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Aaron Donohoe

Senior Research Scientist





Department Affiliation

Polar Science Center


B.A. Physics, Bowdoin College, 2003

Ph.D. Atmospheric Sciences, University of Washington, 2011


2000-present and while at APL-UW

The largest ever recorded heatwave — Characteristics and attribution of the Antarctic heatwave of March 2022

Blanchard-Wigglesworth, E., T. Cox, Z.I. Espinosa, and A. Donohoe, "The largest ever recorded heatwave — Characteristics and attribution of the Antarctic heatwave of March 2022," Geophys. Res. Lett., 50, doi:10.1029/2023GL104910, 2023.

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16 Sep 2023

An unprecedented heatwave impacted East Antarctica in March 2022, peaking at 39°C above climatology, the largest temperature anomaly ever recorded globally. We investigate the causes of the heatwave, the impact of climate change, and a climate model's ability in simulating such an event. The heatwave, which was skillfully forecast, resulted from a highly anomalous large-scale circulation pattern that advected an Australian airmass to East Antarctica in 4 days and produced record atmospheric heat fluxes. Southern Ocean sea surface temperatures anomalies had a minimal impact on the heatwave's amplitude. Simulations from a climate model fail to simulate such a large temperature anomaly mostly due to biases in its large-scale circulation variability, showcasing a pathway for future model improvement in simulating extreme heatwaves. The heatwave was made 2°C warmer by climate change, and end of 21st century heatwaves may be an additional 5–6°C warmer, raising the prospect of near-melting temperatures over the interior of East Antarctica.

Diagnosing mechanisms of hydrologic change under global warming in the CESM1 Large Ensemble

Siler, N., D.B. Bonan, and A. Donohoe, "Diagnosing mechanisms of hydrologic change under global warming in the CESM1 Large Ensemble," J. Climate, EOR, doi:10.1175/JCLI-D-23-0086.1, 2023.

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7 Sep 2023

Global warming is expected to cause significant changes in the pattern of precipitation minus evaporation (P – E), which represents the net flux of water from the atmosphere to the surface or, equivalently, the convergence of moisture transport within the atmosphere. In most global climate model simulations, the pattern of P – E change resembles an amplification of the historical pattern — a tendency known as "wet gets wetter, dry gets drier". However, models also predict significant departures from this approximation that are not well understood. Here, we introduce a new method of decomposing the pattern of P – E change into contributions from various dynamic and thermodynamic mechanisms, and use it to investigate the response of P – E to global warming within the CESM1 Large Ensemble. In contrast to previous decompositions of P – E change, ours incorporates changes not only in the monthly means of atmospheric winds and moisture, but also in their temporal variability, allowing us to isolate the hydrologic impacts of changes in the mean circulation, transient eddies, relative humidity, and the spatial and temporal distributions of temperature. In general, we find that changes in the mean circulation primarily control the P – E response in the tropics, while temperature changes dominate at higher latitudes. Although the relative importance of specific mechanisms varies by region, at the global scale departures from the wet-gets-wetter approximation over land are primarily due to changes in the temperature lapse rate, while changes in the mean circulation, relative humidity, and horizontal temperature gradients play a secondary role.

Atmospheric heat transport is governed by meridional gradients in surface evaporation in modern-day earth-like climates

Fajber, R., A. Donohoe, S. Ragen, K.C. Armour, and P.J. Kushner, "Atmospheric heat transport is governed by meridional gradients in surface evaporation in modern-day earth-like climates," Proc. Natl. Acad. Sci. U.S.A., 120, doi:10.1073/pnas.2217202120, 2023.

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20 Jun 2023

Evaporation adds moisture to the atmosphere, while condensation removes it. Condensation also adds thermal energy to the atmosphere, which must be removed from the atmosphere by radiative cooling. As a result of these two processes, there is a net flow of energy driven by surface evaporation adding energy and radiative cooling removing energy from the atmosphere. Here, we calculate the implied heat transport of this process to find the atmospheric heat transport in balance with the surface evaporation. In modern-day Earth-like climates, evaporation varies strongly between the equator and the poles, while the net radiative cooling in the atmosphere is nearly meridionally uniform, and as a consequence, the heat transport governed by evaporation is similar to the total poleward heat transport of the atmosphere. This analysis is free from cancellations between moist and dry static energy transports, which greatly simplifies the interpretation of atmospheric heat transport and its relationship to the diabatic heating and cooling that governs the atmospheric heat transport. We further demonstrate, using a hierarchy of models, that much of the response of atmospheric heat transport to perturbations, including increasing CO2 concentrations, can be understood from the distribution of evaporation changes. These findings suggest that meridional gradients in surface evaporation govern atmospheric heat transport and its changes.

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In The News

Scientists found the most intense heat wave ever recorded — in Antarctica

Washington Post, Kasha Patel

In March 2022, temperatures near the eastern coast of Antarctica spiked 70 degrees Fahrenheit (39 degrees Celsius) above normal — making it the most intense recorded heat wave to occur anywhere on Earth, according to a recent study.

24 Sep 2023

New perspectives on the enigma of expanding Antarctic sea ice

Eos — Science News by AGU, Blanchard-Wrigglesworth, Eisenman, Zhang, Sun, and Donohoe

Recent research offers new insights on Antarctic sea ice, which, despite global warming, has increased in overall extent over the past 40 years. Most climate models indicate that Antarctic sea ice extent should have decreased over the past several decades. Here the authors discuss results from three recent independent studies that all applied a "nudging" technique to the same climate model to study the influences of different processes on Antarctic sea ice extent.

11 Feb 2022

Deep, old water explains why Antarctic Ocean hasn't warmed

UW News and Information, Hannah Hickey

Observations and climate models show that the unique currents around Antarctica continually pull deep, centuries-old water up to the surface — seawater that last touched Earth’s atmosphere before the machine age, and has never experienced fossil fuel-related climate change.

30 May 2016

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