TY - RPRT
AU - Francis Warrick
AB - A 4-month test dataset of novel wind vectors derived from the IASI level 2 profiles was made available by EUMETSAT. These provide wind profile information at mid and high latitudes, in the<br />
areas of overlap between successive Metop-B and Metop-C IASI swaths. The IASI winds are derived using the optical flow technique simultaneously on ozone, humidity and temperature retrievals on 25 fixed pressure layers. The test data was passed through IFS to generate background departures&nbsp;(i.e., differences between the observations and a short-range forecast), without assimilating the IASI winds. The departure statistics indicated a widespread and often large slow bias compared to the ECMWF background. The smallest background departures were seen in the low stratosphere pressure layers, the largest around the tropopause. For the troposphere, root mean squared errors against the ECMWF background were overall significantly larger than values for traditional AMVs currently assimilated in the ECMWF system, suggesting larger errors in the IASI winds. It is noted that information on the data quality characteristics should be added in the disseminated dataset, for instance in the form of a quality indicator for each derived wind, as well as information on whether the AMV was derived from cloudy or clear-sky scenes, in order to enable better quality control of the data, independent of a model background.
BT - Eumetsat/ECMWF Fellowship Programme Research Reports
CY - Reading
DA - 11/2025
DO - 10.21957/e172fdfd9b
M1 - RR66
M3 - Eumetsat/ECMWF Fellowship Programme Research Reports
N2 - A 4-month test dataset of novel wind vectors derived from the IASI level 2 profiles was made available by EUMETSAT. These provide wind profile information at mid and high latitudes, in the<br />
areas of overlap between successive Metop-B and Metop-C IASI swaths. The IASI winds are derived using the optical flow technique simultaneously on ozone, humidity and temperature retrievals on 25 fixed pressure layers. The test data was passed through IFS to generate background departures&nbsp;(i.e., differences between the observations and a short-range forecast), without assimilating the IASI winds. The departure statistics indicated a widespread and often large slow bias compared to the ECMWF background. The smallest background departures were seen in the low stratosphere pressure layers, the largest around the tropopause. For the troposphere, root mean squared errors against the ECMWF background were overall significantly larger than values for traditional AMVs currently assimilated in the ECMWF system, suggesting larger errors in the IASI winds. It is noted that information on the data quality characteristics should be added in the disseminated dataset, for instance in the form of a quality indicator for each derived wind, as well as information on whether the AMV was derived from cloudy or clear-sky scenes, in order to enable better quality control of the data, independent of a model background.
PB - ECMWF
PP - Reading
PY - 2025
T2 - Eumetsat/ECMWF Fellowship Programme Research Reports
TI - Quality Assessment of IASI 3D Winds
UR - &nbsp;
SN - RR66
ER -