave radiometer network

“…In this framework, MWR are candidates to supplement radiosonde and satellite observations to feed modern numerical weather prediction (NWP) models through assimilation of their data. This has been recently investigated in a few sporadic cases, assimilating retrieved temperature and humidity profiles into NWP models (Cimini et al, 2012(Cimini et al, , 2014Caumont et al, 2016). Martinet et al (2015) illustrate the attempt to assimilating the primary observable, i.e.…”