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1. Extreme Antarctic Cold of Late Winter 2023

Author

Tomanek, Anastasia J., Mikolajczyk, David E., Lazzara, Matthew A., Di Battista, Stefano, Ding, Minghu, Fontolan Litell, Mariana, Bromwich, David H., Norton, Taylor P., Keller, Linda M., and Welhouse, Lee J.

Published
2024
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3. Characteristics of Surface âMelt Potentialâ over Antarctic Ice Shelves based on Regional Atmospheric Model Simulations of Summer Air Temperature Extremes from 1979/80 to 2018/19

Author

Orr, Andrew, Deb, Pranab, Clem, Kyle R, Gilbert, Ella, Bromwich, David H, Boberg, Fredrik, Colwell, Steve, Hansen, Nicolaj, Lazzara, Matthew A, Mooney, Priscilla A, Mottram, Ruth, Niwano, Masashi, Phillips, Tony, Pishniak, Denys, Reijmer, Carleen H, van de Berg, Willem Jan, Webster, Stuart, and Zou, Xun

Published
2023

6. Tropical teleconnection impacts on Antarctic climate changes

Author

Li, Xichen, Cai, Wenju, Meehl, Gerald A, Chen, Dake, Yuan, Xiaojun, Raphael, Marilyn, Holland, David M, Ding, Qinghua, Fogt, Ryan L, Markle, Bradley R, Wang, Guojian, Bromwich, David H, Turner, John, Xie, Shang-Ping, Steig, Eric J, Gille, Sarah T, Xiao, Cunde, Wu, Bingyi, Lazzara, Matthew A, Chen, Xianyao, Stammerjohn, Sharon, Holland, Paul R, Holland, Marika M, Cheng, Xiao, Price, Stephen F, Wang, Zhaomin, Bitz, Cecilia M, Shi, Jiuxin, Gerber, Edwin P, Liang, Xi, Goosse, Hugues, Yoo, Changhyun, Ding, Minghu, Geng, Lei, Xin, Meijiao, Li, Chuanjin, Dou, Tingfeng, Liu, Chengyan, Sun, Weijun, Wang, Xinyue, and Song, Chentao

Subjects
Climate Action
Abstract

Over the modern satellite era, substantial climatic changes have been observed in the Antarctic, including atmospheric and oceanic warming, ice sheet thinning and a general Antarctic-wide expansion of sea ice, followed by a more recent rapid loss. Although these changes, featuring strong zonal asymmetry, are partially influenced by increasing greenhouse gas emissions and stratospheric ozone depletion, tropical–polar teleconnections are believed to have a role through Rossby wave dynamics. In this Review, we synthesize understanding of tropical teleconnections to the Southern Hemisphere extratropics arising from the El Niño–Southern Oscillation, Interdecadal Pacific Oscillation and Atlantic Multidecadal Oscillation, focusing on the mechanisms and long-term climatic impacts. These teleconnections have contributed to observed Antarctic and Southern Ocean changes, including regional rapid surface warming, pre-2015 sea ice expansion and its sudden reduction thereafter, changes in ocean heat content and accelerated thinning of most of the Antarctic ice sheet. However, due to limited observations and inherent model biases, uncertainties remain in understanding and assessing the importance of these teleconnections versus those arising from greenhouse gases, ozone recovery and internal variability. Sustained pan-Antarctic efforts towards long-term observations, and more realistic dynamics and parameterizations in high-resolution climate models, offer opportunities to reduce these uncertainties.

