by Allison Sayer for Seward City News-
The National Atmospheric and Oceanic Administration (NOAA) plans to launch a new polar-orbiting satellite early on the morning of November 14. This satellite, called JPSS-1 (Joint Polar Satellite System), will improve forecasting and monitoring capabilities in Alaska. This is the first of a series of four satellites (JPSS-1, JPSS-2, JPSS-3, JPSS-4) that will launch over the next fifteen years.
The JPSS series, and their prototype Suomi NPP (National Polar-orbiting Program), carry extremely advanced monitoring instruments. The instruments are more precise and have more capabilities than their predecessors’ instruments.
What is a Polar Orbiting Satellite?
Polar orbiting satellites are especially important to high latitude regions such as Alaska. A polar orbiting satellite travels longitudinally, from pole to pole, crossing the equator. As the satellite travels through space, the earth spins beneath it. This animation from NOAA demonstrates polar orbiting satellites’ paths.
The other type of weather observation satellites, geostationary satellites, remain above a fixed point on Earth. There are currently two geostationary weather satellites that are fixed above the equator. They provide constant images of Earth’s surface, but they cannot “see” the poles very well due to the planet’s curvature.
Another difference between polar orbiting and geostationary satellites is their height above Earth’s surface. Geostationary satellites are over 22,000 miles away, but polar orbiting satellites are much closer. JPSS-1 is set to orbit only 512 miles above the surface.
The New Generation of Instruments
In 2011, NOAA and NASA launched Suomi NPP as a test satellite. Suomi NPP is named in honor of meteorologist Verner E. Suomi. It carries several instruments that the JPSS series will carry. NOAA and the National Weather Service (NWS) have been extremely impressed with the data Suomi NPP has delivered.
One of Suomi NPP’s critical innovations is the Day/Night Band on the Visible and Infrared Imaging Suite (VIIRS). The Day/Night Band can use the tiniest amount of moonlight or other reflected light to form an image.
Prior to the Day/Night band, weather observations were compromised by darkness. Having images of storms and other weather 24 hours per day greatly enhances short term forecasting. Images taken at night also greatly improve early morning aviation and sea ice navigation forecasts. The Day/Night band is especially helpful to us in the high latitudes, where it is dark for so much of the winter.
Some of the other differences between the new and old instruments are differences in resolution rather than differences in kind. To understand that, we can consider a subject we are more familiar with.
The old way to map the sea floor was to lower a lead line to the bottom of the sea in several places, and record the depth. Cartographers connected the dots to the best of their ability. In contrast, modern ships tow seismic instruments that take continuous depth readings. The readings are synthesized by software into a map.
The basic premise of both of these methods is the same: measure the water depth and connect the dots. However, the new method has many, many more data points. The new method also has so much data that a computer is necessary to compile it all.
Similarly, meteorologists have been collecting vertical profiles of the atmosphere for a long time. Vertical profiles showing the temperature and water vapor concentrations at various heights are important tools for predicting the weather. The older polar-orbiting satellites currently collect these data using sounders. Weather balloons collect this information as well.
The new generation sounder has six times the resolution of sounders on previous satellites. This increase in resolution gives meteorological models much more information, greatly improving weather forecasting. This information is critical to predicting the path of potentially damaging storms.
Eric Stevens of The Geographic Information Network of Alaska at the University of Alaska-Fairbanks explains more about the new polar orbiting satellites’ capabilities in this interview with meteorologist Dave Snider on Alaska Public Media.
There are a total of five precision instruments on board the JPSS satellite with many capabilities. The instruments can also be used in tandem with each other to tease out difficult problems. The applications include predicting volcanic ash plumes, spotting extremely small forest fires, measuring carbon dioxide concentrations, monitoring sea ice, and many more.
The data collected will not only be used to predict short term phenomena such as weather. They are critical to long term climate observation and monitoring.
What Will Change When JPSS-1 Launches?
When JPSS-1 joins Suomi NPP in space, it will immediately double the number of observations made at each point on Earth. This will have an immediate impact on forecast accuracy. The two satellites will orbit in a staggered configuration to make this possible.
Scientists on earth will be able to receive data from JPSS-1 faster than they did from Suomi NPP. This increased speed is important to short term forecasting. Scientists use satellites not only to forecast rain and wind events, but also to forecast smoke and ash trajectories, air quality, and other hazards. These are important to assess in as close to real time as possible.
The JPSS program is also important because it gives continuity to the data scientists collect. Having the same type of data over time helps to create stronger models for making weather forecasts. It also is essential to long term global monitoring. JPSS-2 will launch in five years, JPSS-3 in ten, and JPSS-4 in fifteen. Scientists can build models and perform long term research with reasonable confidence the data will continue to be available.
JPSS-1 is currently scheduled to launch at 1:47 am on November 14. Live coverage is set to begin at 1:15 am on NASA TV.