Intercomparison of TCCON and MUSICA Water Vapour Products

Friday, 19 December 2014
Dan Weaver1, Kim Strong1, Nicholas M Deutscher2, Matthias Schneider3, Thomas Blumenstock3, John Robinson4, Justus Notholt5, Vanessa Sherlock4, David W T Griffith6, Sabine Barthlott3, Omaira E Garcia7, Dan Smale4, Mathias Palm2, Nicholas B Jones6, Frank Hase3, Rigel Kivi8, Yolanda González Ramos7, Kei Yoshimura9, Eliezer Sepúlveda7, Ángel J Gómez-Peláez7, Michael Gisi3, Regina Kohlhepp3, Thorsten Warneke2, Susanne Dohe3, Andreas Wiegele3, Emanuel Christner10, Bernard Lejeune11 and Philippe Demoulin11, (1)University of Toronto, Toronto, ON, Canada, (2)University of Bremen, Institute of Environmental Physics, Bremen, Germany, (3)Karlsruhe Institute of Technology, Karlsruhe, Germany, (4)NIWA National Institute of Water and Atmospheric Research, Wellington, New Zealand, (5)University of Bremen, Bremen, Germany, (6)University of Wollongong, Wollongong, Australia, (7)Agencia Estatal de Meteorología, Izana Atmospheric Research Centre, Santa Cruz de Tenerife, Spain, (8)Finnish Meteorological Institute, Helsinki, Finland, (9)Atmosphere and Ocean Research Institute University of Tokyo, Tokyo, Japan, (10)Karlsruhe Institute of Technology, Atmospheric trace gas measurements and remote sensing, Karlsruhe, Germany, (11)University of Liège, Institute of Astrophysics and Geophysics, Liège, Belgium
We present an intercomparison between the water vapour products from the Total Carbon Column Observing Network (TCCON) and the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA), two datasets from ground-based Fourier Transform InfraRed (FTIR) spectrometers with good global representation. Where possible, comparisons to radiosondes are also included.

The near-infrared TCCON measurements are optimized to provide precise monitoring of greenhouse gases for carbon cycle studies; however, TCCON’s retrievals also produce water vapour products. The mid-infrared MUSICA products result from retrievals optimized to give precise and accurate information about H2O, HDO, and δD. The MUSICA water vapour products have been validated by extensive intercomparisons with H2O and δD in-situ measurements made from ground, radiosonde, and aircraft (Schneider et al. 2012, 2014), as well as by intercomparisons with satellite-based H2O and δD remote sensing measurements (Wiegele et al., 2014). This dataset provides a valuable reference point for other measurements of water vapour.

This study is motivated by the limited intercomparisons performed for TCCON water vapour products and limited characterisation of their uncertainties. We compare MUSICA and TCCON products to assess the potential for TCCON measurements to contribute to studies of the water cycle, water vapour’s role in climate and use as a tracer for atmospheric dynamics, and to evaluate the performance of climate models.

The TCCON and MUSICA products result from measurements taken using the same FTIR instruments, enabling a comparison with constant instrumentation. The retrieval techniques differ, however, in their method and a priori information. We assess the impact of these differences and characterize the comparability of the TCCON and MUSICA datasets.