利用卫星减轻火山灾害对航空的影响

A joint NOAA/NASA satellite is one of several satellites providing valuable information to aviators about volcanic hazards. An aviation "orange" alert was posted on August 18, 2014, for Bárðarbunga, a stratovolcano located under the Vatnajökull glacier in Iceland, indicating the "volcano shows heightened or escalating unrest with increased potential of eruption." Much of the information leading to that alert came from satellites including Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on board the National Oceanic and Atmospheric Administration (NOAA)/NASA Suomi National Polar-orbiting Partnership (Suomi NPP).

While the Vatnajökull ice cap and its seismic activity has been gradually increasing over the past seven years, these recent events in Iceland are reminiscent of the destructive aftermath from the 2010 eruption of the Eyjafjallajökull volcano in Iceland. The Eyjafjallajökull eruption caused a six-day travel ban over the controlled airspace of many European countries. Data from NOAA satellites were used in the volcanic ash detection and property retrieval algorithm to create products to be used by the Volcanic Ash Advisory Centers (VAAC), including the London VAAC. The data given to the air traffic control organizations provided the information they needed to make the decision to divert and ground more than 4,000 flights. The ban was in effect to address the possibility of volcanic ash ejection causing damage to aircraft engines and risking human life. This was the largest air-traffic shut down since World War II, costing $1.7 billion in losses for the airline industry, as well as innumerable losses within freight imports and exports; tourism industries and the access to fresh food and essential goods.

Recently, Mike Pavolonis, is a NOAA scientist from the Center for Satellite Applications and Research (STAR) presented his work on How Weather Satellites are Mitigating Aviation-related Volcanic Hazards during a NOAA event. "Only 10 percent of the world's volcanoes are routinely monitored from the ground, making satellites the only frequently available tool that can reliably identify volcanic eruptions anywhere in the world," Pavolonis said. Advanced analysis of data from polar orbiting and geostationary satellites reduces the probability of a disastrous and/or costly aircraft encounter with volcanic ash and helps to minimize the cost associated with avoiding volcanic ash.

NOAA operates two of the nine Volcanic Ash Advisory Centers -- the Anchorage Alaska VACC and the Washington VAAC -- that provide operational support to the aviation sector to warn about these hazards for over a decade. He highlighted how volcanic ash can severely impact air travel, melting in a plane engine's combustion chamber and even shutting the engine down completely. This occurred in June 1982, when a British Airways B747 aircraft flew into a volcanic ash cloud from Mount Galunggung (Indonesia) and lost power in all four engines. They dropped from 37,000 feet to 12,000 feet before three engines were restarted and the plane was able to make an emergency landing in Jakarta, Indonesia.