My Research

Current Research

Antarctic Atmospheric Rivers in the Present and Future Climate

Using climate models, we can study how atmospheric rivers (ARs) and their impacts on ice sheets may change in a warming climate. Here, we apply our AR detection algorithm to the Community Earth System Model (CESM) version 2. We then examine how increases in atmospheric moisture content and changes in the large-scale atmospheric circulation impact AR activity in the 21st century. This includes their frequency and intensity, as well as AR impacts on the surface of Antarctica - snow, rain, and melt.

Past Projects

Meteorology of Thwaites Eastern Ice Shelf

As part of the International Thwaites Glacier Collaboration, two automatic weather stations were installed on Thwaites Eastern Ice Shelf (West Antarctica) in January 2020. These weather stations produced an invaluable record of snow accumulation, temperature, winds, and surface pressure in this remote region of the world.

We used these observations in two ways:

  1. To compare with atmospheric reanalyses, such as ERA5 and MERRA-2. These helped us understand what types of weather patterns may be missed by the reanalyses, which we use frequently to analyze the weather and climate in West Antarctica.

  2. To track a unique event called an “atmospheric river family”. This event involved a series of 3 atmospheric rivers that made landfall over the ice shelf in rapid succession, just 2 weeks after the automatic weather stations were installed. We performed a deep analysis of the large scale drivers, surface characteristics, and snowfall and melt impacts of the event.

Two publications are associated with this study of extreme snowfall on Thwaites Eastern Ice Shelf and its large-scale atmospheric drivers:

  • Maclennan et al. (2023). Climatology and surface impacts of atmospheric rivers on West Antarctica. The Cryosphere. doi: 10.5194/tc-17-865-2023

  • Maclennan and Lenaerts (2021). Large-Scale Atmospheric Drivers of Snowfall over Thwaites Glacier, Antarctica. Geophysical Research Letters. doi: 10.1029/2021GL093644

Impacts of Atmospheric Rivers on Antarctic Precipitation

MODIS Corrected Reflectance showing clouds and atmospheric circulation around Antarctica on 07 February 2020 NASA Worldview Database

Map of Antarctica showing the location of Thwaites Eastern Ice Shelf.

Automatic Weather Station on Thwaites Eastern Ice Shelf, Antarctica.

(a) Relative contribution of atmospheric rivers to the mean annual precipitation, by glacier basin. (b) Contribution of atmospheric rivers to the inter-annual variability in precipitation. Maclennan, Lenaerts, et al. (2022)

Here we performed a comprehensive analysis of the impacts of atmospheric rivers (ARs) on precipitation (snowfall and rainfall) over Antarctica. While ARs are extremely rare in Antarctica, occurring only ~1% of the time, we found that they produce significant impacts on the surface mass balance of the ice sheet. ARs are associated with 13% of the total annual precipitation over Antarctica, and 35% of the year-to-year variability in precipitation. To complement this analysis of Antarctic AR impacts, we also compared different AR detection algorithms for Antarctica and the Southern Ocean, and examined AR links to modes of atmospheric variability.

For full results, see the studies:

  • Maclennan et al. (2022). Contribution of Atmospheric Rivers to Antarctic Precipitation. Geophysical Research Letters. doi: 10.1029/2022GL100585

  • Shields et al. (2022). Evaluating Uncertainty and Modes of Variability for Antarctic Atmospheric Rivers. Geophysical Research Letters. doi: 10.1029/2022GL099577