Parameter Study of Tropical Cyclones in Rotating Radiative–Convective Equilibrium with Column Physics and Resolution of a 25-km GCM

Abstract Rotating radiative–convective equilibrium is studied by extracting the column physics of a mesoscale-resolution global atmospheric model that simulates realistic hurricane frequency statistics and then coupling it to rotating hydrostatic dynamics in doubly periodic domains. The parameter study helps in understanding the tropical cyclones simulated in the global model and also provides a reference point for analogous studies with cloud-resolving models. The authors first examine the sensitivity of the equilibrium achieved in a large square domain (2 × 104 km on a side) to sea surface temperature, ambient rotation rate, and surface drag coefficient. In such a large domain, multiple tropical cyclones exist simultaneously. The size and intensity of these tropical cyclones are investigated. The variation of rotating radiative–convective equilibrium with domain size is also studied. As domain size increases, the equilibrium evolves through four regimes: a single tropical depression, an intermittent tropical cyclone with widely varying intensity, a single sustained storm, and finally multiple storms. As SST increases or ambient rotation rate f decreases, the sustained storm regime shifts toward larger domain size. The storm’s natural extent in large domains can be understood from this regime behavior. The radius of maximum surface wind, although only marginally resolved, increases with SST and increases with f for small f when the domain is large enough. These parameter dependencies can be modified or even reversed if the domain is smaller than the storm’s natural extent.

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Tropical Cyclones in Rotating Radiative–Convective Equilibrium with Coupled SST

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-16-0195.1 ◽

2017 ◽

Vol 74 (3) ◽

pp. 879-892 ◽

Cited By ~ 9

Author(s):

Wenyu Zhou ◽

Isaac M. Held ◽

Stephen T. Garner

Keyword(s):

Boundary Layer ◽

Angular Momentum ◽

Tropical Cyclones ◽

Atmospheric Model ◽

Ocean Model ◽

Sea Surface ◽

Global Atmospheric Model ◽

Small Depth ◽

Ocean Layer ◽

Slab Ocean

Abstract Tropical cyclones are studied under the idealized framework of rotating radiative–convective equilibrium, achieved in a large doubly periodic f plane by coupling the column physics of a global atmospheric model to rotating hydrostatic dynamics. Unlike previous studies that prescribe uniform sea surface temperature (SST) over the domain, SSTs are now predicted by coupling the atmosphere to a simple slab ocean model. With coupling, SSTs under the eyewall region of tropical cyclones (TCs) become cooler than the environment. However, the domain still fills up with multiple long-lived TCs in all cases examined, including at the limit of the very small depth of the slab. The cooling of SSTs under the eyewall increases as the depth of the slab ocean layer decreases but levels off at roughly 6.5 K as the depth approaches zero. At the eyewall, the storm interior is decoupled from the cooler surface and moist entropy is no longer well mixed along the angular momentum surface in the boundary layer. TC intensity is reduced from the potential intensity computed without the cooling, but the intensity reduction is smaller than that estimated by a potential intensity taking into account the cooling and assuming that moist entropy is well mixed along angular momentum surfaces within the atmospheric boundary layer.

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Weak Tropical Cyclones Dominate the Poleward Migration of the Annual Mean Location of Lifetime Maximum Intensity of Northwest Pacific Tropical Cyclones since 1980

Journal of Climate ◽

10.1175/jcli-d-17-0019.1 ◽

2017 ◽

Vol 30 (17) ◽

pp. 6873-6882 ◽

Cited By ~ 18

Author(s):

Ruifen Zhan ◽

Yuqing Wang

Keyword(s):

Tropical Cyclones ◽

Large Scale ◽

Surface Wind ◽

Surface Wind Speed ◽

Maximum Intensity ◽

Sea Surface ◽

Northwest Pacific ◽

The Past ◽

Increasing Trend ◽

Sst Warming

The poleward migration of the annual mean location of tropical cyclone (TC) lifetime maximum intensity (LMI) has been identified in the major TC basins of the globe over the past 30 years, which is particularly robust over the western North Pacific (WNP). This study has revealed that this poleward migration consists mainly of weak TCs (with maximum sustained surface wind speed less than 33 m s−1) over the WNP. Results show that the location of LMI of weak TCs has migrated about 1° latitude poleward per decade since 1980, while such a trend is considerably smaller for intense TCs. This is found to be linked to a significant decreasing trend of TC genesis in the southern WNP and a significant increasing trend in the northwestern WNP over the past 30 years. It is shown that the greater sea surface temperature (SST) warming at higher latitudes associated with global warming and its associated changes in the large-scale circulation favor more TCs to form in the northern WNP and fewer but stronger TCs to form in the southern WNP.

