Cyclone Model Research Articles

Performance evaluation of cyclone models for similar body diameter and flowrate using CFD

Abstract The present study performs numerical simulations of a few popular medium-to-high efficiency cyclone models viz. Stairmand cyclone, Swift cyclone, Patterson-Munz cyclone, Obermair cyclone, and Lapple cyclone to compare their performance. The reason to undertake this study is that these models are widely used for benchmark studies or for the validation by the researchers. Earlier, all these geometries were investigated experimentally by respective inventors that bear different sizes. Hence, for the sake of performance comparison, the diameter (D = 0.29 m) and a volume flow rate (Q = 0.135401 m3/s) of the fluid in all the models is the same - the latter is used to calculate the inlet velocity in each cyclone model. We have not considered a similar Reynolds number condition for comparison as it will change the volume flow rate of the flow. Apart from the pressure drop and collection efficiency values, we present the details of the flow field inside each model. Conclusive results indicate that the Patterson-Munz cyclone has the lowest pressure drop while the Swift cyclone has the highest collection efficiency. Interestingly, the cut-off diameter in the swift cyclone is found to be minimum.

Typhoons and Tigers—flood risk in the Sundarbans

The many small inhabited islands of the Sundabarn region in north east India and Bangladesh, are subject to sea water flooding during cyclones. The objective is to predict flood risk so that improvements to flood defences can be prioritised. There are a few records of flood heights at a very limited set of locations, but there are long term data on cyclones that can be used to drive a simulation model to estimate flood risk at any points in the Sundarbans. The cyclone data is used to fit a stochastic model for cyclones. The cyclone model is combined with a deterministic storm surge model that provides sea level at the boundary of the Sundarbans. A hydraulic routing model, MIKE–21, is then used to predict water levels over a grid of interior points. The combined deterministic surge and routing models are approximated by a regression type model, so the stochastic simulation can quickly generate thousand of years of flood events. Results from a simulation are presented.

A theoretical method to characterize the resistance effects of nonflat terrain on wind fields in a parametric wind field model for tropical cyclones

Traditionally, an empirical speed-up factor was introduced to reflect the effects of nonflat terrain on near-surface wind speeds. In this paper, the resistance effects of nonflat terrain are considered by introducing the terrain drag coefficient in the parametric wind field model for tropical cyclones (TCs) with a theoretical method. Terrain effects on wind fields are investigated in complex areas along the coastal zone in China under TC conditions. The results show that the terrain drag coefficient is the function of the slope angle and is sensitive to the spatial resolution. After including the resistance effect of nonflat terrain, the TC intensities weaken overall during landfall, with a slight enhancement near the coastal zone. The wind speeds outside the radius of the maximum wind speed decrease, while the wind speeds within the radius of the maximum wind speed increase. Both the TC eye and the radius of maximum wind speed shrink, which is more obvious when the TC center is entirely over land. As a result, the location and magnitude of the maximum wind speed are affected by the nonflat terrain. The changed structure of the wind fields demonstrates the necessity of considering the effects of nonflat terrain in simulating the wind fields under TC conditions.

A Diagnostic Analysis of the Mechanisms for Arctic Cyclone Intensity Evolution

Abstract The intensity evolution of Arctic cyclones (ACs) is examined via cyclone parameter space and composite analyses based on approximately 18 000 AC tracks during 1979–2021. Cyclone parameter spaces are defined by various parameters representing the cyclone structure and physical processes relevant to cyclone development. It is shown that intensifying ACs are associated with diabatic heating and characterized by a cold core in both the lower and upper troposphere, as well as a thermally asymmetric and vertically tilted structure. In contrast, the decay phase is associated with diabatic cooling and characterized by a vertically aligned cyclone with reduced horizontal asymmetry. The cyclone parameter space analysis also indicates a warm core in the lower troposphere for a subset of ACs, which may reflect a frontal occlusion. The transition from AC intensification to decay, on average, is marked by a sharp decrease in both upward motion and diabatic heating, along with the vertical alignment of the cyclone structure. Following this transition, an upright cyclone may persist for a long time due to the weak background vertical wind shear, diabatic cooling, and weak Rossby wave energy dispersion. The evolution of ACs can thus be regarded as a two-stage process: a baroclinic development stage aided by diabatic heating, during which the AC evolution may conform with the Norwegian model for midlatitude cyclones, and a slow decay stage of an equivalent barotropic cyclone, which may leave a remnant tropopause polar vortex after the erosion of the surface circulation. Significance Statement Arctic cyclones are the primary weather system in the Arctic and are also an important component in the Arctic climate system owing to their role in modulating Arctic sea ice variability and poleward moisture and energy transport. We examined the cyclone structural characteristics and physical processes associated with the Arctic cyclone intensity evolution and proposed a two-stage conceptual model. A better understanding of the Arctic cyclone intensity change mechanisms will help us better anticipate the changes in Arctic cyclone activity in a warmer climate.

