Dresden 2011 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 1: Poster Session

UP 1.9: Poster

Dienstag, 15. März 2011, 18:30–20:30, P2

Validation of Atmospheric Water Vapor Soundings from the Differential Absorption Lidar (DIAL) with the Solar FTIR System on Mt. Zugspitze — •Hannes Vogelmann, Ralf Sussmann, Thomas Trickl, and Tobias Borsdorff — Karlsruhe Institute of Technology (KIT), IMK-IFU, Garmisch-Partenkirchen

We present an intercomparison of three years of measurements of integrated water vapor (IWV) performed by the mid-infrared solar FTIR instrument on the summit of Mt. Zugspitze (2964 m asl.) and the nearby near-infrared DIAL at the Schneefernerhaus research station (UFS, 2675 m asl.). The FTIR is one of the most accurate and precise IWV sounders and taken as the reference here. By calculating the FTIR-DIAL correlation we derive an almost ideal slope of 0.99(1), a correlation coefficient of R = 0.99, an IWV intercept of 0.056(42) mm, and a bias of 0.097(26) mm from the scatter plot. From a subset of coincidences with an optimum temporal and spatial matching between DIAL and FTIR we obtain a conservative estimate of the precision of the DIAL which is better than 0.1 mm. We found that for a coincidence interval of 22 min the difference in IWV from the two systems is dominated by the volume mismatch (hor. dist.: 680 m). Major results: 1. The IWV soundings by FTIR and DIAL agree very well in spite of the differing wavelength regions with different spectroscopic line parameters and retrieval algorithms used. 2. Deriving an estimate of the precision of state-of-the-art IWV sounders from intercomparison experiments requires a temporal matching on the shorter 10-min scale and a spatial matching on the smaller 1-km scale.