A. P. H. Goede

Ozone depletion observed by the Airborne Submillimeter Radiometer (ASUR) during the Arctic winter 1999/2000

[1]xa0In the winter 1999/2000 the Airborne Submillimeter Radiometer (ASUR) participated in the Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment/Third European Stratospheric Experiment on Ozone project on board the NASA research aircraft DC-8. During three deployments in early December 1999, late January, and early March 2000, the ASUR instrument took various measurements of ozone and key species related to stratospheric ozone chemistry. After the sunlight reached the vortex region in January 2000 peak values of about 1.8 ppb ClO were measured by ASUR. There was nearly no ozone destruction observed during the period between mid December 1999 and late January 2000. As expected from ASUR observation of high chlorine activation and continuously low temperatures until mid March, significant ozone depletion was observed between late January and mid March 2000. In order to determine ozone loss it is important to separate dynamical and chemical effects. Since N2O is a good tracer due to its chemical stability in the lower stratosphere for determining ozone changes due to descent of air, ozone loss can be estimated from simultaneous measurements of ozone and N2O by ASUR. Between mid December 1999 and mid March 2000 a chemical ozone loss of about 30% (eq 1.1 ppm) in the altitude range between 19.0 and 22.2 km and of about 40% (eq 1.15 ppm) between 16.0 and 18.1 km was observed. The air masses subsided 2.1–3.2 km in the lower stratosphere due to diabatic descent in the period from mid December 1999 to mid March 2000 as derived from ASUR N2O measurements. Vortex-averaged ASUR measurements of ozone are systematical greater than results from the Global Ozone Monitoring Experiment (GOME) which has a similar vertical resolution than ASUR. This, however, has little impact on the determination of delta ozone and chemical loss estimates.

Seasonal and latitudinal variation of atmospheric methane: A ground‐based and ship‐borne solar IR spectroscopic study

[1]xa0Column-averaged volume mixing ratios of CH4 were retrieved with a precision of better than 0.5% from infrared solar absorption spectra obtained at Ny-Alesund (Spitsbergen, 79°N) between 1997 and 2004 and during two ship cruises (54°N–34°S) on the Atlantic in 2003. The retrieval has been performed in a spectral region available to all operational FTIR (Fourier Transform InfraRed) spectrometers performing solar absorption measurements. The seasonality and the long-term increase of the tropospheric volume-mixing ratio, derived from the infrared measurements agree well with data from surface sampling at this site. The latitudinal variation of ship-borne measurements between 54°N and 34°S is in agreement with inverse model simulations which are optimized vs. the global NOAA/ESRL measurements.

The geostationary scanning imaging absorption spectrometer (GeoSCIA) mission: requirements and capabilities

Abstract Instrumentation aboard satellite platforms in Low Earth Orbit (LEO) have been successfully used to measure back scattered and reflected light from atmosphere. Inversion of such observation enable trace gas amounts and distributions in the stratosphere and the troposphere to be derived. LEO measurements are restricted to a specific time at a given location. Contrary to that several tropospheric processes, for example pollution episodes, have a strong diurnal variation and variability or they are masked by the highly variable processes in the troposphere, for example clouds. This obviously defines the need to perform measurements with high spatial and temporal resolution. Measurements of the back scattered and reflected solar light from spectrometers on geostationary platforms enable diurnal variations and variability of constituents to be retrieved at high spatial (25 km × 25 km) and temporal (full Earth disk every 30 min) resolution. The geostationary imaging absorption spectrometer mission GeoSCIA is a concept yielding such data. Details of the mission objectives and requirements will be discussed.

Sciamachy instrument development for poem-1

Abstract In this paper the phase B development of the SCIAMACHY instrument is presented. Discussed in detail are the optical unit including its calibration method and the detector assemblies including early performance results. Signal to noise analyses stress the importance of thermal background radiation in the NIR channels. Ways to reduce the various noise sources are presented.

SCIAMACHY - The Need for Atmospheric Research from Space

The Earth’s atmosphere is part of a complex system comprising the Sun and the Earth. Throughout the Earth’s history this system responded to natural and anthropogenic phenomena. To assess the significance of changes induced by natural and anthropogenic activities, a detailed understanding of the physical and chemical processes controlling the composition of the global atmosphere is required. Space-based remote sensing instruments can contribute many of the required geophysical parameters on various spatial and temporal scales. The scientific goals of the imaging absorption spectrometer SCIAMACHY, flying on the European ENVISAT platform, are wide ranging and encompassing the need to improve our understanding of biogeochemical cycling and assess the impact of man on the Earth system. SCIAMACHY is an absorption spectrometer sensing simultaneously electromagnetic radiation in the range from the UV to SWIR. It observes the scattered and reflected spectral radiance in nadir and limb geometry, the spectral radiance transmitted through the atmosphere in solar and lunar occultation geometry and both the extraterrestrial solar irradiance and lunar radiance. Research using SCIAMACHY data includes the following topics: tropospheric ozone, air quality, the transport and transformation of pollution, global climate change, the exchange between the stratosphere and troposphere, stratospheric chemistry and dynamics, mesopheric and thermospheric composition, and solar variability. SCIAMACHY was proposed in the 1980s and is now part of the current fleet of atmospheric remote sensing missions. Due to its success, several missions with SCIAMACHY heritage will extend the important data sets far into the twenty-first century.

GODIVA, a European project for ozone and trace gas measurements from gome

GODIVA (GOME Data Interpretation, Validation and Application) is a European Commission project aimed at the improvement of GOME (Global Ozone Monitoring Experiment) data products. Existing data products include global ozone, NO2 columns and (ir)radiances. Advanced data products include O3 profiles, BrO, HCHO and OClO columns. These data are validated by ground-based and balloon borne instruments. Calibration issues are investigated by in-flight monitoring using several complementary calibration sources, as well as an on-ground replica of the GOME instrument. The results will lead to specification of operational processing of the EUMETSAT ozone Satellite Application Facility as well as implementation of the improved and new GOME data products in the NILU database for use in the European THESEO (Third European Stratospheric Experiment on Ozone) campaign of 1999.

Sciamachy instrument design

The primary scientific objective of SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) is the global measurement of trace gases in the troposphere and the stratosphere. SCIAMACHY comprises two high resolution optical spectrometers scanning the atmosphere simultaneously in nadir and in limb. It retrieves the concentrations of trace gases from observations of transmitted, back scattered and reflected light from the atmosphere in the wavelength range between 0.24 and 2.4 μm. Important ozone chemistry and greenhouse gases, including O3, NO2, N2O, CH4, CO and CO2 are measured. In this paper the instrument design is presented, carried out as part of a recently successfully completed phase A feasibility study for the first European Polar Platform (1997) and the ATMOS-Umwelt Forschungs Satellit (1995).