Published
2021

8. Year of Polar Prediction : A Focus on Antarctica

Author

Bromwich, David H., Werner, Kirstin, Casati, Barbara, Powers, Jordan G., Gorodetskaya, Irina V., Massonnet, Francois, Vitale, Vito, Heinrich, Victoria J., Liggett, Daniela, Arndt, Stefanie, Barja, Boris, Bazile, Eric, Carpentier, Scott, Carrasco, Jorge F., Choi, Taejin, Choi, Yonghan, Colwell, Steven R., Cordero, Raul R., Gervasi, Massimo, Haiden, Thomas, Hirasawa, Naohiko, Inoue, Jun, Jung, Thomas, Kalesse, Heike, Kim, Seong-Joong, Lazzara, Matthew A., Manning, Kevin W., Norris, Kimberley, Park, Sang-Jong, Reid, Phillip, Rigor, Ignatius, Rowe, Penny M., Schmithüsen, Holger, Seifert, Patric, Sun, Qizhen, Uttal, Taneil, Zannoni, Mario, and Zou, Xun

Published
2021

12. Major Artifacts in ERA5 2‐m Air Temperature Trends Over Antarctica Prior to and During the Modern Satellite Era.

Author

Bromwich, David H., Ensign, Alexandra, Wang, Sheng‐Hung, and Zou, Xun

Abstract

Global reanalyzes are widely used for investigations of Antarctic climate variability and change. The European Centre for Medium‐Range Weather Forecasts 5th generation reanalysis (ERA5) is well regarded and spans 1940 to today. We investigate whether ERA5 reliably represents the 2‐m air temperature trends across the 1940–2022 (83 years) period at seasonal and annual time scales. We compare ERA5 temperatures with an observation‐based temperature reconstruction for Antarctica (RECON) that has monthly resolution for 1958–2022, the period of reliable observational availability. Results for individual stations are also examined. ERA5 anomalously warms Antarctica in relation RECON especially for the period prior to 1979 when satellite observations over the Southern Ocean were sparse. Trend hotspots that are shown to be artifacts are found at three locations and are present until today. The results demonstrate that ERA5 temperature trends can be questionable even today, but variability is well captured after 1979. Plain Language Summary: Reanalyzes are especially useful for describing and understanding the climate of regions where observations are few and far between. Reanalyzes are not actual conditions but approximations that have strengths as well as weaknesses. A continuing reanalysis challenge for higher latitudes of the Southern Hemisphere that has caused many previous artifacts is the transition from few satellite observations over the Southern Ocean prior to 1979 to the relative abundance since. Here we examine the 2‐m air temperature from the latest global reanalysis from ECMWF for Antarctica and show that it is still challenged by the 1979 transition. ERA5 warms Antarctica much too rapidly especially prior to 1979 and contains artificial trend hotspots at three locations right up to the present. ERA5 cannot be used for Antarctic temperature climate change applications prior to 1979 but can be applied for this purpose after 1979 with appropriate caution. Key Points: ERA5 air temperatures have spurious trends for most regions of Antarctica prior to 1979Artificial trend hotspots are present at three low elevation sites until the presentERA5 cannot be used for temperature climate change studies over Antarctica earlier than 1979 but can be selectively applied post 1979 [ABSTRACT FROM AUTHOR]

Published
2024
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14. The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH)

Author

Bromwich, David H., Werner, Kirstin, Casati, Barbara, Powers, Jordan G., Gorodetskaya, Irina V., Massonnet, François, Vitale, Vito, Heinrich, Victoria J., Liggett, Daniela, Arndt, Stefanie, Barja, Boris, Bazile, Eric, Carpentier, Scott, Carrasco, Jorge F., Choi, Taejin, Choi, Yonghan, Colwell, Steven R., Cordero, Raul R., Gervasi, Massimo, Haiden, Thomas, Hirasawa, Naohiko, Inoue, Jun, Jung, Thomas, Kalesse, Heike, Kim, Seong-Joong, Lazzara, Matthew A., Manning, Kevin W., Norris, Kimberley, Park, Sang-Jong, Reid, Phillip, Rigor, Ignatius, Rowe, Penny M., Schmithüsen, Holger, Seifert, Patric, Sun, Qizhen, Uttal, Taneil, Zannoni, Mario, and Zou, Xun

Published
2020

15. AWARE in West Antarctica : Clouds, climate, and critical ice melt

Author

Lubin, Dan, Zhang, Damao, Silber, Israel, Scott, Ryan C., Kalogeras, Petros, Battaglia, Alessandro, Bromwich, David H., Cadeddu, Maria, Eloranta, Edwin, Fridlind, Ann, Frossard, Amanda, Hines, Keith M., Kneifel, Stefan, Leaitch, W. Richard, Lin, Wuyin, Nicolas, Julien, Powers, Heath, Quinn, Patricia K., Rowe, Penny, Russell, Lynn M., Sharma, Sangeeta, Verlinde, Johannes, and Vogelmann, Andrew M.

