scholarly journals On the Use of Ocean Dynamic Temperature for Hurricane Intensity Forecasting

2018 ◽  
Vol 33 (2) ◽  
pp. 411-418 ◽  
Author(s):  
Karthik Balaguru ◽  
Gregory R. Foltz ◽  
L. Ruby Leung ◽  
Samson M. Hagos ◽  
David R. Judi
Keyword(s):  
Prediction Models ◽  
Vertical Mixing ◽  
Model Performance ◽  
Heat Content ◽  
Sea Surface ◽  
Surface Cooling ◽  
Hurricane Intensity ◽  
Dynamic Temperature ◽  
Intensity Prediction ◽  
Heat Potential

Abstract Sea surface temperature (SST) and tropical cyclone heat potential (TCHP) are metrics used to incorporate the ocean’s influence on hurricane intensification into the National Hurricane Center’s Statistical Hurricane Intensity Prediction Scheme (SHIPS). While both SST and TCHP serve as useful measures of the upper-ocean heat content, they do not accurately represent ocean stratification effects. Here, it is shown that replacing SST within the SHIPS framework with a dynamic temperature Tdy, which accounts for the oceanic negative feedback to the hurricane’s intensity arising from storm-induced vertical mixing and sea surface cooling, improves the model performance. While the model with SST and TCHP explains about 41% of the variance in 36-h intensity changes, replacing SST with Tdy increases the variance explained to nearly 44%. These results suggest that representation of the oceanic feedback, even through relatively simple formulations such as Tdy, may improve the performance of statistical hurricane intensity prediction models such as SHIPS.

scholarly journals Impact of a Warm Ocean Eddy’s Circulation on Hurricane-Induced Sea Surface Cooling with Implications for Hurricane Intensity

2012 ◽  
Vol 141 (3) ◽  
pp. 997-1021 ◽  
Author(s):  
Richard M. Yablonsky ◽  
Isaac Ginis
Keyword(s):  
Wind Stress ◽  
Storm Track ◽  
Heat Content ◽  
Ocean Model ◽  
Sea Surface ◽  
Surface Cooling ◽  
Hurricane Intensity ◽  
Hurricane Wind ◽  
Hurricane Intensification ◽  
Sea Surface Cooling

Abstract Upper oceanic heat content (OHC) in advance of a hurricane is generally superior to prestorm sea surface temperature (SST) for indicating favorable regions for hurricane intensification and maintenance. OHC is important because a hurricane’s surface winds mix the upper ocean and entrain cooler water into the oceanic mixed layer from below, subsequently cooling the sea surface in the region providing heat energy to the storm. For a given initial SST, increased OHC typically decreases the wind-induced sea surface cooling, and a warm ocean eddy (WCR) has a higher OHC than its surroundings, so conditions typically become more favorable for a hurricane to intensify when the storm’s core encounters a WCR. When considering hurricane intensity, however, one often-neglected aspect of a WCR is its anticyclonic circulation. This circulation may impact the location and magnitude of the hurricane-induced sea surface cooling. Using an ocean model, either prescribed hurricane wind stress or wind stress obtained via coupling to a hurricane model is applied to an initial ocean condition in which the SST is homogeneous, but a WCR is embedded in an otherwise horizontally homogeneous subsurface density field. Based on model experiments, when a WCR is located to the right of the storm track (in the Northern Hemisphere), the interaction of the WCR’s circulation with the hurricane-induced cold wake can cause increased sea surface cooling under the storm core and decreased storm intensity relative to the scenario where no WCR is present at all. Therefore, the presence of a WCR in advance of a hurricane sometimes creates a less favorable condition for hurricane intensification.

scholarly journals Southern Ocean heat storage, reemergence, and winter sea ice decline induced by summertime winds

2020 ◽  
pp. 1-47
Author(s):  
Edward W. Doddridge ◽  
John Marshall ◽  
Hajoon Song ◽  
Jean-Michel Campin ◽  
Maxwell Kelley
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Mixed Layer ◽  
Vertical Mixing ◽  
Heat Content ◽  
Ice Cover ◽  
Sea Surface ◽  
Surface Mixed Layer ◽  
Surface Cooling ◽  
Westerly Winds

