Passage Of Cyclone Research Articles

Response of Air–Sea Fluxes and Oceanic Features to the Coupling of Ocean–Atmosphere–Wave During the Passage of a Tropical Cyclone

A coupled ocean–atmosphere–wave model was used to assess the impact of model coupling on the simulations of air–sea fluxes, surface currents, waves, and temperature profile during the passage of a tropical cyclone (TC) Phailin in the Bay of Bengal. Four numerical experiments with different coupling configurations among the atmosphere, ocean, and wave models were carried out to identify differences in simulated atmospheric and oceanic parameters. The simulated track and intensity of Phailin agree well with the observations. The inter-comparison of model experiments with different coupling options highlights the importance of better air–sea fluxes in the coupled model as compared to the uncoupled model towards an improvement in the simulation of TC Phailin. The coupled model configurations overcome the cold bias (up to − 2 °C) in sea surface temperature simulated by the uncoupled ocean model. A higher magnitude of the surface drag coefficient in the uncoupled atmosphere model enhanced the bottom stress (> 2 N m−2). As a result of excess momentum transfer to the sea surface, the uncoupled ocean model produced stronger surface currents as compared to the coupled model. The inclusion of the wave model increases the sea surface roughness and, thereby, improves the wind speed and momentum flux at the air–sea interface. The maximum significant wave height in the coupled model was about 2 m lower than the uncoupled wave model. The model experiments demonstrate that the periodic feedback among the atmosphere, ocean, and wave models leads to a better representation of momentum and heat fluxes that improves the prediction of a tropical cyclone.

Response of Gamma-Ray Spectrum During Ockhi Cyclone

Cyclone Ockhi hit Sri Lanka and southern parts of India in Nov-Dec 2017 with a devastating social impact. The present paper reports that the cyclone had a significant effect on the γ-ray flux measured by NaI (Tl) detector. An overall decrease is observed in the γ-ray flux during the passage of cyclone; however, a detailed investigation revealed that different energies show varying results. In the energy range between 250 keV – 450 keV, a decrease up to ~ 14% is observed, whereas an increase up to ~ 45% is observed in the energy range between 600 keV – 2.7 MeV. The energies above 2.7 MeV do not show any change. This is the first-ever observation of the varying effects of the cyclone with the energy bands of the γ-ray spectrum. We found that the increase observed in the energy range of 600 keV – 2.7 MeV is primarily associated with the increase in the terrestrial radioactivity (peaks of Rn-222 daughters), which is due to the rainfall brought over by the cyclone. The high energy γ-rays originating from cosmic ray are not affected due to the cyclone. The study indicates that the decrease in the lower energy range of the γ-ray flux could be due to the attenuation caused by the increased tropospheric air-mass associated with the cyclone over the observation site.

Using networked Pandora observations to capture spatiotemporal changes in total column ozone associated with stratosphere-to-troposphere transport

Accurately capturing the evolution of episodic stratosphere-to-troposphere transport is critical due to the potential impacts on both climate and air quality. Until now, investigating associated spatiotemporal gradients in total column ozone (TCO) has primarily been the task of observations from polar-orbiting satellites as well as high-resolution models. We explore how a network of five ground-based Pandora spectrometer systems can be utilized in a similar fashion. The passage of a strong mid-latitude cyclone in March 2018 and its associated stratospheric intrusion is used as a case demonstrating the ability of networked Pandora observations to contextualize these regions of transport across space and time. Results show that the high temporal resolution of Pandora observations and the networked approach were able to resolve increases in TCO associated with stratosphere-to-troposphere transport and to capture the spatial context of the chosen episode. The use of networked Pandora observations shows promise for additional transport studies and for supporting future geostationary atmospheric composition satellite missions and modeling efforts.

A coupled model analyses on the interaction between oceanic eddies and tropical cyclones over the Bay of Bengal

