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February 2011 Issue

Loss of Reflectivity Doubles Arctic Climate Model Estimates
A new analysis of the Northern Hemisphere's "albedo feedback" over a 30-year period concludes that the region's loss of reflectivity due to snow and sea ice decline is more than double what state-of-the-art climate models estimate.

The findings are important, researchers say, because they suggest that Arctic warming amplified by the loss of reflectivity could be even more significant than previously thought.

The study was published online in late January in Nature Geoscience.

"The cryosphere isn't cooling the Earth as much as it did 30 years ago, and climate model simulations do not reproduce this recent effect," said Karen Shell, an assistant professor at Oregon State University's (OSU) College of Oceanic and Atmospheric Sciences and one of the authors of the study. "Though we don't necessarily attribute this to global warming, it is interesting to note that none of the climate models used for the 2007 International Panel on Climate Change report showed a decrease of this magnitude."

As part of the study, Shell, lead author Mark Flanner of the University of Michigan and their colleagues compared Northern Hemisphere cryosphere changes between 1979 and 2008 in 18 different climate models to changes in actual snow, ice and reflectivity measurements of the same period. They determined that mean radiative forcing—the amount of energy reflected into the atmosphere—ranged from 4.6 to 2.2 watts per square meter.

During the 30-year study period, cryosphere cooling declined by 0.45 watts per square meter. The authors attribute that decline equally to loss of snow and sea ice.

"Some of the decline may be natural climate variability," Shell said. "Thirty years isn't a long enough time period to attribute this entirely to 'forcing,' or anthropogenic influence. But the loss of cooling is significant. The rate of energy being absorbed by the Earth through cryosphere decline—instead of being reflected back to the atmosphere—is almost 30 percent of the rate of extra energy absorption due to carbon dioxide increase between pre-industrial values and today."

The albedo process is simple, scientists say, but difficult to measure on a broad scale. Researchers have discovered that variations in the snow and ice result in different albedo impacts. For example, pools of melted water on top of sea ice can have significantly less reflectivity.

"While the current group of models underestimates these Northern Hemisphere cryosphere changes, new models will be released this year that will have better representations of snow and ice," Shell said. For more information, visit www.nature.com.

New NOAA Buoy to Help Close Gap in Climate Understanding
To better understand the effects of the ocean on climate and weather, scientists from NOAA's Pacific Marine Environmental Laboratory (PMEL) recently deployed an Ocean Climate Station mooring on the edge of the warm Agulhas Return Current (ARC) southeast of South Africa. Although there is an array of climate buoys positioned in the tropics, this is one of only two deep-ocean climate buoys positioned below the Tropic of Capricorn; the other is located south of Australia.

"With this mooring, we will be able to measure how this powerful current warms the atmosphere and some of the effects this has on the local meteorology and climate," said Dr. Meghan Cronin, principal investigator and oceanographer at PMEL. "More heat is released to the atmosphere in the ARC region than anywhere else in the entire Southern Hemisphere. This heating can affect winds, clouds and rainfall over a broad region."

Sensors on the buoy measure wind, air temperature, relative humidity, rain, solar and infrared radiation, barometric pressure, sea-surface temperature and salinity, and near-surface currents.

"The buoy will also carry sensors to measure how much atmospheric carbon dioxide is absorbed into the ocean in this critical region for the global climate system," said Dr. Christopher Sabine, oceanographer at PMEL and participant in the ARC project.

The mooring was deployed at 4,300 meters using the South African Fisheries ship Algoa. Data are relayed to shore in near-real time and made available through PMEL and other climate and weather data centers. For more information, visit www.pmel.noaa.gov.

New ROV For Deep Sea Research
The Leibniz Institute of Marine Sciences (IFM-GEOMAR) in Kiel, Germany, took delivery of a new medium-sized remotely operated vehicle (ROV) named PHOCA in December. Its primary purpose will be to install and maintain the institute's deep-sea observatory, MoLab.

"Two-thirds of the Earth's surface are basically unknown to us, as they are covered by oceans with depths of several kilometers," said Dr. Olaf Pfannkuche, scientific head of the Technology and Logistics Centre of IFM-GEOMAR. "If we want to understand the functioning of the Earth, we need to monitor these two-thirds more intensely and on a long-term time scale. MoLab is an important step into this direction."

PHOCA is a medium-sized work-class Comanche ROV manufactured by Sub-Atlantic Ltd. (Aberdeen, Scotland). It weighs 1.5 tons with an operational working depth of 3,000 meters.

PHOCA was chosen because of its compatibility with the KIEL 6000 ROV, which has been in operation at IFM-GEOMAR since 2007. For example, the winches and umbilicals of both ROVs are interchangeable. Similarly, PHOCA's two manipulators are of the same type as one of KIEL 6000's manipulators, thus minimizing training time for operation and maintenance, the institute said.

Another advantage of PHOCA, IFM-GEOMAR said, is that it can be deployed off small institute research vessels like RV Poseidon or RV Alkor.

The new ROV will at first be primarily used for installation and maintenance of the modular multidisciplinary underwater observatory MoLab, developed at IFM-GEOMAR.

The first sea trials for MoLab and the new ROV are expected to take place this spring. For more information, visit www.ifm-geomar.de.


2012:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC
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