Kerry A. Emanuel

Kerry A. Emanuel
Massachusetts Institute of Technology | MIT · Department of Earth Atmospheric and Planetary Sciences

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366
Publications
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Publications

Publications (366)
Article
Full-text available
Tropical cyclones (TCs) are drivers of extreme rainfall and surge, but the current and future TC rainfall–surge joint hazard has not been well quantified. Using a physics-based approach to simulate TC rainfall and storm tides, we show drastic increases in the joint hazard from historical to projected future (SSP5–8.5) conditions. The frequency of j...
Article
Full-text available
Tropical cyclones (TCs, also known as hurricanes and typhoons) generally form at low latitudes with access to the warm waters of the tropical oceans, but far enough off the equator to allow planetary rotation to cause aggregating convection to spin up into coherent vortices. Yet, current prognostic frameworks for TC latitudes make contradictory pre...
Article
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Historical records of Atlantic hurricane activity, extending back to 1851, show increasing activity over time, but much or all of this trend has been attributed to lack of observations in the early portion of the record. Here we use a tropical cyclone downscaling model driven by three global climate analyses that are based mostly on sea surface tem...
Preprint
Full-text available
In theoretical models of tropical dynamics, the effects of both surface friction and upward wave radiation through interaction with the stratosphere are oft-ignored, as they greatly complicate mathematical analysis. In this study, we relax the rigid-lid assumption and impose surface drag, which allows the barotropic mode to be excited in equatorial...
Article
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Pluvial floods generated by tropical cyclones (TCs) are one of the major concerns for coastal communities. Choosing Houston as an example, we demonstrate that there will be significantly elevated risk of TC rainfall and flood in the future warming world by coupling downscaled TCs from Model Intercomparison Project Phase 6 models with physical hydro...
Article
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The EUREC4A field campaign, designed to test hypothesized mechanisms by which clouds respond to warming and benchmark next-generation Earth-system models, is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic - eastward and southeastward of Barbados. It was the first campaign that atte...
Article
Potential intensity (PI) has been shown to have a linear sensitivity to sea surface temperature (SST) of about 8 m s ⁻¹ K ⁻¹ , which is close to the sensitivity of PI in simulations subject to a weak temperature gradient (WTG) approximation. This suggests that most of the PI variance is associated with local rather than global SST variations. We ve...
Preprint
Full-text available
Tropical cyclones (TCs) are among the largest drivers of extreme rainfall and surge, but current and future TC joint hazard has not been well quantified. We utilize a physics-based approach to simulate TC rainfall and storm tides and quantify their joint hazard under historical conditions and a future (SSP5 8.5) climate projection. We find drastic...
Preprint
This paper presents a modeling approach for probabilistic estimation of hurricane wind-induced damage to infrastructural assets. In our approach, we employ a Nonhomogeneous Poisson Process (NHPP) model for estimating spatially-varying probability distributions of damage as a function of hurricane wind field velocities. Specifically, we consider a p...
Article
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Tropical cyclones (TCs) cause negative sea surface temperature (SST) anomalies by vertical mixing and other processes. Such cold wakes can cover substantial areas and persist for a month or longer. It has long been hypothesized that cold wakes left behind by intense TCs reduce the likelihood of subsequent TC development. Neither this hypothesis, no...
Article
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We use a high-resolution regional climate model to investigate the changes in Atlantic tropical cyclone (TC) activity during the period of the mid-Holocene (MH: 6000 years BP) with a larger amplitude of the seasonal cycle relative to today. This period was characterized by increased boreal summer insolation over the Northern Hemisphere, a vegetated...
Article
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The extent and impact of climate-related extreme events depend on the underlying meteorological, hydrological, or climatological drivers as well as on human factors such as land use or population density. Here we quantify the pure effect of historical and future climate change on the exposure of land and population to extreme climate impact events...
Article
We concur with Makarieva et al. that in our earlier work on the hurricane differential Carnot cycle, we neglected the work done in lifting water and the dissipation of kinetic energy in the outflow (we explicitly acknowledged neglecting these terms). Here, we relax those assumptions, affirm the conclusion of Makarieva et al. that the water lifting...
Article
This paper describes the development of a model framework for Forecasts of Hurricanes Using Large-Ensemble Outputs (FHLO). FHLO quantifies the forecast uncertainty of a tropical cyclone (TC) by generating probabilistic forecasts of track, intensity, and wind speed that incorporate the state-dependent uncertainty in the large-scale field. The main g...
Article
Full-text available
Tropical cyclones pose a significant flood risk to vast land regions in their path because of extreme precipitation. Thus it is imperative to quantitatively assess this risk. This study compares exceedance frequencies of tropical cyclone precipitation derived from two independent observational datasets with those estimated using a tropical cyclone...
Preprint
Full-text available
We use a high-resolution regional climate model to investigate the changes in Atlantic tropical cyclone (TC) activity during a warm climate state, the mid-Holocene (MH: 6,000 yrs BP). This period was characterized by increased boreal summer insolation, a vegetated Sahara, and reduced airborne dust concentrations. A set of sensitivity experiments we...
Article
Global models comprising the sixth generation Coupled Climate Model Intercomparison Project (CMIP6) are downscaled using a very high resolution but simplified coupled atmosphere-ocean tropical cyclone model, as a means of estimating the response of global tropical cyclone activity to increasing greenhouse gases. As with a previous downscaling of CM...
Article
This article presents an azimuthally asymmetric gradient hurricane wind field model that can be coupled with hurricane track models for engineering wind risk assessments. The model incorporates low-wavenumber asymmetries into the maximum wind intensity parameter of the Holland et al. (2010) wind field model. The amplitudes and phases of the asymmet...
Conference Paper
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Coastal and inland residents often face a barrage of information when a hurricane threatens. These include graphical and textual products from forecast entities such as the National Hurricane Center and local National Weather Service (NWS) offices, evacuation orders from local governments, and a wide variety of information from traditional media, b...
Article
In their comment, Žagar and Szunyogh raised concerns about a recent study by Zhang et al. that examined the predictability limit of midlatitude weather using two up-to-date global models. Zhang et al. showed that deterministic weather forecast may, at best, be extended by 5 days, assuming we could achieve minimal initial-condition uncertainty (e.g....
Article
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Climate change is not only about changes in means of climatic variables such as temperature, precipitation and wind, but also their extreme values which are of critical importance to human society and ecosystems. To inspire the Swedish climate research community and to promote assessments of international research on past and future changes in extr...
Article
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One of the most destructive natural hazards, tropical cyclone (TC)-induced coastal flooding, will worsen under climate change. Here we conduct climatology-hydrodynamic modeling to quantify the effects of sea level rise (SLR) and TC climatology change (under RCP 8.5) on late 21st century flood hazards at the county level along the US Atlantic and Gu...
Article
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Model projections of tropical cyclone (TC) activity response to anthropogenic warming in climate models are assessed. Observations, theory, and models, with increasing robustness, indicate rising global TC risk for some metrics that are projected to impact multiple regions. A 2°C anthropogenic global warming is projected to impact TC activity as fo...
Article
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The criteria and assumptions that were used to derive the steady-state tropical cyclone intensity and structure theory of Emanuel and Rotunno are assessed using three-dimensional convection-allowing simulations using the Weather Research and Forecasting Model. One real-data case of Hurricane Patricia (2015) and two idealized simulations with and wi...
Article
Full-text available
Tropical cyclones pose a significant flood risk to vast land regions in their path because of extreme precipitation. Thus it is imperative to quantitatively assess this risk. This study compares exceedance frequencies of tropical cyclone precipitation derived from two independent observational datasets with those estimated using a tropical cyclone...
Article
Full-text available
An assessment was made of whether detectable changes in tropical cyclone (TC) activity are identifiable in observations and whether any changes can be attributed to anthropogenic climate change. Overall, historical data suggest detectable TC activity changes in some regions associated with TC track changes, while data quality and quantity issues cr...
Article
This study investigates relationships between observed tropical cyclone (TC) maximum intensities and potential intensity (PI) over the seasonal cycle. To directly compare observed and potential intensities, one must account for month-to-month variability in TC tracks and frequencies. Historical TC best track data and reanalysis PI calculations are...
Article
The hazard to the city of Mumbai, India, from a possible severe tropical cyclone under the recent historical climate is considered. The authors first determine, based on a review of primary sources, that the Bombay Cyclone of 1882, documented in a number of print and Internet sources and claimed to have caused 100 000 or more deaths, did not occur....
Article
Potential intensity (PI) is an analytical bound on steady, inviscid, axisymmetric hurricane wind speed. Studies have shown that simulated hurricane azimuthal wind speed can greatly exceed a PI bound on the maximum gradient wind. This disparity is called superintensity (SI) and has been attributed to the contribution of the unbalanced flow to the az...
Article
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Solar geoengineering (SG) has the potential to restore average surface temperatures by increasing planetary albedo 1–4 , but this could reduce precipitation 5–7 . Thus, although SG might reduce globally aggregated risks, it may increase climate risks for some regions 8–10 . Here, using the high-resolution forecast-oriented low ocean resolution (HiF...
Article
Full-text available
Understanding the predictability limit of day-to-day weather phenomena such as midlatitude winter storms and summer monsoonal rainstorms is crucial to numerical weather prediction (NWP). This predictability limit is studied using unprecedented high-resolution global models with ensemble experiments of the European Centre for Medium-Range Weather Fo...
Article
Recent flood disasters in the United States (2005, 2008, 2012); the Philippines (2012, 2013); and Britain (2014) illustrate how vulnerable coastal cities are to storm surge flooding ( 1). Floods caused the largest portion of insured losses among all catastrophes around the world in 2013 ( 2). Population density in flood-prone coastal zones and mega...
Article
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The devastating impact by Hurricane Sandy (2012) again showed New York City (NYC) is one of the most vulnerable cities to coastal flooding around the globe. The low-lying areas in NYC can be flooded by nor'easter storms and North Atlantic hurricanes. The few studies that have estimated potential flood damage for NYC base their damage estimates on o...
Article
The recent article by Li and Toumi (2018, https://doi.org/10.1029/2018GL079677) published in Geophysical Research Letters explored the potential for improving tropical cyclone intensity forecasts by assimilating synthetic coastal surface currents from high-frequency radar observations. Although it is an idealized study using simulated observations,...
Article
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The ongoing emission of greenhouse gases (GHGs) is triggering changes in many climate hazards that can impact humanity. We found traceable evidence for 467 pathways by which human health, water, food, economy, infrastructure and security have been recently impacted by climate hazards such as warming, heatwaves, precipitation, drought, floods, fires...
Article
A framework for conceptual understanding of slow, convectively coupled disturbances is developed and applied to several canonical tropical problems, including the water vapor content of an atmosphere in radiative-convective equilibrium, the relationship between convective precipitation and column water vapor, Walker-like circulations, self-aggregat...
Article
To paraphrase former Speaker of the House Tip O'Neill, “All climate change is local”—that is, society reacts most immediately to changes in local weather such as regional heat waves and heavy rainstorms. Such phenomena are not well resolved by the current generation of coupled climate models. Here it is shown that dynamical downscaling of climate r...
Article
Recent studies have suggested that the Madden-Julian oscillation is a result of an instability driven mainly by cloud-radiation feedbacks, similar in character to self-aggregation of convection in nonrotating, cloud-permitting simulations of radiative-convective equilibrium (RCE). Here we bolster that inference by simulating radiative-convective eq...
Article
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A century ago, meteorologists regarded tropical cyclones as shallow vortices, extending upward only a few kilometers into the troposphere, and nothing was known about their physics save that convection was somehow involved. As recently as 1938, a major hurricane struck the densely populated northeastern United States with no warning whatsoever, kil...
Article
A two-column radiative–convective equilibrium (RCE) model is used to study the depth of convection that develops in the subsiding branch of a Walker-like overturning circulation. The model numerically solves for two-dimensional non-rotating hydrostatic flow, which is damped by momentum diffusion in the boundary layer and model interior, and by conv...
Article
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Radiative-convective equilibrium is a simple paradigm for the tropical climate, in which radiative cooling balances convective heating in the absence of lateral energy transport. Recent studies have shown that a large-scale circulation may spontaneously develop from radiative-convective equilibrium through the interactions among water vapor, radiat...
Article
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We examine a recently developed physics-based tropical cyclone rainfall (TCR) model and apply it to assess the mechanisms that dominate the magnitude and spatial distribution of TC rainfall, with Hurricanes Isabel (2003) and Irene (2011) as study cases. We evaluate the TCR model using Weather and Research Forecasting (WRF) Model simulations. TCR-ge...
