Start
March 30, 2022 - 3:00 pm
End
March 30, 2022 - 4:00 pm
Categories
Weather and Climate SystemsWeather and Climate Systems
Relationships between Cloud Condensation Nuclei Concentrations and Lidar Observables for Specific Aerosol types and their Applications in Evaluating Aerosol-Cloud Interactions
Emily Lenhardt
Wednesday, March 30
3:00 PM
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Aerosols that activate to become cloud droplets, termed cloud condensation nuclei (CCN), provide the direct microphysical link that drive aerosol-cloud interactions (ACI), which remain a source of high uncertainty compared to other radiative forcings of climate. CCN are often characterized using column-effective proxies such as aerosol optical depth (AOD), resulting in a lack of information about their vertical distributions. Here we present an approach to estimate vertically-resolved CCN concentrations using relationships between in situ CCN concentration and High Spectral Resolution Lidar 2 (HSRL-2) aerosol extinction (EXT) and backscatter (BSC) coefficients obtained during the ObseRvations of Aerosols above Clouds and their intEractionS (ORACLES) campaign. These relationships allow for accurate estimation of CCN concentration from lidar measurements alone for relatively dry conditions (ambient relative humidity < 40-50%) and specifically for biomass burning aerosols (BBA) that are dominant in the Southeast Atlantic (SEA).
Using this method of developing relationships between in situ CCN concentration and lidar EXT and BSC coefficients, we explore how such analysis can be extended to other regions with different dominant aerosol types and how it may be able to be adjusted for higher ambient relative humidities. Additionally, there exists a unique opportunity to analyze ACI using resultant lidar-derived, vertically-resolved CCN curtains. This talk will outline future work using cloud probe, Moderate Resolution Imaging Spectroradiometer (MODIS), and Research Scanning Polarimeter (RSP) retrieved and derived values of cloud properties such as effective radius (r_eff), effective variance (v_eff), cloud droplet number concentration (N_d), cloud optical thickness (COT), and liquid water path (LWP) to evaluate their relationships with CCN concentration both above and below clouds.