The Role of Turbulence in an Intense Tropical Cyclone: Momentum Diffusion, Eddy Viscosities, and Mixing Lengths

Abstract Improved representation of turbulent processes in numerical models of tropical cyclones (TCs) is expected to improve intensity forecasts. To this end, the authors use a large-eddy simulation (with 31-m horizontal grid spacing) of an idealized category 5 TC to understand the role of turbulent processes in the inner core of TCs and their role on the mean intensity. Azimuthally and temporally averaged budgets of the momentum fields show that TC turbulence acts to weaken the maximum tangential velocity, diminish the strength of radial inflow into the eye, and suppress the magnitude of the mean eyewall updraft. Turbulent flux divergences in both the vertical and radial directions are shown to influence the TC mean wind field, with the vertical being dominant in most of the inflowing boundary layer and the eyewall (analogous to traditional atmospheric boundary layer flows), while the radial becomes important only in the eyewall. The validity of the downgradient eddy viscosity hypothesis is largely confirmed for mean velocity fields, except in narrow regions which generally correspond to weak gradients of the mean fields, as well as a narrow region in the eye. This study also provides guidance for values of effective eddy viscosities and vertical mixing length in the most turbulent regions of intense TCs, which have rarely been measured observationally. A generalized formulation of effective eddy viscosity (including the Reynolds normal stresses) is presented. Significance Statement This study uses a turbulence-resolving simulation of a category 5 tropical cyclone to understand the role of turbulence in intense storms. Results show that turbulence clearly modulates storm structure and intensity. This study provides guidance for the values of turbulent quantities (which are usually parameterized in comparatively coarse operational TC forecast models) in scarcely observed regions of intense storms. Furthermore, a complete formulation of the effective eddy viscosities is proposed, incorporating contributions from typically ignored Reynolds normal stress terms.

Comparison of experimental, empirical, and CFD pressure losses of lab-scale sampling cyclones

Significant efforts remain to be undertaken to achieve efficient separation of particulate matter. Devices widely used for this purpose are cyclone separators. This study investigates the pressure loss phenomena and flow structures within cyclone devices, aiming to elaborate and optimize their performance. Traditional cyclone models: (i) Muschelknautz, (ii) Stairmand, and (iii) PM1 Sharp Cut, are evaluated alongside the innovative vortex limiter cyclone (VL) to distinguish their advantages and limitations. The focus is on describing the relation between pressure loss and flow characteristics of the different cyclones with the same design separation diameter of 1μm. Empirical pressure loss correlations analyze how pressure losses vary within different cyclone devices. It was proven that predictions depend on cyclone size and operational parameters. Computational Fluid Dynamics (CFD) simulations further elucidate pressure loss mechanisms, highlighting the complexities inherent in modeling cyclonic behavior accurately. In conclusion, this study contributes to advancing the understanding of cyclone performance by elucidating the intricate interplay between pressure loss phenomena and flow structures. Such insights hold profound indications for optimizing cyclone separator design and operation in diverse industrial applications.