Published
2020

16. AWARE : The Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment

Author

Lubin, Dan, Zhang, Damao, Silber, Israel, Scott, Ryan C., Kalogeras, Petros, Battaglia, Alessandro, Bromwich, David H., Cadeddu, Maria, Eloranta, Edwin, Fridlind, Ann, Frossard, Amanda, Hines, Keith M., Kneifel, Stefan, Leaitch, W. Richard, Lin, Wuyin, Nicolas, Julien, Powers, Heath, Quinn, Patricia K., Rowe, Penny, Russell, Lynn M., Sharma, Sangeeta, Verlinde, Johannes, and Vogelmann, Andrew M.

Published
2020

17. January 2016 extensive summer melt in West Antarctica favoured by strong El Niño

Author

Nicolas, Julien P, Vogelmann, Andrew M, Scott, Ryan C, Wilson, Aaron B, Cadeddu, Maria P, Bromwich, David H, Verlinde, Johannes, Lubin, Dan, Russell, Lynn M, Jenkinson, Colin, Powers, Heath H, Ryczek, Maciej, Stone, Gregory, and Wille, Jonathan D

Subjects
Earth Sciences, Oceanography, Physical Geography and Environmental Geoscience, Climate Change Science, Life Below Water, Climate Action
Abstract

Over the past two decades the primary driver of mass loss from the West Antarctic Ice Sheet (WAIS) has been warm ocean water underneath coastal ice shelves, not a warmer atmosphere. Yet, surface melt occurs sporadically over low-lying areas of the WAIS and is not fully understood. Here we report on an episode of extensive and prolonged surface melting observed in the Ross Sea sector of the WAIS in January 2016. A comprehensive cloud and radiation experiment at the WAIS ice divide, downwind of the melt region, provided detailed insight into the physical processes at play during the event. The unusual extent and duration of the melting are linked to strong and sustained advection of warm marine air toward the area, likely favoured by the concurrent strong El Niño event. The increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events.

Published
2017

18. Winter Targeted Observing Periods during the Year of Polar Prediction in the Southern Hemisphere (YOPP-SH)

Author

Bromwich, David H., Gorodetskaya, Irina V., Carpentier, Scott, Alexander, Simon, Bazile, Eric, Heinrich, Victoria J., Massonnet, Francois, Powers, Jordan G., Carrasco, Jorge F., Cayette, Arthur, Choi, Taejin, Chyhareva, Anastasia, Colwell, Steven R., Cordeira, James M., Cordero, Raul R., Doerenbecher, Alexis, Durán-Alarcón, Claudio, French, W. John R., Gonzalez-Herrero, Sergi, Guyot, Adrien, Haiden, Thomas, Hirasawa, Naohika, Imazio, Paola Rodriguez, Kawzenuk, Brian, Krakovska, Svitlana, Lazzara, Matthew A., Litell, Mariana Fontolan, Manning, Kevin W., Norris, Kimberley, Park, Sang-Jong, Ralph, F. Martin, Rowe, Penny M., Sun, Qizhen, Vitale, Vito, Wille, Jonathan D., Zhang, Zhenhai, Zou, Xun, Bromwich, David H., Gorodetskaya, Irina V., Carpentier, Scott, Alexander, Simon, Bazile, Eric, Heinrich, Victoria J., Massonnet, Francois, Powers, Jordan G., Carrasco, Jorge F., Cayette, Arthur, Choi, Taejin, Chyhareva, Anastasia, Colwell, Steven R., Cordeira, James M., Cordero, Raul R., Doerenbecher, Alexis, Durán-Alarcón, Claudio, French, W. John R., Gonzalez-Herrero, Sergi, Guyot, Adrien, Haiden, Thomas, Hirasawa, Naohika, Imazio, Paola Rodriguez, Kawzenuk, Brian, Krakovska, Svitlana, Lazzara, Matthew A., Litell, Mariana Fontolan, Manning, Kevin W., Norris, Kimberley, Park, Sang-Jong, Ralph, F. Martin, Rowe, Penny M., Sun, Qizhen, Vitale, Vito, Wille, Jonathan D., Zhang, Zhenhai, and Zou, Xun

