The SEA region has recently experienced an intensive period of observation by land and air, including the DOE/ARM Layered Atlantic Smoke Interactions with Clouds (LASIC) campaign on Ascension Island from June 2016 to October 2017 and the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) aircraft campaign based out of Walvis Bay, Namibia, in September 2016 and São Tomé and Príncipe in August 2017 and October 2018. Early results from the ORACLES-2016 deployment have demonstrated that the observational challenge in assessing ACI may be greater than previously recognized because the accumulation of entrained above-cloud aerosol over the course of days often matters more than instantaneous smoke-cloud contact in determining MBL properties. A corollary of this finding is that the impact of smoke above the MBL in the southernmost reaches of the SEA will be manifested upstream days later due to the prevailing southerly MBL flow.
The passage of midlatitude cyclones was observed to influence the location of the smoke plumes and cloud decks during ORACLES deployments. In addition, work done in anticipation of the LASIC and ORACLES campaigns has shown that the column loading and spatial pattern of aerosol over the SEA is influenced by the strength of the southern African Easterly Jet during the biomass burning season. We use reanalysis and satellite products to evaluate what systematic effects these and related circulation patterns have on warm cloud properties over the SEA, focusing on Nd, and how these effects vary geographically and seasonally.