Jet makes marathon flights to uncover secrets of atmosphere
By flying nearly 50,000 kilometres between the Arctic Ocean and the Antarctic coast, a specially designed jet repeatedly sampled the air at a broad range of altitudes.
London: By flying nearly 50,000 kilometres between the Arctic Ocean and the Antarctic coast, a specially designed jet repeatedly sampled the air at a broad range of altitudes, thereby helping scientists in building the most detailed profile of the atmosphere yet.
In spring this year, during its third of five planned missions, a specially outfitted Gulfstream V jet, owned by the US National Science Foundation and operated by the National Center for Atmospheric Research in Boulder, Colorado, journeyed northwards, nearly reaching the Pole before turning south towards the Antarctic.
The plane made occasional refuelling stops along the way, and then largely retraced its eastern Pacific route before returning to its home base.
As it flew, the plane (formerly known as HIAPER — the High-Performance Instrumented Airborne Platform for Environmental Research) repeatedly climbed as high as 13.7 kilometres and dipped down to a nail-biting 150 metres above the ocean waves, all the while sampling more than 100 atmospheric constituents, including greenhouse gases, aerosols and a suite of natural and industrial chemicals.
Now, early results from that flight and two previous ones with the same aircraft, presented on 9 August at a joint assembly of the American Geophysical Union and several Latin American societies in Iguaçu Falls, Brazil, are yielding surprises in the distribution of trace gases and airborne pollution.
Scientists generally have to rely on ground measurements and then use mathematical models to extrapolate upwards when they need to create a picture of the global atmosphere, said Steve Wofsy, an atmospheric researcher at Harvard University in Cambridge, Massachusetts, and the principal investigator for the 4-million dollar HIAPER Pole-to-Pole Observations (HIPPO) project.
"That’s like studying the ocean by studying what is on the surface of the ocean," Nature quoted him as saying.
On the other hand, HIPPO can help modellers to test their ability to reproduce the atmosphere in three dimensions.
Among the surprises to come out of HIPPO data are nitrous oxide concentrations that consistently seem to increase with altitude.
"Yet the models all show concentrations decreasing with altitude," said Wofsy.
The implication is that models are either not properly accounting for the transport of nitrous oxide or they are missing a source of the greenhouse gas, he added.
The HIPPO team also found that black carbon particles originating in Asia and beyond taper off much more quickly than expected over the Pacific.