Nutrient cycling in Lake Tanganyika is influenced by the tilting of the thermocline (Coulter 1991). Prevailing southeast winds during the four month dry season (May through September) cause the thermocline to rise in the south bringing nutrient rich waters from depth to the surface at the southern end of the lake (Coulter 1991). However, related upwelling events also occur in the north, bringin...

[1] A warming trend has been detected in the world’s oceans in recent decades. The basin-averaged warming, however, shows a complex vertical structure in the Indian and Pacific oceans. Warming in the upper ocean-with maxima near the surfaceaccompanies a strong cooling in the upper thermocline. Analysis of observed data and model solutions from this study reveals that the complex structure is co...

The oscillatory nature of El Ni~ no-Southern Oscillation results from an intricate superposition of near-equilibrium balances and out-of-phase disequilibrium processes between the ocean and the atmosphere. The main objective of the present work is to perform an exhaustive spatiotemporal analysis of the upper ocean heat budget in an ensemble of state-of-the-art ocean assimilation products. We pu...

Accurately capturing the observed mean period of ENSO in general circulation models (GCMs) is often challenging, and it is therefore useful to understand which parameters and processes affect this period. A computationally efficient simulation-based approach is used to extract both the dominant eigenvalues and corresponding eigenvectors of the linearized model from the Zebiak–Cane intermediate-...

The dynamics of El Niño–SouthernOscillation (ENSO) are studied in terms of the balance between energy input from the winds (via wind power) and changes in the storage of available potential energy in the tropical ocean. Presently, there are broad differences in the way global general circulation models simulate the dynamics, magnitude, and phase of ENSO events; hence, there is a need for simple...

Effects of atmospheric intraseasonal oscillations (ISOs) on the Indian Ocean zonal dipole mode (IOZDM) are investigated by analyzing available observations and a suite of solutions to an ocean general circulation model, namely, the Hybrid Coordinate Ocean Model (HYCOM). Data and model solutions for the period 1991–2000 are analyzed, a period that includes two strong IOZDM events, during 1994 an...

Enormous strides have been made towards the goal of operational predictions of seasonal and interannual climate fluctuations, especially as regards the phenomenon El Niño. To initialize models, measurements are available from an impressive array of instruments that monitor the tropical Pacific continually; coupled general circulation models of the ocean and atmosphere are already capable of rep...

A dichotomy exists between rates of nitrogen fixation directly measured by biological techniques, and rates inferred from the geochemical distributions of excess nitrate within the thermocline of the North Atlantic Ocean. Part of the dichotomy relates to the temporal and spatial uncoupling between the event (i.e., nitrogen fixation by diazotrophs) and signal (i.e., excess nitrate (DINxs) in the...

The twentieth-century simulations using by 17 coupled ocean–atmosphere general circulation models (CGCMs) submitted to the Intergovernmental Panel on Climate Change’s Fourth Assessment Report (IPCC AR4) are evaluated for their skill in reproducing the observed modes of Indian Ocean (IO) climate variability. Most models successfully capture the IO’s delayed, basinwide warming response a few mont...

A unique open-ocean upwelling exists in the tropical South Indian Ocean (SIO), a result of the negative wind curl between the southeasterly trades and equatorial westerlies, raising the thermocline in the west. Analysis of in-situ measurements and a model-assimilated dataset reveals a strong influence of subsurface thermocline variability on sea surface temperature (SST) in this upwelling zone....