Three European spacecraft will launch from northern Russia presently on a mission to make the most comprehensive global maps yet of Earth's magnetic field. Known as Swarm, the trio of satellites should help scientists comprehend better how the field is generated, and why it appears to be weakening.
The European Space Agency mission is going up from the Plesetsk Cosmodrome on a customized intercontinental ballistic projectile. Lift-off is timed for 12:02 GMT. The satellites are expected to split from the Breeze upper-stage of their Rocket launcher some 91 minutes later, at an elevation of 490km. A period of commissioning and testing will then follow before the Swarm starts their four-year measurement campaign.
Leonid Yurganov, Senior Research Scientist, Joint Center for Earth Systems Technology, University of Maryland Baltimore County
Below an abstract of a paper written by Leonid Yurganov, Xiaozhen Xiong and Ira Liefer, and submitted for presentation at the AGU-Fall meeting 2013.
ABSTRACT: The trace gas sensitivity of Thermal InfraRed (TIR) sounders (AIRS, IASI, TANSO) is greatest in the middle and upper troposphere; though, lower troposphere (1-2 km of altitude) sensitivity is less but not negligible. As a result, where methane largely is constrained to the lower troposphere, as is common in the Arctic particularly the marine Arctic, retrievals from these instruments provides important synoptic data on high latitude methane sources. Low Arctic water vapor content favors a better sensitivity to methane as well: H2O is the main absorber in the 7.8 micrometers spectral region.
Both AIRS/Aqua v6 (NASA) and IASI/Metop-A (NOAA/NESDIS/CLASS retrievals) methane data averaged over 0-4 km altitude clearly demonstrate increased methane concentrations over the Barents and Norwegian Seas (BNS) with seasonal maximum in December - March. Similar increases are observed over the Kara, Laptev, and Chukchi Seas for September-November, i.e. during the period of minimum ice cover over the Arctic (Figures 1 and 2). Comparison of a long series of AIRS data with in situ methane concentrations at the Zeppelin NILU observatory (Svalbard) show good agreement both in amplitude and phase of seasonal variations. Agreement with Barrow NOAA continuous methane in situ data is much worse, which likely results from lower thermal contrast in winter over the cold and icy surfaces of the Eastern Arctic. Further surface validation is by a comparison of total methane columns with the Sun-Tracking FTIR at Ny-Alesund, Svalbard (TCCON network).
These analyses demonstrate that TIR satellites are capable of detecting Arctic methane enhancements from space, particularly over relatively warm year-round water surfaces such as the BNS. Ongoing research is addressing further verification of retrieved methane columns by collecting data with a cavity ring-down spectroscopy analyzer for methane and carbon dioxide on board of the Russian Research Vessel Akademik Fedorov during the expedition NABOS-2013. Data will be collected to measure marine methane concentrations and vertical fluxes between Norway and the Eastern Arctic (New Siberian Islands) between 20 August and 23 September, 2013.
Figure 1
Figure 2. methane concentrations over the Barents and Norwegian Seas (BNS), over the Kara, Laptev, and East Siberian Seas, and over Eurasia (between 50 and 70 degrees North)
Fossil fuel combustion creates carbon emissions that increase atmospheric thickness, warming climate. The occurrence of wildfire increases with climate warming, increasing soot loading of the atmosphere. Some of this soot is transported through the atmosphere and is deposited on glaciers, lowering their reflectivity, increasing solar energy absorption, increasing melt rates.
In parts of Greenland where winter snow loss during each melt season exposes impurity-rich bare ice, the surface reflectivity drops from 85% to 30%. Consequently, most of the 24-hour sunlight goes into ice melt. In this Dark Zone, the impact of soot manifests strongest in a self-reinforcing feedback loop that research by Jason Box has shown to have doubled melt rates in the past decade.
High on the inland ice sheet where melting is rare, satellite data show surface darkening making the researchers suspect that wildfire and industrial soot are to blame. Darkening here promotes snowpack heating, bringing earlier melt, keeping melt going longer. Here is where this feedback is changing the ice sheet in surprising ways, leading to complete surface melting in year 2012.
To measure the extent to which soot particles enhance melting, Jason Box is organizing a Greenland ice sheet expedition for 2013. The Dark Snow Project expedition is to be the first of its kind, made possible by crowd-source funding.
