Abstract. The remote sensing of the atmospheric greenhouse gases methane (CH 4 ) and carbon dioxide (CO 2 ) in the troposphere from instrumentation aboard satellites is a new area of research. In this manuscript, results obtained from observations of the up-welling radiation in the near-infrared by SCIAMACHY on board ENVISAT are presented. Vertical columns of CH 4 , CO 2 and oxygen (O 2 ) have been retrieved and the (air or) O 2 -normalised CH 4 and CO 2 column amounts, the dry air column averaged mixing ratios XCH 4 and XCO 2 derived. In this manuscript the first results, obtained by using the version 0.4 of the Weighting Function Modified (WFM) DOAS retrieval algorithm applied to SCIAMACHY data, are described and compared with global models. For the set of individual cloud free measurements over land the standard deviation of the difference with respect to the models is in the range ∼100-200 ppbv (5-10%) for XCH 4 and ∼14-32 ppmv (4-9%) for XCO 2 . The interhemispheric difference of the methane mixing ratio, as determined from single day data, is in the range 30-110 ppbv and in reasonable agreement with the corresponding model data (48-71 ppbv). The weak inter-hemispheric difference of the CO 2 mixing ratio can also be detected with single day data. The spatiotemporal pattern of the measured and the modelled XCO 2 are in reasonable agreement. However, the amplitude of the difference between the maximum and the minimum for SCIAMACHY XCO 2 is about ±20 ppmv which is about a factor of four larger than the variability of the model data which is about ±5 ppmv. More studies are needed to explain the observed differences. The XCO 2 model field shows low CO 2 concentrations beginning of January 2003 over a spatially extended CO 2 sink region located Correspondence to: M. Buchwitz (michael.buchwitz@iup.physik.uni-bremen.de) in southern tropical/sub-tropical Africa. The SCIAMACHY data also show low CO 2 mixing ratios over this area. According to the model the sink region becomes a source region about six months later and exhibits higher mixing ratios. The SCIAMACHY and the model data over this region show a similar time dependence over the period from January to October 2003. These results indicate that for the first time a regional CO 2 surface source/sink region has been detected by measurements from space. The interpretation of the SCIAMACHY CO 2 and CH 4 measurements is difficult, e.g., because the error analysis of the currently implemented retrieval algorithm indicates that the retrieval errors are on the same order as the small greenhouse gas mixing ratio changes that are to be detected.

in the high Northern Hemisphere (HNH) (30°-90°N) using two different approaches: total column amounts of CO retrieved from infrared solar spectra and CO mixing ratios measured in situ at ground-based stations. The data were averaged, and anomalies of the CO HNH burden (deviations of the total tropospheric mass between 30°N and 90°N from the mean seasonal profile, determined as the 5 year average) were analyzed. The anomalies obtained from in situ and total column data agree well and both show two maxima, by far the largest in October 1998 and a lower one in August 1996. A noticeable decrease of the positive 1998 summer anomaly with increasing height was found. A box model was applied, and anomalies in source rates were obtained under the assumption of insignificant interannual sink variations. In August 1998 the HNH emission anomaly was estimated to be 38 Tg month À1. The annual 1998 emission positive anomaly was 96 Tg yr À1

Abstract. Carbon monoxide total column amounts in the atmosphere have been measured in the High Northern Hemisphere (30°-90° N, HNH) between January 2002 and December 2003 using infrared spectrometers of high and moderate resolution and the Sun as a light source. They were compared to ground-level CO mixing ratios and to total column amounts measured from space by the Terra/MOPITT instrument. All these data reveal increased CO abundances in 2002-2003 in comparison to the unperturbed 2000-2001 period. Maximum anomalies were observed in September 2002 and August 2003. Using a simple two-box model, the corresponding annual CO emission anomalies (referenced to 2000-2001 period) have been found equal to 95Tg in 2002 and 130Tg in 2003, thus close to those for 1996 and 1998. A good correlation with hot spots detected by a satellite radiometer allows one to assume strong boreal forest fires, occurred mainly in Russia, as a source of the increased CO burdens.

Abstract. With the Match technique, which is

[1] Column-averaged volume mixing ratios of CO 2 have been obtained by ground based high-resolution solar absorption spectrometry at Ny-Alesund (Spitsbergen, 79°N) in 2002 -2003 and during two ship cruises (54°N-34°S) on the Atlantic in 2003. Precisions are better than 0.4% at Ny-Alesund and better than 0.6% for the cruises. The observed 11 ppmv (part per million by volume) seasonal amplitude of the CO 2 column at Ny-Alesund is about 5 ppmv smaller than surface in situ data and 2 -4 ppmv greater than model-predictions. The latitudinal gradient of column CO 2 inferred from shipborne measurements is less than 2 ppmv in Oct/Nov 2003. During the cruise in Jan/Feb 2003 the observed latitudinal variation is about 7 ppmv. This strong variation is caused by pollution events (biomass burning) and natural variations. Low CO 2 columns observed between 5°S -15°S are attributed to a strong seasonal amplitude of CO 2 over Central Africa.