Time Series Evaluation of the Current Collection of NASA MODIS Science Team Cloud Products

The MODIS science team cloud mask (NASA Earth Science Data Set filenames MOD35 and MYD35 for MODIS Terra and Aqua, respectively) and cloud-top and optical property products (MOD06/MYD06) are used routinely for cloud process, radiative and model-evaluation studies. With nearly a 19- and 17-year data record for MODIS Terra and Aqua, respectively, the cloud products are just beginning to be useful for climate analyses. However, the utility of the data records for this purpose fundamentally depends on instrument stability. The most recent MODIS Atmosphere Team reprocessing (Collection 6.1) addressed continuing instrument degradation in both MODIS instruments, most notably the increasing cross-talk occurring in several MODIS Terra infrared channels that resulted in pronounced artifacts in cloud detection trends for the later years of the Collection 6.0 time series. Previously, Collection 5 cloud property products showed artifacts in trends and ENSO correlations associated with scan-dependent shortwave channel radiometric calibration degradation, particularly for MODIS Terra. While the older MODIS Terra imager has had the more significant degradation issues, MODIS Aqua is showing analogous radiometric issues. We will present an overview of how instrument temporal artifacts aliased into the cloud products in previous collections, and showcase the improvements seen in the recent 6.1 Level-1B (instrument) and Level-2 cloud product reprocessing. Analyses will include time series trends for a variety of cloud products as well as product correlations associated with ENSO phases.