The Bay of Bengal (BOB) region of Indian Ocean is affected by numerous tropical cyclones during pre- and post-monsoon seasons when various eddies are generated in the central and western bay. Here, numerical simulations of few tropical cyclones (Aila, Laila, Phailin, Hudhud and Madi) that occurred in different seasons are carried out using an ocean atmosphere coupled numerical model, consisting of Weather Research and Forecasting (WRF) and Regional Ocean Modeling Systems (ROMS), to analyse the influence of eddies on tropical cyclone intensifications over the bay. The model is able to track the tropical cyclones with less error, while the central pressure and wind speed are underestimated. Also, the coupling process steer the cyclones to the observed track compared to standalone WRF model. The variations in simulated sea surface temperature and salinity are in agreement with the satellite and in situ measurements. During the passage of Phailin and Hudhud over the eddies, the cyclones intensified almost twice of their initial central pressure and wind (before interacting with eddies), which the model captured very well. The eddy feedback factor, which estimate the influence of warm eddies on tropical cyclones, is about 152% for Phailin and 90% for Hudhud. In the case of the pre-monsoon cyclones, Aila and Laila, the eddy feedback factor is estimated up to 36% and 21%, respectively. Madi cyclone lost its intensification up to 80% because of its interaction with a cold eddy. These predictions are comparable with that of the observations during the cyclone passage. Also it is noted that the warm eddy regions resulted in the maximum transfer of latent heat resulting in strong intensifications of the cyclones. Our study reveals that the eddies play an important role in the intensification and dissipation of BOB cyclones and understanding their nature can help in estimating the track and intensity of cyclones.

Satellite Evidence of Upper Ocean Responses to Cyclone Nilofar

ABSTRACTCyclone Nilofar was the third-strongest cyclone in the Arabian Sea. It was a category 4 cyclone that arrived in last week of October 2014. It lingered in the Arabian Sea for 10 days and caused a significant phytoplankton bloom that was detected by satellite observation. In this study, the authors investigated the ocean biological and physical responses to cyclone Nilofar using chlorophyll a (chl a) concentration, sea surface temperature (SST), sea surface height anomaly (SSHA), sea surface wind measurements derived from different satellites, and in situ data. The maximum chl a concentration (>3.34 mg m−3) increased about 28 times in the Arabian Sea after the passage of the cyclone in comparison with the chl a concentration (0.12–0.92 mg m−3) before the passage of cyclone. Using the relationship of wind stress curl and upwelling, the authors found that during the cyclone the speed of upwelling increased more than 18 times compared with the speed in the period before the cyclone. Moreover, the mixed layer deepened by about 40 m. These findings reveal that the enhancement of chl a concentration was triggered by strong vertical mixing and upwelling. Along the track of the cyclone, the maximum sea surface cooling (4°–5°C) took place in the Arabian Sea along segments A–B and D–F where the translation speed of the cyclone was only 0.9–1.3 m s−1, and the mixed-layer depth was about 10 m in the pre-cyclone period. However, the drop in SST along segment C–D was only 1°–2°C, whereas in the pre-cyclone period the translation speed of the cyclone was 3.1–4.4 m s−1, and the mixed-layer depth was about 25 m in. So, the extent of the SST drop was probably due to the translation speed of the cyclone and the depth of the mixed layer. In addition, the region with the largest decline in SSHA can indicate the location of maximum cooling.

Water Circulation Off the Northeastern Coast of Sakhalin during the Passage of Three Types of Deep Cyclones over the Sea of Okhotsk

Based on the numerical simulation of water circulation in the Sea of Okhotsk in 1986 to 2015, the impact of deep cyclones on the circulation off the northeastern coast of Sakhalin is studied. The circulation in the Sea of Okhotsk is simulated with the COSMO-Ru-INMOM-CICE model configuration, where the COSMO-Ru and INMOM resolve explicitly the mesoscale atmosphere and ocean dynamics and the CICE resolves the ice cover evolution. The extreme atmospheric events associated with the intensive cyclone activity over the Sea of Okhotsk during the cold season are classified. It is found that high velocity is typical of the cyclones coming to the sea from Sakhalin, and wind speed on the periphery is higher for the cyclones coming to the Sea of Okhotsk from the south and southwest. The analysis of water circulation response off the northeastern coast of Sakhalin demonstrates that the meridional current velocity on the shelf increased by several times from the sea surface to the bottom for all types of cyclones. On the edge of the shelf, southern currents intensified in the surface and bottom layers during the passage of cyclones and at the intermediate depths during the passage of fronts. On the continental slope, southern currents intensified in the surface, intermediate, and bottom layers depending on the type of extreme events.

An ICT Integration Approach on Malagasy Agriculture: The Case of Vanilla Production

The cultivation of vanilla is one of the economic pillars of Madagascar. Yet, since its liberalization in 1995, this sector has experienced recurrent production instability. In an attempt to enhance the production performance in this sector, this article will try to study the causes of this production instability, and propose a sustainable alternative to the vanilla production in Madagascar. Indeed, during this research, the empirical research analysis revealed on the one hand a poor communication management of the vanilla sector in the spread of timely information and an annual passage of tropical cyclones. Besides, the literature review suggests that one alternative could be introduced through the integration of new technologies such as ICT.