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Enhanced intensity of global tropical cyclones during the mid-Pliocene warm period

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1608950113 ◽

2016 ◽

Vol 113 (46) ◽

pp. 12963-12967 ◽

Cited By ~ 17

Author(s):

Qing Yan ◽

Ting Wei ◽

Robert L. Korty ◽

James P. Kossin ◽

Zhongshi Zhang ◽

...

Keyword(s):

Tropical Cyclones ◽

Power Dissipation ◽

Atmospheric Model ◽

Historical Record ◽

Warm Period ◽

Global Atmospheric Model ◽

Peak Intensity ◽

The Pacific ◽

Present World

Given the threats that tropical cyclones (TC) pose to people and infrastructure, there is significant interest in how the climatology of these storms may change with climate. The global historical record has been extensively examined, but it is short and plagued with recurring questions about its homogeneity, limiting its effectiveness at assessing how TCs vary with climate. Past warm intervals provide an opportunity to quantify TC behavior in a warmer-than-present world. Here, we use a TC-resolving (∼25 km) global atmospheric model to investigate TC activity during the mid-Pliocene warm period (3.264−3.025 Ma) that shares similarities with projections of future climate. Two experiments, one driven by the reconstructed sea surface temperatures (SSTs) and the other by the SSTs from an ensemble of mid-Pliocene simulations, consistently predict enhanced global-average peak TC intensity during the mid-Pliocene coupled with longer duration, increased power dissipation, and a poleward migration of the location of peak intensity. The simulations are similar to global TC changes observed during recent global warming, as well as those of many future projections, providing a window into the potential TC activity that may be expected in a warmer world. Changes to power dissipation and TC frequency, especially in the Pacific, are sensitive to the different SST patterns, which could affect the viability of the role of TCs as a factor for maintaining a reduced zonal SST gradient during the Pliocene, as recently hypothesized.

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Future Changes in the Baiu Rain Band Projected by a 20-km Mesh Global Atmospheric Model: Sea Surface Temperature Dependence

SOLA ◽

10.2151/sola.2008-022 ◽

2008 ◽

Vol 4 ◽

pp. 85-88 ◽

Cited By ~ 26

Author(s):

Shoji Kusunoki ◽

Ryo Mizuta

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Temperature Dependence ◽

Atmospheric Model ◽

Sea Surface ◽

Global Atmospheric Model ◽

Rain Band

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The characteristics and structure of extra-tropical cyclones in a warmer climate

Weather and Climate Dynamics ◽

10.5194/wcd-1-1-2020 ◽

2020 ◽

Vol 1 (1) ◽

pp. 1-25 ◽

Cited By ~ 3

Author(s):

Victoria A. Sinclair ◽

Mika Rantanen ◽

Päivi Haapanala ◽

Jouni Räisänen ◽

Heikki Järvinen

Keyword(s):

