ITWG ATOVS monitoring page
Monitoring websitesThe following links can be used to visit and compare monitoring of the fit of ATOVS, SSM/I and AIRS radiances against short range (six hour) forecasts from NWP
- Met Office 6 and 24 ATOVS hourly radiance monitoring plots
- NCEP 6 hourly radiance monitoring plots
- CMC 24 hourly radiance monitoring plots
- ECMWF 24 hourly satellite radiance monitoring plots
- DMI ATOVS daily monitoring statistics
- DWD ATOVS monitoring reports
- Meteo France (Toulouse) 6 hourly radiance monitoring plots v
NWP.
Please contact Herve Benichou (Meteo France) for access information. - Meteo-France (CMS Lannion) 24 hourly radiance monitoring plots v radiosonde
- The Met Office's AIRS monitoring page
- The NWP SAF SSMI monitoring report
- NRL NOGAPS and NAVDAS radiance monitoring
The following links can be used to visit and compare monitoring of the fit of ATOVS, SSM/I and AIRS data coverage in NWP data assimilation systems.
- Met Office daily data coverage plots for assimilation of ATOVS
- ECMWF daily data coverage plots for assimilation of ATOVS
The following link can be used to compare observational sensitivities in an operational NRL NWP system.
The
NWP SAF ATOVS monitoring webpagealso gives monitoring for a wide range
of satellite data including data from other instruments which are relevant
to ITWG but not directly covered by ITWG activities.
The
NOAA POES status webpage gives channel by channel status for ATOVS
instruments. The NWP WG of ITWG maintains a list of channel by
channel usage for ATOVS and assumed observation errors. This is
described in the NWP WG website section on Observation errors.
Discussion of satellite radiance monitoring at NWP centre
At the ATOVS workshop at ECMWF in 1999
agreement was reached on what should be monitored on external websites
for ATOVS.
Mean and standard deviation of Observed - Background and Bias corrected
observed - background for the regions 90N-70N, 70N-20N, 20N-20S,
20S-70S, 70S-90S. Ideally monitoring would also be presented separately
for sea, land and sea ice. Some centres might choose to monitor all data
and data following quality control but some only monitor data after
quality control. In the latter case it may depend very much what the
quality control does as to what the monitoring looks like. For example
some recent data problems have not been visible in every centre's
monitoring because in some centre's monitoring the bad data is already
excluded whereas in another centre's monitoring it is still included.
Therefore centres were urged to make it very clear what quality control
and data selection they used in producing their monitoring reports. The
length of time shown in monitoring plots varies from one month to two
years. Again some centres offer a choice of a short and long time period
plot. A minority of websites also included scan dependent bias plots.
Some websites average data over 24 hours, others 6 hours and again some
offer a choice.
The format of plots varies but the main problem in comparing them is
taking account of the variations in paragraph 1. Broadly speaking though
it should be possible to achieve an "observation-forecast" standard
deviation of difference for a tropospheric sounding channels after bias
correction and appropriate quality control to under 0.15 K with
negligible bias. Near surface and upper tropospheric and stratospheric
sounding channels will fit much less well. Near surface channels fit
will depend very much on choice of surface emissivity scheme and cloud
detection and quality control, but will probably be of order 1 K
standard deviation. Stratospheric channels will have a rising standard
deviation of fit with increasing altitude, reaching several kelvin for
channels peaking above 10 hPa. If any centres results are very far from
these values it may be a cause for concern.
There are few sources of literature for ATOVS monitoring...suggestions for
additions would be very welcome!