Naslov
The importance of the wind stress and wind stress curl for the upwelling along the California coast in June 1999

Autori
Beg Paklar, Gordana ; Koračin, Darko ; Dorman, Clive ; McCord, Travis

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
EARTH: OUR CHANGING PLANET, Proceedings of IUGG XXIV General Assembly, IAMAS / Ubertini, Lucio ; Manciola, Piergiorgio ; Casadei, Stefano - Perugia, 2007

ISBN
978-88-95852-25-4

Skup
IUGG XXIV General Assembly

Mjesto i datum
Perugia, Italija, 02.07.2007. - 13.07.2007

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
numerical modelling; wind stress curl; upwelling

Sažetak
The US northwest Pacific coast is embedded within the California Current System, a classical eastern boundary current and a well-known upwelling area. Recent in situ and satellite data analysis as well as modelling studies reveal complex spatial and temporal variability of the whole system, in which the wind stress is an important driving mechanism. The circulation along the California Coast in June 1999 was influenced by strong upwelling-favourable winds. Wind field was simulated with Mesoscale Model 5 (MM5), whose results were highly correlated with satellite and in situ wind measurements. Detailed analysis of the wind stress and wind stress curl reveal a pattern with positive wind stress curl in a narrow band along the coast and a wide area with negative wind stress curl further offshore, which resulted from spatial distribution of the wind velocity maxima and the changes in the orientation of the coastline. To study the wind-induced circulation and the importance of the wind stress curl, Princeton Ocean Model (POM) was setup for the California and Baja California coasts. MM5 outputs were used for forcing POM with interactively calculated wind stress and heat fluxes. In the basic experiment initial conditions for the temperature field were determined from the sea surface temperature (SST) used in the MM5 simulation with a climatological vertical profile. The initial salinity field was homogeneous and the velocity field was initialised with a state of rest. Modelled surface currents indicate off-shore flow in the deep areas and dominant poleward current in the near-shore area. At the beginning of the month offshore currents are present in the whole domain but the strength of the poleward near-shore current is increasing with time. Besides the basic experiment, several sensitivity studies were performed to study the influence of the wind stress curl, initial density gradients, bottom topography, interaction with deeper ocean and horizontal resolution of the models. The alongshore poleward current obtained in the basic experiment and supported by direct measurements is replaced with equatorward current in the curl-free experiment. Furthermore, a significant temperature drop occurs along the entire coast in the curl-free experiment, whereas the areas of maximum upwelling are limited to the regions with wind maximum in the basic experiment. Modelling results were compared with SST satellite estimates and in situ measurements of temperatures and currents. Hourly SST measured at thirteen NCDC buoys were used to evaluate sensitivity studies by RMS errors of the corresponding model results.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA