scholarly journals Impacts of the Wave-Dependent Sea Spray Parameterizations on Air–Sea–Wave Coupled Modeling under an Idealized Tropical Cyclone

2021 ◽  
Vol 9 (12) ◽  
pp. 1390
Author(s):  
Xingkun Xu ◽  
Joey J. Voermans ◽  
Qingxiang Liu ◽  
Il-Ju Moon ◽  
Changlong Guan ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Thermal Effects ◽  
Wind Wave ◽  
Numerical Models ◽  
Heat Fluxes ◽  
Sea Spray ◽  
Local Wind ◽  
Coupled Modeling ◽  
Sea Level Pressure ◽  
Sea Wave

While sea spray can significantly impact air–sea heat fluxes, the effect of spray produced by the interaction of wind and waves is not explicitly addressed in current operational numerical models. In the present work, the thermal effects of the sea spray were investigated for an idealized tropical cyclone (TC) through the implementation of different sea spray models into a coupled air–sea–wave numerical system. Wave-Reynolds-dependent and wave-steepness-dependent sea spray models were applied to test the sensitivity of local wind, wave, and ocean fields of this TC system. Results show that while the sensible heat fluxes decreased by up to 231 W m−2 (364%) and 159 W m−2 (251%), the latent heat fluxes increased by up to 359 W m−2 (89%) and 263 W m−2 (76%) in the simulation period, respectively. This results in an increase of the total heat fluxes by up to 135 W m−2 (32%) and 123 W m−2 (30%), respectively. Based on different sea spray models, sea spray decreases the minimum sea level pressure by up to 7 hPa (0.7%) and 8 hPa (0.8%), the maximum wind speed increases by up to 6.1 m s−1 (20%) and 5.7 m s−1 (19%), the maximum significant wave height increases by up to 1.1 m (17%) and 1.6 m (25%), and the minimum sea surface temperature decreases by up to 0.2 °C (0.8%) and 0.15 °C (0.6%), respectively. As the spray has such significant impacts on atmospheric and oceanic environments, it needs to be included in TC forecasting models.

scholarly journals The Application of Barnes Filter to Positioning the Center of Landed Tropical Cyclone in Numerical Models

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Haibo Zou ◽  
Shanshan Wu ◽  
Xueting Yi ◽  
Nan Wu
Keyword(s):  
Numerical Model ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Numerical Models ◽  
Small Scale ◽  
Model Output ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Distance Difference

After a tropical cyclone (TC) making landfall, the numerical model output sea level pressure (SLP) presents many small-scale perturbations which significantly influence the positioning of the TC center. To fix the problem, Barnes filter with weighting parameters C=2500 and G=0.35 is used to remove these perturbations. A case study of TC Fung-Wong which landed China in 2008 shows that Barnes filter not only cleanly removes these perturbations, but also well preserves the TC signals. Meanwhile, the centers (track) obtained from SLP processed with Barnes filter are much closer to the observations than that from SLP without Barnes filter. Based on the distance difference (DD) between the TC center determined by SLP with/without Barnes filter and observation, statistics analysis of 12 TCs which landed China during 2005–2015 shows that in most cases (about 85%) the DDs are small (between −30 km and 30 km), while in a few cases (about 15%) the DDs are large (greater than 30 km even 70 km). This further verifies that the TC centers identified from SLP with Barnes filter are more accurate compared to that directly obtained from model output SLP. Moreover, the TC track identified with Barnes filter is much smoother than that without Barnes filter.

scholarly journals WIND WAVE FREQUENCIES IN A TROPICAL CYCLONE REGION

1978 ◽  
Vol 1 (16) ◽  
pp. 3
Author(s):  
Rodney J. Sobay
Keyword(s):  
Tropical Cyclone ◽  
Continental Shelf ◽  
Wind Wave ◽  
Wave Climate ◽  
Extreme Value Analysis ◽  
Local Wind ◽  
Value Analysis ◽  
Coral Sea ◽  
Wave Conditions

Australia's Coral Sea coast from Bundaberg north to Cape York has a wind wave climate that is almost unique. The coastline is afforded unparalleled protection from the 1900 km Great Barrier Reef, yet it lies in a tropical cyclone region and must expect recurrent intense wind and wave conditions. The Great Barrier Reef is a continuous chain of quite separate coral reef clusters located near the edge of the continental shelf. The separate reefs are often exposed at low tide, the inner fringe of the clusters ranges from 10 km offshore north of Cairns to 200 km offshore south of Rockhampton and the outer fringe is typically some 50 km further offshore, beyond which the ocean bed drops rapidly away. Incident wave energy from the Coral Sea is invariably dissipated on the outer edge of the Reef and wave conditions on the continental shelf can reasonably be considered due to local wind conditions. The Reef imposes an effective fetch limitations on wave generation over the continental shelf and there is, as a consequence, a moderately rapid response of wave conditions to changes in local wind conditions. A pronounced diurnal variation in the wind climate is reflected also in the wave climate and the stability of the region's tropical climate leads to frequent calm to slight sea conditions. This stability however is occasionally exploded by the generation and passage of a tropical cyclone in mid to late summer. Large waves can be generated by the intense winds of the tropical cyclone (hurricane or typhoon), often an order of magnitude greater than those in response to non-cyclonic events. The rational design of coastal structures and the rational pursuit of coastal zone management requires appropriate estimates of the frequency of occurrence of waves of various heights. Ideally such information is obtained from an extreme value analysis of long term wave records at the particular site in question. Permanent wave recording programs unfortunately have only become common practice in the present decade and wave records, if they exist at all for a particular site, are rarely long enough to allow a satisfactory extreme value analysis. It is clear, in the Australian context at least, that historical wave data alone is not yet sufficient to derive satisfactory estimates of long term wave frequencies. The alternative is system modelling. Wind is a major meteorological variable and its long term recording has been a standard meteorological practice now for over half a century.

scholarly journals A Coupled Atmosphere–Wave–Ocean Modeling System: Simulation of the Intensity of an Idealized Tropical Cyclone

2011 ◽  
Vol 139 (1) ◽  
pp. 132-152 ◽  
Author(s):  
Bin Liu ◽  
Huiqing Liu ◽  
Lian Xie ◽  
Changlong Guan ◽  
Dongliang Zhao
Keyword(s):  
Tropical Cyclone ◽  
Negative Feedback ◽  
Heat Fluxes ◽  
Ocean Modeling ◽  
Sea Surface ◽  
Sea Spray ◽  
Wave Coupling ◽  
Sst Cooling ◽  
Ocean Coupling ◽  
The Impact

Abstract A coupled atmosphere–wave–ocean modeling system (CAWOMS) based on the integration of atmosphere–wave, atmosphere–ocean, and wave–current interaction processes is developed. The component models consist of the Weather Research and Forecasting (WRF) model, the Simulating Waves Nearshore (SWAN) model, and the Princeton Ocean Model (POM). The coupling between the model components is implemented by using the Model Coupling Toolkit. The CAWOMS takes into account various wave-related effects, including wave state and sea-spray-affected sea surface roughness, sea spray heat fluxes, and dissipative heating in atmosphere–wave coupling. It also considers oceanic effects such as the feedback of sea surface temperature (SST) cooling and the impact of sea surface current on wind stress in atmosphere–ocean coupling. In addition, wave–current interactions, including radiation stress and wave-induced bottom stress, are also taken into account. The CAWOMS is applied to the simulation of an idealized tropical cyclone (TC) to investigate the effects of atmosphere–wave–ocean coupling on TC intensity. Results show that atmosphere–wave coupling strengthens the TC system, while the thermodynamic coupling between the atmosphere and ocean weakens the TC as a result of the negative feedback of TC-induced SST cooling. The overall effects of atmosphere–wave–ocean coupling on TC intensity are determined by the balance between wave-related positive feedback and the negative feedback attributable to TC-induced SST cooling.

scholarly journals Contributions of Surface Sensible Heat Fluxes to Tropical Cyclone. Part II: The Sea Spray Processes

2015 ◽  
Vol 72 (11) ◽  
pp. 4218-4236 ◽  
Author(s):  
Zhanhong Ma ◽  
Jianfang Fei ◽  
Xiaoping Cheng ◽  
Yuqing Wang ◽  
Xiaogang Huang
Keyword(s):  
Latent Heat ◽  
Thermal Effects ◽  
Potential Temperature ◽  
Heat Fluxes ◽  
Sea Spray ◽  
Sensible Heat ◽  
Equivalent Potential ◽  
Moisture Effects ◽  
Spray Droplets ◽  
Surface Enthalpy

Abstract In Part II of this study, the roles of surface sensible heat fluxes (SHX) in tropical cyclones (TCs) are further investigated in the context of sea spray processes. Results show that the sea spray evaporation is favorable for the TC intensification through enhancing the surface latent heat fluxes (LHX). Unlike the results in Part I, the removal of SHX has led to a somewhat weaker TC by inclusion of sea spray. This is because the spray-mediated latent heat fluxes are simultaneously diminished after cutting down the SHX. Without the warming of SHX from the ocean, the surface air becomes cooler and thereby closer to saturation, which substantially hinders the evaporation of sea spray droplets. Therefore, the SHX are instrumental for sustaining the release of latent heat fluxes by sea spray evaporation. In the experiments of Part I and this study, the reduced total surface enthalpy fluxes as a result of the removal of SHX do not necessarily result in weakened TCs, while the larger LHX basically correspond to stronger TCs. This suggests that the TC intensity is largely dependent on the LHX rather than the total surface enthalpy fluxes, although the latter is generally dominated by the former. Relative roles of thermal and moisture effects in radially elevating the surface equivalent potential temperature θe are also compared. The contributions of thermal effects account for 30%–35% of the total changes in θe for mature TCs, no matter whether SHX from the ocean are included. This further implies that the SHX contribute insignificantly to the spinup of a TC.

scholarly journals The Effects of Sea Spray and Atmosphere–Wave Coupling on Air–Sea Exchange during Tropical Cyclone

2017 ◽  
Author(s):  
Nikhil Garg ◽  
Yin Kwee Eddie Ng ◽  
Srikanth Narasimalu
Keyword(s):  
Tropical Cyclone ◽  
Numerical Simulations ◽  
Surface Waves ◽  
Momentum Flux ◽  
Ocean Surface ◽  
Heat Fluxes ◽  
Sea Spray ◽  
Sea State ◽  
Ocean Surface Waves ◽  
State Dependent

Abstract. The study investigates the role of air–sea interface using numerical simulations of an Atlantic Hurricane Arthur (2014). More specifically, present study aims to discern the role ocean surface waves and sea spray play in modulating the intensity and structure of a tropical cyclone (TC). To investigate the effects of ocean surface waves and sea spray, numerical simulations were carried out using a coupled atmosphere–wave model where a sea spray microphysical model was incorporated within the coupled model. Furthermore, this study also explores how sea spray generation can be modelled using wave energy dissipation due to whitecaps, where whitecaps are considered as the primary mode of spray droplets generation at hurricane intensity wind speeds. Three different numerical simulations including sea state dependent momentum flux, sea spray mediated heat flux and combination of former two processes with sea spray mediated momentum flux were conducted. The foregoing numerical simulations were evaluated against the National Data Buoy Center (NDBC) buoy and satellite altimeter measurements as well as a control simulation using an uncoupled atmosphere model. The results indicate that the model simulations were able to capture the storm track and intensity, where the surface wave coupling results in a stronger TC. Moreover, it is also noted that when only spray mediated heat fluxes are applied in conjunction with sea state dependent momentum flux, they result in a slightly weaker TC, albeit stronger compared to the control simulation. However, when spray mediated momentum flux is applied together with spray heat fluxes, it results in a comparably stronger TC. The results presented here alludes to the role surface friction plays in intensification of a TC.

scholarly journals The effects of sea spray and atmosphere–wave coupling on air–sea exchange during a tropical cyclone

2018 ◽  
Vol 18 (8) ◽  
pp. 6001-6021 ◽  
Author(s):  
Nikhil Garg ◽  
Eddie Yin Kwee Ng ◽  
Srikanth Narasimalu
Keyword(s):  
Tropical Cyclone ◽  
Numerical Simulations ◽  
Surface Waves ◽  
Momentum Flux ◽  
Ocean Surface ◽  
Heat Fluxes ◽  
Sea Spray ◽  
Sea State ◽  
Ocean Surface Waves ◽  
State Dependent

Abstract. The study investigates the role of the air–sea interface using numerical simulations of Hurricane Arthur (2014) in the Atlantic. More specifically, the present study aims to discern the role ocean surface waves and sea spray play in modulating the intensity and structure of a tropical cyclone (TC). To investigate the effects of ocean surface waves and sea spray, numerical simulations were carried out using a coupled atmosphere–wave model, whereby a sea spray microphysical model was incorporated within the coupled model. Furthermore, this study also explores how sea spray generation can be modelled using wave energy dissipation due to whitecaps; whitecaps are considered as the primary mode of spray droplets generation at hurricane intensity wind speeds. Three different numerical simulations including the sea- state-dependent momentum flux, the sea-spray-mediated heat flux, and a combination of the former two processes with the sea-spray-mediated momentum flux were conducted. The foregoing numerical simulations were evaluated against the National Data Buoy Center (NDBC) buoy and satellite altimeter measurements as well as a control simulation using an uncoupled atmosphere model. The results indicate that the model simulations were able to capture the storm track and intensity: the surface wave coupling results in a stronger TC. Moreover, it is also noted that when only spray-mediated heat fluxes are applied in conjunction with the sea-state-dependent momentum flux, they result in a slightly weaker TC, albeit stronger compared to the control simulation. However, when a spray-mediated momentum flux is applied together with spray heat fluxes, it results in a comparably stronger TC. The results presented here allude to the role surface friction plays in the intensification of a TC.

scholarly journals Tropical cyclone simulations over Bangladesh at convection permitting 4.4 km & 1.5 km resolution

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hamish Steptoe ◽  
Nicholas Henry Savage ◽  
Saeed Sadri ◽  
Kate Salmon ◽  
Zubair Maalick ◽  
...  
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Tropical Cyclones ◽  
Weather Forecasting ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Level Pressure ◽  
Medium Range ◽  
Gust Speed

AbstractHigh resolution simulations at 4.4 km and 1.5 km resolution have been performed for 12 historical tropical cyclones impacting Bangladesh. We use the European Centre for Medium-Range Weather Forecasting 5th generation Re-Analysis (ERA5) to provide a 9-member ensemble of initial and boundary conditions for the regional configuration of the Met Office Unified Model. The simulations are compared to the original ERA5 data and the International Best Track Archive for Climate Stewardship (IBTrACS) tropical cyclone database for wind speed, gust speed and mean sea-level pressure. The 4.4 km simulations show a typical increase in peak gust speed of 41 to 118 knots relative to ERA5, and a deepening of minimum mean sea-level pressure of up to −27 hPa, relative to ERA5 and IBTrACS data. The downscaled simulations compare more favourably with IBTrACS data than the ERA5 data suggesting tropical cyclone hazards in the ERA5 deterministic output may be underestimated. The dataset is freely available from 10.5281/zenodo.3600201.

scholarly journals The Effect of Atmosphere–Ocean Coupling on the Structure and Intensity of Tropical Cyclone Bejisa in the Southwest Indian Ocean

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 688
Author(s):  
Soline Bielli ◽  
Christelle Barthe ◽  
Olivier Bousquet ◽  
Pierre Tulet ◽  
Joris Pianezze
Keyword(s):  
Tropical Cyclone ◽  
Mixed Layer ◽  
Heat Fluxes ◽  
Sea Surface ◽  
Ocean Mixed Layer ◽  
Surface Cooling ◽  
Southwest Indian Ocean ◽  
Left Hand ◽  
Sea Surface Cooling ◽  
The Impact

A set of numerical simulations is relied upon to evaluate the impact of air-sea interactions on the behaviour of tropical cyclone (TC) Bejisa (2014), using various configurations of the coupled ocean-atmosphere numerical system Meso-NH-NEMO. Uncoupled (SST constant) as well as 1D (use of a 1D ocean mixed layer) and 3D (full 3D ocean) coupled experiments are conducted to evaluate the impact of the oceanic response and dynamic processes, with emphasis on the simulated structure and intensity of TC Bejisa. Although the three experiments are shown to properly capture the track of the tropical cyclone, the intensity and the spatial distribution of the sea surface cooling show strong differences from one coupled experiment to another. In the 1D experiment, sea surface cooling (∼1 ∘C) is reduced by a factor 2 with respect to observations and appears restricted to the depth of the ocean mixed layer. Cooling is maximized along the right-hand side of the TC track, in apparent disagreement with satellite-derived sea surface temperature observations. In the 3D experiment, surface cooling of up to 2.5 ∘C is simulated along the left hand side of the TC track, which shows more consistency with observations both in terms of intensity and spatial structure. In-depth cooling is also shown to extend to a much deeper depth, with a secondary maximum of nearly 1.5 ∘C simulated near 250 m. With respect to the uncoupled experiment, heat fluxes are reduced from about 20% in both 1D and 3D coupling configurations. The tropical cyclone intensity in terms of occurrence of 10-m TC wind is globally reduced in both cases by about 10%. 3D-coupling tends to asymmetrize winds aloft with little impact on intensity but rather a modification of the secondary circulation, resulting in a slight change in structure.

Field observations of sea spray under Tropical Cyclone Olwyn

2020 ◽  
Vol 70 (11) ◽  
pp. 1439-1448
Author(s):  
Hongyu Ma ◽  
Alexander V. Babanin ◽  
Fangli Qiao
Keyword(s):  
Tropical Cyclone ◽  
Sea Spray ◽  
Field Observations

scholarly journals Analysis of Atmospheric and Ionospheric Variations Due to Impacts of Super Typhoon Mangkhut (1822) in the Northwest Pacific Ocean

2021 ◽  
Vol 13 (4) ◽  
pp. 661
Author(s):  
Mohamed Freeshah ◽  
Xiaohong Zhang ◽  
Erman Şentürk ◽  
Muhammad Arqim Adil ◽  
B. G. Mousa ◽  
...  
Keyword(s):  
Wind Speed ◽  
Pacific Ocean ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Northwest Pacific ◽  
Northwest Pacific Ocean ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Super Typhoon ◽  
The Northwest Pacific Ocean

The Northwest Pacific Ocean (NWP) is one of the most vulnerable regions that has been hit by typhoons. In September 2018, Mangkhut was the 22nd Tropical Cyclone (TC) over the NWP regions (so, the event was numbered as 1822). In this paper, we investigated the highest amplitude ionospheric variations, along with the atmospheric anomalies, such as the sea-level pressure, Mangkhut’s cloud system, and the meridional and zonal wind during the typhoon. Regional Ionosphere Maps (RIMs) were created through the Hong Kong Continuously Operating Reference Stations (HKCORS) and International GNSS Service (IGS) data around the area of Mangkhut typhoon. RIMs were utilized to analyze the ionospheric Total Electron Content (TEC) response over the maximum wind speed points (maximum spots) under the meticulous observations of the solar-terrestrial environment and geomagnetic storm indices. Ionospheric vertical TEC (VTEC) time sequences over the maximum spots are detected by three methods: interquartile range method (IQR), enhanced average difference (EAD), and range of ten days (RTD) during the super typhoon Mangkhut. The research findings indicated significant ionospheric variations over the maximum spots during this powerful tropical cyclone within a few hours before the extreme wind speed. Moreover, the ionosphere showed a positive response where the maximum VTEC amplitude variations coincided with the cyclone rainbands or typhoon edges rather than the center of the storm. The sea-level pressure tends to decrease around the typhoon periphery, and the highest ionospheric VTEC amplitude was observed when the low-pressure cell covers the largest area. The possible mechanism of the ionospheric response is based on strong convective cells that create the gravity waves over tropical cyclones. Moreover, the critical change state in the meridional wind happened on the same day of maximum ionospheric variations on the 256th day of the year (DOY 256). This comprehensive analysis suggests that the meridional winds and their resulting waves may contribute in one way or another to upper atmosphere-ionosphere coupling.

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