Weather satellites give meteorologists a wide range of data on the atmosphere that helps them improve forecasts. They monitor cloud temperature, air speed and moisture levels over the oceans, among other factors.
Meteorologists use satellites to spot weather systems and patterns hours to days before they’re detected by surface observing instruments, like radar. This extended view also helps them spot tornadoes and the movement of ice in the Arctic.
Geostationary Operational Environmental Satellites (GOES)
GOES satellites are a critical component of the United States weather system. Their observations are ingested into numerical weather prediction (NWP) computer models and help meteorologists to make accurate, life-saving forecasts of severe weather conditions and environmental hazards.
Using a geosynchronous orbit, these “eyes in the sky” hover above the Earth’s surface and remain stationary. This allows them to observe the Earth’s atmosphere for long periods of time and gather important atmospheric data as often as every 30 seconds in a hemisphere.
When a storm develops, these satellites can provide real-time information to warn meteorologists of flash floods, hail storms, tornadoes and hurricanes. They can also detect ice fields and map the movement of sea and lake ice.
In addition to their meteorological capabilities, these satellites collect imagery that can be used for other purposes such as assessing fire risks. They can help to identify smoke and volcanic ash from wildfires, as well as detect the presence of fog, dust, atmospheric rivers and other hazardous conditions.
NOAA’s next generation of satellites, called GOES-R, are in development and are set for launch within the next two years. Their sensors will be able to more accurately detect and pinpoint the location of fires. They will also be able to use hyperspectral infrared sounders that will aid in forecasting flooding.
The newest generation of NOAA’s GOES-R series satellites, which are being built by Lockheed Martin, will provide more timely and accurate weather forecasts than ever before. Their systems and instruments will allow for a more complete dataset than previously available on polar satellites.
They will also be able to monitor the movements of storms across the Pacific Ocean. This will help meteorologists understand the risks of wildfires and other hazardous weather conditions in western areas.
According to Krissy Hurley, a NOAA Warning Coordination Meteorologist, the GOES-T satellite will also be able to fill in gaps in weather observation where current weather balloons and other observation equipment are not available. This will include monitoring wildfires in the western United States, which can be lifesaving for people in remote areas.
Polar-Orbiting Satellites (POES)
Polar-orbiting satellites, also called meteorological or geophysical satellites, orbit at a low altitude (about 800 km) and make passes near the earth’s surface. The satellites can see a swath beneath them as the earth rotates on its axis, and can collect data in this swath several times each day.
These satellites are vitally important to weather forecasting and climate research. They provide a long-term view of the planet’s changing climate, which helps scientists gain insight into global climate trends, ocean dynamics, forest fires and tropical storms, and many other environmental conditions.
They are used to create global weather patterns that help predict severe weather events such as tornado outbreaks, heat waves, blizzards, hurricanes, floods and wildfires. The data they collect are also invaluable for monitoring vegetation, sea ice and atmospheric moisture levels.
NOAA’s POES satellites are in sun-synchronous, circular orbits and their altitudes typically range from 700 to 800 kilometers. Each satellite captures imagery from successive orbits, overlapping each other’s data to offer daily global coverage from multiple locations.
Each satellite has a variety of instruments that allow it to perform several different tasks, such as imaging the earth, collecting atmospheric soundings of temperature and humidity, measuring global sea surface temperatures, and monitoring volcanic eruptions and cloud cover. In addition, it has a special water vapor channel that allows it to detect the amount of moisture in the atmosphere.
The polar-orbiting data are used in combination with ground measurements to produce snowmelt and run-off estimates at NWS River Forecast Centers. They also provide information on liquid water equivalent, which can be used to determine how much liquid water would be in an area if it were to melt and become rain or snow.
NOAA’s polar-orbiting satellites are managed by the agency and are funded on a cost-reimbursement basis. They are a part of the Joint Polar Satellite System (JPSS) which includes GOES and NASA’s polar-orbiting Earth observing missions. The most recent polar-orbiting satellite, Suomi NPP (NOAA-19) was launched in 2011 and is providing NOAA’s forecasters with vital data that are essential for their ability to issue accurate weather forecasts for the United States.
