Cyclonic Wind Stress Curl Research Articles

Feedback Mechanism Among Decadal Oscillations in Northern Hemisphere Atmospheric Circulation, Sea Ice, and Ocean Circulation

Decadal oscillations of the ice cover in the Barents Sea are examined for the period since 1950. They are highly correlated with atmospheric circulation when that circulation has an anomalous low pressure over the Barents Sea and Eurasian Basin, while the ice cover is weakly correlated with local air temperature. A feedback mechanism between Barents Sea ice and the atmospheric circulation is suggested; increased cyclonic wind-stress curl reduces cold Arctic flow to the Barents Sea and reduces the sea ice. The reduced ice cover encourages heat flux from the Barents Sea to the atmosphere, tending to reinforce the low pressure. This positive feedback amplifies the oscillations of the air–ice–ocean system driven by external forcing with relatively weak decadal variability. A two-level ocean model, which is driven by prescribed buoyancy flux and wind stresses, confirms that Arctic outflow to the Barents Sea decreases during a cyclonic wind stress.

Interannual Fluctuations of the Tropical Pacific Wind Field and the Southern Oscillation

Abstract Linear regression analysis of tropical Pacific winds versus a Southern Oscillation Index (SOI) show departures from the seasonal mean wind associated with the phase of SOI. When the SOI is low the largest departures are westerlies on the equator and in the subtropics west of the dateline. The Intertropical Convergence Zone (ITCZ) and the South Pacific Convergence Zone (SPCZ) shift equatorward. Departures from mean wind are strongest from September through February and weakest from March to May. The usual pattern of cyclonic wind stress curl in the tropics and anticyclonic wind stress curl in the subtropics intensifies when the SOI is low. Effects of these changes on ocean circulation are discussed and compared to changes in ocean circulation data.

Wind Generation of the Costa Rica Dome

Upwelling in the Costa Rica Dome is seasonal and the result of the localized cyclonic wind stress curl. Fluctuations in the wind stress curl in the fall release the upwelled region as a Rossby wave. Similar low-latitude domes are hypothesized to be ubiquitous to those oceans where a localized cyclonic wind stress curl is associated with an Intertropical Convergence Zone.

The Thermocline Response to Transient Atmospheric Forcing in the Interior Midlatitude North Pacific 1976–1978

Abstract The Ekman pumping mechanism for altering the depth of the main thermocline in response to wind stress curl is tested in the central midlatitude North Pacific. According to this mechanism, the depth of the main thermocline should decrease under cyclonic wind stress curl and increase under anticyclonic wind stress curl. For the two years 1976–78, temperature measurements from an XBT measurement program between North America and Japan have allowed the monthly thermal structure to be measured over an area 30–50°N, 130–170°W, accompanied with synoptic estimates of wind stress curl. Working with anomalous estimates that deviate from the normal seasonal cycle, the month-to-month secular change in the depth of the main thermocline during the nine months of each year from February to October is found to have responded to the anomalous wind stress curl according to what was expected from the Ekman pumping mechanism. The expected and observed secular changes in the thermocline depth for these times of the y...