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© 2013. American Geophysical Union. All Rights Reserved. Eos, Vol. 94, No. 8, 19 February 2013 PAGE 76 August Arctic cyclone was strongest summer storm on record For nearly 2 weeks in August 2012, a powerful cyclone churned the Arctic Ocean, driving down surface pressures and garnering significant public attention. Spawned over Siberia on 2 August, the storm, which came to be known as the “Great Arctic Cyclone of 2012,” died when it made landfall on the shores of the Canadian High Arctic. Based on observational records, researchers noted at the time that the Great Arctic Cyclone had the lowest sea surface pressure ever recorded for an Arctic summer cyclone. Because the storm coincided with what went on to become the record‐breaking season for minimum Arctic sea ice extent, some researchers questioned whether the storm’s severity may have been fueled by climate change. To identify the dynamics that may have been responsible for the storm’s great strength and longevity—and to determine whether the August 2012 storm really lived up to its moniker— Simmonds and Rudeva used a cyclone analysis algorithm on the records of the National Centers for Environmental Prediction’s Climate Forecast System Reanalysis. Considering the storm’s central pressure, intensity, radius, depth, and longevity, the authors found that the August 2012 cyclone was the strongest summer storm on record and the 13th largest when the typically larger winter cyclones were considered as well. From 1979 to 2012, the length of the reanalysis record, there were 19,625 cyclones. The authors suggest that a tropopause polar vortex, a persistent cyclonic rotation in the upper atmosphere, that formed roughly 2 weeks before the onset of the Great Arctic Cyclone contributed to the storm’s strength. They add that rather than the cyclone being fueled by reduced sea ice extent, the storm instead spurred the ice’s decline. ( Geophysical Research Letters, doi:10.1029/2012GL054259, 2012) —CS New satellite record of sea surface temperature Sea surface temperature is one of the key variables scientists track in studying climate changes; it is also important to meteorology and oceanography. Merchant et al. describe a new 20‐year record of sea surface tempera- ture. The record was created using infrared imagery from the Along‐Track Scanning Radiometers (ATSR) as part of the ATSR Reprocessing for Climate (ARC) project. The new record, the authors report, is more accurate and stable than previous satellite‐ based sea surface temperature records. In addition, the satellite measurements in the new record are independent of in situ measurements and thus provide a valuable corroboration of the in situ record. The authors believe the new data set will be useful for quantifying interannual variability in sea surface temperature as well as major sea surface temperature anomalies. ( Journal of Geophysical Research‐Oceans, doi:10.1029/2012JC008400, 2012) —EB Io’s volcanism controls Jupiter’s magnetospheric activity Jupiter’s volcanic moon Io spews out volcanic gas, which reaches its atmosphere and becomes ionized, forming what is known as the Io plasma torus. This plasma torus can interact with Jupiter’s magneto- sphere, possibly affecting auroral activity there. To help determine whether Io’s volcanic activity affects Jupiter’s magneto- sphere, Yoneda et al. analyzed ground‐based observations of Jupiter’s sodium nebula, which provides an indication of Io’s volcanic activity and plasma content in the Io plasma torus, along with satellite‐based measure- ments of the radio emission called hectomet- ric (HOM) emission, which is a sign of Jupiter’s auroral activity. The researchers observed that Jupiter’s sodium nebula was enhanced in late May through early June 2007, indicating that Io’s volcanic activity increased during that period. They observed that shortly after this enhance- ment began, Jupiter’s HOM emission intensity decreased. As a result, the authors conclude that increased volcanic activity on Io lessens auroral activity in Jupiter’s magnetosphere. ( Geophysical Research Letters, doi:10.1002/ grl.50095, 2013) —EB Seabirds influence Arctic methane and nitrous oxide emissions Seabird activity is contributing significantly to methane and nitrous oxide emissions in the Arctic tundra, a new study shows. Methane emissions, which play an important role in the global carbon cycle, and nitrous oxide fluxes, a key element in the nutrient cycle, are predicted to increase in the Arctic and contribute to Arctic warming in the near future. To study the effects of seabird activity on variations in nitrous oxide and methane fluxes from the tundra to the atmosphere, Zhu et al . compared fluxes from a seabird sanctuary and two non‐seabird colonies on Ny‐Ålesund, Svalbard, Norway. They found that seabird activity was a major factor in these emissions. Mean fluxes of nitrous oxide were about 18 micrograms per square meter per hour at the seabird sites, compared with about 8 micrograms per square meter per hour at the tundra sites without seabirds. For methane, seabird activity actually changed the tundra from a methane sink to a source: mean fluxes of methane were about 53 micrograms per square meter per hour at the seabird sites and about ‐83 micrograms per square meter per hour at the sites without seabirds. The researchers considered other factors that could influence methane and nitrous oxide emissions, including soil moisture and temperature. However, they found that seabird activity was the predominant factor in controlling the flux of these gases from the tundra to the atmosphere. They concluded that sites with high seabird activity are likely to be hotspots of methane and nitrous oxide emissions. ( Journal of Geophysical Research‐ Biogeosciences, doi:10.1029/2012JG002130, 2012) —EB — ERNIE BALCERAK, Staff Writer, and COLIN SCHULTZ, Writer Average distribution of sea surface temperature in the month of October, from 20 years of satellite data. Renbin Zhu A seabird sanctuary, located at Ny-Ålesund (78° 55′′N, 11° 56′E) on the western coast of Spitsbergen, Svalbard, in the High Arctic region. In this sanctuary, the active main species of seabirds include Arctic duck, razor-billed auk, and kittiwake.
