Consistency between GRUAN sondes, LBLRTM and IASI
- 1AEMET, C/Leonardo Prieto Castro, 8, Ciudad Universitaria, 28071 Madrid, Spain
- 2University of Valencia, Physics Faculty, Carrer del Dr. Moliner, 50, 46100 Burjassot, Valencia, Spain
- 3Earth Observation Science, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
- 4National Centre for Earth Observation, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
- 5Deutscher Wetterdienst, Meteorologisches Observatorium Lindenberg, Richard-Aßmann-Observatorium, Am Observatorium 12, 15848 Lindenberg/Tauche, Germany
Abstract. Radiosonde soundings from the GCOS Reference Upper-Air Network (GRUAN) data record are shown to be consistent with Infrared Atmospheric Sounding Instrument (IASI)-measured radiances via LBLRTM (Line-By-Line Radiative Transfer Model) in the part of the spectrum that is mostly affected by water vapour absorption in the upper troposphere (from 700 hPa up). This result is key for climate data records, since GRUAN, IASI and LBLRTM constitute reference measurements or a reference radiative transfer model in each of their fields. This is specially the case for night-time radiosonde measurements. Although the sample size is small (16 cases), daytime GRUAN radiosonde measurements seem to have a small dry bias of 2.5 % in absolute terms of relative humidity, located mainly in the upper troposphere, with respect to LBLRTM and IASI. Full metrological closure is not yet possible and will not be until collocation uncertainties are better characterized and a full uncertainty covariance matrix is clarified for GRUAN.