Benefit of the MTG candidate Infra-Red Sounding mission to regional forecast

 

1. Project Objective

 

The objective of the study is to document the added value of water vapor observations derived from a hyperspectral infrared sounding instrument on a geostationary satellite for regional forecasting. An Observation System Simulation Experiment (OSSE) is proposed to document the impact of such observations. In such an experiment, synthetic observations, either retrieved water vapor profiles or simulated radiance observations, are assimilated into a regional forecast model to analyze the impact of such observations on the performance of the forecast.

 

2. Detailed Work Plan

 

Three phases are planned.

 

2.1 Phase I

 

2.1.1 Preparation

 

A period of 5 days for the OSSE will be identified and proposed to EUMETSAT, including a justification of the particular choice.

 

A short description of the nature model (MM5), the forecast model (WRF) and the data assimilation scheme (WRF-Var) will be written. Necessary tests of the two models will be performed.

 

2.1.2 Nature run

 

A nature run will be carried out using the nature model. The model is planned to have a resolution of 4 km and 500x500x35 grid points. The output will be at every 10 min. The results will be made available to EUMETSAT.

 

2.1.3 Initial OSSE

 

The modeled temperature and humidity fields extracted from the nature run will be assimilated to give initial states for forecast runs. Forecasts from these initial states will be compared to the results of the nature run. This OSSE will document the ideal case, namely that observations by IRS can be used to derive the exact state of the atmosphere. Uncertainties of observation errors will be considered in this OSSE.

 

The second OSSE run will be based on temperature and humidity profiles generated by retrieval simulations using the results of the nature run. These retrieval profiles will be made available by EUMETSAT. This OSSE shall document a semi-realistic case, namely where uncertainties in the retrieved profiles due to retrieval uncertainties are introduced. The assimilation scheme will use the observation errors generated by the retrieval method.

 

2.2 Phase II

 

Additional analyses of the Phase I results will be performed and when required additional OSSE runs will be executed.

 

In addition to the OSSEs mentioned in Phase I, an OSSE based on the retrieved humidity profiles will be performed to document a semi-realistic case, namely where uncertainties in the retrieved profiles due to retrieval uncertainties are introduced. The assimilation scheme adopted for the forecast model shall use the observation errors generated by the retrieval method. The results of this OSSE will be used to document the importance of humidity information derived from MTG-IRS observations.

 

2.3 Phase III

 

The calibration of the OSSE setup will be performed using radiosonde observations.

 

First, pseudo radiosonde observations will be extracted form the nature run. Then three experiments will be conducted.

 

Exp 1. No-obs. The forecast model will be run over the 5-day period.

 

Exp 2. Pseudo-obs. A virtual reality run will be made using the data assimilation scheme, the pseudo observations and the forecast model.

 

Exp 3. Real-obs. A real reality run will then be made using the virtual reality configuration, except the real radiosonde observations will be used.

 

The impact of the pseudo observations (Exp 2 – Exp 1) and that of the real observations (Exp 3 – Exp 1) will be assessed by using forecast error reductions. The results will be used to evaluate the OSSE results for the MTG-IRS candidate mission.

 

3. Time table

 

 

1

2

3

4

5

6

7

8

9

10

11

12

Phase I

 

 

 

 

 

 

 

 

 

 

 

 

Phase II

 

 

 

 

 

 

 

 

 

 

 

 

Phase III

 

 

 

 

 

 

 

 

 

 

 

 

 

KO

 

PR

 

 

 

 

 

MR

 

 

FR

 

KO: Kick-off meeting, 19 January 2007, NCAR

PR: Preliminary results Review, 5-6 March 2007, EUMETSAT

MR: Mid-term Review, September 2007, EUMETSAT

FR: Final Review, December 2007, NCAR

 

4. The Team

 

The work will be carried out at NCAR and the University of Hawaii.

 

Dr Xiang-Yu Huang, a member of the MMT, will lead the project. He will work on the project for a total of 2 months time. He is currently working at NCAR and has the following corresponding address:

 

Dr Xiang-Yu Huang

NCAR, MMM, P.O. Box 3000, Boulder, CO 80307-3000, USA

Email: huangx@ucar.edu

Tel: 1-303-497-8975

 

Hongli Wang, a PhD student, will work full time on the project.

 

Dr N.N., a project scientist, will work on the project part time.

 

Dr Xin Zhang, University of Hawaii, will collaborate with the team. Two visits are also planned.