The Jason-2 satellites are part of an international collaboration between NOAA, the French Space Agency Centre National d’Etudes Spatiales (CNES), and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). They monitor ocean heights and help predict hurricanes.
The Poseidon-3 radar altimeter on Jason-2 is derived from the Poseidon-1 on TOPEX/Poseidon and the Poseidon-2 on Jason 1. It measures sea level, wave heights and wind speed, and determines the path delay caused by water vapor in the atmosphere. It also records atmospheric temperature and humidity.
This instrument was designed for a higher accuracy than the Poseidon-2 that was used on Jason-1, so it was built using a new generation of DGXX-S receivers. The DGXX-S receivers use improved calculation models such as Ultra-Stable Oscillator frequency drift and along-track acceleration to improve calculations of satellite position.
Another primary payload on Jason-2 is the DORIS instrument, which provides real-time location and precise orbit determination for geophysical studies. DORIS is a dual-frequency GPS receiver system with a laser tracking array that uses the round-trip time of a laser beam to calculate the exact location and orientation of the satellite.
It will be placed in the same orbit as Jason 2 at an altitude of 1,336 km, inclined 66 degrees to provide virtually complete coverage of ice-free ocean surfaces. It weighs about 600 kg and has 550 W of power.
As the only operational radar altimeter in low-Earth orbit, Jason-2 is vital for the world’s weather forecasters and scientists. Its data are used to track climate change factors that affect sea level, such as changes in sea ice or evaporation. The altimeter also helps NOAA forecast the strength of tropical cyclones by mapping the ocean heat content that fuels hurricanes and helps determine their path over land.
In 2017, ground teams noticed that the Jason-2 satellite was depleting its propellant reserve and had begun to age, but they were able to maneuver the satellite to a lower orbit away from other operational missions. This allowed the satellite to continue taking measurements of the same location on the ocean. The lower orbit also increased the resolution of the satellite’s images, allowing researchers to conduct marine gravity studies and map the seafloor topography.
Weather forecasters and emergency responders have two primary needs for weather satellites: a fixed view of their home territory at all times so they can watch and measure tornadoes, wildfires and major storms, and global data to help them make better predictions that help them prepare for severe weather. These satellites, which circle Earth 512 miles above the surface in a polar orbit 14 times a day, provide these essential measurements and imagery.
Suomi NPP, launched in October 2011, is a critical bridge between NOAA’s legacy environmental satellites and the next-generation Joint Polar Satellite System (JPSS), which NASA and NOAA plan to launch in 2017. Its five instruments are used for weather forecasting, including a new generation of microwave sounders that capture atmospheric temperature and water vapor information that’s vital to assessing and predicting weather and climate conditions.
These measurements can be ingested into weather models, which are critical for making accurate forecasts. They can also help scientists learn about the Earth’s complex systems and predict how these systems will change in the future.
NOAA’s National Weather Service, or NWS, is one of the main users of data and operational measurements from Suomi NPP. In fact, over 90% of the data ingested into weather models comes from this satellite.
Another Suomi NPP instrument, the Cross-track Infrared Sounder or CrIS, is helping improve NOAA’s weather forecasting by producing higher spatial and vertical resolution data about atmospheric temperature and water vapor that, when fully operational, will greatly enhance NOAA’s climate and weather forecast models.
The CrIS hyperspectral sounder consists of 2,211 infrared channels, compared with 19 on earlier systems, that measure more light, temperature and moisture than previously available measurements. This increased sensitivity helps meteorologists produce more precise, longer-range forecasts than ever before.
These observations can be a valuable part of a long-term archive that helps track how the atmosphere is changing over time, according to NASA. They also collect information on particles in the air – smoke from wildfires, airborne dust during dust and sandstorms, urban and industrial pollution, and ash from erupting volcanoes.