The datasets include:
- COWVR STP-H8 Surface Wind Vector and Column-Integrated Atmospheric Water Measurements Version 10.0 (COWVR_STPH8_L2_EDR_V10.0): This Level 2 dataset from the COWVR instrument provides geolocated surface wind vectors, precipitable water vapor, and integrated cloud liquid water, as well as the microwave brightness temperatures used to derive them.
- COWVR STP-H8 Antenna and Microwave Brightness Temperatures Version 10.0 (COWVR_STPH8_L1_TSDR_V10.0): This Level 1 dataset from the COWVR instrument provides calibrated, geo-located antenna temperature and brightness temperatures, along with the sensor telemetry used to derive those values. Brightness temperatures are derived from the microwave band frequencies 18.7 gigahertz (GHz), 23.8 GHz, and 34.5 GHz. (Note: This product is best suited for a calibration/validation user or sensor expert.)
- TEMPEST STP-H8 Antenna and Microwave Brightness Temperatures Version 10.0 (TEMPEST_STPH8_L1_TSDR_V10.0): This Level 1 dataset from the TEMPEST instrument includes satellite-based observations of calibrated, geo-located antenna temperature and brightness temperatures, along with the sensor telemetry used to derive those values. Brightness temperatures are derived from the microwave band frequencies 87, 164, 174, 178 and 181 GHz. (Note: This product is best suited for a calibration/validation user or sensor expert.)
Version 10.0 is the first unrestricted public release of these data, which are named as such to be consistent with the internal version numbering of the project team prior to release. These datasets cover the period from January 2022 to the present, with forward streaming planned until August of 2025. Both the Level 1 and Level 2 datasets provide data in HDF5 format, with roughly one file per hour (the orbital period of the International Space Station is approximately 90 minutes).
Delivering Data Faster and More Frequently
Developed by JPL and launched into space on December 21, 2021, COWVR and TEMPEST are passive microwave radiometers deployed on the Japanese Experiment Module Exposed Facility (JEM-EF) of the ISS for a three-year mission. From their perch on the ISS, COWVR and TEMPEST will provide crucial data that scientists use to forecast weather and climate. COWVR is responsible for measuring the speed and direction of winds blowing over the ocean surface, while TEMPEST observes the vertical distribution of water vapor and moisture in the atmosphere.
Such measurements are vital to weather prediction, as heat and moisture from the ocean influences atmospheric conditions and winds play a key role in driving ocean currents and distributing masses of warm air. Better insight into how these processes interact is key to more accurate forecasting, but getting the requisite data to study them can be difficult.
From 2003 to 2020, measurements of ocean surface wind vectors, rain rates, and total precipitable water were primarily obtained by the WindSat instrument aboard the DoD’s Coriolis satellite. Traveling in Sun-synchronous orbit, WindSat had an equatorial crossing time of 6 p.m. and a revisit time of 8 days. Now, COWVR and TEMPEST are filling the data gap left by WindSat’s departure, and revisiting locations within the ISS’s orbit with greater frequency.
According to PO.DAAC Data Engineer Dean Henze, the release of these first dataset from COWVR and TEMPEST is significant, as co-located measurements of wind vectors and integrated water measurements at the air-sea interface will be immensely beneficial for both weather forecasting and climate research.
"Having these co-located wind and water data allows users to circumvent the uncertainties scientists may encounter when trying to combine wind and atmospheric data from instruments on different satellites," he said. “Also, because these instruments are on the ISS, which is not in Sun-synchronous orbit, they will pass over the same locations at different times of the day. This is helpful for filling in some of the time-of-day gaps when conducting research or observing storms, particularly in the middle latitudes.”
The ISS moves above the planet in low-Earth orbit, traveling from west to east about 16 times per day between 52° North and South latitude. This means the majority of COWVR’s and TEMPEST’s observations will be over areas in the mid-latitudes and the tropics, which are prone to storms, and revisit them more frequently. Further, because COWVR and TEMPEST will use NASA’s Tracking and Data Reply Satellite System (TDRSS) to send their data back to Earth, scientists and forecasters can receive COWVR and TEMPEST data in near real-time.
"The more frequent measurements and low latency data offered by these instruments can be fed into storm tracking systems and weather models at a faster rate, which allow scientists to update their forecasts more often," said Henze. “This will be very beneficial in the mid-latitudes and in the tropics where there are a lot of storms.”
About the STP-H8 Mission
The goal of the DoD-sponsored STP-H8 mission is to demonstrate new low-cost microwave sensor technologies for weather applications.
The COWVR instrument is no bigger than a minifridge and TEMPEST is even smaller—about the size of a cereal box. Yet, while they might be small in size, these instruments are tasked with a big job: making the same high-quality atmospheric observations as weather satellites many times their size at a fraction of the cost.
To make that happen, the Air-Sea interface and Atmospheric Profile observatory (ASAP) Science Working Group (SWG) formed in 2021 to advance research and applications with COWVR and TEMPEST data, as the simultaneous measurements of air-sea interface and atmospheric profiles present significant advantages for research and applications in storm forecasting, air-sea interactions, climate sciences, and model improvements. With support from NASA, the ASAP-SWG plans to develop additional water vapor profile, precipitation rate, and ice water path data products using the STP-H8 mission observations. A list of the anticipated products from COWVR and TEMPEST is available on the STP-H8 mission website.
Data Access
COWVR and TEMPEST instrument data from January 2022 to the present are being reprocessed by the COWVR-TEMPEST Project Team and ingested by PO.DAAC, NASA’s designated archive and distribution center for the STP-H8 mission data, as they become available. Data can be accessed and downloaded via the PO.DAAC website, Earthdata Search, and the PO.DAAC Data Subscriber Tool.
