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Using Satellites for Forecasting

GOES West image GOES West water vapor image GOES West image


Using environmental satellites to observe the Earth from space is one of the key tools in forecasting weather, analyzing climate, and monitoring hazards worldwide. This 24-hour global coverage provides us with a never-ending stream of information critical for making decisions affecting everything from what you are going to wear today to governments making decisions about how to deal with climate change. The National Oceanic and Atmospheric Administration (NOAA) Satellite Information Service in collaboration with the National Aeronautics and Space Administration (NASA) and the U.S. Air Force, manages and operates fleets of weather and environmental monitoring satellites. There are two main types of environmental satellites: geostationary and polar-orbiting.

Geostationary Operational Environmental Satellites: When you watch your local newscaster present the weather forecast, and they show an image of weather over the whole United States, you are seeing imagery from NOAA Geostationary Operational Environmental Satellites, or GOES. GOES orbit 35,800 km (22,300 miles) above the Earth's equator at speeds equal to Earth's rotation, which maintain their positions relative to Earth. The GOES provide constant monitoring of various areas of the planet. To fully cover Alaska, Hawaii, the entire continental United States, and the Pacific and Atlantic Ocean (for tropical storms), NOAA operates two GOES satellites simultaneously - GOES-East and GOES-West. The satellites provide constant coverage of the western hemisphere by taking photographic images every 15 minutes. These "constant eyes" are critical for identifying severe weather, snow storms, tropical storms and hurricanes. GOES protect our lives and property every day - constantly watching for new storms and severe weather.

Polar Operational Environmental Satellites: When you wonder on Wednesday what the weather will be like over the weekend you turn to weather forecasters, who rely on NOAA Polar Operational Environmental Satellites, or POES, to help make their predictions. POES make regular 360° orbits around the Earth's poles from about 833 km (517 miles) above the Earth's surface. The Earth constantly rotates counterclockwise underneath the path of the satellite making for a different view with each orbit. It takes the satellite approximately 1.5 hours complete a full orbit. In a 24-hour period, the 14 orbits of each polar satellite provide two complete views of weather around the world. By having imagery of the whole globe, meteorologists are able to develop models to predict the weather out to five to ten days. NOAA partners with EUMETSAT to constantly operate two polar-orbiting satellites - one POES and a European polar-orbiting satellite called Metop. When polar-orbiting satellites fly over severe weather, they can also give us very detailed pictures of the storms given how much closer they are to storms than GOES. In addition to weather analysis and forecasting, data from the POES series support a broad range of environmental monitoring applications including climate research and prediction, global sea surface temperature measurements, measurements of temperature and humidity of the atmosphere, ocean dynamics research, volcanic eruption monitoring, forest fire detection, and global vegetation analysis. Instruments on POES are critical for providing long-term, sustained observations used for determining the long term changes in climate conditions around the world. Finally, POES assist in search and rescue by locating people, planes and ships, who have activated emergency locator beacons.

In addition to basic imagery, on-board sensors detect cloud, land, and ocean temperatures, as well as monitor activities of the sun. NOAA GOES are also used in identifying when satellite emergency locator beacons have been activated to help with Search and Rescue activities.

MetOp is a series of polar orbiting meteorological satellites operated by the European Organisation for the Exploitation of Meteorological Satellites. The satellites are all part of the EUMETSAT Polar System.

Ocean Surface Topography Mission (OSTM)/JASON-2: One aspect of climate change is sea level rise, which affects much of the world's population that live in coastal areas. To measure the height of the ocean around the world, NOAA participates in a joint Ocean Surface Topography Mission (OSTM) program between NOAA, NASA, France's Centre National d'Etudes Spatiales (CNES), and European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). This is a joint effort by the four organizations to measure sea surface height by using a radar altimeter mounted on a low-earth orbiting satellite called Jason-2. Satellite altimetry data provides sea surface heights for determining ocean circulation, climate change and sea-level rise. These sea surface height measurements are necessary for ocean modeling, forecasting El NiÑo/La NiÑa events, and hurricane intensity prediction.


Tracking Ash Clouds
Satellite imagery is also used to track the ash cloud after a volcanic eruption.

Alaska contains over 130 volcanoes and volcanic fields, which have been active within the last two million years. These volcanoes are catalogued on the National Volcano Observatory's web site.

Of these volcanoes, about 90 have been active within the last 10,000 years (and might be expected to erupt again), and more than 50 have been active within historical time (since about 1760, for Alaska).

The volcanoes in Alaska make up well over three-quarters of U.S. volcanoes that have erupted in the last two hundred years.

Alaska's volcanoes are potentially hazardous to passenger and freight aircraft as jet engines sometimes fail after ingesting volcanic ash. Based on information provided by the Federal Aviation Administration, that more than 80,000 large aircraft per year, and 30,000 people per day, are in the skies over and potentially downwind of Aleutian volcanoes, mostly on the heavily traveled great-circle routes between Europe, North America, and Asia. Volcanic eruptions from Cook Inlet volcanoes (Spurr, Redoubt, Iliamna, and Augustine) can have severe impacts, as these volcanoes are nearest to Anchorage, Alaska's largest population center.


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