Tropical Cyclones ◽

Diabatic Heating ◽

Vertical Motion ◽

Atmospheric Model ◽

Sea Surface ◽

Intermediate Step ◽

Thermal Advection ◽

Vorticity Advection ◽

Omega Equation ◽

Total Column

Abstract. Little is known about how the structure of extra-tropical cyclones will change in the future. In this study aqua-planet simulations are performed with a full-complexity atmospheric model. These experiments can be considered an intermediate step towards increasing knowledge of how, and why, extra-tropical cyclones respond to warming. A control simulation and a warm simulation in which the sea surface temperatures are increased uniformly by 4 K are run for 11 years. Extra-tropical cyclones are tracked, cyclone composites created, and the omega equation applied to assess causes of changes in vertical motion. Warming leads to a 3.3 % decrease in the number of extra-tropical cyclones, with no change to the median intensity or lifetime of extra-tropical cyclones but to a broadening of the intensity distribution resulting in both more stronger and more weaker storms. Composites of the strongest extra-tropical cyclones show that total column water vapour increases everywhere relative to the cyclone centre and that precipitation increases by up to 50 % with the 4 K warming. The spatial structure of the composite cyclone changes with warming: the 900–700 hPa layer averaged potential vorticity, 700 hPa ascent, and precipitation maximums associated with the warm front all move polewards and downstream, and the area of ascent expands in the downstream direction. Increases in ascent forced by diabatic heating and thermal advection are responsible for the displacement, whereas increases in ascent due to vorticity advection lead to the downstream expansion. Finally, maximum values of ascent due to vorticity advection and thermal advection weaken slightly with warming, whereas those attributed to diabatic heating increase. Thus, cyclones in warmer climates are more diabatically driven.

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Process-Oriented Diagnosis of Tropical Cyclones in High-Resolution GCMs

Journal of Climate ◽

10.1175/jcli-d-17-0269.1 ◽

2018 ◽

Vol 31 (5) ◽

pp. 1685-1702 ◽

Cited By ~ 15

Author(s):

Daehyun Kim ◽

Yumin Moon ◽

Suzana J. Camargo ◽

Allison A. Wing ◽

Adam H. Sobel ◽

...

Keyword(s):

Heat Flux ◽

High Resolution ◽

Tropical Cyclones ◽

Surface Heat Flux ◽

Surface Wind ◽

Atmospheric Model ◽

Surface Heat ◽

The Other ◽

Near Surface ◽

Surface Latent Heat Flux

This study proposes a set of process-oriented diagnostics with the aim of understanding how model physics and numerics control the representation of tropical cyclones (TCs), especially their intensity distribution, in GCMs. Three simulations are made using two 50-km GCMs developed at NOAA’s Geophysical Fluid Dynamics Laboratory. The two models are forced with the observed sea surface temperature [Atmospheric Model version 2.5 (AM2.5) and High Resolution Atmospheric Model (HiRAM)], and in the third simulation, the AM2.5 model is coupled to an ocean GCM [Forecast-Oriented Low Ocean Resolution (FLOR)]. The frequency distributions of maximum near-surface wind near TC centers show that HiRAM tends to develop stronger TCs than the other models do. Large-scale environmental parameters, such as potential intensity, do not explain the differences between HiRAM and the other models. It is found that HiRAM produces a greater amount of precipitation near the TC center, suggesting that associated greater diabatic heating enables TCs to become stronger in HiRAM. HiRAM also shows a greater contrast in relative humidity and surface latent heat flux between the inner and outer regions of TCs. Various fields are composited on precipitation percentiles to reveal the essential character of the interaction among convection, moisture, and surface heat flux. Results show that the moisture sensitivity of convection is higher in HiRAM than in the other model simulations. HiRAM also exhibits a stronger feedback from surface latent heat flux to convection via near-surface wind speed in heavy rain-rate regimes. The results emphasize that the moisture–convection coupling and the surface heat flux feedback are critical processes that affect the intensity of TCs in GCMs.

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Case Studies of Tropical Cyclones and Phytoplankton Blooms over Atlantic and Pacific Regions

Earth Interactions ◽

10.1175/2013ei000517.1 ◽

2013 ◽

Vol 17 (17) ◽

pp. 1-19 ◽

Cited By ~ 8

Author(s):

Ashley M. Merritt-Takeuchi ◽

Sen Chiao

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Case Studies ◽

Tropical Cyclones ◽

Surface Wind ◽

Ocean Basin ◽

Sea Surface ◽

Phytoplankton Blooms ◽

Near Surface ◽

Chl A

Abstract This study investigates phytoplankton blooms following the passage of tropical cyclones in the Atlantic and Pacific Ocean basins. The variables of sea surface temperature (SST), chlorophyll (Chl-a), precipitation, and storm surface winds were monitored for two case studies, Typhoon Xangsane (2006) and Hurricane Earl (2010). Strong near-surface wind from tropical cyclones creates internal friction, which causes deep nutrient enriched waters to displace from the bottom of the ocean floor up toward the surface. In return, the abundance of upwelled nutrients near the surface provides an ideal environment for the growth of biological substances such as chlorophyll and phytoplankton. The inverse correlation coefficients of SST and Chl-a for this study are −0.67 and −0.26 for Xangsane and Earl, respectively. This suggests that, regardless of ocean basin, changing sea surface temperature and chlorophyll concentrations can be correlated to various characteristics of tropical cyclones including precipitation and surface wind, which in combination results in an increase of phytoplankton.