Abstract

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 days 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 SIPN South analysis of predictions of the sea ice growth period reveals that the forecast skill is superior to the sea ice retreat phase.

Published
2024

26. A Reconciled Estimate of Ice-Sheet Mass Balance

Author

Shepherd, Andrew, Ivins, Erik R, A, Geruo, Barletta, Valentina R, Bentley, Mike J, Bettadpur, Srinivas, Briggs, Kate H, Bromwich, David H, Forsberg, René, Galin, Natalia, Horwath, Martin, Jacobs, Stan, Joughin, Ian, King, Matt A, Lenaerts, Jan TM, Li, Jilu, Ligtenberg, Stefan RM, Luckman, Adrian, Luthcke, Scott B, McMillan, Malcolm, Meister, Rakia, Milne, Glenn, Mouginot, Jeremie, Muir, Alan, Nicolas, Julien P, Paden, John, Payne, Antony J, Pritchard, Hamish, Rignot, Eric, Rott, Helmut, Sørensen, Louise Sandberg, Scambos, Ted A, Scheuchl, Bernd, Schrama, Ernst JO, Smith, Ben, Sundal, Aud V, van Angelen, Jan H, van de Berg, Willem J, van den Broeke, Michiel R, Vaughan, David G, Velicogna, Isabella, Wahr, John, Whitehouse, Pippa L, Wingham, Duncan J, Yi, Donghui, Young, Duncan, and Zwally, H Jay

Subjects
Climate Action, Antarctic Regions, Climate Change, Geographic Information Systems, Greenland, Ice Cover, General Science & Technology
Abstract

We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agreement between different satellite methods--especially in Greenland and West Antarctica--and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by -142 ± 49, +14 ± 43, -65 ± 26, and -20 ± 14 gigatonnes year(-1), respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year(-1) to the rate of global sea-level rise.

Published
2012

28. A spatially calibrated model of annual accumulation rate on the Greenland Ice Sheet (1958–2007)

Author

Burgess, Evan W, Forster, Richard R, Box, Jason E, Mosley‐Thompson, Ellen, Bromwich, David H, Bales, Roger C, and Smith, Laurence C

Subjects
Climate Action, Meteorology & Atmospheric Sciences
Abstract

Past estimates of Greenland Ice Sheet accumulation rates have been multiyear climatologies based on ice/firn cores and coastal precipitation records. Existing annually resolved estimates have incompletely quantified uncertainty, owing primarily to incomplete spatial coverage. This study improves upon these shortcomings by calibrating annual (1958-2007) solid precipitation output from the Fifth Generation Mesoscale Model modified for polar climates (Polar MM5) using firn core and meteorological station data. The calibration employs spatial interpolation of regionally derived linear correction functions. Residual uncertainties exhibit coherent spatial patterns, which are modeled via spatial interpolation of root mean squared errors. Mean 1958-2007 Greenland Ice Sheet annual accumulation rate is 337 ± 48 mm/yr water equivalent (w.e.) or 591 ± 83 Gt/yr. Annual estimates contain one standard deviation uncertainties of 74 mm/yr w.e., 22%, or 129 Gt/yr. Accumulation rates in southeast Greenland are found to exceed 2000 mm/yr w.e. and to dominate interannual variability in Greenland Ice Sheet total accumulated mass, representing 31% of the whole. Accumulation rates in the southeast are of sufficient magnitude to affect the sign of Greenland mass balance during some years. The only statistically significant temporal change in total ice sheet accumulation in the 1958-2007 period occurred between 1960 and 1972, when a simultaneous accumulation increase and decrease occurred in west and east Greenland, respectively. No statistically significant uniform change in ice sheet-wide accumulation is evident after 1972. However, regional changes do occur, including an accumulation increase on the west coast post-1992. The high accumulation rates of 2002-2003 appear to be confined to the southeast. Copyright 2010 by the American Geophysical Union.

