A document by Melinda T Berman. Click on the document to view its contents.

In recent years, global kilometer-scale convection-permitting models have shown promising results in producing realistic convection and precipitation. Cold pools, which can be represented by km-scale models, are identified as one of the significant mesoscale processes responsible for modulating the life cycle of mesoscale organized convection. However, there is still a lack of understanding about cold pool properties across the spatio-temporal scales, as well as their representation in models. In this study, a 2.5 km global Icosahedral Nonhydrostatic (ICON) model simulation run for 40 days (06 UTC 01 Aug - 23 UTC 10 Sep 2016) from the Dynamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains (DYAMOND) initiative is used to identify thermal cold pools (using Tv) over the tropical oceans. The diurnal cycle of simulated thermal cold pools is compared against NASA’s RapidScat-observed gradient feature (GF) frequency and IMERG precipitation. ICON and IMERG exhibit morning peaks in cold pool activity similar to RapidScat GF frequency but miss the afternoon peak. Advanced Scatterometer (ASCAT) and RapidScat GF spatial climatology is also compared to ICON cold pools, where ICON shows more cold pools over the Indo-Pacific and western Atlantic basins. Random forest regression is applied to identify critical environmental properties with column water vapor found to be most important for controlling cold pool properties. Regional differences between cold pool properties are explored, where easterly waves dominate the eastern Pacific and Atlantic cold pool activity. The western Pacific and the Indian Ocean cold pools are controlled by local mesoscale forcing and intraseasonal oscillations.

Aerosols acting as cloud condensation nuclei (CCN) play a fundamental role in droplet formation and cloud development in the atmosphere. Several studies have focused on the representation of aerosol-cloud interactions to improve cloud parametrizations and deep moist convection representation in numerical models. However, the effect of aerosol concentration on mixed-phase clouds is complex as it can not be directly measured and it is far from being fully understood. Then, observation of CCN distributions, variability, and exploration of possible sources can help go deeper into the effects of aerosols on cloud and precipitation processes. From October 2018 to April 2019, Cloud, Aerosol, and Complex Terrain Interactions field campaign (CACTI) took place in central Argentina. An ARM-DOE Mobility Facility was installed in Villa Yacanto, Cordoba to understand the processes affecting orographic deep convective initiation in the region. CCNs in situ observations from a Mobile Aerosol Observation System were analyzed. Amazon biomass burning is one of the known sources of aerosols in central and northern Argentina however during CACTI measurement period low rate emissions were observed from this source. Then, local aerosol source regions were investigated by backward trajectories with lagrangian dispersion model FLEXPART to determine their possible interaction with extreme precipitation events.