Public Abstract

DE-SC0025464: Impacts of cloud-aerosol-meteorology relations in mixed-phase clouds on radiative fluxes over high Latitudes

Award Status: Active

Institution: Board of Regents of the University of Oklahoma, Norman, OK
UEI: EVTSTTLCEWS5
DUNS: 848348348

Most Recent Award Date: 09/12/2024
Number of Support Periods: 1
PM: Stehr, Jeffrey

Current Budget Period: 09/01/2024 - 02/28/2026
Current Project Period: 09/01/2024 - 08/31/2027
PI: McFarquhar, Greg

Supplement Budget Period: N/A

Public Abstract

Significant uncertainties in the surface radiation budget in Earth system models (ESMs) exist over the Southern Ocean. As model output is sensitive to parameterizations of mixed-phase and ice cloud processes, and as cloud reflective properties are sensitive to liquid, mixed-phase and ice cloud properties, that in turn are influenced by aerosol properties and large scale meteorological conditions, it is critical to improve understanding of key aerosol, cloud, precipitation and radiative transfer processes. However, model parameterizations are challenged to adequately represent cloud and aerosol processes due to minimal observations existing over the Southern Ocean. Data collected in prior Department of Energy Atmospheric Radiation Measurement program (DOE ARM)-supported field campaigns over the Southern Ocean show large seasonal variations, significant supercooled liquid water, and frequent precipitation below cloud base. But the representativeness of these findings for the entire Southern Ocean is not known because data have been obtained in only a few locations and exhibit latitudinal trends and dependence on synoptic conditions. Thus, this project will use observations from the Cloud and Precipitation Experiment at kennaook (CAPE-k) project to examine controls on aerosol and cloud properties, including those of mixed-phase and ice clouds, over the Southern Ocean. Using CAPE-k data supplemented with data from the Measurements of Aerosols Radiation and Clouds over the Southern Ocean (MARCUS), Macquarie Island Cloud Radiation Experiment (MICRE), and Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) we will analyze how cloud, precipitation and radiative properties depend on season and on aerosol and meteorological conditions to test these hypotheses: 1) Given meteorological constraints, radiative biases in models are dominated by the representation of mixed-phase cloud processes over the Southern Ocean; 2) At similar surface temperatures and latitudes, systematic differences between Arctic and Southern Ocean clouds cloud properties exist and are more closely linked to environmental conditions than aerosol amount; 3) The concentrations of cloud condensation nuclei and aerosols are more correlated with precipitation presence than with surface wind speeds regardless of large scale meteorological conditions or geographic location; 4) Liquid, ice, and mixed-phase cloud and precipitation properties of boundary layer clouds are more closely correlated with cloud-base and mid-cloud updrafts and environmental conditions than to variations in accumulation mode aerosol concentrations; 5) The presence of ice in drizzle over the Southern Ocean is better correlated with cloud updraft velocity than with accumulation aerosol or ice nucleating particle concentrations; We will use data from in-situ aerosol, thermodynamic, meteorological, ground-based precipitation probes, radar, lidar, and radiometer sensors from CAPE-k and the kennaook station to derive and retrieve aerosol and cloud microphysical properties, heights, coverage and updraft speeds. We will develop a value-added product of environmental conditions including temperature, lower atmospheric stability, estimated inversion strength, cold air outbreak index, convective available potential energy, wind speed and direction, air mass origin, meteorological regime, cloud coupling to boundary layer, and closed/open cell classification. Multivariate statistical tests will determine significance of correlations between cloud, aerosol and dynamical properties and dependence on environmental conditions, and used to evaluate simulations. Simulations will examine how cloud, precipitation and radiative properties depend on the environment and aerosols, and explore how the representation of cloud microphysics, the boundary layer, and surface fluxes affects radiative fluxes in models at various scales using the DOE-supported models, Energy Exascale Earth System Model (E3SM) Single Column Model (SCM) and Doubly Periodic Simple Cloud-Resolving E3SM Atmosphere Model (DP-SCREAM). The implementation of ice multiplication processes in the Predicted Particle Properties (P3) microphysics scheme will be critical for determining controls on mixed-phase and ice-phase cloud properties.

Significant uncertainties in the surface radiation budget in Earth system models (ESMs) exist over the Southern Ocean. As model output is sensitive to parameterizations of mixed-phase and ice cloud processes, and as cloud reflective properties are sensitive to liquid, mixed-phase and ice cloud properties, that in turn are influenced by aerosol properties and large scale meteorological conditions, it is critical to improve understanding of key aerosol, cloud, precipitation and radiative transfer processes. However, model parameterizations are challenged to adequately represent cloud and aerosol processes due to minimal observations existing over the Southern Ocean. Data collected in prior Department of Energy Atmospheric Radiation Measurement program (DOE ARM)-supported field campaigns over the Southern Ocean show large seasonal variations, significant supercooled liquid water, and frequent precipitation below cloud base. But the representativeness of these findings for the entire Southern Ocean is not known because data have been obtained in only a few locations and exhibit latitudinal trends and dependence on synoptic conditions. Thus, this project will use observations from the Cloud and Precipitation Experiment at kennaook (CAPE-k) project to examine controls on aerosol and cloud properties, including those of mixed-phase and ice clouds, over the Southern Ocean.

Using CAPE-k data supplemented with data from the Measurements of Aerosols Radiation and Clouds over the Southern Ocean (MARCUS), Macquarie Island Cloud Radiation Experiment (MICRE), and Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) we will analyze how cloud, precipitation and radiative properties depend on season and on aerosol and meteorological conditions to test these hypotheses:

1) Given meteorological constraints, radiative biases in models are dominated by the representation of mixed-phase cloud processes over the Southern Ocean;

2) At similar surface temperatures and latitudes, systematic differences between Arctic and Southern Ocean clouds cloud properties exist and are more closely linked to environmental conditions than aerosol amount;

3) The concentrations of cloud condensation nuclei and aerosols are more correlated with precipitation presence than with surface wind speeds regardless of large scale meteorological conditions or geographic location;

4) Liquid, ice, and mixed-phase cloud and precipitation properties of boundary layer clouds are more closely correlated with cloud-base and mid-cloud updrafts and environmental conditions than to variations in accumulation mode aerosol concentrations;

5) The presence of ice in drizzle over the Southern Ocean is better correlated with cloud updraft velocity than with accumulation aerosol or ice nucleating particle concentrations;

We will use data from in-situ aerosol, thermodynamic, meteorological, ground-based precipitation probes, radar, lidar, and radiometer sensors from CAPE-k and the kennaook station to derive and retrieve aerosol and cloud microphysical properties, heights, coverage and updraft speeds. We will develop a value-added product of environmental conditions including temperature, lower atmospheric stability, estimated inversion strength, cold air outbreak index, convective available potential energy, wind speed and direction, air mass origin, meteorological regime, cloud coupling to boundary layer, and closed/open cell classification. Multivariate statistical tests will determine significance of correlations between cloud, aerosol and dynamical properties and dependence on environmental conditions, and used to evaluate simulations.

Simulations will examine how cloud, precipitation and radiative properties depend on the environment and aerosols, and explore how the representation of cloud microphysics, the boundary layer, and surface fluxes affects radiative fluxes in models at various scales using the DOE-supported models, Energy Exascale Earth System Model (E3SM) Single Column Model (SCM) and Doubly Periodic Simple Cloud-Resolving E3SM Atmosphere Model (DP-SCREAM). The implementation of ice multiplication processes in the Predicted Particle Properties (P3) microphysics scheme will be critical for determining controls on mixed-phase and ice-phase cloud properties.