Published
2010

31. ARCTIC RADIATION-ICEBRIDGE SEA AND ICE EXPERIMENT : The Arctic Radiant Energy System during the Critical Seasonal Ice Transition

Author

Smith, William L., Hansen, Christy, Bucholtz, Anthony, Anderson, Bruce E., Beckley, Matthew, Corbett, Joseph G., Cullather, Richard I., Hines, Keith M., Hofton, Michelle, Kato, Seiji, Lubin, Dan, Moore, Richard H., Rosenhaimer, Michal Segal, Redemann, Jens, Schmidt, Sebastian, Scott, Ryan, Song, Shi, Barrick, John D., Blair, J. Bryan, Bromwich, David H., Brooks, Colleen, Chen, Gao, Cornejo, Helen, Corr, Chelsea A., Ham, Seung-Hee, Kittelman, A. Scott, Knappmiller, Scott, LeBlanc, Samuel, Loeb, Norman G., Miller, Colin, Nguyen, Louis, Palikonda, Rabindra, Rabine, David, Reid, Elizabeth A., Richter-Menge, Jacqueline A., Pilewskie, Peter, Shinozuka, Yohei, Spangenberg, Douglas, Stackhouse, Paul, Taylor, Patrick, Thornhill, K. Lee, van Gilst, David, and Winstead, Edward

Published
2017

33. SIPN South: six years of coordinated seasonal Antarctic sea ice predictions

Author

Massonnet, François, primary, Barreira, Sandra, additional, Barthélemy, Antoine, additional, Bilbao, Roberto, additional, Blanchard-Wrigglesworth, Edward, additional, Blockley, Ed, additional, Bromwich, David H., additional, Bushuk, Mitchell, additional, Dong, Xiaoran, additional, Goessling, Helge F., additional, Hobbs, Will, additional, Iovino, Doroteaciro, additional, Lee, Woo-Sung, additional, Li, Cuihua, additional, Meier, Walter N., additional, Merryfield, William J., additional, Moreno-Chamarro, Eduardo, additional, Morioka, Yushi, additional, Li, Xuewei, additional, Niraula, Bimochan, additional, Petty, Alek, additional, Sanna, Antonella, additional, Scilingo, Mariana, additional, Shu, Qi, additional, Sigmond, Michael, additional, Sun, Nico, additional, Tietsche, Steffen, additional, Wu, Xingren, additional, Yang, Qinghua, additional, and Yuan, Xiaojun, additional

Published
2023
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34. Influence of local scale and oceanic teleconnections on regional fire danger and wildfire trends

Author

Justino, Flavio, Bromwich, David H., Wang, Sheng-Hung, Althoff, Daniel, Schumacher, Vanucia, da Silva, Alex, Justino, Flavio, Bromwich, David H., Wang, Sheng-Hung, Althoff, Daniel, Schumacher, Vanucia, and da Silva, Alex

Abstract

Studies and observations have pointed out that recent wildfires have been more severe and burned area is increasing in tropical regions. The current study aims at investigating the influence of oceanic climate modes and their teleconnection on global fire danger and trends in the 1980–2020 interval. Disentangling these trends demonstrates that across the extratropics they are primarily related to increases in temperature, whereas in the tropics changes in short-term precipitation distribution dominates the trends. Moreover, the environmental impact of short-term precipitation is dependent on local vegetation type and tightly related to oceanic temperatures far from the burned areas. Indeed, in the 2001–2020 period, a warmer tropical North Atlantic was associated with more fires in the Amazon and Africa, whereas ENSO has weakened the fire activity in equatorial Africa. The remarkable impact of oceanic modes of climate variability in inducing environmental conditions conducive to fires, has particular relevance for the seasonal spatiotemporal wildfire forecasts. Although local aspects are crucial for fire management, long-term predictions should take into account the behavior of potential climate drivers located far from the region of interest. Such teleconnections can be identified ahead of local weather anomalies.