Presentation
Full-text available
We introduce a new mode of thought on tropical cyclone (TC) intensification, namely, how can one ascertain the theoretical and practical upper bounds of TC intensification, given an initial vortex structure and expected environmental conditions. The expectation of an upper bound of intensification is partially motivated by observations showing that...
Article
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What: Accurate records of historical tropical cyclones are invaluable for scientific research and risk quantification. Yet most tropical cyclone data were collected in aid of operational forecasting with mixed attention to its use as a climate archive. To remedy this, as far as possible, a comprehensive reanalysis of Atlantic tropical cyclones was...
Article
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In Paris, France, December 2015, the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) invited the Intergovernmental Panel on Climate Change (IPCC) to provide a special report in 2018 on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission...
Article
Real-time ensemble forecasts from the Pennsylvania State University (PSU) WRF EnKF system (APSU) for Hurricane Joaquin (2015) are examined in this study. The ensemble forecasts, from early in Joaquin’s life cycle, displayed large track spread, with nearly half of the ensemble members tracking Joaquin toward the U.S. East Coast and the other half tr...
Article
Full-text available
Solar geoengineering refers to a range of proposed methods for counteracting global warming by artificially reducing sunlight at Earth’s surface. The most widely known solar geoengineering proposal is stratospheric aerosol injection (SAI), which has impacts analogous to those from volcanic eruptions. Observations following major volcanic eruptions...
Article
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We estimate, for current and future climates, the annual probability of areally averaged hurricane rain of Hurricane Harvey’s magnitude by downscaling large numbers of tropical cyclones from three climate reanalyses and six climate models. For the state of Texas, we estimate that the annual probability of 500 mm of area-integrated rainfall was abou...
Article
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Organized convection in the tropics occurs across a range of spatial and temporal scales and strongly influences cloud cover and humidity. One mode of organization found is “self-aggregation,” in which moist convection spontaneously organizes into one or several isolated clusters despite spatially homogeneous boundary conditions and forcing. Self-a...
Article
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Space-borne observations reveal that 20–40% of marine convective clouds below the freezing level produce rain. In this paper we speculate what the prevalence of warm rain might imply for convection and large-scale circulations over tropical oceans. We present results using a two-column radiative–convective model of hydrostatic, nonlinear flow on a...
Article
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Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, conv...
Article
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The flood hazard in New York City depends on both storm surges and rising sea levels. We combine modeled storm surges with probabilistic sea-level rise projections to assess future coastal inundation in New York City from the preindustrial era through 2300 CE. The storm surges are derived from large sets of synthetic tropical cyclones, downscaled f...
Article
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Robust estimates of tropical cyclone risk can be made using large sets of storm events synthesized from historical data or from physics-based algorithms. While storm tracks can be synthesized very rapidly from statistical algorithms or simple dynamical models (such as the beta-and-advection model), estimation of storm intensity by using full-physic...
Article
Western North Pacific tropical cyclone (TC) model tracks are analyzed in two large multi-model ensembles, spanning a large variety of models and multiple future climate scenarios. Two methodologies are used to synthesize the properties of TC tracks in this large dataset: cluster analysis and mass moments ellipses. First, the models' TC tracks are c...
Article
Athermodynamic constraint on convective available potential energy (CAPE) in continental environments is established using an idealized one-dimensional model. This theoretical model simplifies the synoptic-scale preconditioning framework for continental severe convection by considering a dry adiabatic column that comes into contact with a moist lan...
Article
Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleosediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it...
Article
Full-text available
Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, i...
Article
Full-text available
Tropical cyclone (TC) outflow and its relationship to TC intensity change and structure were investigated in the Office of Naval Research Tropical Cyclone Intensity (TCI) field program during 2015 using dropsondes deployed from the innovative new HDSS (High Definition Sounding System) and remotely sensed observations from HIRAD (Hurricane Imaging R...
Article
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Recent studies have investigated trends and interannual variability in the potential intensity (PI) of tropical cyclones (TCs), but relatively few have examined TC PI seasonality or its controlling factors. Potential intensity is a function of environmental conditions that influence thermodynamic atmosphere-ocean disequilibrium and the TC thermodyn...