Monitoring Changes in Tropospheric Constitution from Space

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

Andreas Richter

University of Bremen, Inst. of Environmental Physics, Otto-Hahn-Allee 1,
D-28359 Bremen, Germany
Tel.:  +49 421 218 4474
Fax:  +49 421 218 4555

Starting with the GOME instrument, a series of space-borne UV/visible nadir viewing spectrometers will be operated throughout the next years. These instruments will create a data base of measurements eventually spanning several decades of atmospheric observations. The resulting data set should be a valuable tool to access changes in atmospheric constitution, and could be used for monitoring the effects of anthropogenic activities and changes in emission patterns.

The key to a combined use of measurements from different instruments is the creation of a consistent and continuous time series. This involves several points, in particular:

   correction of instrumental drifts and artefacts in the measurements of a single instrument;

   compensation for instrumental differences such as spatial resolution, sampling pattern, time of measurement, or retrieval method for different instruments; and

   long-term validation of the satellite measurements.

This project will attempt to address this issue starting with tropospheric NO2 measurements from GOME and SCIAMACHY and extending it to OMI and GOME-2 data as they become available. Depending on the available resources, other trace species such as HCHO and SO2 will also be included.

Tropospheric NO2 columns will be determined using the same retrieval on all instruments, and consistency will be established by analysing time periods of overlapping measurements. A particular focus will be on monitoring long-term stability by evaluation of retrievals made in different spectral regions and for other absorbers with known distribution (O4, O2). Where necessary, corrections will be implemented to ensure consistent data sets. Validation will be performed using ground-based multi-axis DOAS systems. Once a consistent and consolidated data set has been created, it will be analysed for seasonal, inter-annual and long-term changes in the observed concentrations.

Time schedule

 

2004

2005

2006

2007

Data Retrieval

***

***

**

**

Data Consolidation

**

***

**

*

Validation

**

**

**

 *

Interpretation

 

*

***

***

 Approximate manpower and cost

 

2004

2005

2006

2007

Personnel / man-years

0.5

1

1

0.5

Yearly cost (kEuro)

15

30

30

15

Likely funding agencies

DFG, European Union

Co-workers

John Burrows, Bernd Sierk and Folkard Wittrock, University of Bremen