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Retrieval of cloud parameters from the new sensor generation satellite multispectral measurement

Retrieval of cloud parameters from the new sensor generation satellite multispectral measurement F. ROMANO and V. CUOMO. ITSC-XII Lorne, Victoria, Australia. Main Object: Improvement using AMSU data and high spectral resolution data (IASI and IMG) in

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Retrieval of cloud parameters from the new sensor generation satellite multispectral measurement

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  1. Retrieval of cloud parameters from the new sensor generation satellite multispectral measurement F. ROMANO and V. CUOMO ITSC-XII Lorne, Victoria, Australia

  2. Main Object: • Improvement using AMSU data and high spectral resolution data (IASI and IMG) • in • cloud detection • cloud clearing • cloud forcing radiative • retrieval of cloud parameters ITSC-XII Lorne, Victoria, Australia

  3. TOP CLOUD HEIGH • The cloud radiative forcing the simple difference between cloud and cleared radiances can be useful in the estimation of top cloud height. • Accurate cloud clearing and cloud detection packages are necessary to estimate cloud radiative forcing. ITSC-XII Lorne, Victoria, Australia

  4. IASI Cloud Clearing Scheme IASI Data Cloud Mask IASI/AMSU REG. COEF. AMSU Data Synthetic IASI Data Clear IASI FOV in the Box Variogram Kriging interpolation Cleared IASI data and errors ITSC-XII Lorne, Victoria, Australia

  5. IASI Cloud Clearing Test DATASET • R. Rizzi’s Cloudy Dataset (CDS) • M. Madricardi’s AMSU Brightness Temperature Data set ITSC-XII Lorne, Victoria, Australia

  6. CLOUD CLEARING RESULTS Results, on the basis of IASI simulated data and ATOVS data, show that the root mean square error of the Kriging clear brightness temperatures estimates is well below 1°K for any IASI or HIRS channels. ITSC-XII Lorne, Victoria, Australia

  7. IASI/AMSU CLOUD DETECTION AMSU data have been used in order to have some information about the clear radiance field. The test based on AMSU data allow to detect all the overcast FOVs and high cloud. Low clouds, thin cirrus clouds and partially FOVs cloudy is detected using some tests based on IASI or IMG signatures. ITSC-XII Lorne, Victoria, Australia

  8. IASI/AMSU CLOUD DETECTION VALIDATION • R. Rizzi’s Cloudy Dataset (CDS) • M. Madricardi’s AMSU Dataset ITSC-XII Lorne, Victoria, Australia

  9. IMG/AMSU CLOUD DETECTION VALIDATION • MEASURED IMG DATA • COLLOCATED AMSU/MSU DATA ITSC-XII Lorne, Victoria, Australia

  10. CO2 slicing method • CO2 slicing has been extensively used to retrieve cloud top pressure and cloud effective emissivity. The radiance from a partially cloudy air column region can be written as: • Using Radiative Transfer Equation and after simple operation we obtain: ITSC-XII Lorne, Victoria, Australia

  11. CLOUD TOP HEIGHT : Single Cloud Level • For two close spectral channels and viewing the same FOV can be written as: ITSC-XII Lorne, Victoria, Australia

  12. In order to apply the CO2 slicing technique to IASI data, it is necessary to select the best pairs of frequency to be use in the cloud top retrieval. The method used, select all the channel in the (700 – 753 cm-1) absorption band whose weighting functions peak between 200 mb and 900 mb. It use all the possible combinations of those channels, with the first channel in the pair always associated with the lower wavenumber. ITSC-XII Lorne, Victoria, Australia

  13. Then apply the CO2 slicing technique to retrieve the cloud top heights, using all the selected channel pairs. • Finally selected the number of pairs that best satisfy the radiative transfer equation for all the spectral channels. • For each FOV the pairs number of different solutions found are used to evaluate a cost function: ITSC-XII Lorne, Victoria, Australia

  14. The solution associated to the smallest values of cost function are averaged to determine the cloud top height. • Increasing the number of channel pairs used in average causes a improvement in the accuracy of the top cloud height retrieval. • At the end the algorithm select 36 pairs of channels. ITSC-XII Lorne, Victoria, Australia

  15. When the cloud height is known, the cloud effective emissivity has been estimate using the infrared window channel data (893 cm-1) by means from the follow relation: ITSC-XII Lorne, Victoria, Australia

  16. To examine the performance of the top cloud height and effective emissivity algorithm, the numerical simulations of clear and cloudy radiances were carried out using synthetic data from LBLRTM. • Additional instrumental noise were simulated according to IASI specification noise level. ITSC-XII Lorne, Victoria, Australia

  17. Radiances are simulated for ten cloud-top pressure (900 mb, 850 mb, 830 mb, 800 mb, 730 mb, 750 mb, 730 mb, 700 mb, 650 mb, 600 mb) • for four cloud amounts (0.1, 0.5, 0.7, 1) • and for the U.S. Standard climatological profile, for all the frequency used in the algorithm measured ITSC-XII Lorne, Victoria, Australia

  18. CLOUD TOP HEIGHT : Two Cloud Level The cloud forcing when you consider two level cloud (upper and lower cloud) can be expressed as: From all the solutions we select these best satisfies the radiative transfer equation for all spectral channels. ITSC-XII Lorne, Victoria, Australia

  19. In the same way we defined a cost function and the solutions associated to the smallest values are averaged to determine the upper and lower cloud top height. • Increasing the channel pairs number used in average causes a improvement in the accuracy of the top cloud height retrieval. • At the end the algorithm select 44 pairs of channels ITSC-XII Lorne, Victoria, Australia

  20. Cloud Top height Package Validation The top cloud height package has been apply at the simulated CDS-IASI cloud data. Between the 91200 FOVs 1010 FOVs with a single cloud layer and 605 FOVs with two cloud levels have been selected. The temperature profile and the profiles of atmospheric transmittance for the spectral frequency have been calculated as a function of top cloud top pressure. The cloud top altitude is assumed to vary according to the 43 pressure discrete layering. ITSC-XII Lorne, Victoria, Australia

  21. Single Cloud Level ITSC-XII Lorne, Victoria, Australia

  22. Two Cloud Levels ITSC-XII Lorne, Victoria, Australia

  23. Two Cloud Levels ITSC-XII Lorne, Victoria, Australia

  24. Conclusions and Future Work AMSU data and high spectral resolution IASI and IMG sounders data can greatly be improved retrieval cloud parameters. The cloud top pressure and the effective emissivity retrieval are in good agreement with the true theoretical values. The cloud top pressure retrieved packages will be extend to multiple cloud levels. Validation, based on radiosonde and meteorological radar, will be extend to IMG and AIRS measured data. ITSC-XII Lorne, Victoria, Australia

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