Assimilation of humidity and temperature observations retrieved from ground-based microwave radiometers into a convective-scale NWP model
Date Issued
2016
Author(s)
Caumont, Olivier
•
Cimini, Domenico
•
Löhnert, Ulrich
•
Alados-Arboledas, Lucas
•
Bleisch, René
•
•
Ferrario, Massimo Enrico
•
Haefele, Alexander
•
Huet, Thierry
•
Madonna, Fabio
•
Pace, Giandomenico
Abstract
Temperature and humidity retrievals from an international network of ground-based micro-
wave 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.
Volume
142
Issue
700
Start page
2692
Issn Identifier
0035-9009
Ads BibCode
2016QJRMS.142.2692C
Rights
open.access
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