Comparing High Spectral Resolution with Broadband IR Cloud Top Pressure Determinations

This research focuses on extending the HIRS (High Resolution Infrared Radiation Sounder) cloud data set to include IASI (Infrared Atmospheric Sounding Interferometer) and CrIS (Cross-Track Infrared Sounder) data. This involves reducing the high spectral resolution IASI and CrIS measurements to resemble the HIRS broadband spectral coverage and estimating the cloud top pressures (CTPs) and effective emissivities. In addition the high spectral resolution data is investigated to characterize the uncertainties in the broadband cloud products. To date co-located HIRS and IASI data from MetOp were used to compare the CTPs using dual-regression (DR), which is a hyperspectral retrieval algorithm developed at SSEC, on IASI and on simulated HIRS, and CO2-slicing on HIRS. CO2-slicing on IASI is also investigated. Finally all are compared with CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) cloud top determinations; CTPs (IASI, HIRS-DR, HIRS-CO2, CALIOP) are sorted by CALIOP determinations of cloud optical depth at individual CTPs.