Weather Satellites: Keeping an Eye on Irene From Above

Geek Culture

Hurricane Irene From GOES-EastHurricane Irene From GOES-East

Hurricane Irene seen from GOES-East on August 24th (Image: NASA)

Many eyes are currently focused on Hurricane Irene churning through the Atlantic, and very important group of eyes are watching the giant cyclone from above. These are the eyes that give the forecasters on the ground the vital information they need to issue warnings to those in the path of the powerful storm and many other weather phenomena. So where does the raw data come from that is used to predict weather? The answer is much higher than the cloud tops.

There is a literal fleet of satellites circling the Earth observing atmospheric conditions. Some of them are relatively low flying in Low Earth Orbit, or LEO, and some are much higher in a Geostationary Orbit, or GEO. Lets start with the satellites that have the ultimate high ground.

For the United States, the weather high ground is occupied by the Geostationary Operational Environmental Satellites, or GOES. There are always two GOES satellites operating, GOES-East and GOES-West. GOES-East is currently stationed at longitude 75 degrees west and GOES-West is at longitude 135 degrees west. By definition of being at GEO, they are both 22,236 miles directly above the equator. There is an additional GOES satellite, referred to as GOES-South, that is near GOES-East at 60 degrees west and provides coverage for South America. These satellites are operated by the National Oceanic and Atmospheric Administration, or NOAA, and are always looking down at the Earth providing a breathtaking image of the full disc of our planet. The images are captured in 5 bands of light ranging from visible to infrared. These different bands capture different information about the atmosphere and cloud cover. There is also a sounder on-board that provides atmospheric profiles. Do the GOES satellites stop at atmospheric weather? Nope. They also provide a great deal of information on space weather and even have receivers that listen for, and report on, emergency search and rescue beacons.

If we drop about 22,000 miles from geostationary orbit we find a mix of satellites in Polar LEO orbits. This is where we start getting a sense of the fleet of satellites in operation. They are operated by NASA, NOAA, EUMETSAT (which stands for European Organisation for the Exploitation of Meteorological Satellites), and a host of other organizations worldwide. Just on a quick look-up I can count over two dozen satellites monitoring the Earth and its atmosphere from polar orbit and that was certainly not a comprehensive list. Only a handful of those satellites are operated by NOAA and used for day to day weather forecasting, called the Polar Operational Environmental Satellites, or POES. There are six satellites in the POES group, NOAA-15 through NOAA-19 and the European METOP-A. They are divided into two groups based on local time when the cross the equator in their orbit, AM or PM. These satellites host a comprehensive suite of instruments that take a deep look at the atmosphere. They, like their GOES brethren, also host emergency search and rescue beacon receivers. The POES satellites, along with their NASA Earth Observing System (EOS) brethren and satellites provided by countries all over the world, give us amazing insight into our planet.

So, now that you know a little about the satellites that are out there, how can you see the data for yourself? Well, part of that answer is that you are seeing that data all the time in weather forecasts. The data from all of the NOAA operational satellites, and some NASA satellites, is processed by NOAA’s National Environmental Satellite, Data, and Information Service (NESDIS) and provided for weather forecasting. That being said, I know our GeekDad audience and you want to get at some of the data yourself. I provide some links below with the following warning: As with all science data, the closer you get to the raw data, the more expertise may be required to make heads or tails of what you are seeing. Sure, some of the GOES images show you some obvious cloud and moisture data (which has actually undergone some processing before you see anything) but you might have a little more trouble with the 85 GHz microwave sounder data.

A good start is the NESDIS Satellite Products home page. From there you can navigate to information from the GOES satellites and the Polar satellites directly. Right now, following the Geostationary path to the East US data, I can pull up the shortwave infrared data that is less than an hour old and clearly shows a very intimidating Irene. Similarly, I can pull up data from the polar orbiting microwave sounder to look at the rainfall rates and I am presented with data that is only about 3 hours old and shows some serious rainfall within Irene. I could never walk through all of the data available because there is a great deal there from a multitude of satellites and instruments on those satellites.

Other data is available from NASA who is good about making sure good imaging information gets out quickly for major events, such as Irene. Just like NESDIS, NASA has a great website set up as one stop shopping but specific to monitoring Hurricanes. Here you will find information from the GOES-East satellite, the Terra satellite, the Tropical Rainfall Measurement Mission (TRMM), and even the International Space Station. There is also an impressive video that was captured on the ISS of Irene.

The future of weather observation is being developed now. The first to launch will be the NPP satellite the October. NPP is the next polar orbiting weather operational weather satellite and a pathfinder to the new Joint Polar Satellite System (JPSS) series of satellites. JPSS is the next evolution from the current POES program. The next generation GOES satellites are also under development and there are several other satellites on the drawing board to monitor the Earth. That is a ton of information being generated. I love to look at the bare data as much as the next guy but it also makes me very glad that there is a dedicated fleet of meteorologists and climate experts to help me understand what it all means and are doing their best to keep us all safe. If you, like me, are currently under those forecast cones for Irene, be prepared, heed the warnings, and stay safe!

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