Published
2023
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35. SIPN South: six years of coordinated seasonal Antarctic sea ice predictions

Author

Massonnet, François, Barreira, Sandra, Barthélemy, Antoine, Bilbao, Roberto, Blanchard-Wrigglesworth, Edward, Blockley, Ed, Bromwich, David H, Bushuk, Mitchell, Dong, Xiaoran, Goessling, Helge F, Hobbs, Will, Iovino, Doroteaciro, Lee, Woo-Sung, Li, Cuihua, Meier, Walter N, Merryfield, William J, Moreno-Chamarro, Eduardo, Morioka, Yushi, Li, Xuewei, Niraula, Bimochan, Petty, Alek, Sanna, Antonella, Scilingo, Mariana, Shu, Qi, Sigmond, Michael, Sun, Nico, Tietsche, Steffen, Wu, Xingren, Yang, Qinghua, Yuan, Xiaojun, Massonnet, François, Barreira, Sandra, Barthélemy, Antoine, Bilbao, Roberto, Blanchard-Wrigglesworth, Edward, Blockley, Ed, Bromwich, David H, Bushuk, Mitchell, Dong, Xiaoran, Goessling, Helge F, Hobbs, Will, Iovino, Doroteaciro, Lee, Woo-Sung, Li, Cuihua, Meier, Walter N, Merryfield, William J, Moreno-Chamarro, Eduardo, Morioka, Yushi, Li, Xuewei, Niraula, Bimochan, Petty, Alek, Sanna, Antonella, Scilingo, Mariana, Shu, Qi, Sigmond, Michael, Sun, Nico, Tietsche, Steffen, Wu, Xingren, Yang, Qinghua, and Yuan, Xiaojun

Abstract

Antarctic sea ice prediction has garnered increasing attention in recent years, particularly in the context of the recent record lows of February 2022 and 2023. As Antarctica becomes a climate change hotspot, as polar tourism booms, and as scientific expeditions continue to explore this remote continent, the capacity to anticipate sea ice conditions weeks to months in advance is in increasing demand. Spurred by recent studies that uncovered physical mechanisms of Antarctic sea ice predictability and by the intriguing large variations of the observed sea ice extent in recent years, the Sea Ice Prediction Network South (SIPN South) project was initiated in 2017, building upon the Arctic Sea Ice Prediction Network. The SIPN South project annually coordinates spring-to-summer predictions of Antarctic sea ice conditions, to allow robust evaluation and intercomparison, and to guide future development in polar prediction systems. In this paper, we present and discuss the initial SIPN South results collected over six summer seasons (December-February 2017-2018 to 2022-2023). We use data from 22 unique contributors spanning five continents that have together delivered more than 3000 individual forecasts of sea ice area and concentration. The SIPN South median forecast of the circumpolar sea ice area captures the sign of the recent negative anomalies, and the verifying observations are systematically included in the 10-90% range of the forecast distribution. These statements also hold at the regional level except in the Ross Sea where the systematic biases and the ensemble spread are the largest. A notable finding is that the group forecast, constructed by aggregating the data provided by each contributor, outperforms most of the individual forecasts, both at the circumpolar and regional levels. This indicates the value of combining predictions to average out model-specific errors. Finally, we find that dynamical model predictions (i.e., based on process-based general circula

Published
2023

36. Characteristics of Surface “Melt Potential” over Antarctic Ice Shelves based on Regional Atmospheric Model Simulations of Summer Air Temperature Extremes from 1979/80 to 2018/19

