Quintus Kleipool

SCIAMACHY on ENVISAT: in-flight optical performance and first results

The Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) is a contribution to the ENVISAT-1 satellite, which has been launched in March 2002. The SCIAMACHY instrument measures sunlight transmitted, reflected and scattered by the Earths atmosphere or surface simultaneously from the UV to the SWIR spectral region (214 - 2380 nm) in nadir, limb, and occultation viewing geometry. SCIAMACHY allows the characterisation of the composition of the Earth atmosphere from the ground to the mesosphere. This paper gives an overview of the SCIAMACHY instrument and its in-flight detector, spectral and radiometric performance. Furthermore first results on trace gas retrieval from limb and nadir measurement mode will be summarised.

Error analysis of a heterodyne submillimeter sounder for the detection of stratospheric trace gases.

Heterodyne submillimeter detection techniques represent an important development in the field of remote sensing of atmospheric composition. The disclosure of this wavelength region by new low-noise detectors and multichannel high-resolution spectrometers leads to expectations of improved accuracy and vertical resolution of the vertical composition profiles derived from these measurements. Because of the low-noise levels of newly developed receivers, special care is required to ensure that fundamental limitations of the components used do not contribute to systematic errors exceeding the random errors. Operated in an upward-looking geometry, the sensitivity of the retrieval algorithm to noise and instrumental errors can be rather high, and hence instrumental limitations could induce large uncertainties in the derived atmospheric information. Instrumental uncertainties typical for a passive heterodyne sounder are quantified, and their effects on the accuracy of the derived vertical mixing ratio profiles are presented.

In-flight calibration of the ozone monitoring instrument

This paper discusses various aspects of the on-ground and in-flight calibration of the OMI instrument.

PDR status for TROPOMI, the Sentinel 5 precursor instrument for air quality and climate observations

The Tropospheric Monitoring Instrument (TROPOMI) is being developed for launch in 2014 on ESAs Sentinel 5 Precursor satellite. TROPOMI is a passive sun backscatter spectrograph using the ultraviolet-to-SWIR wavelengths to have good sensitivity down to the surface. Together with its spatial resolution of 7 x 7 km2 it allows good observations of sources and sinks of air quality and climate related gases and aerosols. This spatial resolution results in a high fraction of cloud-free observations and is combined with a wide cross-flight swath to allow daily coverage of the complete Earth. The instrument has as predecessors the OMI instrument (Ozone Monitoring Instrument) on NASAs AURA satellite and the SCIAMACHY instrument on ESAs ENVISAT, where the push broom concept is derived from OMI and the SWIR observations from SCIAMACHY. The wavelength bands of TROPOMI are a UV band (270 - 320 nm) for the ozone profile and SO2 products, a UVIS band (320 - 500 nm) for O3, NO2, BrO, HCHO and OClO total columns, a NIR band (675 - 775 nm) for clouds and H2O columns and a SWIR band (2305 - 2385 nm) for CH4 and CO columns and the HDO/H2O ratio. The paper will give an overview of the challenges and current performances. The TROPOMI UVN module is funded by the Netherlands and the SWIR module and platform is provided via ESA. The instrument development is now a truly European programme with contributions from several countries.

The TROPOMI instrument: first H/W results

The Tropospheric Monitoring Instrument, TROPOMI, is a passive UV-VIS-NIR-SWIR spectrograph, which uses sun backscattered radiation to study the Earths atmosphere and to monitor air quality, on both global and local scale. It follows in the line of SCIAMACHY (2002) and OMI (2004), both of which have been very successful. OMI is still operational. TROPOMI is scheduled for launch in 2015. Compared with its predecessors, TROPOMI will take a major step forward in spatial resolution and sensitivity. The nominal observations are at 7 x 7 km2 at nadir and the signal-tonoises are sufficient for trace gas retrieval even at very low albedos (2 to 5%). This allows observations of air quality at sub-city level. TROPOMI has reached CDR status and production of flight model units has started. Flight detectors have been produced and detector electronics is expected to be finished by mid-2013. The instrument control unit is undergoing extensive tests, to ensure full instrument functionality. Early results are promising and this paper discusses these H/W results, as well as some challenges encountered during the development of the instrument.