Characteristics of Drag Coefficient in Different Coastal Regions of the South China Sea Under Tropical Cyclones–An Observational Study

To investigate the values of 10-m drag coefficient (CD) in different coastal areas under the influence of tropical cyclones, the present study used the observational data from four towers in different coastal areas of the South China Sea (SCS) during six tropical cyclone (TC) passages, and employed the eddy covariance method and the flux profile method. The analysis of footprint showed that the fluxes at Zhizai Island (ZZI), Sanjiao Island (SJI) and Donghai Island (DHI) were influenced basically by the ocean, and the flux at Shangyang Town (SYT) was influenced mainly by the land. The results showed that the dependence relationships of CD on 10-m wind speed (U10) in four different coastal areas under the influence of TCs were different. CD at ZZI and SJI initially increased and then decreased as U10 increased, similar to the pattern over the ocean. CD at ZZI and SJI represented the values over shallow water with seawater depths of ~7 m and ~2 m, respectively. Moreover, the critical wind speed at which CD peaked gradually decreased as the seawater depth became shallower in the coastal areas. CD at DHI and SYT decreased monotonously as U10 increased, similar to the pattern over the land. CD at DHI represented the value over the transition zone from shallow water to coastal land, and CD at SYT represented the value over the coastal land. Meanwhile, the eddy covariance method and the flux profile method were compared at ZZI and SYT during TC passages. It was found that their CD values obtained by the two methods were close. Finally, the parameterizations of observed u* and CD as a function of U10 over four different coastal areas were given under the influence of high winds. These parameterizations of observed CD may be used in high-resolution numerical models for landfalling TC forecast.

Formation of Wind Gusts in an Extratropical Cyclone in Light of Doppler Lidar Observations and Large-Eddy Simulations

AbstractDamaging gusts in windstorms are represented by crude subgrid-scale parameterizations in today’s weather and climate models. This limitation motivated the Wind and Storms Experiment (WASTEX) in winter 2016–17 in the Upper Rhine Valley over southwestern Germany. Gusts recorded at an instrumented tower during the passage of extratropical cyclone “Thomas” on 23 February 2017 are investigated based on measurements of radial wind with ≈70-m along-beam spacing from a fast-scanning Doppler lidar and realistic large-eddy simulations with grid spacings down to 78 m using the Icosahedral Nonhydrostatic model. Four wind peaks occur due to the storm onset, the cold front, a precipitation line, and isolated showers. The first peak is related to a sudden drop in dewpoint and results from the downward mixing of a low-level jet and a dry layer within the warm sector characterized by extremely high temperatures for the season. While operational convection-permitting forecasts poorly predict the storm onset overall, a successful ensemble member highlights the role of upstream orography. Lidar observations reveal the presence of long-lasting wind structures that result from a combination of convection- and shear-driven instability. Large-eddy simulations contain structures elongated in the wind direction that are qualitatively similar but too coarse compared to the observed ones. Their size is found to exceed the effective model resolution by one order of magnitude due to their elongation. These results emphasize the need for subkilometer-scale measuring and modeling systems to improve the representation of gusts in windstorms.

Trends in Hazardous Phenomena over the Far Eastern Seas Caused by Tropical Cyclones

The numerical modeling of wind and sea waves with the WAVEWATCH III discrete spectral model is used to analyze their frequency in the range of hazardous values in the Sea of Japan and the Sea of Okhotsk in 1979-2018. It is found that, in most cases, these events are caused by the passage of tropical cyclones. Some long-term trends are revealed in the frequency of hazardous phenomena (wind and sea waves) and tropical cyclones passing over the Far Eastern seas. The relation between the passage of tropical cyclones and the atmospheric circulation features over some parts of the region is found.

Tropical cyclones alter short-term activity patterns of a coastal seabird

BackgroundMobile organisms in marine environments are expected to modify their behavior in response to external stressors. Among environmental drivers of animal movement are long-term climatic indices influencing organism distribution and short-term meteorological events anticipated to alter acute movement behavior. However, few studies exist documenting the response of vagile species to meteorological anomalies in coastal and marine systems.MethodsHere we examined the movements of Eastern brown pelicans (Pelecanus occidentalis carolinensis) in the South Atlantic Bight in response to the passage of three separate hurricane events in 2 years. Pelicans (n = 32) were tracked with GPS satellite transmitters from four colonies in coastal South Carolina, USA, for the entirety of at least one storm event. An Expectation Maximization binary Clustering algorithm was used to discretize pelican behavioral states, which were pooled into ‘active’ versus ‘inactive’ states. Multinomial logistic regression was used to assess behavioral state probabilities in relation to changes in barometric pressure and wind velocity.ResultsIndividual pelicans were more likely to remain inactive during tropical cyclone passage compared to baseline conditions generally, although responses varied by hurricane. When inactive, pelicans tended to seek shelter using local geomorphological features along the coastline such as barrier islands and estuarine systems.ConclusionsOur telemetry data showed that large subtropical seabirds such as pelicans may mitigate risk associated with spatially-extensive meteorological events by decreasing daily movements. Sheltering may be related to changes in barometric pressure and wind velocity, and represents a strategy common to several other classes of marine vertebrate predators for increasing survival probabilities.

