Jonathan Douglas Wille

Last Name

Wille

First Name

Jonathan Douglas

ORCID

0000-0002-3918-5204

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03777 - Knutti, Reto / Knutti, Reto

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Publications 1 - 10 of 10

The extraordinary March 2022 East Antarctica “heat” wave
Wille, Jonathan Douglas; Alexander, Simon P.; Amory, Charles; et al. (2024)
Journal of Climate
Between 15 and 19 March 2022, East Antarctica experienced an exceptional heat wave with widespread 30°–40°C temperature anomalies across the ice sheet. In Part I, we assessed the meteorological drivers that generated an intense atmospheric river (AR) that caused these record-shattering temperature anomalies. Here, we continue our large collaborative study by analyzing the widespread and diverse impacts driven by the AR landfall. These impacts included widespread rain and surface melt that was recorded along coastal areas, but this was outweighed by widespread high snowfall accumulations resulting in a largely positive surface mass balance contribution to the East Antarctic region. An analysis of the surface energy budget indicated that widespread downward longwave radiation anomalies caused by large cloud-liquid water contents along with some scattered solar radiation produced intense surface warming. Isotope measurements of the moisture were highly elevated, likely imprinting a strong signal for past climate reconstructions. The AR event attenuated cosmic ray measurements at Concordia, something previously never observed. Last, an extratropical cyclone west of the AR landfall likely triggered the final collapse of the critically unstable Conger Ice Shelf while further reducing an already record low sea ice extent.
Impact of the atmospheric river occurring in March 2022 on east Antarctica on Cosmic-Rays measurements
Hubert, Guillaume; Ricaud, Philippe; Favier, Vincent; et al. (2024)
PoS: Proceedings of Science ~ Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)
The primary cosmic rays (CRs) interact with atmospheric atoms, producing secondary CRs (neutron, proton, muon etc.). Meteorological conditions influence the secondary CRs properties, such as the atmospheric pressure and the hydrometric properties (snowfall, the atmospheric water vapor and liquid water, the soil moisture). The CHINSTRAP project aims at recording CR induced-neutron spectra at Concordia Antarctic station, over a wide energy range from meV up to tens of GeV with a short time resolution. At the same time, a radiometer records continuously the water vapor contents and temperatures profiles (HAMSTRAD project). In March 2022, an atmospheric river (AR) caused some of the highest temperature anomalies ever observed over Antarctica (absolute temperature record of -9.4 °C on March 18th at Concordia). The ARs transport large amounts of moisture from the mid- to high-latitudes, modifying considerably usual dry conditions observed at Concordia. This AR event attenuated CRs measurements at Concordia, something previously never observed. A first analysis shows a correlation between the CR induced neutron flux decreases (in the order of 15%) and the increases of the integrated water vapor and liquid water path (IWV and LWP, respectively). This work demonstrates the importance of CRs attenuation during particle transport mechanisms in a highly saturated atmosphere.
Winter Targeted Observing Periods during the Year of Polar Prediction in the Southern Hemisphere (YOPP-SH)
Bromwich, David H.; Gorodetskaya, Irina V.; Carpentier, Scott; et al. (2024)
Bulletin of the American Meteorological Society
The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) held seven targeted observing periods (TOPs) during the 2022 austral winter to enhance atmospheric predictability over the Southern Ocean and Antarctica. The TOPs of 5–10-day duration each featured the release of additional radiosonde balloons, more than doubling the routine sounding program at the 24 participating stations run by 14 nations, together with process-oriented observations at selected sites. These extra sounding data are evaluated for their impact on forecast skill via data denial experiments with the goal of refining the observing system to improve numerical weather prediction for winter conditions. Extensive observations focusing on clouds and precipitation primarily during atmospheric river (AR) events are being applied to refine model microphysical parameterizations for the ubiquitous mixed-phase clouds that frequently impact coastal Antarctica. Process studies are being facilitated by high-time-resolution series of observations and forecast model output via the YOPP Model Intercomparison and Improvement Project (YOPPsiteMIIP). Parallel investigations are broadening the scope and impact of the YOPP-SH winter TOPs. Studies of the Antarctic tourist industry’s use of weather services show the scope for much greater awareness of the availability of forecast products and the skill they exhibit. The Sea Ice Prediction Network South (SIPN South) analysis of predictions of the sea ice growth period reveals that the forecast skill is superior to the sea ice retreat phase.
The Extraordinary March 2022 East Antarctica “Heat” Wave. Part I: Observations and Meteorological Drivers
