The link between the Barents Sea and ENSO events reproduced by NEMO model
Abstract. An analysis of observational data in the Barents Sea along a meridian at 33°30´ E between 70°30´ and 72°30´ N has reported a negative correlation between El Niño/La Niña-Southern Oscillation (ENSO) events and water temperature in the top 200 m: the temperature drops about 0.5 °C during warm ENSO events while during cold ENSO events the top 200 m layer of the Barents Sea is warmer. Results from 1 and 1/4-degree global NEMO models show a similar response for the whole Barents Sea. During the strong warm ENSO event in 1997–1998 an anticyclonic atmospheric circulation is settled over the Barents Sea instead of a usual cyclonic circulation. This change enhances heat loses in the Barents Sea, as well as substantially influencing the Barents Sea inflow from the North Atlantic, via changes in ocean currents. Under normal conditions along the Scandinavian peninsula there is a warm current entering the Barents sea from the North Atlantic, however after the 1997–1998 event this current is weakened. During 1997–1998 the model annual mean temperature in the Barents Sea is decreased by about 0.8 °C, also resulting in a higher sea ice volume. In contrast during the cold ENSO events in 1999–2000 and 2007–2008 the model shows a lower sea ice volume, and higher annual mean temperatures in the upper layer of the Barents Sea of about 0.7 °C. An analysis of model data shows that the Barents Sea inflow is the main source for the variability of Barents Sea heat content, and is forced by changing pressure and winds in the North Atlantic. However, surface heat-exchange with atmosphere can also play a dominant role in the Barents Sea annual heat balance, especially for the subsequent year after ENSO events.