Impact of nonlinearity on changing the a priori of trace gas profile estimates from the Tropospheric Emission Spectrometer (TES) S. S. Kulawik1, K. W. Bowman1, M. Luo1, C. D. Rodgers2, and L. Jourdain1 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA 2University Oxford, Clarendon Lab, Oxford OX1 3PU, UK
Abstract. Non-linear maximum a posteriori (MAP) estimates of atmospheric profiles from
the Tropospheric Emission Spectrometer (TES) contains a priori information
that may vary geographically, which is a confounding factor in the analysis
and physical interpretation of an ensemble of profiles. One mitigation
strategy is to transform profile estimates to a common prior using a linear
operation thereby facilitating the interpretation of profile variability.
However, this operation is dependent on the assumption of not worse than
moderate non-linearity near the solution of the non-linear estimate. The
robustness of this assumption is tested by comparing atmospheric retrievals
from the Tropospheric Emission Spectrometer processed with a uniform prior
with those processed with a variable prior and converted to a uniform prior
following the non-linear retrieval. Linearly converting the prior following
a non-linear retrieval is shown to have a minor effect on the results as
compared to a non-linear retrieval using a uniform prior when compared to
the expected total error, with less than 10% of the change in the prior
ending up as unbiased fluctuations in the profile estimate results.
Citation: Kulawik, S. S., Bowman, K. W., Luo, M., Rodgers, C. D., and Jourdain, L.: Impact of nonlinearity on changing the a priori of trace gas profile estimates from the Tropospheric Emission Spectrometer (TES), Atmos. Chem. Phys., 8, 3081-3092, doi:10.5194/acp-8-3081-2008, 2008.