scholarly journals Anomalous Oceanic Conditions in the Central and Eastern North Pacific Ocean during the 2014 Hurricane Season and Relationships to Three Major Hurricanes

2020 ◽  
Vol 8 (4) ◽  
pp. 288
Author(s):  
Victoria L. Ford ◽  
Nan D. Walker ◽  
Iam-Fei Pun

The 2014 Northeast Pacific hurricane season was highly active, with above-average intensity and frequency events, and a rare landfalling Hawaiian hurricane. We show that the anomalous northern extent of sea surface temperatures and anomalous vertical extent of upper ocean heat content above 26 °C throughout the Northeast and Central Pacific Ocean may have influenced three long-lived tropical cyclones in July and August. Using a variety of satellite-observed and -derived products, we assess genesis conditions, along-track intensity, and basin-wide anomalous upper ocean heat content during Hurricanes Genevieve, Iselle, and Julio. The anomalously northern surface position of the 26 °C isotherm beyond 30° N to the north and east of the Hawaiian Islands in 2014 created very high sea surface temperatures throughout much of the Central Pacific. Analysis of basin-wide mean conditions confirm higher-than-average storm activity during strong positive oceanic thermal anomalies. Positive anomalies of 15–50 kJ cm−2 in the along-track upper ocean heat content for these three storms were observed during the intensification phase prior to peak intensity, advocating for greater understanding of the ocean thermal profile during tropical cyclone genesis and development.

2020 ◽  
Vol 33 (3) ◽  
pp. 1031-1050 ◽  
Author(s):  
Cheng-Hsiang Chih ◽  
Chun-Chieh Wu

AbstractThe statistical relationships between tropical cyclones (TCs) with rapid intensification (RI) and upper-ocean heat content (UOHC) and sea surface temperature (SST) from 1998 to 2016 in the western North Pacific are examined. RI is computed based on four best track datasets in the International Best Track Archive for Climate Stewardship (IBTrACS). The statistical analysis shows that the UOHC and SST are higher in the RI duration than in non-RI duration. However, TCs with high UOHC/SST do not necessarily experience RI. In addition, the UOHC and SST are lower in the storm inner-core region due to storm-induced ocean cooling, and the UOHC reduces more significantly than the SST along the passages of TCs in the lower-latitude regions. Moreover, most of the RI (non-RI) duration is associated with the higher (lower) UOHC, but this is not the case for the SST pattern. Meanwhile, the TC intensification rate during the RI period does not appear to be sensitive to the SST, but shows statistically significant differences in the UOHC. In addition, there is a statistically significant increasing trend in the UOHC underlying TCs from 1998 to 2016. It is also noted that the percentages of the TCs with RI show different polynomial and linear trends based on different calculations of the RI events and RI durations. Finally, it is shown that there is no statistically significant difference in the UOHC, SST, and the percentage of RI among the five categories of ENSO events (i.e., strong El Niño, weak El Niño, neutral, weak La Niña, and strong La Niña).


2019 ◽  
Vol 32 (10) ◽  
pp. 3005-3023 ◽  
Author(s):  
Martha W. Buckley ◽  
Tim DelSole ◽  
M. Susan Lozier ◽  
Laifang Li

Abstract Understanding the extent to which Atlantic sea surface temperatures (SSTs) are predictable is important due to the strong climate impacts of Atlantic SST on Atlantic hurricanes and temperature and precipitation over adjacent landmasses. However, models differ substantially on the degree of predictability of Atlantic SST and upper-ocean heat content (UOHC). In this work, a lower bound on predictability time scales for SST and UOHC in the North Atlantic is estimated purely from gridded ocean observations using a measure of the decorrelation time scale based on the local autocorrelation. Decorrelation time scales for both wintertime SST and UOHC are longest in the subpolar gyre, with maximum time scales of about 4–6 years. Wintertime SST and UOHC generally have similar decorrelation time scales, except in regions with very deep mixed layers, such as the Labrador Sea, where time scales for UOHC are much larger. Spatial variations in the wintertime climatological mixed layer depth explain 51%–73% (range for three datasets analyzed) of the regional variations in decorrelation time scales for UOHC and 26%–40% (range for three datasets analyzed) of the regional variations in decorrelation time scales for wintertime SST in the extratropical North Atlantic. These results suggest that to leading order decorrelation time scales for UOHC are determined by the thermal memory of the ocean.


2017 ◽  
Vol 74 (2) ◽  
pp. 219-238 ◽  
Author(s):  
Junqiao Feng ◽  
Fei-fei Jin ◽  
Dunxin Hu ◽  
Shoude Guan

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