USAP-DC

Project Summary Overview The Antarctic Peninsula (AP) has been warming faster than the global average since the mid-1960s. Concurrent loss of ice shelves has been associated with glacial discharge into the ocean, with important implications for sea level rise. Surface melt associated with near-surface temperature rise is considered to be a major driver for ice loss, and clouds (particularly liquid-bearing clouds) and water vapor have been implicated in this warming. Clouds and atmospheric water vapor have strong radiative signals that vary seasonally and with cloud properties. In addition, clouds play an important role in several mechanisms that have been linked to warming on the AP. We will use surface- and satellite-based measurements to characterize clouds and humidity. This project maximizes value by using a variety of previous, ongoing, and planned measurements made by an international group of collaborators. This includes novel measurements on the AP, such as lidar and in situ balloon-borne cloud water. These will be compared to outputs from the Polar Weather Research Forecasting model, after which measurements and model results will be used to quantify clouds, water vapor, and radiation and their effects on the surface energy balance at three strategically-located stations: Rothera (upwind of the AP), Marambio (downwind of the AP) and Escudero (north of the AP), in order to provide a detailed characterization of cloud radiative and precipitation-formation properties and their role in surface warming and melt events. Intellectual Merit This work will enhance our understanding of the contributions of clouds, water vapor and radiation to warming over the AP. Processes governing phase partitioning and amounts of supercooled liquid water are crucial for understanding surface melt, and will be explored. In addition, the role of clouds and moisture during foehn and atmospheric river (AR) events, which have been associated with major warming events over the AP, will be characterized. During foehn winds, westerly winds warm and dry as they flow over the AP, often leading to cloud formation on the upwind side and cloud clearance on the lee side, with large influxes of shortwave radiation on the lee side (radiative heating) that exacerbate the temperature differential. The upwind clouds can drive precipitation and latent heating, which can be enhanced by ARs (long corridors of moisture). These mechanisms lead to our hypotheses: 1) Through their effect on the surface energy balance, clouds play an important role in surface warming on the AP; this role is seasonally varying and sensitive to cloud thermodynamic phase, 2) Radiative heating during foehn events is an important contributor to warming at the northern AP, and 3) The radiative effects of clouds and water vapor have strong influences on heating before and during AR events, with significant differences on the two sides of the AP. The proposed work includes novel and creative ways to improve our understanding of polar systems, and is thus a good fit with the goals of OPP. Broader Impacts It is crucial to human welfare to understand mechanisms responsible for the rapid pace of Antarctic ice loss. This work will lead to a better understanding of how clouds are impacting surface melt on the AP in the changing climate. In addition, the proposed work will include several undergraduate research projects. Finally, broader impacts include public outreach through participation at the Pacific Science Center in Seattle, WA. We will bring polar science to the public through free, open-access summer courses at public libraries that will allow the public to gain hands-on experience working with polar data through the use of educational computational modules. These modules have been developed as part of other NSF-funded work, and will be modified to be more suitable to a general audience. We will advertise through local High Schools, with the goal of increasing the participation of women and other groups underrepresented in STEM. This outreach seeks to increase the polar and climate literacy of the public while introducing them to data science, a powerful and rapidly-growing field.

Person	Role
Zou, Xun	Investigator and contact

Antarctic Ocean and Atmospheric Sciences	Award # 2127633
Antarctic Ocean and Atmospheric Sciences	Award # 2127632

USAP-2127633_1

None in the Database

1. Rowe, P. M., Walden, V. P., Brandt, R. E., Town, M. S., Hudson, S. R., & Neshyba, S. (2022). Evaluation of Temperature‐Dependent Complex Refractive Indices of Supercooled Liquid Water Using Downwelling Radiance and In‐Situ Cloud Measurements at South Pole. Journal of Geophysical Research: Atmospheres, 127(1). Portico. (doi:10.1029/2021jd035182)
2. Zou, X., Rowe, P. M., Gorodetskaya, I., Bromwich, D. H., Lazzara, M., Cordero, R. R., Zhang, Z., Kawzenuk, B., Cordeira, J. M., Wille, J. D., Ralph, F. M., & Bai, L. (2022). Strong Warming over the Antarctic Peninsula during Combined Atmospheric River and Foehn Events: Contribution of Shortwave Radiation and Turbulence. (doi:10.1002/essoar.10512808.1)
3. Guy, H., Brooks, I. M., Turner, D. D., Cox, C. J., Rowe, P. M., Shupe, M. D., Walden, V. P., & Neely, R. R. (2023). Observations of Fog‐Aerosol Interactions Over Central Greenland. Journal of Geophysical Research: Atmospheres, 128(13). Portico. (doi:10.1029/2023jd038718)
4. Zou, X., Rowe, P. M., Gorodetskaya, I., Bromwich, D. H., Lazzara, M. A., Cordero, R. R., Zhang, Z., Kawzenuk, B., Cordeira, J. M., Wille, J. D., Ralph, F. M., & Bai, L. (2023). Strong Warming Over the Antarctic Peninsula During Combined Atmospheric River and Foehn Events: Contribution of Shortwave Radiation and Turbulence. Journal of Geophysical Research: Atmospheres, 128(16). Portico. (doi:10.1029/2022jd038138)
5. Wille, J. D., Alexander, S. P., Amory, C., Baiman, R., Barthélemy, L., Bergstrom, D. M., Berne, A., Binder, H., Blanchet, J., Bozkurt, D., Bracegirdle, T. J., Casado, M., Choi, T., Clem, K. R., Codron, F., Datta, R., Di Battista, S., Favier, V., Francis, D., … Zou, X. (2024). The Extraordinary March 2022 East Antarctica “Heat” Wave. Part I: Observations and Meteorological Drivers. Journal of Climate, 37(3), 757–778. (doi:10.1175/jcli-d-23-0175.1)
6. Wille, J. D., Alexander, S. P., Amory, C., Baiman, R., Barthélemy, L., Bergstrom, D. M., Berne, A., Binder, H., Blanchet, J., Bozkurt, D., Bracegirdle, T. J., Casado, M., Choi, T., Clem, K. R., Codron, F., Datta, R., Battista, S. D., Favier, V., Francis, D., … Zou, X. (2024). The Extraordinary March 2022 East Antarctica “Heat” Wave. Part II: Impacts on the Antarctic Ice Sheet. Journal of Climate, 37(3), 779–799. (doi:10.1175/jcli-d-23-0176.1)