How to use and interpret MOPITT Retrievals

V3 Data Quality Statement

Averaging Kernels

In order to properly compare MOPITT Level 2 Data with models or other measurements the MOPITT averaging kernels MUST be used.  The averaging kernels are also valuable as an indication of the vertical resolution of the measurements.

Please consult the document, Calculation and Application of MOPITT Averaging Kernels (PDF, by Merritt Deeter, updated 24 Jul 2002), for the details on calculating and using averaging kernels.

A priori data

MOPITT retrievals rely on CO and CH₄ a priori data. MOPITT data users need these data in order to calculate the MOPITT averaging kernels. Different versions of archived MOPITT retrieval data may be based on somewhat different a priori data. Therefore, it is important that MOPITT data users download the a priori file which is consistent with the specific version of MOPITT retrieval data being analyzed.

  V2 a priori data file
  V3 a priori data file
  Plot of V3 apriori CO profile and diagonal of covariance matrix

Sample programs

Sample IDL programs for calculating averaging kernels from the covariance matrix and application of averaging kernels to a 'true' profile:

• Routine for reading a priori file (V3 a priori): read_apriori_dat_v3.pro
• Routine for calculating averaging kernels (using V3 a priori): calc_avgker_v3.pro
• Routine for reading MOPITT data files: read_mopitt.pro
• Program with sample data that shows how to construct the retrieved covariance matrix from the form in data files, calculate averaging kernels, and apply to a comparison profile: example_avgker_calc.pro
• output plot

Examples of averaging kernels

• Over Australia (desert)
• Over South Pacific

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