Determining the size, mixing state, & organic associations of ocean-derived & long-range transported African aerosol over N. Atlantic marine boundary
Abstract
This project leverages a collaboration between the University of Miami, the Naval Research Laboratory (NRL), the University of Wisconsin, and the University of Michigan in response to the Direct Research Initiative (DRI): #Moisture and Aerosol Gradients/Physics of Inversion Evolution(MAGPIE)#. The PI will provide in situ measurements of aerosol size, mixing state, and morphology and compare these measurements with both aerosol radiative measurements taken by NRL as well as high spectral resolution lidar (HSRL) of aerosol and cloud vertical profiles collected by U Wisconsin. Our proposed measurements provide insight into #how inversions, aerosol/cloud particulates, and moisture fluxes interact as a holistic system#. We will use the Ragged Point atmospheric research site operated bythe University of Miami as well as airborne measurements to execute our proposed measurements. Ragged Point is a receptor for locally emitted sea spray aerosol in addition to dust and smoke transported at altitude from Africa.Our goal is to characterize the physicochemical properties of long-range dust and smoke transport events compared to ocean-derived aerosol, and through our collaborativeefforts, to betterunderstand airmass mixing and exchange in the marine boundary layer as well as the impact of dust and smoke on vertical gradients in radiation, cloud structure, and inversions. We will also elucidate the abundance of supercoarse mode dust (dust with diameters > 10Pm) as well as thecomposition, phase, and mixing state of organic material that impact aerosol radiative properties and particle sphericity likely influencing source determinations made by the HSRL. In achieving this goal, we will test several hypotheses including: 1) Dust transported at lower altitudes in winter and spring will contain more fine particles and fewer supercoarse mode aerosol compared to its summertime counterpart; 2) Dust does not undergo extensive chemical aging; however, it does coagulate with sea spray during detrainment, altering the hygroscopic and radiative properties of dust. Dust is more frequently mixed with sea spray in the winter than the summer due to the transport altitude. 3) The sources of organic material will vary seasonally, coming from the ocean and biological material in summer and smoke and pollution during winter and spring.Characterizing this material will be critical to validate HSRL vertical aerosol profiles; 4) Aerosol mixing state and source can be leveraged to understand the extent of vertical mixing from the free troposphere to the surface and the surface to the upper atmosphere.To test our hypotheses, we will continuously measure dust, light absorbing carbonaceous aerosol, aerosol optical depth (AOD), and particle size distributions. Intensive measurements of aerosol mixing state will be performed during dedicated field studies. We will then compare our aerosolmeasurements to the HSRL and NRL#s radiative measurements to elucidate the exchange of air masses that help mix the boundary layer through up and down drafts as well as the impact of organic aerosol and African smoke and dust on aerosol radiative properties, cloud structure, and inversions that can suppress convective mixing. Our aerosol measurements will also provide insight into whether dust undergoes chemical aging and whether supercoarse mode particles remain aloft during transport, which affects dust-cloud interactions aswell as dust radiative properties. The proposed work will generate multiple benefits for ONR including an improved understanding of: 1) aerosol-cloud interactions that affect cloud structure and formation, 2) the aerosol radiation budget, and 3) the role of aerosols in maintaining inversions over the N. Atlantic Basin that will lead to improvements in the next generation of naval numerical models and remote sensing aerosol retrievals.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142512003
Entities
People
- Cassandra Gaston
Organizations
- Office of Naval Research
- United States Navy
- University of Miami