SOW for SAM.gov RFI.pdf

STATEMENT OF WORK

Implementation of Entrainment Zoon and Surface Roughness into SAM-Chamber

Background Cloud formation and dissipation play a crucial role in energy balance and hydrological cycle on

Earth. However, cloud evolution is controlled by key microphysical processes (e.g., droplet activation, condensational growth, collisional growth, entrainment, and mixing) which are still not fully understood at the fundamental level and thus cause uncertainties in future climate projection. These microphysical processes cannot be easily explored under atmospheric cloud conditions due to the complex interactions and feedbacks among dynamics, radiation, and microphysics therein. A laboratory facility would provide the optimal settings to address these knowledge gaps under well-controlled conditions. Recently, BNL is working on a DOE-NSF co-funded project entitled “A community Laboratory Facility for Exploring and Sensing of Aerosol-Cloud-Drizzle Processes: The Aerosol-Cloud-Drizzle Convection Chamber” (acronym name, ACDC2). One objective of ACDC2 involves activities related to the design of a large cloud chamber suitable for drizzle formation using large-eddy simulations. This subcontract research will serve the ACDC2 project by developing an advanced numerical model for chamber simulations that can be served as a digital twin of chamber research and design.

SAM-Chamber, which is adapted and modified from the well-established System for Atmospheric Modeling (SAM), has been used to simulate cloud formed in the Michigan Tech Pi Cloud Chamber (Yang et al., 2022). However, the current SAM-Chamber is not ready to simulate the entrainment experiments in which cloud microphysical properties are influenced by a dry air flow entered from the top region of the Pi chamber. In addition, the SAM-Chamber cannot simulate the surface roughness experiment where the chamber surface is roughed artificially such that the turbulence inside the Pi chamber is enhanced. The objective of this project is to modify the SAM-Chamber to have the capability to simulate entrainment and surface roughness experiments to explore aerosol-cloud-turbulence interactions under different conditions. The outcome of this project will benefit the ACDC2 project, providing timely input as we approach the final stages of the design.

Scope of Work Dr. Marat Khairoutdinov will participate in this project with researchers from BNL. His task will be to implement an entrainment zoon and surface roughness capability into SAM-Chamber.

Dr. Khairoutdinov is the author of SAM model and is uniquely positioned to execute the project. Dr. Khairoutdinov’s tasks are as follows:

1. Implement an entrainment zoon into SAM-Chamber based on Pi chamber observations.

2. Implement surface rough topography into SAM-Chamber.

3. Conduct tests of the implementations in simulations of the Pi chamber.

References Yang, Fan, Mikhail Ovchinnikov, Subin Thomas, Alexander Khain, Robert McGraw, Raymond A.

Shaw, and Andrew M. Vogelmann. "Large-Eddy Simulations of a Convection Cloud Chamber:

Sensitivity to Bin Microphysics and Advection." Journal of Advances in Modeling Earth Systems 14, no. 5, https://doi.org/10.1029/2021MS002895, 2022.

Approved: _______________________________________ Fan Yang Technical Representative

Far Yug

05/02/2023