Measurement report: Impact of African aerosol particles on cloud evolution in a tropical montane cloud forest in the Caribbean

Abstract

Abstract. African aerosol particles, traveling thousands of kilometers before reaching the Americas and the Caribbean, directly scatter and absorb solar radiation and indirectly impact climate by serving as cloud condensation nuclei (CCN) or ice-nucleating particles (INPs) that form clouds. These particles can also affect the water budget by altering precipitation patterns that subsequently affect ecosystems. As part of the NSF-funded Luquillo Critical Zone Observatory, field campaigns were conducted during the summers of 2013 (23 d), 2014 (11 d), and 2015 (92 d) at Pico del Este, a site in a tropical montane cloud forest on the Caribbean Island of Puerto Rico. Cloud microphysical properties, which included liquid water content, droplet number concentration, and droplet size, were measured. Using products from models and satellites, as well as in situ measurements of aerosol optical properties, periods of high- and low-dust influence were identified. The results from this study suggest that meteorology and air mass history have a more important effect on cloud processes than aerosols transported from Africa. In contrast, air masses that arrived after passing over the inhabited islands to the southeast led to clouds with much higher droplet concentrations, presumably due to aerosols formed from anthropogenic emissions.

Effects of aerosol particles on precipitation and cloud parameters over East Africa-Ethiopia using MODIS satellite data: Part 01

“…And the parameters are higher on the Terra instrument relative to the Aqua instrument. Even if there are also contradictory findings to our results, the studies undergone by different scholars we discussed above and others (Li et al, 2014;Ngaina et al, 2014;Boiyo et al, 2018;Torres-Delgado et al, 2021;Kalisa et al, 2023) about the seasonality of the parameters fluctuation, the different local activities, and the long-range aerosol particles transport to the study area regions confirmed our observation.…”

Influence of air mass origin on microphysical properties of low-level clouds in a subarctic environment

“…Several observation efforts and experiments have been made to explore how air masses affect 55 climate and the cloud macrophysical and microphysical properties (e.g., Hobbs and Rangno 1998; Gultepe et al, 2000;Orbe et al,2015b;Solomon and Shupe 2019;Delgado et al, 2021). Hobbs and Rangno (1998) highlighted that air masses from the south resulted in the highest overall aerosol number concentration measured in altocumulus clouds over the Beaufort Sea.…”

Experimental studies on cloud condensation nuclei activation and cloud microphysical properties

“…Investigating subarctic clouds is of particularly high interest due to the Arctic amplification effect, since the Arctic surface energy budget and Arctic warming feedback are affected by cloud-related radiative processes (e.g., . Several observation efforts and experiments have been made to explore how air masses affect climate and the cloud macrophysical and microphysical properties (e.g., Hobbs and Rangno, 1998;Gultepe et al, 2000;Orbe et al, 2015b;Solomon and Shupe, 2019;Torres-Delgado et al, 2021). Hobbs and Rangno (1998) highlighted that air masses from the south resulted in the highest overall aerosol number concentration measured in altocumulus clouds over the Beaufort Sea.…”