This article was updated June 13 to include the role of the University Corporation for Atmospheric Research.
SAN FRANCISCO – Tropical storm and space weather forecasts will improve with the help of observations from radio occultation satellites scheduled for launch June 24 on a SpaceX Falcon Heavy, National Oceanic and Atmospheric Administration officials said June 11.
The six-satellite Constellation Observing System for Meteorology, Ionosphere and Climate-2 (COSMIC-2), a joint U.S.-Taiwan program, will improve forecasts by providing “temperature and pressure information in the lower atmosphere and electron density measurements in the upper atmosphere,” Elsayed Talaat, director of NOAA’s Satellite and Information Service Office of Projects, Planning and Analysis, said in a June 11 press briefing.
Meteorologists are convinced that radio occultation data, which measures how radio waves from the Global Positioning System and other navigation constellations bend as they move through the atmosphere, could improve the accuracy of weather forecast models. Radio occultation measurements rank “as one of the top contributors to reducing short-term forecast errors in part because of their low bias and their ability to be used in presence of clouds and precipitation,” Daryl Kleist, a physical scientist at NOAA’s Environmental Modeling Center, said during the briefing.
NOAA plans to draw 5,000 daily radio occultation profiles from the COSMIC-2 mission, known in Taiwan as FORMOSAT-7. COSMIC-2 satellites destined for equatorial orbit will measure temperature and pressure in the in the tropics and subtropics even at the lowest levels of the atmosphere, Kleist said. Operational weather forecasts will assimilate COSMIC-2 observations within 30 minutes with the help of the University Corporation for Atmospheric Research (UCAR), the entity responsible for processing and disseminating COSMIC-2 data.
Accurate observations of temperature and humidity throughout the tropics is particularly important to forecasts because the tropics hold “most of the moisture that drives global weather patterns,” Louis Uccellini, NOAA National Weather Service director, said in a statement.
The six original COSMIC satellites were launched in 2006 by the U.S. and Taiwan in a mission designed, managed and operated by UCAR. Taiwan’s National Space Organization led integration and testing of the satellites built by Orbital Science Corp., now part of Northrop Grumman. The constellation produced a maximum of 1,500 to 2,000 daily soundings. Now, only one satellite in the COSMIC series continues to feed weather forecast models, providing hundreds of daily temperature and moisture profiles, Kleist said.
To augment that information, NOAA gathers data from the Global Navigation Satellite System Receiver for Atmospheric Sounding on Eumetsat MetOp satellites. The agency also is preparing to add radio occultation soundings to operational forecasts from Korea’s Kompsat-5 mission launched in 2013 and Spain’s PAZ satellite launched in 2018, Kleist said.
Originally, the U.S. and Taiwan planned to send six COSMIC-2 satellites into equatorial orbit and another six into polar orbit. The United States and Taiwan cancelled plans for the polar-orbiting satellites in 2017 citing budget constraints.
Data from international partners like Eumetsat will mitigate the loss of the polar-orbiting satellites, Talaat said. In addition, NOAA is examining whether commercial radio occultation constellations could provide observations in polar regions, he added.
Last year, NOAA awarded contracts to GeoOptics, PlanetIQ and Spire Global in the second round of its Commercial Weather Data Pilot. NOAA is currently gathering those observations, which the agency is evaluating to determine their utility for operational weather forecasting.
COSMIC-2 satellites carry three instruments. The Tri-Global Navigation Satellite System Radio Occultation Receiver, developed by NASA’s Jet Propulsion Laboratory, senses atmospheric temperature, pressure and moisture in addition to measuring electron density in the upper atmosphere. Ball Aerospace built the Ion Velocity Meter, an instrument developed by the University of Texas, Dallas, to sense ion velocity, concentration and composition, while measuring upper atmosphere electron density. The Air Force and SRI International developed COSMIC-2’s Radio Frequency Beacon to measure electron content in the upper atmosphere.
Taiwan’s National Space Organization purchased COSMIC-2 satellites from Surrey Satellite Technology Ltd. The satellites are scheduled to undergo seven months of checkout, calibration and validation led by Taiwan before their observations make their way into weather models.
