HR: 08:45h
AN: C31B-04    [Abstracts]
TI: Evidence for Recent Surface/Atmosphere Feedbacks in the East Siberian Sea during Spring
AU: * Overland, J E
EM: james.e.overland@noaa.gov
AF: NOAA/Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AU: Bond, N A
EM: nicholas.bond@noaa.gov
AF: JISAO/University of Washington, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AU: Wang, M
EM: muyin.wang@noaa.gov
AF: JISAO/University of Washington, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AB: Arctic climate responds to multiple factors including intrinsic variability in atmospheric circulation, internal feedbacks and external forcing, in unknown proportion. The present analysis quantifies the contribution of the anomalous atmospheric circulation relative to the anomalous surface heating for the East Siberian Sea during the springs (March-May) of 200-2005, a period of surface air temperatures that were 4-6 C warmer than normal. The circulation for this period featured an anomalous lower to middle tropospheric high pressure ridge extending from Alaska to the North Pole and a low pressure trough extending from the Sea of Okhotsk to west-central Siberia. This geopotential height anomaly pattern bears little resemblance to either of the two main modes of northern hemispheric climate variability, the Arctic Oscillation or its Pacific counterpart, the Pacific North American pattern. Horizontal temperature advection due to the anomalous southerly flow accounts for roughly 10 W/m2 of anomalous heating in the East Siberian Sea. This heating appears to have been reinforced in the planetary boundary layer by anomalous surface heating of roughly 10-20 W/m2, which is consistent with systematically thin sea ice in recent springs. Increased temperatures in the lower atmosphere have an impact on the motion field through the thermal wind effect. An interesting implication is that the atmosphere may be more sensitive to thin ice conditions in spring than to ice-free conditions in summer. The large-scale atmospheric circulation could shift back to a pattern favoring northerly flow anytime in the future; it will be interesting to see the regional response in sea ice and surface temperature if this happens.
DE: 1610 Atmosphere (0315, 0325)
DE: 1621 Cryospheric change (0776)
DE: 3307 Boundary layer processes
DE: 3349 Polar meteorology
DE: 9315 Arctic region (0718, 4207)
SC: Cryosphere [C]
MN: Fall Meeting 2005