Comparison and synergy of stratospheric ozone measurements by satellite limb sounders and the ground-based microwave radiometer SOMORA

International audienceStratospheric O3 profiles obtained by the satellite limb sounders Aura/MLS, ENVISAT/MIPAS, ENVISAT/GOMOS, SAGE-II, SAGE-III, UARS/HALOE are compared to coincident O3 profiles of the ground-based microwave radiometer SOMORA in Switzerland. Data from the various measurement techniques are within 10% at altitudes below 45 km. At altitudes 45?60 km, the relative O3 differences are within a range of 50% Larger deviations at upper altitudes are attributed to larger relative measurement errors caused by lower O3 concentrations. The spatiotemporal characteristics of the O3 differences (satellite ? ground station) are investigated by analyzing about 5000 coincident profile pairs of Aura/MLS (retrieval version 1.5) and SOMORA. The probability density function of the O3 differences is represented by a Gaussian normal distribution (except for profile pairs around the stratopause at noon). The dependence of the O3 differences on the horizontal distance between the sounding volumes of Aura/MLS and SOMORA is derived. While the mean bias (Aura/MLS ? SOMORA) is constant with increasing horizontal distance (up to 800 km), the standard deviation of the O3 differences increases from around 8 to 12% in the mid-stratosphere. Geographical maps yield azimuthal dependences and horizontal gradients of the O3 difference field around the SOMORA ground station. Coherent oscillations of O3 are present in the time series of Aura/MLS and SOMORA (e.g., due to traveling planetary waves). Ground- and space-based measurements often complement one another. We introduce the double differencing technique which allows both the cross-validation of two satellites by means of a ground station and the cross-validation of distant ground stations by means of one satellite. Temporal atmospheric noise in the geographical ozone map over Payerne is significantly reduced by combination of the data from SOMORA and Aura/MLS. These analyses illustrate the synergy between ground-based and space-based measurements

Feasibility of one-crystal GaAs artificial pyroelectric array

Multifunction properties of GaAs and other III-V semi-insulating crystals could be expanded by the artificial decreasing of their electric response symmetry that could be transformed from piezo- into a pyroelectric class. Artificial pyroelectricity of III-V type semiconductors forms a basis for one-crystal pyroelectric sensor. The voltage sensitivity of GaAs (111)-cut is the similar to PZT pyroelectric ceramics, so GaAs wafer could be used as a thermal-to-electric transducer in a new microelectronic device named pyrotransistor. The last is uncooling far infrared (IR) detector based on MESFET technology

Ground-based validation of EOS-Aura OMI NO2 vertical column data in the midlatitude mountain ranges of Tien Shan (Kyrgyzstan) and Alps (France)

Ground-based UV-visible instruments for NO2 vertical column measurements have been operating at Issyk-Kul station, in Kyrgyzstan, and Observatoire de Haute-Provence (OHP), in France, since 1983 and 1992, respectively. These measurements have already been used for validation of ERS-2 Global Ozone Monitoring Experiment (GOME) and Envisat Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) NO2 column data. Building upon the successful missions of GOME and SCIAMACHY, the Ozone Monitoring Experiment (OMI) was launched by NASA onboard the EOS Aura satellite in July 2004. Here we present the results of recent comparisons between OMI NO2 operational data (standard product) and correlative ground-based twilight measurements in midlatitudes, at Issyk-Kul and OHP, in 2004–2006. The stratospheric NO2 columns, observed by OMI and our ground-based instruments, have been corrected for NO2 diurnal change and normalized to local noon values using a photochemical box model. According to our comparison, OMI stratospheric NO2 columns underestimate ground-based measurements by (0.3 ± 0.3) × 1015 molecules/cm2 and (0.7 ± 0.6) × 1015 molecules/cm2 at Issyk-Kul and OHP, respectively. The effect of tropospheric pollution on the NO2 measurements in both regions of observations has been identified and discussed