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The Response of Tropical Cyclone Statistics to an Increase in CO2 with Fixed Sea Surface Temperatures

Journal of Climate ◽

10.1175/jcli-d-11-00050.1 ◽

2011 ◽

Vol 24 (20) ◽

pp. 5353-5364 ◽

Cited By ~ 84

Author(s):

Isaac M. Held ◽

Ming Zhao

Keyword(s):

Tropical Cyclone ◽

Vertical Motion ◽

Atmospheric Model ◽

Sea Surface ◽

Intensity Increase ◽

Average Intensity ◽

Sea Surface Temperatures ◽

Global Atmospheric Model ◽

Relative Contribution ◽

Surface Temperatures

Abstract The effects on tropical cyclone statistics of doubling CO2, with fixed sea surface temperatures (SSTs), are compared to the effects of a 2-K increase in SST, with fixed CO2, using a 50-km resolution global atmospheric model. Confirming earlier results of Yoshimura and Sugi, a significant fraction of the reduction in globally averaged tropical storm frequency seen in simulations in which both SST and CO2 are increased can be thought of as the effect of the CO2 increase with fixed SSTs. Globally, the model produces a decrease in tropical cyclone frequency of about 10% due to doubling of CO2 and an additional 10% for a 2-K increase in SST, resulting in roughly a 20% reduction when both effects are present. The relative contribution of the CO2 effect to the total reduction is larger in the Northern than in the Southern Hemisphere. The average intensity of storms increases in the model with increasing SST, but intensity remains roughly unchanged, or decreases slightly, with the increase in CO2 alone. As a result, when considering the frequency of more intense cyclones, the intensity increase tends to compensate for the reduced total cyclone numbers for the SST increase in isolation, but not for the CO2 increase in isolation. Changes in genesis in these experiments roughly follow changes in mean vertical motion, reflecting changes in convective mass fluxes. Discussion of one possible perspective on how changes in the convective mass flux might alter genesis rates is provided.

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Sea Surface Salinity Response to Tropical Cyclones Based on Satellite Observations

Remote Sensing ◽

10.3390/rs13030420 ◽

2021 ◽

Vol 13 (3) ◽

pp. 420

Author(s):

Jingru Sun ◽

Gabriel Vecchi ◽

Brian Soden

Keyword(s):

Tropical Cyclones ◽

Sea Surface ◽

Sea Surface Salinity ◽

Surface Salinity ◽

Translation Speed ◽

Salinity Stratification ◽

Left Hand ◽

In Situ Data ◽

Salinity Response ◽

The Right

Multi-year records of satellite remote sensing of sea surface salinity (SSS) provide an opportunity to investigate the climatological characteristics of the SSS response to tropical cyclones (TCs). In this study, the influence of TC winds, rainfall and preexisting ocean stratification on SSS evolution is examined with multiple satellite-based and in-situ data. Global storm-centered composites indicate that TCs act to initially freshen the ocean surface (due to precipitation), and subsequently salinify the surface, largely through vertical ocean processes (mixing and upwelling), although regional hydrography can lead to local departure from this behavior. On average, on the day a TC passes, a strong SSS decrease is observed. The fresh anomaly is subsequently replaced by a net surface salinification, which persists for weeks. This salinification is larger on the right (left)-hand side of the storm motion in the Northern (Southern) Hemisphere, consistent with the location of stronger turbulent mixing. The influence of TC intensity and translation speed on the ocean response is also examined. Despite having greater precipitation, stronger TCs tend to produce longer-lasting, stronger and deeper salinification especially on the right-hand side of the storm motion. Faster moving TCs are found to have slightly weaker freshening with larger area coverage during the passage, but comparable salinification after the passage. The ocean haline response in four basins with different climatological salinity stratification reveals a significant impact of vertical stratification on the salinity response during and after the passage of TCs.

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