Modulating Effects of Mesoscale Oceanic Eddies on Sea Surface Temperature Response to Tropical Cyclones Over the Western North Pacific

2018 ◽  
Vol 123 (1) ◽  
pp. 367-379 ◽  
Author(s):  
Zhanhong Ma ◽  
Jianfang Fei ◽  
Xiaogang Huang ◽  
Xiaoping Cheng
2020 ◽  
Vol 33 (21) ◽  
pp. 9129-9143
Author(s):  
Jun Gao ◽  
Haikun Zhao ◽  
Philip J. Klotzbach ◽  
Chao Wang ◽  
Graciela B. Raga ◽  
...  

AbstractThis study examines the possible impact of tropical Indian Ocean (TIO) sea surface temperature anomalies (SSTAs) on the proportion of rapidly intensifying tropical cyclones (PRITC) over the western North Pacific (WNP) during the extended boreal summer (July–November). There is a robust interannual association (r = 0.46) between TIO SSTAs and WNP PRITC during 1979–2018. Composite analyses between years with warm and cold TIO SSTAs confirm a significant impact of TIO SSTA on WNP PRITC, with PRITC over the WNP basin being 50% during years with warm TIO SSTAs and 37% during years with cold TIO SSTAs. Tropical cyclone heat potential appears to be one of the most important factors in modulating the interannual change of PRITC over the WNP with a secondary role from midlevel moisture changes. Interannual changes in these large-scale factors respond to SSTA differences characterized by a tropics-wide warming, implying a possible global warming amplification on WNP PRITC. The possible footprint of global warming amplification of the TIO is deduced from 1) a significant correlation between TIO SSTAs and global mean SST (GMSST) and a significant linear increasing trend of GMSST and TIO SSTAs, and 2) an accompanying small difference of PRITC (~8%) between years with detrended warm and cold TIO SSTAs compared to the difference of PRITC (~13%) between years with nondetrended warm and cold TIO SSTAs. Global warming may contribute to increased TCHP, which is favorable for rapid intensification, but increased vertical wind shear is unfavorable for TC genesis, thus amplifying WNP PRITC.


2007 ◽  
Vol 20 (22) ◽  
pp. 5497-5509 ◽  
Author(s):  
Kerry Emanuel

Abstract Revised estimates of kinetic energy production by tropical cyclones in the Atlantic and western North Pacific are presented. These show considerable variability on interannual-to-multidecadal time scales. In the Atlantic, variability on time scales of a few years and more is strongly correlated with tropical Atlantic sea surface temperature, while in the western North Pacific, this correlation, while still present, is considerably weaker. Using a combination of basic theory and empirical statistical analysis, it is shown that much of the variability in both ocean basins can be explained by variations in potential intensity, low-level vorticity, and vertical wind shear. Potential intensity variations are in turn factored into components related to variations in net surface radiation, thermodynamic efficiency, and average surface wind speed. In the Atlantic, potential intensity, low-level vorticity, and vertical wind shear strongly covary and are also highly correlated with sea surface temperature, at least during the period in which reanalysis products are considered reliable. In the Pacific, the three factors are not strongly correlated. The relative contributions of the three factors are quantified, and implications for future trends and variability of tropical cyclone activity are discussed.


2013 ◽  
Vol 26 (11) ◽  
pp. 3745-3765 ◽  
Author(s):  
Wei Mei ◽  
Claudia Pasquero

Abstract The spatial structure and temporal evolution of the sea surface temperature (SST) anomaly (SSTA) associated with the passage of tropical cyclones (TCs), as well as their sensitivity to TC characteristics (including TC intensity and translation speed) and oceanic climatological conditions (represented here by latitude), are thoroughly examined by means of composite analysis using satellite-derived SST data. The magnitude of the TC-generated SSTA is larger for more intense, slower-moving, and higher-latitude TCs, and it occurs earlier in time for faster-moving and higher-latitude storms. The location of maximum SSTA is farther off the TC track for faster-moving storms, and it moves toward the track with time after the TC passage. The spatial extension of the cold wake is greater for more intense and for slower-moving storms, but its shape is quite independent of TC characteristics. Consistent with previous studies, the calculations show that the mean SSTA over a TC-centered box nearly linearly correlates with the wind speed for TCs below category 3 intensity while for stronger TCs the SSTA levels off, both for tropical and subtropical regions. While the linear behavior is expected on the basis of the more vigorous mixing induced by stronger winds and is derived from a simple mixed-layer model, the level-off for intense TCs is discussed in terms of the dependence of the maximum amplitude of the area-mean SSTA on TC translation speed and depth of the prestorm mixed layer. Finally, the decay time scale of the TC-induced SSTA is shown to be dominated by environmental conditions and has no clear dependence on its initial magnitude and on TC characteristics.


2011 ◽  
Vol 26 (3) ◽  
pp. 371-387 ◽  
Author(s):  
Xiaodong Hong ◽  
Craig H. Bishop ◽  
Teddy Holt ◽  
Larry O’Neill

Abstract This paper examines the sensitivity of short-term forecasts of the western North Pacific subtropical high (WNPSH) and rainfall to sea surface temperature (SST) uncertainty using the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS). A comparison of analyzed SSTs with satellite observations of SST indicates that SST analysis errors are particularly pronounced on horizontal scales from 100 to 200 km, similar to the mesoscale eddy scales in the Kuroshio region. Since significant oceanic variations occur on these scales, it is of interest to examine the effects of representing this small-scale uncertainty with random, scale-dependent perturbations. An SST ensemble perturbation generation technique is used here that enables temporal and spatial correlations to be controlled and produces initial SST fields comparable to satellite observations. The atmospheric model develops large uncertainty in the Korea and Japan area due to the fluctuation in the horizontal pressure gradient caused by the location of the WNPSH. This, in turn, increases the variance of the low-level jet (LLJ) over southeast China, resulting in large differences in the moist transport flux from the tropical ocean and subsequent rainfall. Validation using bin-mean statistics shows that the ensemble forecast with the perturbed SST better distinguishes large forecast error variance from small forecast error variance. The results suggest that using the SST perturbation as a proxy for the ocean ensemble in a coupled atmosphere and ocean ensemble system is feasible and computationally efficient.


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