JCSDA Projects - Assimilation of AIRS Radiances

Proposal Name:

Assimilation of AIRS Radiances and Further Development of the Expected Error Method in the Global Forecast System

Principal Investigators:

• Tom Zapotocny
• James Jung, CIMSS
• Collaborator: John LeMarshall, Australian Bureau of Meteorology
• EMC contact: Russ Treadon, NWS/NCEP

Date:

12 March 2007

Description:

This project is to diagnose satellite data impacts in NCEP's Global Forecast System (GFS). Our primary focus during FY06 was on the assimilation of MODIS winds and AIRS radiances. The MODIS winds have been made operational in the GFS; however, there is still ample work to be done in optimizing the positive effects these data types have on GFS simulations. A second task completed during FY06 was to investigate the impact of systematically removing NOAA polar orbiting data from the GFS to simulate the failure of one and/or two satellites (Figure 1, below). The project has recently started exploring the "expected error" method developed by Le Marshall et al. (2004) on GOES and MODIS winds. The team has also started work on calculating surface emissivity from AIRS data. Preliminary results from the EE experiments and the AIRS surface emissivity are also presented (Figure 2, below).

Task Objectives:

For all of the data assimilation experiments presented here, PIs propose to use the latest versions of NCEP's GDAS/GFS when possible. As resources permit team will conduct experiments during two seasons at the current operational resolution of T382L64. Project team has been upgrading algorithms to work in the latest releases of NCEP's GSI. Team has also switched to using the GFS in sigma-p coordinates. JCSDA computer resources capable of running the GDAS/GFS at the operational resolution will be required during FY07 for all experiments outlined in this section.

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Figure 1. Geographical distribution of forecast impact to vertically integrated precipitable water during January-February 2003 from the (a) 2_NOAA experiment and (b) 3_NOAA experiment. The shading interval is 12.5%.

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Figure 2. Comparisons of AIRS derived emissivity versus CRTM calculated emissivity over ocean for wavelength (left) and scan angle (right)