Public Abstract

DE-SC0025266: Using ARM data to explore processes associated with Southern Ocean cloud feedback using MARCUS, AWARE, and CAPE-K data

Award Status: Active

Institution: University of Utah, Salt Lake City, UT
UEI: LL8GLEVH6MG3
DUNS: 009095365

Most Recent Award Date: 08/19/2024
Number of Support Periods: 1
PM: Stehr, Jeffrey

Current Budget Period: 09/01/2024 - 08/31/2025
Current Project Period: 09/01/2024 - 08/31/2027
PI: Mace, Gerald

Supplement Budget Period: N/A

Public Abstract

Using ARM data to explore processes associated with Southern Ocean cloud feedback using MARCUS, AWARE, and CAPE-k data Principal Investigator: Jay Mace, University of Utah Co-Investigator: Gannet Hallar, University of Utah How much the Earth will warm as we approach a doubling of the greenhouse gas carbon dioxide, known as the Earth's climate sensitivity, depends upon how clouds on Earth will change with the warming. One of the most critical cloud types that determine whether changes in clouds will amplify the warming is marine clouds in the lower atmosphere over the oceans. These clouds are ubiquitous on Earth and are especially prominent in the middle and high latitude Southern Ocean. The Southern Ocean is a vast maritime region and is the only circumpolar ocean basin. Given the presence of an ice-covered high-altitude continent at the pole, the Southern Ocean is a unique climatic region. Numerical models of the Earth's climate have shown that, not only is the climate system very sensitive to changes in clouds over the Southern Ocean, but the simulation of marine low clouds over the Southern Ocean in climate models is highly uncertain. The sensitivity and uncertainty are due to inadequate understanding of two key cloud processes: 1) how many cloud droplets form in a marine low cloud on certain aerosol nuclei and 2) how that condensed water is eventually lost as precipitation in the form of light snow or drizzle. Because human-caused aerosol is nearly nonexistent in the Southern Ocean, the crux of the issue is the extent to which aerosol of biological origin contribute to the aerosol particle population and whether there are aerosols that are good at forming snow. The DOE ARM program has invested heavily in collecting important data sets in the Southern Ocean region. In this project we will take advantage of the ARM data sets, combined with data from NASA satellites, to explore several of the most important questions pertaining to the way clouds work over the Southern Ocean. We will examine data collected at McMurdo Station regarding whether high concentrations of biogenic aerosol are transported over the Ross Sea in flows that descend from the high-altitude ice sheet. We will then examine how that aerosol is transported northward and modified in cloud and precipitation processes. Finally, we will examine the precipitation in marine low clouds over this region, with the goal of quantifying how much snow versus liquid drizzle occurs and what that difference in precipitation phase means to the fate of clouds in the Southern Ocean. What we learn from this investigation will be used to improve the simulation of clouds over the Southern Ocean and ultimately improve our understanding of the Earth's climate sensitivity.

Using ARM data to explore processes associated with Southern Ocean cloud feedback using MARCUS, AWARE, and CAPE-k data

Principal Investigator: Jay Mace, University of Utah

Co-Investigator: Gannet Hallar, University of Utah

How much the Earth will warm as we approach a doubling of the greenhouse gas carbon dioxide, known as the Earth's climate sensitivity, depends upon how clouds on Earth will change with the warming. One of the most critical cloud types that determine whether changes in clouds will amplify the warming is marine clouds in the lower atmosphere over the oceans. These clouds are ubiquitous on Earth and are especially prominent in the middle and high latitude Southern Ocean. The Southern Ocean is a vast maritime region and is the only circumpolar ocean basin. Given the presence of an ice-covered high-altitude continent at the pole, the Southern Ocean is a unique climatic region. Numerical models of the Earth's climate have shown that, not only is the climate system very sensitive to changes in clouds over the Southern Ocean, but the simulation of marine low clouds over the Southern Ocean in climate models is highly uncertain. The sensitivity and uncertainty are due to inadequate understanding of two key cloud processes: 1) how many cloud droplets form in a marine low cloud on certain aerosol nuclei and 2) how that condensed water is eventually lost as precipitation in the form of light snow or drizzle. Because human-caused aerosol is nearly nonexistent in the Southern Ocean, the crux of the issue is the extent to which aerosol of biological origin contribute to the aerosol particle population and whether there are aerosols that are good at forming snow. The DOE ARM program has invested heavily in collecting important data sets in the Southern Ocean region. In this project we will take advantage of the ARM data sets, combined with data from NASA satellites, to explore several of the most important questions pertaining to the way clouds work over the Southern Ocean. We will examine data collected at McMurdo Station regarding whether high concentrations of biogenic aerosol are transported over the Ross Sea in flows that descend from the high-altitude ice sheet. We will then examine how that aerosol is transported northward and modified in cloud and precipitation processes. Finally, we will examine the precipitation in marine low clouds over this region, with the goal of quantifying how much snow versus liquid drizzle occurs and what that difference in precipitation phase means to the fate of clouds in the Southern Ocean. What we learn from this investigation will be used to improve the simulation of clouds over the Southern Ocean and ultimately improve our understanding of the Earth's climate sensitivity.