Comparison of the Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) cloud properties using PATMOS-x

Consistency among various data sets is necessary to conduct climatological studies, both using satellite data as well as reanalysis studies using numerical prediction models (NWPs). NWPs currently use satellite data for over 90% of their initialization input. It has been found that polar winds derived from the MODIS instrument, for example, greatly improved forecasts in both the northern and southern hemisphere. In fact, the incorporation of polar winds will be implemented in the National Center for Environmental Prediction (NCEP) model runs as part of the next system upgrade. This becomes more important as NWPs use more satellite data for their initialization and as more advance instruments from the national polar and geostationary satellite imagers (VIIRS and ABI) and from the current set (AVHRR and GOES) become available, improving the remote sensing capabilities of clouds. Data from the current operational sensors provides roughly 30 years of data and therefore comprises the bulk of the satellite data used to understanding decadal cloud variability. In order for cloud climatological studies from the operational sensors to be relevant to studies encompassing upcoming advanced sensors, research and analysis are required to develop methods to make physically consistent climate data records from both the current and future sensors.

In this paper, we explore, through the MODIS instrument, the consistency in the cloud optical depth and particle records from the AVHRR and GOES imagers and those derived from the additional channels offered by MODIS. We demonstrate the physical basis for the observed differences and propose methods to make the time series more consistent. Our focus here is on oceanic water cloud but we intend to extend this work to other cloud properties and other regions.