Internal variability of North Atlantic tropical cyclones

Done, James M.; Bruyère, Cindy L.; Ge, Ming; Jaye, Abigail

doi:10.1002/2014jd021542

Cited by 30 publications

(23 citation statements)

References 96 publications

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“…This study does not additionally explore the role of internal variability for the potential predictability of the 2012 drought. Internal variability is an intrinsic property of the climate system, emanating from regions of conditional or baroclinic instability [ Nikiéma and Laprise , , ] and for regional domain results in a range of solutions consistent with the boundary conditions [e.g., Done et al , ; Lucas‐Picher et al , ]. Perturbed physics, on the other hand, produce solutions to a slightly different model climate, and the resulting range is commonly found to be large compared to internal variability [ Solman and Pessacg , ].…”

Section: Experimental Setup and Reference Data Setmentioning

confidence: 99%

“…Regional climate modeling is a powerful tool to explore regional physical mechanisms, and ensembles can provide a measure of the prediction uncertainty. Ensemble studies of seasonal prediction of extremes create ensemble members through the use of perturbed initial conditions [e.g., Toth and Kalnay , ; Buizza and Palmer , ; Houtekamer and Derome , ; Done et al , ]. However, these initial condition ensembles are generally unable to provide the spread obtained through varying model physics [e.g., Buizza et al , ; Stensrud et al , ].…”

Section: Introductionmentioning

confidence: 99%

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Potential predictability sources of the 2012 U.S. drought in observations and a regional model ensemble

PaiMazumder

Done

2016

JGR Atmospheres

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The 2012 drought was the most severe and extensive summertime U.S. drought in half a century with substantial economic loss and impacts on food security and commodity prices. A unique aspect of the 2012 drought was its rapid onset and intensification over the Southern Rockies, extending to the Great Plains during late spring and early summer, and the absence of known precursor large‐scale patterns. Drought prediction therefore remains a major challenge. This study evaluates relationships among snow, soil moisture, and precipitation to identify sources of potential predictability of the 2012 summer drought using observations and a Weather Research and Forecasting model multiphysics ensemble experiment. Although underestimated in intensity, the drought signal is robust to the way atmospheric physical processes are represented in the model. For the Southern Rockies, soil moisture exhibits stronger persistence than precipitation in observations and the ensemble experiment. Correlations between winter/spring snowmelt and concurrent and following season soil moisture, and between soil moisture and concurrent and following season precipitation, in both observations and the model ensemble, suggest potential predictability beyond 1 and 2 month lead‐time reside in the land surface conditions for apparent flash droughts such as the 2012 drought.

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Section: Experimental Setup and Reference Data Setmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Potential predictability sources of the 2012 U.S. drought in observations and a regional model ensemble

PaiMazumder

Done

2016

JGR Atmospheres

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“…An inspection of the time series suggests that the nudging simulation correctly captures most active and inactive seasons in the observations, but the RAS simulation occasionally misrepresents the sign of seasonal activity anomaly. However, the skill difference may have some uncertainty, as the internal variability of the atmosphere can introduce noise into the simulated TC statistics (e.g., Done et al, 2014;Mei et al, 2019;). An in-depth examination of the TC simulations is available in the supporting information.…”

Section: Preliminary Simulations: Interior Nudging Versus Parameterizmentioning

confidence: 99%

Impacts of Extratropical Weather Perturbations on Tropical Cyclone Activity: Idealized Sensitivity Experiments With a Regional Atmospheric Model

Zhang

Knutson

Garner

2019

Geophysical Research Letters

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Extratropical weather perturbations have been linked to Atlantic tropical cyclones (TCs) activity in observations. However, modeling studies of the extratropical impact are scarce and disagree about its importance and climate implications. Using a nonhydrostatic regional atmospheric model, we explore the extratropical impact by artificially suppressing extratropical weather perturbations at the tropical-extratropical interface. Our 22-year simulations of August-October suggest that the extratropical suppression adds~3.7 Atlantic TCs per season on average, although the response varies among individual years. The TC response mainly appears within 30-40°N, where tropical cyclogenesis frequency quadruples compared to control simulations. This increased cyclogenesis, accompanied by a strong increase of midtropospheric relative humidity, arises as the perturbation suppression reduces the extratropical interference of TC development. The suppression of extratropical perturbations is highly idealized but may suggest mechanisms by which extratropical atmospheric variability potentially influences TC activity in past or future altered climate states. Plain Language SummaryRecent observational studies suggest that Atlantic hurricane activity is strongly affected by extratropical weather processes, but modeling studies disagree about the importance of such an impact. Using a regional atmospheric model, we conduct idealized experiments to explore the extratropical impact on Atlantic hurricane activity. Our simulations of 22 hurricane seasons show that artificially suppressing extratropical weather perturbations at the northern boundary in the model can increase hurricane activity significantly. The response of the model's hurricane activity varies from season to season, which may contribute to the different responses found among earlier modeling studies. Notably, the strongest response of hurricane activity appears within 30-40°N, where the number of hurricane formations quadruples compared to reference simulations. The perturbation reduction also helps hurricanes to move more slowly and smoothly with fewer disruptions from the high latitudes. These experiments, though idealized, suggest that the extratropical atmospheric circulation plays an important moderating role in limiting Atlantic hurricane formation. These experiments also could have implications for hurricane activity in the distant past or in coming decades, for example, if climate warming were accompanied by a weakening or poleward shift of extratropical weather systems.

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“…The so-called twin simulations, i.e., LAM integrations identical in all respect, except having slightly different initial conditions, may with time lead to substantially different solutions. This phenomenon has been referred to as internal variability (IV) in the existing literature [e.g., Giorgi and Bi, 2000;Christensen et al, 2001;Rinke et al, 2004;Lucas-Picher et al, 2008a;Crétat et al, 2011;Done et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

Internal variability of fine‐scale components of meteorological fields in extended‐range limited‐area model simulations with atmospheric and surface nudging

Šeparović

Husain

2015

JGR Atmospheres

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Internal variability (IV) in dynamical downscaling with limited-area models (LAMs) represents a source of error inherent to the downscaled fields, which originates from the sensitive dependence of the models to arbitrarily small modifications. If IV is large it may impose the need for probabilistic verification of the downscaled information. Atmospheric spectral nudging (ASN) can reduce IV in LAMs as it constrains the large-scale components of LAM fields in the interior of the computational domain and thus prevents any considerable penetration of sensitively dependent deviations into the range of large scales. Using initial condition ensembles, the present study quantifies the impact of ASN on IV in LAM simulations in the range of fine scales that are not controlled by spectral nudging. Four simulation configurations that all include strong ASN but differ in the nudging settings are considered. In the fifth configuration, grid nudging of land surface variables toward high-resolution surface analyses is applied. The results show that the IV at scales larger than 300 km can be suppressed by selecting an appropriate ASN setup. At scales between 300 and 30 km, however, in all configurations, the hourly near-surface temperature, humidity, and winds are only partly reproducible. Nudging the land surface variables is found to have the potential to significantly reduce IV, particularly for fine-scale temperature and humidity. On the other hand, hourly precipitation accumulations at these scales are generally irreproducible in all configurations, and probabilistic approach to downscaling is therefore recommended.

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Internal variability of North Atlantic tropical cyclones

Cited by 30 publications

References 96 publications

Potential predictability sources of the 2012 U.S. drought in observations and a regional model ensemble

Potential predictability sources of the 2012 U.S. drought in observations and a regional model ensemble

Impacts of Extratropical Weather Perturbations on Tropical Cyclone Activity: Idealized Sensitivity Experiments With a Regional Atmospheric Model

Internal variability of fine‐scale components of meteorological fields in extended‐range limited‐area model simulations with atmospheric and surface nudging

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