Volume and heat transports in the world oceans from an ocean general circulation model

Abstract

ABSTRACT.Monitoring the volume and heat transports around the world oceans is of fundamental importance in the study of the climate system, its variability, and possible changes. The application of an Oceanic General Circulation Model for climatic studies needs that its dynamic and thermodynamic fields are in equilibrium. The time spent by the model to reach this equilibrium is called spin-up time. This work presents some results obtained from the application of the Modular Ocean Model version 4.0 initialized with temperature, salinity, velocity and sea surface height data already in equilibrium from an ocean data assimilation experiment conducted by Geophysical Fluid Dynamics Laboratory (GFDL). The use of this dataset as initial condition aimed to diminish the spin-up time of the oceanic model. The model was integrated for seven years. Volume and heat transports in different sections around the world oceans showed to be in good agreement with the literature. The results showed a well defined seasonal cycle starting at the second integration year, also some important dynamic and thermodynamic aspects of the Global Ocean Circulation, as the great conveyor belt, are well reproduced. The obtained results could constitute an important data source to be used as initial and boundary conditions in regional ocean model experiments as well as for long integration runs in order to study oceanic climate variability.Keywords: ocean climate, computational modeling, volume transport, heat transport. RESUMO.O monitoramento dos transportes de volume e calor nos oceanosé de fundamental importância para o estudo do sistema climático, sua variabilidade e possíveis mudanças. A aplicação de Modelos de Circulação Global dos Oceanos em estudos climáticos necessita que os dados dinâmicos e termodinâmicos gerados pelos mesmos se encontrem em equilíbrio. Esse trabalho apresenta alguns resultados obtidos a partir da aplicação do Modular Ocean Model , em sua versão 4.0, inicializado com campos de temperatura, salinidade, velocidade e elevação da superfície livre em equilíbrio, oriundos do experimento de assimilação de dados oceânicos conduzido pelo Geophysical Fluid Dynamics Laboratory (GFDL). O uso desse conjunto de dados objetivou a diminuição do tempo de "spin-up" do modelo oceânico utilizado. O modelo foi integrado por sete anos, ao fim dos quais foram estimados transportes de volume e calor em diferentes seções ao redor do globo. Tais estimativas demonstraram boa concordância com valores estimados em trabalhos anteriores. Os resultados demonstraram a ocorrência de um ciclo sazonal oceânico bem definido a partir do segundo ano de integração do modelo, assim como importantes aspectos da circulação oceânica global como o "conveyor belt", os giros subtropicais oceânicos e o escoamento associadoà Corrente Circumpolar Antártica. O experimento realizado demonstrou a importância desse modelo como fonte de dados a ser utilizado como condições iniciais e de contorno em modelos regionais de circulação oceânica, assim como para longas integrações...

FORTE 2.0: a fast, parallel and flexible coupled climate model

“…Transport through Drake Passage weakens rapidly from an initial value of > 160 Sv, and from the year 200 it settles around 110-115 Sv. This is lower than the recent observation-based estimate of 173 Sv (Donohue et al, 2016) or previous estimated values of around 130-140 Sv (e.g. Cunningham et al, 2003) but within the range seen in other coupled climate models (Beadling et al, 2020).…”

Persistent meanders and eddies lead to quasi-steady Lagrangian transport patterns in a weak western boundary current

“…The method to compute climatological Lagrangian coherent structures (cLCS) was developed recently by Duran et al 26 and has been used to extract important Lagrangian transport patterns from large velocity time series. Pattern identification include (1) isolated regions where trajectories are unlikely to leave or enter; (2) regions that attract nearby parcels of water and therefore are more susceptible to pollution impacts; and (3) recurrent transport patterns. Some recent studies have shown the relevance of cLCS.…”

FORTE 2.0: a fast, parallel and flexible coupled climate model

“…Globally, the OHT reaches 1.4 PW, instead of the 2.1 ± 0.3 PW computed by Trenberth and Caron (2001). Over the Southern Ocean (35-65°S) OHT is northward, a characteristic seen previously in MOM-based ocean models (de Freitas Assad et al, 2009). This may be related to the strong warm SST bias present over region 40-60°S ( Fig.…”