Retrieval of Tropospheric Ozone Columns from UV-nadir Measurements
by GOME/ERS-2, GOME-2/METOP and OMI Instruments

A contribution to ACCENT-TROPOSAT-2, Task Group 1

Pieter Valks

German Aerospace Center (DLR), Remote Sensing Technology Institute (IMF),
Oberpfaffenhofen, D-82234, Wessling, Germany
Tel.:  +49-8153-281466
Fax:  +49-8153-281446

The activities envisaged within the framework of the AT-2 programme are described below. Phase 1 includes the activity for the first eighteen months of the AT-2 programme. The activities for the second phase of the AT-2 programme are listed under Phase 2. 

Phase 1

Activity 1

Within the framework of TROPOSAT-1, tropical tropospheric ozone columns (TTOCs) have been successfully determined with a convective-cloud-differential (CCD) method, using ozone column and cloud measurements from GOME. The GOME-CCD method uses above-cloud and clear-sky ozone column measurements to derive a monthly-mean TTOC below 200 hPa (see TROPOSAT final report). In this activity, a TTOC data-record will be produced for the whole GOME period (1995-2003). It is expected that the ongoing improvements of the ozone column and cloud retrieval algorithms for GOME will enhance the accuracy of the TTOC. Therefore, improved GOME ozone column and cloud data, reprocessed with the latest state-of-art GOME retrieval algorithms, will be used to derive the TTOC.

Phase 2

Activity 2

The GOME-TTOC data-set will be extended, using the upcoming OMI and GOME-2 satellite instruments. The small ground pixel size of the OMI and GOME-2 instruments makes it possible to improve the spatial and temporal resolution of the tropical tropospheric ozone fields.

Activity 3

The cloud-differential method will be extended to a cloud slicing method, in which ozone column measurements are used above clouds with different cloud-top pressures. With the cloud slicing method, it is possible to retrieve ozone information for different tropospheric layers, as has been demonstrated by Ziemke et al. [2001], using TOMS total ozone measurements and THIR cloud top pressure data. Because of the large ground pixel of GOME, the number of cloudy and clear-sky measurements is generally too small to apply such a cloud slicing method. However, the OMI and GOME-2 satellite instruments will greatly enhance the possibilities to retrieve information about the tropospheric ozone profile with the cloud slicing method. The small ground-pixel of these instruments will allow more frequent observations between clouds, thus giving better penetration into the troposphere. In this activity, the cloud slicing method will first be applied for the (sub)-tropics, using ozone column and cloud measurements from OMI and GOME-2. In the next step, the cloud-slicing approach will be extended to the mid-latitudes, including Europe.

Time schedule

 

2004

2005

2006

2007

2008

Activity 1

*

*

 

 

 

Activity 2

 

*

*

 

 

Activity 3

 

*

*

**

**

Approximate manpower and cost

 

2004

2005

2006

2007

2008

Personnel / man-years

0.1

0.2

0.2

0.2

0.2

Yearly cost (kECU)

11

22

22

22

22

Likely funding agencies

DLR

Co-worker

Dr. Ronald van der A

          Royal Netherlands Meteorological Institute

          Climate Research and Seismology Department

          Atmospheric Composition Research Division

          PO Box 201, 3730 AE De Bilt

          The Netherlands

 

 


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