OMI Algorithm Theoretical Basis Document Volume II - NASA's Earth ...

ATBD-OMI-02 53.1.1.3.1.2.Heritage...................................................................................................................................................... 33Product description .................................................................................................................................... 333.2. ALGORITHM DESCRIPTION ................................................................................................343.2.1. Slant Column Density ................................................................................................................................ 34Basic concept ............................................................................................................................................. 34Ring effect .................................................................................................................................................. 35Instrumental Errors.................................................................................................................................... 36Fit window ................................................................................................................................................. 37Fit Method.................................................................................................................................................. 373.2.2. Air Mass Factor (AMF) ............................................................................................................................. 38Computation............................................................................................................................................... 38Radiative transfer model............................................................................................................................ 40Look-up-Table............................................................................................................................................ 403.2.3. Cloud Correction........................................................................................................................................ 42Cloud Model............................................................................................................................................... 42Air Mass Factor for Partly Cloudy Conditions.......................................................................................... 42Ghost Column ............................................................................................................................................ 42Total Vertical Column Density................................................................................................................... 433.3. ERROR ANALYSIS.............................................................................................................433.3.1. Slant column density.................................................................................................................................. 43Forward model errors................................................................................................................................ 44A priori errors............................................................................................................................................ 44Instrument errors ....................................................................................................................................... 443.3.2. Air mass factor (AMF)............................................................................................................................... 45Forward model errors................................................................................................................................ 45A priori errors............................................................................................................................................ 463.3.3. Cloud correction......................................................................................................................................... 463.3.4. Error Budget............................................................................................................................................... 473.3.5. Exceptional Cases ...................................................................................................................................... 47Desert Dust ................................................................................................................................................ 47Biomass Burning........................................................................................................................................ 47Polar Stratospheric Clouds........................................................................................................................ 48Large Solar Zenith Angles ......................................................................................................................... 483.4. VALIDATION.....................................................................................................................483.4.1.3.4.2.Algorithm validation .................................................................................................................................. 49Product validation ...................................................................................................................................... 493.5. ACKNOWLEDGMENTS .......................................................................................................503.6. REFERENCES.....................................................................................................................504. OZONE PROFILE ALGORITHM.............................................................................534.1. OVERVIEW........................................................................................................................534.1.1. Historical Background ............................................................................................................................... 534.1.2. Processing Overview.................................................................................................................................. 544.1.3. Product Description.................................................................................................................................... 554.2. THE FORWARD MODEL......................................................................................................564.2.1. Introduction................................................................................................................................................ 564.2.2. Atmospheric state input to the RTM.......................................................................................................... 56Trace Gas Databases ................................................................................................................................. 56Aerosols...................................................................................................................................................... 57Temperature/humidity................................................................................................................................ 57Clouds ........................................................................................................................................................ 57Surface ....................................................................................................................................................... 574.2.3. Radiative transfer model (RTM)................................................................................................................ 57Single-scattering RTM ............................................................................................................................... 58Multiple-scattering RTM............................................................................................................................ 58Computation of Jacobians.......................................................................................................................... 59Sphericity correction at large viewing angle ............................................................................................. 60Version 2 – August 2002