Biophysical Submesoscale Processes in the Wake of Hurricane Ivan: Simulations and Satellite Observations

Tropical cyclone induced phytoplankton productivity is examined using a tropical cyclone version of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®). A four-component Nutrient–Phytoplankton–Detritus biological model is integrated into COAMPS to create a fully integrated air-ocean-wave-biology model. This study investigates the upper ocean physical and biological states before and after Hurricane Ivan traversed the central Gulf of Mexico, in mid-September 2004. Elevated concentrations of surface chlorophyll-a appear in the simulation two days after the passage of the tropical cyclone, and these results are spatially and temporally coherent with Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data for this time period. Model results reveal enhancement of chlorophyll-a in submesoscale filaments on the periphery of a warm-core eddy that are dominated by large values of lateral strain and relative vorticity at the surface. The vertical circulation of the filament, with its associated upward vertical motion, permits surface ventilation of cold, nitrogen-rich water and subsequent stimulation of primary biological production. Here, we show for the first time that coupled biological-physical submesoscale processes may be simulated via a fully integrated air-sea-wave-biology tropical cyclone model that provides a mechanistic explanation of the conspicuous features revealed in satellite ocean color imagery following Ivan.

Is Cyclone JAL Stimulated Chlorophyll-A Enhancement Increased Over the Bay of Bengal?

Tropical cyclone JAL developed in the south Bay of Bengal and worn south coastal Andhra Pradesh on November 7, 2010. The main objective of this study was to investigate the ocean’s response before and after the passage of cyclone in the southern Bay by utilizing the multi-satellite approach. For this study, I used Sea Surface Temperature (SST), Chlorophyll-a (Chl-a), and Sea Surface Height (SSH) data production from different remote sensing satellites. JAL induced large scale of upwelling within large cooling of sea surface (~ 1.2°C), enhancement of Chl-a ~ 0.4 mg/m3 in the open ocean and 2-3mg/m3 along the coast, and decrease of SSH (~15cm) in the southeast Bay of Bengal after its passage. After the JAL, the upwelling area expanded rapidly on the shelf break. Chl-a images also revealed high values (~3.3mg/m3) appeared in the shelf region, where the high Chl-a patterns matched the upwelling in terms of location and time. Large offshore surface cooling was also observed mainly to the right of the cyclone track. From the above observations it is evident that cyclonic storm JAL significantly increased upwelling in the southern Bay of Bengal.

On the wave-current interaction during the passage of a tropical cyclone in the Bay of Bengal

The impact of waves on currents and vice-versa is an integral part of the complex coastal dynamics. The wave-current interaction is prominent in the coastal shelf-slope regions, particularly during the passage of a tropical cyclone. In the present study, we describe the importance of wave-current interaction in the northern Bay of Bengal (BoB) using a fully coupled three-dimensional Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modelling system. The COAWST model is applied to the case of a very severe cyclonic storm Phailin that passed over the BoB basin during 10–15 October 2013. To represent the interaction between waves and currents, we utilized the newly implemented vortex-force method in the coupled model. Numerical experiments with different coupling configuration within the COAWST modelling framework were performed to separately identify the effects of wind, tide, and wave-current interaction process. A comparison of model results with the buoy observations of water elevations, currents, and wave measurements shows a good agreement between model and observed data. Various terms of the momentum balance were calculated from the model simulated and diagnosed parameters. A comparison of the horizontal momentum balance term identifies the wave-breaking induced acceleration as one of the leading terms along the storm affected the east coast of India. Further, an increase in the apparent bed roughness caused by waves found to affect the values and distribution of the bottom shear stress. The pressure gradient term showed significant changes to the pure tidal case. The study highlights that the changes in the momentum balance caused by waves includes contributions from the variations in the water level and currents. The most relevant effect on the coastal hydrodynamics was in the form of a wave-induced setup near the location of landfall of the cyclone.

Infrasound Strain Perturbations Caused by Typhoons

The paper addresses excitation of high-power infrasound disturbances in the 7–9 Hz frequency band associated with passage of tropical cyclones (typhoons) in the zone of operation of laser strainmeters installed at Cape Shultz in Primorskii krai.