AbstractThe observational record shows a substantial 40-year upward trend in summertime westerly winds over the Southern Ocean, as characterised by the Southern Annular Mode (SAM) index. Enhanced summertime westerly winds have been linked to cold summertime sea surface temperature (SST) anomalies. Previous studies have suggested that Ekman transport or upwelling is responsible for this seasonal cooling. Here, another process is presented in which enhanced vertical mixing, driven by summertime wind anomalies, moves heat downwards, cooling the sea surface and simultaneously warming the subsurface waters. The anomalously cold SSTs draw heat from the atmosphere into the ocean, leading to increased depth-integrated ocean heat content. The subsurface heat is returned to the surface mixed layer during the autumn and winter as the mixed layer deepens, leading to anomalously warm SSTs and potentially reducing sea ice cover. Observational analyses and numerical experiments support our proposed mechanism, showing that enhanced vertical mixing produces subsurface warming and cools the surface mixed layer. Nevertheless, the dominant driver of surface cooling remains uncertain; the relative importance of advective and mixing contributions to the surface cooling is model dependent. Modeling results suggest that sea ice volume is more sensitive to summertime winds than sea ice extent, implying that enhanced summertime westerly winds may lead to thinner sea ice in the following winter, if not lesser ice extent. Thus, strong summertime winds could precondition the sea ice cover for a rapid retreat in the following melt season.

scholarly journals Impact of Cyclonic Ocean Eddies on Upper Ocean Thermodynamic Response to Typhoon Soudelor

2019 ◽  
Vol 11 (8) ◽  
pp. 938 ◽  
Author(s):  
Jue Ning ◽  
Qing Xu ◽  
Han Zhang ◽  
Tao Wang ◽  
Kaiguo Fan
Keyword(s):  
Vertical Mixing ◽  
Heat Content ◽  
Mesoscale Eddies ◽  
Upper Ocean ◽  
Surface Cooling ◽  
Ocean Eddies ◽  
Horizontal Advection ◽  
Content Change ◽  
Order Of Magnitude ◽  
The Impact

By using multiplatform satellite datasets, Argo observations and numerical model data, the upper ocean thermodynamic responses to Super Typhoon Soudelor are investigated with a focus on the impact of an ocean cyclonic eddy (CE). In addition to the significant surface cooling inside the CE region, an abnormally large rising in subsurface temperature is observed. The maximum warming and heat content change (HCC) reach up to 4.37 °C and 1.73 GJ/m2, respectively. Moreover, the HCC is an order of magnitude larger than that calculated from statistical analysis of Argo profile data in the previous study which only considered the effects caused by typhoons. Meanwhile, the subsurface warming outside the CE is merely 1.74 °C with HCC of 0.39 GJ/m2. Previous studies suggested that typhoon-induced vertical mixing is the primary factor causing subsurface warming but these studies ignored an important mechanism related to the horizontal advection caused by the rotation and movement of mesoscale eddies. This study documents that the eddy-induced horizontal advection has a great impact on the upper ocean responses to typhoons. Therefore, the influence of eddies should be considered when studying the responses of upper ocean to typhoons with pre-existing mesoscale eddies.

scholarly journals Ocean Surface Anomalies after Strong Winds in the Western Mediterranean Sea

2019 ◽  
Vol 7 (6) ◽  
pp. 182
Author(s):  
Francesco Ragone ◽  
Andrea Meli ◽  
Anna Napoli ◽  
Claudia Pasquero
Keyword(s):  
Mediterranean Sea ◽  
Winter Season ◽  
Heat Content ◽  
Sea Surface Height ◽  
Western Mediterranean ◽  
Sea Surface ◽  
Height Anomaly ◽  
Surface Cooling ◽  
Western Mediterranean Sea ◽  
Wind Events

The Western Mediterranean Sea is often subject to intense winds, especially during the winter season. Intense winds induce surface cooling associated with anomalous ocean heat loss, upwelling and diapycnal mixing. In this study we investigate the overall impact of extreme wind events on the upper ocean in the Western Mediterranean sea using sea surface temperature and sea surface height observational data products over the period 1993–2014. We show that the largest thermal anomaly is observed a couple of days after the intense wind event and that it is dependent on the wind intensity. During winter, when deep water formation occurs, it persists for over a month. During summer, when the thermocline is very shallow, the recovery time scale is typically less than 10 days. The sea surface height signal reaches a minimum in correspondence to the intense wind, and normal conditions recover in about six weeks. Unlike for intense winds in the tropics associated to the passage of tropical cyclones, no long term sea surface height anomaly is observed, indicating that the water column heat content is not significantly modified. The observed recovery times suggest instead the possibility of feedbacks on the dynamics of intense cyclones at sub-monthly time scales.

