HR: 12:10h
AN: OS11B-08    [PDF]
TI: Decadal Variability of Circulation in the Arctic Ocean Retrieved From Climatological Data by Variational Method
AU: Nechaev, D
EM: dnechaev@ssc.usm.edu
AF: University of Southern Mississippi, Department of Marine Science, Stennis Space Center, MS 39529 United States
AU: * Yaremchuk, M
EM: maxy@musashimaru.soest.hawaii.edu
AF: International Pacific Research Center, University of Hawaii, Honolulu, HI 96822 United States
AU: Ikeda, M
EM: mikeda@ees.hokudai.ac.jp
AF: Hokudai University, Department of Earth and Environmental Sciences, Sapporo, 065 Japan
AB: An inverse 3D finite-element ocean circulation model has been designed and used to study variability of the Arctic Ocean circulation in the last four decades. We obtained stationary model solutions with the temperature and salinity fields close to the ones given in the Environmental Working Group (EWG, 1998) Atlas. Transports at the open boundaries, wind forcing and hydrographic fields are treated as unknowns, which are varied to minimize a quadratic cost function subject to model constraints. The inverse problem is solved for ten gridded hydrographic data sets that were obtained as winter and summer averages of EWG data over each of the four decades (50's to 80's) and over the whole period of observations (1948--1993) documented in the Atlas. The results show that Arctic circulation in the last four decades has undergone significant changes, which manifest themselves in a) 10% reduction of the ventilation rate in the Atlantic sector of the Arctic Ocean; b) substantial decrease of the advective heat and freshwater import at the lateral boundaries; c) spinning down of the cyclonic gyre in the northern Greenland sea, which is partly driven by deep convection; d) 3400 km$^3$ increase of the net fresh water storage, with 75% taking place in the Atlantic sector of the Arctic Ocean. Most of these changes are similar to the ones observed on seasonal transition from winter to summer climatologies, and indicate that Arctic Ocean is experiencing a shift towards a warmer state.
DE: 4207 Arctic and Antarctic oceanography
DE: 4215 Climate and interannual variability (3309)
DE: 4255 Numerical modeling
DE: 4512 Currents
DE: 4532 General circulation
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting