Assessment and Error Analysis of Terra-MODIS and MISR Cloud-Top Heights Through Comparison With ISS-CATS Lidar

Cloud-top heights (CTH) from the Multiangle Imaging Spectroradiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra constitute our longest-running single-platform CTH record from a stable orbit. Here, we provide the first evaluation of the Terra Level 2 CTH record against collocated International Space Station Cloud-Aerosol Transport System (CATS) lidar observations between 50oN and 50oS. Bias and precision of Terra CTH relative to CATS is shown to be strongly tied to cloud horizontal and vertical heterogeneity and altitude. For single-layered, unbroken, optically thick clouds observed over all altitudes, the uncertainties in MODIS and MISR CTH are -540 +/- 690 m and -280 +/- 370 m, respectively. The uncertainties are generally smaller for lower altitude clouds and larger for optically thin clouds. For multi-layered clouds, errors are summarized herein using both absolute CTH and CATS-layer-altitude proximity to Terra CTH. We show that MISR detects the lower cloud in a two-layered system, provided top-layer optical depth

Automated summary

Cloud-top heights (CTH) records from MISR and MODIS on Terra provide our longest-running single-platform CTH record from a stable orbit. The evaluation of Terra Level 2 CTH record against CATS lidar observations shows that bias and precision of Terra CTH are closely tied to cloud horizontal and vertical heterogeneity, as well as altitude. The uncertainties in MODIS and MISR CTH are related to cloud characteristics, with smaller uncertainties for lower altitude clouds and larger uncertainties for optically thin clouds.