MODIS-VIIRS Cloud Regimes

The MODIS-VIIRS Cloud Regimes are a discrete classification of cloud fields at the mesoscale as observed by the VIIRS sensors aboard the Suomi-NPP and NOAA-20 satellites, as well as the MODIS sensor aboard the Aqua satellite using the Continuity algorithm. Derived by applying the k-means clustering algorithm to joint-histograms of cloud top pressure and cloud optical thickness, the cloud regimes represent different atmospheric systems based on their cloud signatures. This MODIS-VIIRS Cloud Regimes dataset is an independently derived dataset which can be viewed as an extension of the work that produced the MODIS Cloud Regimes (Cho et al. 2021, Oreopoulos 2021). The MODIS-VIIRS Cloud Regimes are derived similarly by applying a k-means clustering algorithm to the joint-histograms at equal-area grids of 110 km every 3-h generated from granule (Level-2) cloud products available from the Continuity Algorithm "CLDPROP" applied on observations by the MODIS Aqua, VIIRS Suomi-NPP, and VIIRS NOAA-20 sensors during the period of March 2018 to February 2023. A cluster number of k = 11 was selected, which when including a clear sky regime gives a total of 12 MODIS-VIIRS Cloud Regimes. Each histogram is then assigned to the nearest k-means centroid to obtain its regime membership. Two variants of the VIIRS Cloud Regimes are available: (1) a 3-h product in the original 110-km native resolution of its derivation, and (2) a 3-h product derived from the 110-km product by nearest neighbor interpolation to 1°. Cho, N., J. Tan, and L. Oreopoulos, 2021: Classifying planetary cloudiness with an updated set of MODIS Cloud Regimes. J. Appl. Meteorol. Climatol., 60, 981–997, https://doi.org/10.1175/JAMC-D-20-0247.1. Oreopoulos, L., 2021: MODIS CR Equal Area 3-Hour. https://doi.org/10.5067/MEASURES/MODISCR/EQAR3H/DATA301.