Surface and Sub‐surface Ocean Response to Tropical Cyclone Phailin: Role of Pre‐existing Oceanic Features

AbstractThe upper oceanic thermal response induced by Tropical Cyclone Phailin (9–14 October 2013) under the influence of East India Coastal Current (EICC) and a cyclonic eddy is investigated and contrasted with the response from open ocean region using a high‐resolution HYbrid Coordinate Ocean Model simulation. There is significant cooling (7° C) inside the cold core eddy and negligible cooling (0.5° C) within the EICC region characterized by the shallow and deeper thermocline, respectively. Our analysis of mixed layer heat budget terms showed that the horizontal advection plays a significant role in determining the temperature tendency for the location within the EICC, in contrary to the general dominance of vertical processes as reported in previous studies during the cyclone period. The analysis for the locations inside eddy and open ocean concurs with the previous studies showing the dominance of vertical processes toward the temperature tendency. Further, near the coast, the surface cooling is minimal compared to the subsurface cooling, dominantly seen between 50‐ and 100‐m depth. This disparity indicates that the factors responsible for the surface temperature anomalies are different from those of subsurface. Our analysis of thermal signatures after the passage of cyclone showed that the EICC and cyclonic eddy contribute to the faster advection of cold wake and recovery of sea surface temperature to the prestorm state.

Possible combined effect of El Niño–Southern Oscillation and Pacific Decadal Oscillation on Korea affecting tropical cyclone passage frequency

AbstractThis study found that the passage frequency of tropical cyclones (TCs) affecting Korea has had negative correlations with the Pacific Decadal Oscillation (PDO) and the El Niño–Southern Oscillation (ENSO) since the early 1980s. To examine the actual combined effects of PDO and ENSO on the passage frequency of TCs affecting Korea, the positive PDO and ENSO years for 9 years and the negative PDO and ENSO years for 9 years were selected during the periods of 1951–1981 (pre‐1981) and 1982–2012 (post‐1981), and then the average difference between these two phases was analyzed. An analysis of anomalous stream flows at 500 hPa showed the formation of anomalous cyclonic circulations in an east‐to‐west direction from East Asia to the North Pacific both in the pre‐1981 and post‐1981 periods in the positive PDO and ENSO years. However, the anomalous cyclones in East Asia were stronger in the pre‐1981 period, whereas the anomalous cyclones in the North Pacific were stronger in the post‐1981 period. Consequently, China, Korea and the west of Japan were affected by strong anomalous northerlies in the pre‐1981 period, and the TC passage frequency was lower in these regions as a result. In the post‐1981 period, these countries were affected by anomalous northwesterlies or anomalous westerlies.

Avaliação da Otimização da Temperatura da Superfície do Mar durante a Passagem de um Ciclone Explosivo no Sudoeste do Oceano Atlântico

Avaliação da Otimização da Temperatura da Superfície do Mar durante a Passagem de um Ciclone Explosivo no Sudoeste do Oceano Atlântico

Two Typical Ionospheric Irregularities Associated With the Tropical Cyclones Tembin (2012) and Hagibis (2014)

AbstractTwo remarkable ionospheric irregularities named equatorial plasma bubble (EPB) and medium‐scale traveling ionospheric disturbance (MSTID) are verified by using multi‐instrumental observations, for example, the ground‐based GPS networks, ionosonde stations, and Swarm satellites, when the tropical cyclones Tembin and Hagibis approached Hong Kong on 26 August 2012 and 15 June 2014, respectively. The low‐latitude plasma bubble over an area of 105–120 °E in longitude was observed during 12:30–17:00 universal time (UT) on 26 August 2012. GPS observations from magnetically conjugate locations indicate that the nighttime bubble during 20:30–01:00 local time (LT = UT + 8h) on 26 August should be formed from the magnetically equatorial region rather than drifted from the west (eastward drift) or generated locally. Different from the EPB, during another cyclone on 15 June 2014, the northwest‐southeast aligned nighttime MSTID was verified in midlatitude regions at a mean horizontal velocity of 156 m/s southwestward propagation during 12:30–17:30 UT when Hagibis was near the mainland coast. By comparing the ionospheric observations during the two cyclones, differences are identified: small‐scale irregularities associated with plasma bubble cause obvious perturbations of the rate of total electron content index with the value of ~3.0 TECU/min; while the MSTID in midlatitude only cause relatively slight rate of total electron content index disturbances with the value of ~1.5 TECU/min. In addition, the magnetic conjugacy of EPB and MSTID in two hemispheres during the passage of tropical cyclones has been also discussed in this study.

Ocean Surface Anomalies after Strong Winds in the Western Mediterranean Sea

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.