Comparing CO2 retrieved from Atmospheric Infrared Sounder with model predictions: Implications for constraining surface fluxes and lower-to-upper troposphere transport

Authors

Yogesh K. Tiwari, Max-Planck Institute for Biogeochemistry
Manuel Gloor, University of Leeds
Richard Engelen, European Centre for MediumRange Weather Forecasts, UK
Frederic Chevallier, Laboratoire des Sciences du Climat et de l’Environnement, France
Christian Rodenbeck, Max-Planck Institute for Biogeochemistry
Stefan Korner, Max-Planck Institute for Biogeochemistry
P Peylin, CNRS
Rob Braswell, University of New Hampshire - Main CampusFollow
M Heimann, Max Planck Institute for Biogeochemistry

Abstract

Large-scale carbon sources and sinks can be estimated by combining atmospheric CO₂concentration data with atmospheric transport inverse modeling. This approach has been limited by sparse spatiotemporal tropospheric sampling. CO₂ estimates from space using observations on recently launched satellites (Atmospheric Infrared Sounder (AIRS)), or platforms to be launched (Infrared Atmospheric Sounding Interferometer (IASI), Orbiting Carbon Observatory (OCO)) have the potential to fill some of these gaps. Here we assess the realism of initial AIRS-based mid-to-upper troposphere CO₂ estimates from European Centre for Medium-Range Weather Forecasts by comparing them with simulations of two transport models (TM3 and Laboratoire Meteorologie Dynamique Zoom (LMDZ)) forced with one data-based set of surface fluxes. The simulations agree closer with one another than with the retrievals. Nevertheless, there is good overall agreement between all estimates of seasonal cycles and north-south gradients within the latitudinal band extending from 30°S to 30°N, but not outside this region. At smaller spatial scales, there is a contrast in the satellite-based retrievals above continents versus above oceans that is absent in the model predictions. Hovmoeller diagrams indicate that in the models, high Northern Hemisphere winter CO₂concentrations propagate toward the tropical upper troposphere via Northern Hemisphere high latitudes, while in retrievals, elevated winter CO₂ appears instantaneously throughout the Northern Hemisphere. This raises questions about lower-to-upper troposphere transport pathways. Prerequisites for use of retrievals to provide an improved constraint on surface fluxes are therefore further improvements in retrievals and better understanding/validation of lower-to-upper troposphere transport and its modeling. This calls for more independent upper troposphere transport tracer data like SF₆ and CO₂.

Department

Earth Sciences, Earth Systems Research Center

Publication Date

9-16-2006

Journal Title

Journal of Geophysical Research: Atmospheres

Publisher

Wiley

Digital Object Identifier (DOI)

10.1029/2005JD006681

Document Type

Article

Recommended Citation

Tiwari, Y. K., M. Gloor, R. J. Engelen, F. Chevallier, C. Ro¨denbeck, S. Ko¨rner, P. Peylin, B. H. Braswell, and M. Heimann (2006), Comparing CO2 retrieved from Atmospheric Infrared Sounder with model predictions: Implications for constraining surface fluxes and lower-to-upper troposphere transport, J. Geophys. Res., 111, D17106, doi:10.1029/2005JD006681.

Rights

Copyright 2006 by the American Geophysical Union.