scholarly journals Further Improvements to the Statistical Hurricane Intensity Prediction Scheme (SHIPS)

2005 ◽  
Vol 20 (4) ◽  
pp. 531-543 ◽  
Author(s):  
Mark DeMaria ◽  
Michelle Mainelli ◽  
Lynn K. Shay ◽  
John A. Knaff ◽  
John Kaplan
Keyword(s):  
Brightness Temperature ◽  
Satellite Altimetry ◽  
Heat Content ◽  
Satellite Observations ◽  
Global Model ◽  
Hurricane Intensity ◽  
East Pacific ◽  
Intensity Prediction ◽  
Time Period ◽  
Prediction Scheme

Abstract Modifications to the Atlantic and east Pacific versions of the operational Statistical Hurricane Intensity Prediction Scheme (SHIPS) for each year from 1997 to 2003 are described. Major changes include the addition of a method to account for the storm decay over land in 2000, the extension of the forecasts from 3 to 5 days in 2001, and the use of an operational global model for the evaluation of the atmospheric predictors instead of a simple dry-adiabatic model beginning in 2001. A verification of the SHIPS operational intensity forecasts is presented. Results show that the 1997–2003 SHIPS forecasts had statistically significant skill (relative to climatology and persistence) out to 72 h in the Atlantic, and at 48 and 72 h in the east Pacific. The inclusion of the land effects reduced the intensity errors by up to 15% in the Atlantic, and up to 3% in the east Pacific, primarily for the shorter-range forecasts. The inclusion of land effects did not significantly degrade the forecasts at any time period. Results also showed that the 4–5-day forecasts that began in 2001 did not have skill in the Atlantic, but had some skill in the east Pacific. An experimental version of SHIPS that included satellite observations was tested during the 2002 and 2003 seasons. New predictors included brightness temperature information from Geostationary Operational Environmental Satellite (GOES) channel 4 (10.7 μm) imagery, and oceanic heat content (OHC) estimates inferred from satellite altimetry observations. The OHC estimates were only available for the Atlantic basin. The GOES data significantly improved the east Pacific forecasts by up to 7% at 12–72 h. The combination of GOES and satellite altimetry improved the Atlantic forecasts by up to 3.5% through 72 h for those storms west of 50°W.

scholarly journals Extreme Sea-Surface Cooling Induced by Eddy Heat Advection During Tropical Cyclone in the North Western Pacific Ocean

2021 ◽  
Vol 8 ◽  
Author(s):  
Chunhua Qiu ◽  
Hong Liang ◽  
Xiujun Sun ◽  
Huabin Mao ◽  
Dongxiao Wang ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Heat Balance ◽  
General Circulation ◽  
Vertical Mixing ◽  
Sea Surface ◽  
Surface Cooling ◽  
Coupled Models ◽  
Heat Advection ◽  
Sea Surface Cooling ◽  
Wave Glider

A tropical cyclone (TC) usually induces strong sea-surface cooling due to vertical mixing. In turn, surface cooling influences the intensities and tracks of TCs. Therefore, the relationship between sea-surface temperature (SST) and TC is one of the important components of air-sea interaction. Sea-surface cooling associated with three TCs (Bailu, Lingling, and Mitag) was investigated based on wave-glider observations, satellite altimetry, and Massachusetts Institute of Technology General Circulation Model (MITgcm) numerical experiments from August 3rd to October 10th, 2019. Surface cooling varied among the three TCs. TC Lingling had the nearest distance to the wave-glider position, the slowest translation speed, and the strongest intensity of three TCs, but extreme cooling (1.4) occurred during TC Bailu. Although MITgcm underestimated the extreme cooling, the SST trend driven by the net heat flux, advection, and vertical mixing within the mixed layer was greater during TC Bailu than during other TCs. Advection was the largest of the three heat balance terms during TC Bailu, while it was quite small during the other two TCs. Interestingly, the extreme cooling occurred at the position of preexisting warm eddy. Based on heat balance analysis, we found that the eddy-induced heat advection transport reached −0.4/day, contributing 60% of the heat balance; this was attributed to extreme cooling via eddy disturbance. We suggest TC Bailu leads to the decrease in SST and increase in the area of the cold eddy, and then, the cooled-enlarged eddy is advected to the neighbored position of wave glider, which observes the extreme cooling. These findings provide the utilization of wave gliders and help improve air-sea coupled models during TCs.

