Teamwork and technology aim to improve forecasting by Dan Corbett
At 11:22am BST on Friday 20th May, a Delta II rocket was successfully launched from Vandenburgh Air Force Base in California. On board was a new weather satellite, NOAA-18 (also known as NOAA-N), loaded with the very latest technology designed to collect information about the Earth’s surface and atmosphere to improve weather and climate prediction across the globe.
NOAA-18 is the 15th satellite in a series of polar-orbiting satellites launched by the United States’ NOAA, the first of which was launched back in 1978. It is, however, the first in a series of polar-orbiters that are part of a joint cooperation project between NOAA and Europe’s EUMETSAT. While NOAA is an old hand, EUMETSAT has yet to launch its first polar-orbiting weather satellite; the first is due in April 2006.
Polar-orbiting satellites can provide detailed information about the entire planet, including the higher latitudes that cannot be observed from geostationary orbit (where a satellite stays at a fixed point above the Earth’s surface). Taking advantage of this is on NOAA-18 is an exciting brand-new instrument, developed by EUMETSAT, called the Microwave Humidity Sounder (MHS).
Amounts of water vapour in the atmosphere can be very small, and its distribution needs to be accurately known to allow meteorologists to predict rainfall. The highly-sensitive MHS will be able to detect even these small amounts, and this information will be used by forecasters for nowcasting (the forecasting of dangerous and fast-forming weather such as tornadoes and flash floods), and by scientists working on numerical models. The amount and distribution of cloud also has a significant effect on the climate, and previously it has been very difficult to represent in climate models. It is hoped information from the MHS will help to greatly improve the modelling of cloud and hence give a better idea about climate change.
NOAA-18 will also provide data for NOAA to feed into their long-range and seasonal outlooks, including forecasts for El Niño and La Niña. After the seasons, these events are the single largest cause of year-to-year climate variability on the Earth. For example the 2002-03 El Niño event reduced rainfall across Australia, causing a drought from which the country is still struggling to recover.
The latest El Niño forecast issued by NOAA’s Climate Prediciton Center suggests that conditions will remain neutral during June to August, but despite this there are indications that Australia will remain drier than average, offering little hope to those affected by the drought described as “the worst in living memory”.
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