Wille, Jonathan Douglas; Alexander, Simon P.; Amory, Charles; et al. (2024)
Journal of Climate
Between 15 and 19 March 2022, East Antarctica experienced an exceptional heat wave with widespread 30°–40°C temperature anomalies across the ice sheet. This record-shattering event saw numerous monthly temperature records being broken including a new all-time temperature record of −9.4°C on 18 March at Concordia Station despite March typically being a transition month to the Antarctic coreless winter. The driver for these temperature extremes was an intense atmospheric river advecting subtropical/midlatitude heat and moisture deep into the Antarctic interior. The scope of the temperature records spurred a large, diverse collaborative effort to study the heat wave’s meteorological drivers, impacts, and historical climate context. Here we focus on describing those temperature records along with the intricate meteorological drivers that led to the most intense atmospheric river observed over East Antarctica. These efforts describe the Rossby wave activity forced from intense tropical convection over the Indian Ocean. This led to an atmospheric river and warm conveyor belt intensification near the coastline, which reinforced atmospheric blocking deep into East Antarctica. The resulting moisture flux and upper-level warm-air advection eroded the typical surface temperature inversions over the ice sheet. At the peak of the heat wave, an area of 3.3 million km² in East Antarctica exceeded previous March monthly temperature records. Despite a temperature anomaly return time of about 100 years, a closer recurrence of such an event is possible under future climate projections. In Part II we describe the various impacts this extreme event had on the East Antarctic cryosphere.
Atmospheric rivers in Antarctica
Wille, Jonathan Douglas; Favier, Vincent; Gorodetskaya, Irina V.; et al. (2025)
Nature Reviews Earth & Environment
Antarctic atmospheric rivers (ARs) are a form of extreme weather that transport heat and moisture from the Southern Hemisphere subtropics and/or mid-latitudes to the Antarctic continent. Present-day AR events generally have a positive influence on the Antarctic ice-sheet mass balance by producing heavy snowfall, yet they also cause melt of sea ice and coastal ice sheet areas, as well as ice shelf destabilization. In this Review, we explore the atmospheric dynamics and impacts of Antarctic ARs over their life cycle to better understand their net contributions to ice-sheet mass balance. ARs occur in high-amplitude pressure couplets, and those strong enough to reach the Antarctic are often formed within Rossby waves initiated by tropical convection. Antarctic ARs are rare events (~3 days per year per location) but have been responsible for 50-70% of extreme snowfall events in East Antarctica since the 1980s. However, they can also trigger extensive surface melting events, such as the final ice shelf collapse of Larsen A in 1995 and Larsen B in 2002. Climate change will likely cause stronger ARs as anthropogenic warming increases atmospheric water vapour. Future research must determine how these climate change impacts will alter the relationship among Antarctic ARs, net ice-sheet mass balance and future sea-level rise.
Rising atmospheric moisture escalates the future impact of atmospheric rivers in the Antarctic climate system
Maclennan, Michelle L.; Winters, Andrew C.; Shields, Christine A.; et al. (2025)
Communications Earth & Environment
Despite their relative rarity, atmospheric rivers are key contributors to the surface mass balance of Antarctica. However, the future role of atmospheric rivers in modulating Antarctic sea-level contributions is a major area of uncertainty. Here, we leverage high-resolution climate simulations to show that Antarctic atmospheric rivers are highly sensitive to future increases in atmospheric moisture, leading to a doubling of atmospheric river frequencies and 2.5 x increase in precipitation from 2066-2100 under present-day thresholds for atmospheric river detection. However, future precipitation impacts are critically dependent on the detection threshold: accounting for moisture increases in the threshold produces smaller, regional changes in atmospheric river frequency, primarily resulting from an eastward shift in the polar jet maximum wind speeds. Our results underscore the importance of using large ensembles to quantify Antarctic atmospheric river responses to variability in projected moisture, which may not be captured when using only a few ensemble members.
Antarctica and the Southern Ocean
Raphael, Marilyn N.; Clem, Kyle R.; Adjou, Mohamed; et al. (2025)
Bulletin of the American Meteorological Society
Polar Aerosol Atmospheric Rivers: Detection, Characteristics, and Potential Applications
Lapere, Rémy; Thomas, Jennie L.; Favier, Vincent; et al. (2024)
Journal of Geophysical Research: Atmospheres
Aerosols play a key role in polar climate, and are affected by long-range transport from the mid-latitudes, both in the Arctic and Antarctic. This work investigates poleward extreme transport events of aerosols, referred to as polar aerosol atmospheric rivers (p-AAR), leveraging the concept of atmospheric rivers (AR) which signal extreme transport of moisture. Using reanalysis data, we build a detection catalog of p-AARs for black carbon, dust, sea salt and organic carbon aerosols, for the period 1980-2022. First, we describe the detection algorithm, discuss its sensitivity, and evaluate its validity. Then, we present several extreme transport case studies, in the Arctic and in the Antarctic, illustrating the complementarity between ARs and p-AARs. Despite similarities in transport pathways during co-occurring AR/p-AAR events, vertical profiles differ depending on the species, and large-scale transport patterns show that moisture and aerosols do not necessarily originate from the same areas. The complementarity between AR and p-AAR is also evidenced by their long-term characteristics in terms of spatial distribution, seasonality and trends. p-AAR detection, as a complement to AR, can have several important applications for better understanding polar climate and its connections to the mid-latitudes.
Drivers of observed winter-spring sea-ice and snow thickness at a coastal site in East Antarctica
Francis, Diana; Fonseca, Ricardo; Nelli, Narendra; et al. (2026)
The Cryosphere
Antarctic sea ice and its snow cover play a pivotal role in regulating the global climate system through feedback on both the atmospheric and the oceanic circulations. Understanding the intricate interplay between atmospheric dynamics, mixed-layer properties, and sea ice is essential for accurate future climate change estimates. This study investigates the mechanisms behind the observed sea-ice and snow characteristics at a coastal site in East Antarctica using in situ measurements in winter-spring 2022. The observed sea-ice thickness peaks at 1.16 m in mid-late October and drops to 0.06 m at the end of November, following the seasonal solar cycle. On the other hand, the snow thickness variability is impacted by atmospheric forcing, with significant contributions from precipitation, Foehn effects, blowing snow, and episodic warm and moist air intrusions, which can lead to changes of up to 0.08 m within a day for a field that is in the range of 0.02-0.18 m during July-November 2022. A high-resolution simulation with the Polar Weather Research and Forecasting model for the 14 July atmospheric river (AR), the only AR that occurred during the study period, reveals the presence of AR rapids and highlights the effects of katabatic winds from the Antarctic Plateau in slowing down the low-latitude air masses as they approach the Antarctic coastline. The resulting convergence of the two airflows, with meridional wind speeds in excess of 45 m s-1, leads to precipitation rates above 3 mm h-1 around coastal Antarctica. The unsteady wind field in response to the passage of a deep low-pressure system with a central pressure that dropped to 931 hPa triggers satellite-derived pack ice drift speeds in excess of 60 km d-1 and promotes the opening up of a polynya in the Southern Ocean around 64 degrees S, 45 degrees E from 14 to 22 July. Our findings contribute to a better understanding of the complex interactions within the Antarctic climate system, providing valuable insights for climate modeling and future projections.
nextGEMS: entering the era of kilometer-scale Earth system modeling
Segura, Hans; Pedruzo-Bagazgoitia, Xabier; Weiss, Philipp; et al. (2025)
Geoscientific Model Development
The Next Generation of Earth Modeling Systems (nextGEMS) project aimed to produce multidecadal climate simulations, for the first time, with resolved kilometer-scale (km-scale) processes in the ocean, land, and atmosphere. In only 3 years, nextGEMS achieved this milestone with the two km-scale Earth system models, ICOsahedral Nonhydrostatic model (ICON) and Integrated Forecasting System coupled to the Finite-volumE Sea ice-Ocean Model (IFS-FESOM). nextGEMS was based on three cornerstones: (1) developing km-scale Earth system models with small errors in the energy and water balance, (2) performing km-scale climate simulations with a throughput greater than 1 simulated year per day, and (3) facilitating new work-flows for an efficient analysis of the large simulations with common data structures and output variables. These cornerstones shaped the timeline of nextGEMS, divided into four cycles. Each cycle marked the release of a new configuration of ICON and IFS-FESOM, which were evaluated at hackathons. The hackathon participants included experts from climate science, software engineering, and high-performance computing as well as users from the energy and agricultural sectors. The continuous efforts over the four cycles allowed us to produce 30-year simulations with ICON and IFS-FESOM, spanning the period 2020–2049 under the SSP3-7.0 scenario. The throughput was about 500 simulated days per day on the Levante supercomputer of the German Climate Computing Center (DKRZ). The simulations employed a horizontal grid of about 5 km resolution in the ocean and 10 km resolution in the atmosphere and land. Aside from this technical achievement, the simulations allowed us to gain new insights into the realism of ICON and IFS-FESOM. Beyond its time frame, nextGEMS builds the foundation of the Climate Change Adaptation Digital Twin developed in the Destination Earth initiative and paves the way for future European research on climate change.

Publications 1 - 10 of 10

Jonathan Douglas Wille

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