scholarly journals Ocean signature of intense wind events in the Western Mediterranean Sea

2018 ◽  
Author(s):  
Francesco Ragone ◽  
Andrea Meli ◽  
Anna Napoli ◽  
Claudia Pasquero
Keyword(s):  
Mediterranean Sea ◽  
Winter Season ◽  
Heat Content ◽  
Sea Surface Height ◽  
Western Mediterranean ◽  
Sea Surface ◽  
Height Anomaly ◽  
Surface Cooling ◽  
Western Mediterranean Sea ◽  
Wind Events

Abstract. The Western Mediterranean Sea is often subject to intense winds, especially during the winter season. The effects of the enhanced enthalpy and momentum fluxes on the upper ocean is investigated using sea surface temperature and sea surface height observational data products in the period 1993–2014. The maximum surface cooling associated with the anomalous ocean heat loss, with upwelling, and with diapycnal mixing is shown to occur a couple of days after the intense wind event, to be dependent on the wind intensity and to persist for over a month during winter, when deep water is formed, and for about 10 days during summer, when the thermocline is very shallow. The sea surface height signal reaches a minimum in correspondence of the intense wind, and normal conditions recover in about six weeks. Unlike for intense winds in the tropics, associated to tropical cyclones, no long term sea surface height anomaly is observed, indicating that the water column heat content is not significantly modified.

Ocean Response to Successive Typhoons Sarika and Haima (2016) in the Northern South China Sea

2020 ◽  
Author(s):  
Han Zhang
Keyword(s):  
South China Sea ◽  
Mixed Layer ◽  
South China ◽  
Model Simulation ◽  
Heat Budget ◽  
Northern South China Sea ◽  
Heat Content ◽  
Sea Surface ◽  
Surface Cooling ◽  
China Sea

<p>Tropical cyclones (TCs) are natural disasters for coastal regions. TCs with maximum wind speeds higher than 32.7 m/s in the north-western Pacific are referred to as typhoons. Typhoons Sarika and Haima successively passed our moored observation array in the northern South China Sea in 2016. Based on the satellite data, the winds (clouds and rainfall) biased to the right (left) sides of the typhoon tracks. Sarika and Haima cooled the sea surface ~4 and ~2 °C and increased the salinity ~1.2 and ~0.6 psu, respectively. The maximum sea surface cooling occurred nearly one day after the two typhoons. Station 2 (S2) was on left side of Sarika’s track and right side of Haima’s track, which is studied because its data was complete. Strong near-inertial currents from the ocean surface toward the bottom were generated at S2, with a maximum mixed-layer speed of ~80 cm/s. The current spectrum also shows weak signal at twice the inertial frequency (2f). Sarika deepened the mixed layer, cooled the sea surface, but warmed the subsurface by ~1 °C. Haima subsequently pushed the subsurface warming anomaly into deeper ocean, causing a temperature increase of ~1.8 °C therein. Sarika and Haima successively increased the heat content anomaly upper than 160 m at S2 to ~50 and ~100 m°C, respectively. Model simulation of the two typhoons shows that mixing and horizontal advection caused surface ocean cooling, mixing and downwelling caused subsurface warming, while downwelling warmed the deeper ocean. It indicates that Sarika and Haima sequentially modulated warm water into deeper ocean and influenced internal ocean heat budget. Upper ocean salinity response was similar to temperature, except that rainfall refreshed sea surface and caused a successive salinity decrease of ~0.03 and ~0.1 psu during the two typhoons, changing  the positive subsurface salinity anomaly to negative.</p>

scholarly journals The Interaction of Supertyphoon Maemi (2003) with a Warm Ocean Eddy

2005 ◽  
Vol 133 (9) ◽  
pp. 2635-2649 ◽  
Author(s):  
I-I. Lin ◽  
Chun-Chieh Wu ◽  
Kerry A. Emanuel ◽  
I-Huan Lee ◽  
Chau-Ron Wu ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Cold Water ◽  
Sea Surface ◽  
Prediction System ◽  
Ocean Mixed Layer ◽  
Hurricane Intensity ◽  
Ocean Eddies ◽  
Intensity Prediction