Author

Orr, Andrew, Deb, Pranab, Clem, Kyle R., Gilbert, Ella, Bromwich, David H., Boberg, Fredrik, Colwell, Steve, Hansen, Nicolaj, Lazzara, Matthew A., Mooney, Priscilla A., Mottram, Ruth, Niwano, Masashi, Phillips, Tony, Pishniak, Denys, Reijmer, Carleen H., Berg, Willem Jan van de, Webster, Stuart, Zou, Xun, Orr, Andrew, Deb, Pranab, Clem, Kyle R., Gilbert, Ella, Bromwich, David H., Boberg, Fredrik, Colwell, Steve, Hansen, Nicolaj, Lazzara, Matthew A., Mooney, Priscilla A., Mottram, Ruth, Niwano, Masashi, Phillips, Tony, Pishniak, Denys, Reijmer, Carleen H., Berg, Willem Jan van de, Webster, Stuart, and Zou, Xun

Abstract

We calculate a regional surface “melt potential” index (MPI) over Antarctic ice shelves that describes the frequency (MPI-freq; %) and intensity (MPI-int; K) of daily maximum summer temperatures exceeding a melt threshold of 273.15 K. This is used to determine which ice shelves are vulnerable to melt-induced hydrofracture and is calculated using near-surface temperature output for each summer from 1979/80 to 2018/19 from two high-resolution regional atmospheric model hindcasts (using the MetUM and HIRHAM5). MPI is highest for Antarctic Peninsula ice shelves (MPI-freq 23%–35%, MPI-int 1.2–2.1 K), lowest (2%–3%, <0 K) for the Ronne–Filchner and Ross ice shelves, and around 10%–24% and 0.6–1.7 K for the other West and East Antarctic ice shelves. Hotspots of MPI are apparent over many ice shelves, and they also show a decreasing trend in MPI-freq. The regional circulation patterns associated with high MPI values over West and East Antarctic ice shelves are remarkably consistent for their respective region but tied to different large-scale climate forcings. The West Antarctic circulation resembles the central Pacific El Niño pattern with a stationary Rossby wave and a strong anticyclone over the high-latitude South Pacific. By contrast, the East Antarctic circulation comprises a zonally symmetric negative Southern Annular Mode pattern with a strong regional anticyclone on the plateau and enhanced coastal easterlies/weakened Southern Ocean westerlies. Values of MPI are 3–4 times larger for a lower temperature/melt threshold of 271.15 K used in a sensitivity test, as melting can occur at temperatures lower than 273.15 K depending on snowpack properties.

Published
2023

37. WMO Evaluation of Two Extreme High Temperatures Occurring in February 2020 for the Antarctic Peninsula Region

Author

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Skansi, Maria de Los Milagros, Colwell, Steve, Bromwich, David H, Jones, Phil, King, John C, Lazzara, Matthew A, Renwick, James, Solomon, Susan, Brunet, Manola, Cerveny, Randall S, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Skansi, Maria de Los Milagros, Colwell, Steve, Bromwich, David H, Jones, Phil, King, John C, Lazzara, Matthew A, Renwick, James, Solomon, Susan, Brunet, Manola, and Cerveny, Randall S

Abstract

ABSTRACTTwo reports of Antarctic region potential new record high temperature observations (18.3°C, 6 February 2020 at Esperanza station and 20.8°C, 9 February 2020 at a Brazilian automated permafrost monitoring station on Seymour Island) were evaluated by a World Meteorological Organization (WMO) panel of atmospheric scientists. The latter figure was reported as 20.75°C in the media. The panel considered the synoptic situation and instrumental setups. It determined that a large high pressure system over the area created föhn conditions and resulted in local warming for both situations. Examination of the data and metadata of the Esperanza station observation revealed no major concerns. However, analysis of data and metadata of the Seymour Island permafrost monitoring station indicated that an improvised radiation shield led to a demonstrable thermal bias error for the temperature sensor. Consequently, the WMO has accepted the 18.3°C value for 1200 LST 6 February 2020 (1500 UTC 6 February 2020) at the Argentine Esperanza station as the new “Antarctic region (continental, including mainland and surrounding islands) highest temperature recorded observation” but rejected the 20.8°C observation at the Brazilian automated Seymour Island permafrost monitoring station as biased. The committee strongly emphasizes the permafrost monitoring station was not badly designed for its purpose, but the project investigators were forced to improvise a nonoptimal radiation shield after losing the original covering. Second, with regard to media dissemination of this type of information, the committee urges increased caution in early announcements as many media outlets often tend to sensationalize and mischaracterize potential records.