Tropical cyclone activity over the past 1200 years at the Pelican Cays, Belize

Tropical cyclone (TC) models indicate that continued planet warming will likely increase the global proportion of powerful TCs (specifically Categories 4 and 5 hurricanes), increasingly jeopardizing low-lying coastal communities and resources such as the Pelican Cays, Belize. The combination of increased coastal development and continued relative sea-level rise puts these communities at even higher risk of damage from TCs. The short TC observational record for the western Caribbean hampers the extensive study of TC activity on centennial timescales, which hinders our ability to fully understand past TC climatology and improve the accuracy of TC models. To better assess TC risk, paleotempestological studies are necessary to put future scenarios in perspective. Here, we present a high-resolution reconstruction of coarser-grained sediment deposits associated with TC (predominately ≥ Category 2 hurricanes) passages over the past 1200 years from Elbow and Lagoon Cays, two coral reef-bounded lagoons at the northern and southern end of the Pelican Cays; the most southern Belizean paleotempestological site to date. Coincident timing of historic storms with statistically significant coarser-grained deposits within cay lagoon sediment cores allows us to determine which historic TCs likely generated event layers (tempestites) archived in the sediment record. Our compilation frequency analysis indicates one active interval (above-normal TC activity) from 1740-1950 CE and one quiet interval (below-normal TC activity) from 850-1018 CE. The active and quiet intervals in the Pelican Cays composite record are anticorrelated with those from nearby and re-analyzed TC records to the north, including the Great Blue Hole (∼100 km north) and the Northeast Yucatan (∼380 km northwest). This site-specific anticorrelation in TC activity along the western Caribbean indicates that we cannot rely on any one single TC record to represent regional TC activity. However, we cannot discount that these anticorrelated periods between the western Caribbean sites are due to randomness. To confirm that the anticorrelation in TC activity among sites from the western Caribbean is indeed a function of climate change and not randomness, an integration of more records and TC model simulations over the past millennium is necessary to assess the significance of centennial-scale variability in TC activity recorded in reconstructions from the western Caribbean.

Cyclone Shapes for Sand and Microplastic Separation: Efficiency and Reynolds Number Relationships

In this study, three geometries were analyzed for sand and microplastic separation to confirm the applicability of cyclones. This research aimed to apply plastic-based samples such as Styrofoam, PET, PP, and PU to an analytical model, characterized by separating sand spread on Korean beaches into different outlets using a cyclone model. Regarding the numerical analysis, the results of sand particle separation were analyzed by designing a general cyclone (Type A), a cone-shaped cyclone (Type B), and a cone-shaped cyclone (Type C) with double the cone length, for four microplastics in three shapes. The results of the analysis of the characteristics showed that Type B, which has a conical shape, achieved an efficiency of 99.3–100% for sand, 72.7% for Styrofoam, and 95.7–100% for other plastics at an exit speed of 5–7 m/s, after which the efficiency decreased as the speed increased. Type C showed an efficiency of 92.2–100% for sand, 66.6–70.8% for Styrofoam, and 61% for PET at 5–10 m/s. Type C showed a maximum efficiency of 95.5% for PP and 73.4% for PU at 11 m/s. As the speed increased, the efficiency decreased. This is believed to be due to differences in the Reynolds number range, which helps separate particles depending on their shape; therefore, the applicability of the cone-shaped cyclone separator for sand and microplastic separation was confirmed, and it was found that an optimal speed condition exists in relation to the Reynolds number.

CYCLONE Modeling Analysis Operation Slab Work Project Conggeang Bridge – Cisumdawu Toll Road Section 5A

CYCLONE Modeling Analysis Operation Slab Work Project Conggeang Bridge – Cisumdawu Toll Road Section 5A

An environment-driven basin scale tropical cyclone model

This paper presents an environment-driven tropical cyclone (TC) model for the Western North Pacific basin, which comprises a revised Poisson regression genesis model, a tailored beta-advection track model, and a fast intensity model. The TC model reproduces the temporal and spatial distributions of genesis events, the motion pattern of tracks, as well as the intensity evolutions along tracks. Risk analyses for Hong Kong and along the southeast coastline of mainland China demonstrate that this model can simulate extreme TC events with high fidelity. And the Gaussian mixture model outperforms the Frank Copula in approximating the joint distributions of the annual maximum wind speeds and the corresponding wind directions. This model is driven by a set of environmental variables including relative vorticity, relative humidity, sea surface temperature, vertical wind shear, potential intensity, sub mixed layer depth stratification, mixture layer depth and so on. This enables the model to not only reproduce historical records, but also make predictions for future TC behaviors under climate change with combination of global climate models. Besides, the computational efficiency of the TC model is comparable to traditional purely statistical models. The proposed model can also be coupled with other natural hazard models to conduct multi-hazard analysis.