Abstract Understanding the interaction of ocean eddies with tropical cyclones is critical for improving the understanding and prediction of the tropical cyclone intensity change. Here an investigation is presented of the interaction between Supertyphoon Maemi, the most intense tropical cyclone in 2003, and a warm ocean eddy in the western North Pacific. In September 2003, Maemi passed directly over a prominent (700 km × 500 km) warm ocean eddy when passing over the 22°N eddy-rich zone in the northwest Pacific Ocean. Analyses of satellite altimetry and the best-track data from the Joint Typhoon Warning Center show that during the 36 h of the Maemi–eddy encounter, Maemi’s intensity (in 1-min sustained wind) shot up from 41 m s−1 to its peak of 77 m s−1. Maemi subsequently devastated the southern Korean peninsula. Based on results from the Coupled Hurricane Intensity Prediction System and satellite microwave sea surface temperature observations, it is suggested that the warm eddies act as an effective insulator between typhoons and the deeper ocean cold water. The typhoon’s self-induced sea surface temperature cooling is suppressed owing to the presence of the thicker upper-ocean mixed layer in the warm eddy, which prevents the deeper cold water from being entrained into the upper-ocean mixed layer. As simulated using the Coupled Hurricane Intensity Prediction System, the incorporation of the eddy information yields an evident improvement on Maemi’s intensity evolution, with its peak intensity increased by one category and maintained at category-5 strength for a longer period (36 h) of time. Without the presence of the warm ocean eddy, the intensification is less rapid. This study can serve as a starting point in the largely speculative and unexplored field of typhoon–warm ocean eddy interaction in the western North Pacific. Given the abundance of ocean eddies and intense typhoons in the western North Pacific, these results highlight the importance of a systematic and in-depth investigation of the interaction between typhoons and western North Pacific eddies.

scholarly journals Ocean Response to Successive Typhoons Sarika and Haima (2016) Based on Data Acquired via Multiple Satellites and Moored Array

2019 ◽  
Vol 11 (20) ◽  
pp. 2360 ◽  
Author(s):  
Han Zhang ◽  
Xiaohui Liu ◽  
Renhao Wu ◽  
Fu Liu ◽  
Linghui Yu ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Model Simulation ◽  
Heat Budget ◽  
Northern South China Sea ◽  
Heat Content ◽  
Sea Surface ◽  
Surface Cooling ◽  
Wind Speeds ◽  
The North ◽  
Salinity Response

Tropical cyclones (TCs) are natural disasters for coastal regions. TCs with maximum wind speeds higher than 32.7 m/s in the north-western Pacific are referred to as typhoons. Typhoons Sarika and Haima successively passed our moored observation array in the northern South China Sea in 2016. Based on the satellite data, the winds (clouds and rainfall) biased to the right (left) sides of the typhoon tracks. Sarika and Haima cooled the sea surface ~4 and ~2 °C and increased the salinity ~1.2 and ~0.6 psu, respectively. The maximum sea surface cooling occurred nearly one day after the two typhoons. Station 2 (S2) was on left side of Sarika’s track and right side of Haima’s track, which is studied because its data was complete. Strong near-inertial currents from the ocean surface toward the bottom were generated at S2, with a maximum mixed-layer speed of ~80 cm/s. The current spectrum also shows weak signal at twice the inertial frequency (2f). Sarika deepened the mixed layer, cooled the sea surface, but warmed the subsurface by ~1 °C. Haima subsequently pushed the subsurface warming anomaly into deeper ocean, causing a temperature increase of ~1.8 °C therein. Sarika and Haima successively increased the heat content anomaly upper than 160 m at S2 to ~50 and ~100 m°C, respectively. Model simulation of the two typhoons shows that mixing and horizontal advection caused surface ocean cooling, mixing and downwelling caused subsurface warming, while downwelling warmed the deeper ocean. It indicates that Sarika and Haima sequentially modulated warm water into deeper ocean and influenced internal ocean heat budget. Upper ocean salinity response was similar to temperature, except that rainfall refreshed sea surface and caused a successive salinity decrease of ~0.03 and ~0.1 psu during the two typhoons, changing the positive subsurface salinity anomaly to negative

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