CIRA Polar Orbiters Database Software (CPOD): Python Software to Make Searching Polar Orbiting Satellite Data Fast and Easy

A common problem for remote sensing applications using non-gridded data from polar-orbiting satellites is rapidly finding data that intersects a region of interest. Selecting a subset of data is usually a first step for any application. For example, Tropical Cyclone (TC) applications require data to be selected around a TC center. This involves using time/space search criteria that varies along the entire length of a TC track. Selecting a subset of data is necessary while using both historical datasets and real-time data. While performing a search using a particular dataset for a few cases is not a difficult problem, supporting a wide variety of datasets and products with fast searches can be very challenging for a small team with limited resources. For this reason, the CIRA Polar Orbiters Database (CPOD) software was developed to quickly and efficiently select data from a global dataset using arbitrary time and space bounds. CPOD was originally developed to support searching data from polar-orbiting satellites for TC applications but can also be used to select data from any global dataset that provides geolocated data. This software is capable of performing searches through datasets consisting of several hundred thousand files in a fraction of a second. Supporting new datasets can often be performed by changing between 5 and 20 lines in a configuration file. If custom code does need to be written to support a new dataset, this can be achieved by writing a "plugin" consisting of a short routine that can be swapped in at runtime. Additionally, this code is designed to run in operational centers that often place strict limits on which Python packages can be installed. The code depends exclusively on the Python standard library, numpy, and any libraries needed to read supported datasets. CPOD has been successfully used at CIRA to assemble TC-centered databases for microwave sounders (Advanced Microwave Sounding Units (AMSU), Advanced Technology Microwave Sounder (ATMS)) on board of several NOAA and MetOp satellites as well as for the Suomi National Polar Orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) imagery. Additionally, CPOD has been used for the collocation of droposondes and radiosondes with AMSU and ATMS data and is being expanded to work with other datasets. CPOD is part of the CIRA Hurricane Intensity and Structure Algorithm (HISA) that is running operationally at the NOAA National Environmental Satellite, Data, and Information Service (NESDIS) and provides objective microwave-based TC intensity estimates from multiple polar-orbiting satellites. A description of the CPOD algorithm will be presented together with examples of applications that utilize its capabilities.