Performance evaluation of cyclone separators with elliptical cross-section using large-eddy simulation

In the present study, cyclone separators with elliptical cross-sections have been studied numerically. Five cyclone models are considered here with the normalized (semi-) major axis (a) and minor axis (b) as: (a/D, b/D) = (0.51, 0.49), (0.52, 0.48), (0.53, 0.47), (0.54, 0.46), and (0.55, 0.45), referred to as the models A, B, C, D, and E, respectively. The standard model is of circular cross-section with a body diameter, D = 0.205 m, and is the reference model for performance comparison. It has been ensured that all the cyclones bear a similar hydraulic diameter, and hence, a nearly similar volume. Apart from the pressure drop and collection efficiency, we also evaluate the periodicity associated with the precessing vortex core around the cyclone axis by performing a fast Fourier transformation to the temporal velocity signal. Conclusive results indicate that both the pressure losses as well as collection efficiencies reduce with increasing the major axis (and reducing the minor axis) values. The mean velocity components undergo significant changes than the velocity fluctuations with stretching of the elliptical cross-section. The models with the largest major axis (or smaller minor axis) may be used as pre-separators to remove larger particles at the lowest pressure drop values.

Modeling and Simulation of Hydroxyapatite Recovery in the Desliming Circuit of the Tapira Industrial Plant, Brazil

The modeling and simulation of industrial mineral processing operations are traditionally used for cyclone sizing and optimizations of industrial operations. However, the main models used are based on the total population of particles in the pulp, thus not distinguishing the individual minerals. This article presents the results of an innovative method that investigated the optimization of the metallurgical recovery of P2O5 in the desliming circuit of a phosphate ore processing plant in Brazil. A survey campaign was carried out in the existing industrial circuit, followed by determining the partition curves for the overall particles and specifically for the hydroxyapatite particles. The results were used to calibrate the Narasimha–Mainza cyclone model. From a Base Case determined with reference to the industrial survey, three optimization scenarios were simulated through cyclone geometries and respective operating conditions changes. Simulated scenarios indicated the possibility of P2O5 metallurgical recovery increasing from 9.4% to 12.7% compared to the Base Case.

Effects of Diameter Parameters on Gas Flow Field Characteristics in Cyclones: An Experimental Investigation

The flow field characteristic is crucial for the separation process of cyclones, which includes time–mean and dynamic characteristics. The structural parameters of the cyclone have an important influence on the internal flow field characteristics, among which the cylinder diameter and vortex finder diameter are important structural parameters. This experimental study aimed to assess the effects of diameter parameters on the flow field characteristics of cyclones, especially the dynamic characteristics, which have received less attention in the literature. A hot wire anemometer (HWA) was employed in measuring the instantaneous tangential velocities in cyclones with different cylinder and vortex finder diameters. Time and frequency domain analyses of the measured data revealed that the diameter parameters of cyclones affected not only the distributions of the time–mean and instantaneous tangent velocities but also the intensity and dominant frequency of the instantaneous tangential velocity fluctuations. First, the maximum tangential velocity in the cyclone increased slightly when the cylinder diameter was increased and decreased significantly when the vortex finder diameter was increased. Second, the tangential velocity fluctuation intensity characterized by the standard deviation (Sd) increased on the same dimensionless axial section when the cylinder diameter was increased and the vortex finder diameter was decreased. It was also found that the increases in cylinder diameter and vortex finder diameter led to the dominant frequencies in the cyclone being reduced. Based on the results of this study, the dominant frequency calculation model for cyclones was improved. The conclusions presented in this study may provide valuable insights into the dynamic characteristics of flow fields in cyclones for future improvements to separation performance.

Towards a global impact-based forecasting model for tropical cyclones

Abstract. Tropical cyclones (TCs) produce strong winds and heavy rains accompanied by consecutive events such as landslides and storm surges, resulting in losses of lives and livelihoods, particularly in regions with high socioeconomic vulnerability. To proactively mitigate the impacts of TCs, humanitarian actors implement anticipatory action. In this work, we build upon such an existing anticipatory action for the Philippines, which uses an impact-based forecasting model for housing damage based on eXtreme Gradient Boosting (XGBoost) to release funding and trigger early action. We improve it in three ways. First, we perform a correlation and selection analysis to understand if Philippines-specific features can be left out or replaced with features from open global data sources. Secondly, we transform the target variable (percentage of completely damaged houses) and not yet grid-based global features to a 0.1∘ grid resolution by de-aggregation using Google Open Buildings data. Thirdly, we evaluate XGBoost regression models using different combinations of global and local features at grid and municipality spatial levels. We first introduce a two-stage model to predict if the damage is above 10 % and then use a regression model trained on all or only high-damage data. All experiments use data from 39 typhoons that impacted the Philippines between 2006–2020. Due to the scarcity and skewness of the training data, specific attention is paid to data stratification, sampling, and validation techniques. We demonstrate that employing only the global features does not significantly influence model performance. Despite excluding local data on physical vulnerability and storm surge susceptibility, the two-stage model improves upon the municipality-based model with local features. When applied to anticipatory action, our two-stage model would show a higher true-positive rate, a lower false-negative rate, and an improved false-positive rate, implying that fewer resources would be wasted in anticipatory action. We conclude that relying on globally available data sources and working at the grid level holds the potential to render a machine-learning-based impact model generalizable and transferable to locations outside of the Philippines impacted by TCs. Also, a grid-based model increases the resolution of the predictions, which may allow for a more targeted implementation of anticipatory action. However, it should be noted that an impact-based forecasting model can only be as good as the forecast skill of the TC forecast that goes into it. Future research will focus on replicating and testing the approach in other TC-prone countries. Ultimately, a transferable model will facilitate the scaling up of anticipatory action for TCs.

