Impact of GOLD Retrieved Thermospheric Temperatures on a Whole
Atmosphere Data Assimilation Model
Abstract
The present investigation evaluates the assimilation of synthetic data
which has properties similar to actual Global-scale Observations of the
Limb and Disk (GOLD) level-2 (L2) and other conventional lower
atmospheric observations. The lower atmospheric and GOLD L2 temperature
(Tdisk) are assimilated in the Whole Atmosphere Community Climate Model
with thermosphere-ionosphere eXtension (WACCMX) using Data Assimilation
Research Testbed (DART). It is found that inclusion of the GOLD Tdisk
improves the forecast root mean square error (RMSE) and bias by 5% and
71%. When compared to lower atmosphere only assimilation the
improvements in RMSE and bias are 20% and 94%. An investigation of the
global DW1 and local diurnal tidal characteristics shows that inclusion
of the GOLD temperatures improves the DW1 by about 8% and diurnal tide
by more than 17%. The percentage improvement in tides is higher at
lower thermospheric altitudes. Considerable improvements in the model
state are also seen at times and locations where there are no GOLD
observations available. These results and the background data
assimilation procedure are presented here, which demonstrates that GOLD
thermospheric temperature is an excellent dataset which can be used for
thermospheric assimilation studies and operational purposes.