Characteristic Vertical Profiles of Cloud Water Composition in Marine Stratocumulus Clouds and Relationships With Precipitation
Abstract
This study uses airborne cloud water composition measurements to characterize the vertical structure of air‐equivalent mass concentrations of water‐soluble species in marine stratocumulus clouds off the California coast. A total of 385 cloud water samples were collected in the months of July and August between 2011 and 2016 and analyzed for water‐soluble ionic and elemental composition. Three characteristic profiles emerge: (i) a reduction of concentration with in‐cloud altitude for particulate species directly emitted from sources below cloud without in‐cloud sources (e.g., Cl− and Na+), (ii) an increase of concentration with in‐cloud altitude (e.g., NO2− and formate), and (iii) species exhibiting a peak in concentration in the middle of cloud (e.g., non–sea‐salt SO42−, NO3−, and organic acids). Vertical profiles of rainout parameters such as loss frequency, lifetime, and change in concentration with respect to time show that the scavenging efficiency throughout the cloud depth depends strongly on the thickness of the cloud. Thin clouds exhibit a greater scavenging loss frequency at cloud top, while thick clouds have a greater scavenging loss frequency at cloud base. The implications of these results for treatment of wet scavenging in models are discussed.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 13, 2018
- Source ID
- 10.1002/2017jd027900
Entities
People
- Alexander MacDonald
- Armin Sorooshian
- Ewan Crosbie
- Haflidi Jonsson
- Hailong Wang
- Hossein Dadashazar
- John H. Seinfeld
- Patrick Chuang
- Richard Flagan
- Zhen Wang
Organizations
- California Institute of Technology
- Langley Research Center
- Naval Postgraduate School
- Office of Naval Research
- Pacific Northwest National Laboratory
- University of Arizona