Performance analysis of multi-inlet cyclone separators considering different shapes and locations of the inlet ducts

The present study analyzes the performance of multi-inlet cyclone separators with different shapes and axial locations of the inlet ducts. The cyclone model having a single inlet has been considered as the reference model. The two inlets are incorporated such that the total cross-sectional area equals the original (single inlet) section – this ensures no change in the inlet velocity. Three cases for the shape of the cross-section have been considered. In the RA variant, the two inlet areas have been halved ensuring the same aspect ratio. In the RH variant, the height of the two inlets is half of the original duct. In the last case of the RW variant, the width of the two inlets is reduced by half of the original area. The impact of relative axial displacement between the two inlets is also analyzed. The advanced closure LES has been used to investigate the flow field as well as the performance. Conclusive results indicate that both pressure losses and collection efficiencies are the lowest in the RH variant and the highest in the RW variant. Furthermore, using continuous wavelet transformation, it has been revealed that the precessing frequency of the vortex core is time-dependent.

Study on flow field characteristics of gas-liquid hydrocyclone separation under vibration conditions.

The complex vibration phenomenon occurs in the downhole environment of the gas-liquid hydrocyclone, which affects the flow field in the hydrocyclone. In order to study the influence of vibration on hydrocyclone separation, the characteristics of the flow field in the downhole gas-liquid hydrocyclone were analyzed and studied under the condition of vibration coupling. Based on Computational Fluid Dynamics (CFD), Computational Solid Mechanics Method (CSM) and fluid-solid coupling method, a fluid-solid coupling mechanical model of a gas-liquid cyclone is established. It is found that under the condition of vibration coupling, the velocity components in the three directions of the hydrocyclone flow field change obviously. The peak values of tangential velocity and axial velocity decrease, and the asymmetry of radial velocity increases. The distribution regularity of vorticity and turbulence intensity in the overflow pipe becomes worse. Among them, the vorticity intensity of the overflow pipe is obviously enhanced, and the higher turbulence intensity near the wall occupies more area distribution range. The gas-liquid separation efficiency of the hydrocyclone will decrease with the increase of the rotational speed of the screw pump, and the degree of reduction can reach more than 10%. However, this effect will decrease with the increase of the rotational speed of the screw pump, so the excitation effect caused by the rotational speed has a maximum limit on the flow field.

Development of frontal boundaries during the extratropical transition of tropical cyclones

AbstractThis study seeks to characterize the development of atmospheric fronts during the extratropical transition (ET) of tropical cyclones (TCs) as a function of their evolution during ET. Composite histograms indicate that the magnitude of the lower atmospheric frontogenesis and average sea‐surface temperature is different based on the nature of the TC's structural change during ET. We find that the development of cold and warm fronts evolves as expected from conceptual models of extratropical cyclones. Composites of these fronts relative to the completion of ET show that azimuth, storm motion, and deep‐layer shear all appear to have equal influence on the frontal positions. TCs that have more fronts at the time of ET onset complete ET more quickly, suggesting that pre‐existing fronts before ET begins may contribute to a shorter ET duration. The orientations of fronts at ET completion in the North Atlantic and west Pacific align with the climatological distributions of the sea‐surface temperatures associated with the western boundary currents in each of those basins. These results provide a perspective on the locations of frontal development within TCs undergoing ET.

