Investigating the assimilation of IASI data in a limited area model

• Main Authors: Roger Randriamampianina, Andrea Storto
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Handle The; Norway; IPY
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1073.1332; http://cimss.ssec.wisc.edu/itwg/itsc/itsc16/proceedings/A20_Randriamampianina_paper.pdf

Abstract The assimilation of IASI data in the ALADIN-HARMONIE/Norway data assimilation system at the Norwegian Meteorological Institute is being carried out in the frame of the THORPEX-IPY Norway project. This project aims to improve the accuracy of highimpact weather forecasts in the Arctic region. The use of a limited number of channels was tested at the first stage using one IASI field of view (FOV) out of four available in each field of regard (FOR). Two techniques to handle the bias correction for satellite radiances (off-line estimation and variational correction) were studied for better assimilation of IASI data on top of ATOVS radiances. The first assimilation trial using CO2 stratospheric channels showed a rather slightly positive than neutral impact of the IASI data on temperature and geopotential. Beside the positive impact of the IASI data, observed mainly in lower troposphere, negative impact in the mid-troposphere was found, especially on humidity fields. Further studies are needed on tuning of the assimilation of the IASI data in order to achieve a better impact in the limited area model (LAM) HARMONIE/Norway system.