We investigate mesoscale turbulence (10–1000 km) in the ocean winds over the Kuroshio Extension ( N– N, E– E) using the QuikSCAT data set (November 1999 to October 2009). We calculate the second (D_jj) and third‐order structure functions (D_jjj) and the spatial variance (V_j) as a function of scale r ( denotes, respectively, the longitudinal (divergent) and transverse (vortical) component). The most interesting results of the analysis follow. Although both and measure the turbulent kinetic energy (TKE), we find that is the more robust measure. The spatial variance density (dV_j/dr) has a broad peak near 450 km (close to the midlatitude Rossby radius of deformation). On interannual time scales, TKE correlates well with the El Niño 3.4 index. According to turbulence theory, the kinetic energy cascades downscale (upscale) if (also skewness ) is negative (positive). Our results for the Kuroshio Extension are consistent with a downscale cascade (indicating convergence dominates). Furthermore, classical turbulence theory predicts that and independent of r; however, we find S_L varies strongly with r, from −4 at small scales to −0.3 at large scales. This nonclassical behavior implies strong‐scale interaction, which we attribute to the rapid, and sometimes explosive, growth of storms in the region through baroclinic instability. Finally, we find that S_T (a measure of cyclonic/anticyclonic asymmetry) is positive (cyclonic) and also varies strongly with r, from 4 at small scales to 0.5 at large scales. New turbulence models are needed to explain these results, and that will benefit Weather Prediction and climate modeling.

The climatological monthly gridded World Ocean Atlas 2013 temperature and salinity data and satellite altimeter sea level anomaly data are used to build two altimeter-derived high-resolution real-time upper layer thickness products based on a highly simplified two-layer ocean model of the South China Sea. One product uses the proportional relationship between the sea level anomaly and upper layer thickness anomaly. The other one adds a modified component ( ${\eta }_M^{\prime }$ ) to account for the barotropic and thermodynamic processes that are neglected in the former product. The upper layer thickness, in this work, represents the depth of the main pycnocline, which is defined as the thickness from the sea surface to the 25 kg/m³ isopycnal depth. The mean upper layer thickness in the semi-closed South China Sea is ~120 m and the mean reduced gravity is ~0.073 m/s², which is about one order of magnitude larger than the value obtained in the open deep ocean. The long-term temperature observations from three moored buoys, the conductivity-temperature-depth profiles from three joint cruises, and the Argo measurements from 2006 to 2015 are used to compare and evaluate these two upper layer thickness products. It shows that adding the ${\eta }_M^{\prime }$ component is necessary to simulate the upper layer thickness in some situations, especially in summer and fall in the northern South China Sea.

Coastal wetlands are affected by both natural processes and human activities. In the present study, the impacts of natural processes on wetland area variations along the Jiangsu coast in the East China Sea were investigated using a long-term high-resolution numerical model (55 years from 1955 to 2010) validated by satellite and gauge observations. In our 55-year simulation, a 1.33 km² yr⁻¹ decreasing trend of wetland area as a result of global warming was identified. It was found that the wetland area varied depending on the following temporal scales: intra-seasonal, seasonal, interannual, and decadal. Tides and steric sea level changes are responsible for the intra-seasonal and seasonal wetland variations, respectively. The long-term variations are attributable to the El Niño-Southern Oscillation and Pacific Decadal Oscillation. These basin-scale phenomena cause changes in the local wind patterns along the Jiangsu coast and impact the wetland variation on long-term scales.

The eastern equatorial Pacific exhibits a pronounced westward propagating sea surface temperature annual cycle (SSTAC). The responses of the equatorial Pacific SSTAC to CO2-induced global warming are examined using 15 Coupled Model Intercomparison Project Phase 5 (CMIP5) experiments. The annual cycle patterns of global-warming simulations over 2006-2100 are compared with that of present-day simulations over 1850-2005. We see no statistically significant changes in SSTAC amplitude in the future. A coupled dynamical diagnostic framework is adopted to assess four factors, including the damping rate, phase speed and strength of the annual and semi-annual harmonic forcing of SSTAC. Under global warming, changes relative to the present-day simulations in these four diagnostic factors have a clear multi-model trend. Most coupled models exhibit relatively weaker (an average of 18%) propagation speed, and stronger annual (18%) and semi-annual (39%) external forcing. Half of the models show a relatively stronger (about one time) damping rate, while the rest show a weaker (30%) damping rate. When these four diagnostic factors are further condensed into a dynamical response factor and a forcing factor, it is revealed that the same annual cycle amplitudes with respect to the present-day simulations may result from the compensations in terms of bias in the dynamical response factor and forcing factor under increased CO2-induced warm climate.