Evaluation of Parametric Tropical Cyclone Surface Winds over the Eastern Australian Region

Abstract Hazard studies based on thousands of synthetic tropical cyclone (TC) events require a validated model representation of the surface wind field. Here, we assess three different TC parametric vortex models with input from four along-track parameter studies of the TC size and shape, based on statistical formulation of the relationships to observed TC intensity, geographic location, and forward transition speed. The 12 model combinations are compared to in situ 10-min observed surface mean wind speeds for 10 TCs that made landfall over Queensland, Australia, which occurred over the period 2006–17. Empirical wind reduction factors to reduce gradient winds to the surface are recalculated for the more recent TCs at both offshore (ocean, small islands, reefs, and moorings) and onshore (land) locations. To improve the wind comparisons over ocean and land, a secondary reduction factor was developed based on an inland decay function. Pearson correlations for the unadjusted modeled peak wind speed from 118 instances of a TC passing a weather station sit between a range of 0.57 and 0.65 for the 12 model combinations. Using the secondary reduction factor based on the inland decay function increases the range of correlation to 0.74–0.81. Based on the assessment of the instances of peak surface wind speed correlations, bias, and root-mean-square error, along with the correlation 48 h around the peak, the top-ranked performing model combination for the region was an along-track parameter study with a double-vortex model, both previously tested for the South Pacific basin. Significance Statement When assessing tropical cyclone hazards, users are presented with several simplified parametric models to describe the surface wind field of tropical cyclones. These parametric models are used routinely for risk assessment of cyclonic winds, as well as for input to surge and wave models used in coastal hazard assessments. Differences between the models include the formulation of the parametric cyclone model, the way winds above the boundary layer are specified at the surface and along-track parameters that describe the cyclones’ size and shape. Of the 12 model combinations investigated in this study, the top-ranked performing model combination for the region was an along-track parameter equation with a double-vortex model, which were both tested previously for the South Pacific basin. Analysis is performed to show unadjusted modeled winds overestimate observed 10-min surface winds over the ocean by around 13% (median) and over land by around 73.9% (median), which is resolved in this study with a secondary empirical wind reduction factor. These findings will support future modeling of tropical cyclone winds for multiple applications, including regional risk assessment and coastal hazard studies.

Tropical Cyclone Modeling With the Inclusion of Wave‐Coupled Processes: Sea Spray and Wave Turbulence

AbstractWaves critically modulate the air‐sea fluxes, and upper‐ocean thermodynamics in a Tropical Cyclone (TC) system. This study improves the modeling of TC intensification by incorporating non‐breaking wave‐induced turbulence and sea spray from breaking waves into an atmosphere‐ocean‐wave coupled model. Notably, wind forecast error decreased by around 10% prior to TCs' peak intensity. The positive feedback of sea spray along with compensatory negative feedback from non‐breaking waves, overall enhanced TCs' intensity. These breaking and non‐breaking wave‐coupled processes consistently cool sea surface temperature, resulting in improvement of the modeled SST. Observed improvements in full‐year TC cases ranging from Categories I to IV in this study suggest that an accurate characterization of ocean wave‐coupled processes is crucial for improving TCs' intensity forecasts and advancing our understanding of severe weather events in both, the atmosphere and ocean.

Constraining an eddy energy dissipation rate due to relative wind stress for use in energy budget-based eddy parameterisations

Abstract. A geostrophic eddy energy dissipation rate due to the interaction of the large-scale wind field and mesoscale ocean currents, or relative wind stress, is derived here for use in eddy energy budget-based eddy parameterisations. We begin this work by analytically deriving a relative wind stress damping term and a baroclinic geostrophic eddy energy equation. The time evolution of this analytical eddy energy in response to relative wind stress damping is compared directly with a baroclinic eddy in a general circulation model for both anticyclones and cyclones. The dissipation of eddy energy is comparable between each model and eddy type, although the numerical model diverges from the analytical model at around day 150, likely due to the presence of non-linear baroclinic processes. A constrained dissipation rate due to relative wind stress is then proposed using terms from the analytical eddy energy budget. This dissipation rate depends on the potential energy of the eddy thermocline displacement, which also depends on eddy length scale. Using an array of ocean datasets, and computing two forms for the eddy length scale, a range of values for the dissipation rate are presented. The analytical dissipation rate is found to vary from 0.25 to 4 times that of a constant dissipation rate employed in previous studies. The dissipation rates are generally enhanced in the Southern Ocean but smaller in the western boundaries. This proposed dissipation rate offers a tool to parameterise the damping of total eddy energy in coarse resolution global climate models and may have implications for a wide range of climate processes.