Published
2023

39. ADVANCING POLAR PREDICTION CAPABILITIES ON DAILY TO SEASONAL TIME SCALES

Author

Jung, Thomas, Gordon, Neil D., Bauer, Peter, Bromwich, David H., Chevallier, Matthieu, Day, Jonathan J., Dawson, Jackie, Doblas-Reyes, Francisco, Fairall, Christopher, Goessling, Helge F., Holland, Marika, Inoue, Jun, Iversen, Trond, Klebe, Stefanie, Lemke, Peter, Losch, Martin, Makshtas, Alexander, Mills, Brian, Nurmi, Pertti, Perovich, Donald, Reid, Philip, Renfrew, Ian A., Smith, Gregory, Svensson, Gunilla, Tolstykh, Mikhail, and Yang, Qinghua

Published
2016

40. PAVING THE WAY FOR THE YEAR OF POLAR PREDICTION

Author

Goessling, Helge F., Jung, Thomas, Klebe, Stefanie, Baeseman, Jenny, Bauer, Peter, Chen, Peter, Chevallier, Matthieu, Dole, Randall, Gordon, Neil, Ruti, Paolo, Bradley, Alice, Bromwich, David H., Casati, Barbara, Chechin, Dmitry, Day, Jonathan J., Massonnet, François, Mills, Brian, Renfrew, Ian, Smith, Gregory, and Tatusko, Renee

Published
2016

45. Intercomparison of Precipitation Estimates over the Arctic Ocean and Its Peripheral Seas from Reanalyses

Author

Mcpartland, Linette N, Webster, Melinda A, Petty, Alek A, Markus, Thorsten, Bromwich, David H, and Cullather, Richard I

Subjects
Geosciences (General)
Abstract

Precipitation over the Arctic Ocean has a significant impact on the basin-scale freshwater and energy budgets but is one of the most poorly constrained variables in atmospheric reanalyses. Precipitation controls the snow cover on sea ice, which impedes the exchange of energy between the ocean and atmosphere, inhibiting sea ice growth. Thus, accurate precipitation amounts are needed to inform sea ice modeling, especially for the production of thickness estimates from satellite altimetry freeboard data. However, obtaining a quantitative estimate of the precipitation distribution in the Arctic is notoriously difficult because of a number of factors, including a lack of reliable, long-term in situ observations; difficulties in remote sensing over sea ice; and model biases in temperature and moisture fields and associated uncertainty of modeled cloud microphysical processes in the polar regions. Here, we compare precipitation estimates over the Arctic Ocean from eight widely used atmospheric reanalyses over the period 2000–16 (nominally the ‘‘new Arctic’’). We find that the magnitude, frequency, and phase of precipitation vary drastically, although interannual variability is similar. Reanalysis-derived precipitation does not increase with time as expected; however, an increasing trend of higher fractions of liquid precipitation (rainfall) is found. When compared with drifting ice mass balance buoys, three reanalyses (ERA-Interim, MERRA, and NCEP R2) produce realistic magnitudes and temporal agreement with observed precipitation events, while two products [MERRA, version 2 (MERRA-2), and CFSR] show large, implausible magnitudes in precipitation events. All the reanalyses tend to produce overly frequent Arctic precipitation. Future work needs to be undertaken to determine the specific factors in reanalyses that contribute to these discrepancies in the new Arctic.

Published
2018
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