A Laboratory Investigation of Spume Generation in High Winds for Fresh and Seawater
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Authors
Mehta, S.
Ortiz‐Suslow, D.G.
Smith, A.W.
Haus, B.K.
Subjects
Advisors
Date of Issue
2019-11
Date
Publisher
American Geophysical Union (AGU)
Language
Abstract
Given spume's role in mediating air‐sea exchange at the base of tropical cyclones or other storm events, the focus of studies on spray dynamics has been within the marine environment. In contrast, spume production in nonseawater bodies has been underexplored and potential differences between sea and freshwater are neglected. The laboratory remains the primary means for directly observing spray processes near the surface because of the challenges to making robust field measurements. There is no standardization on the water type used for these experiments, and the effect this has on the generation process is unknown. This adds uncertainty in our ability to make physically realistic spume generation functions that are ultimately applied to the geophysical domain. We have conducted a laboratory experiment that aims to address this simple, yet overlooked, question of whether water type impacts the spume droplet concentration entrained in the air flow above actively breaking waves. We compared directly imaged concentrations for fresh and seawater droplets produced in 10‐m equivalent winds from 36–54 m/s. Substantially higher concentrations of seawater spume were observed, as compared to freshwater across all particle sizes and wind speeds. The seawater particles' vertical distribution was concentrated near the surface, whereas the freshwater droplets were more uniformly distributed. Our statistical analysis of these findings suggests significant differences in the size‐ and height‐dependent distributions response to increased wind forcing between fresh and seawater. These unexpected findings suggest an unanticipated role of the source water physiochemical properties on the spume generation mechanism.
Type
Article
Description
Data are archived at the University of Miami repository under the name Spray Concentration Measurements from ASIST for Freshwater and Seawater.
The article of record as published may be found at https://doi.org/10.1029/ 2019JD030928
The article of record as published may be found at https://doi.org/10.1029/ 2019JD030928
Series/Report No
Department
Meteorology
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
NSF
ONR
ONR
Funding
This work was funded by NSF through Grant 0933943. Additional support was provided through ONR phase‐resolved wave program under Grant N000141410644
Format
16 p.
Citation
Mehta, S., Ortiz‐Suslow, D. G., Smith, A. W., & Haus, B. K. (2019). A laboratory investigation of spume generation in high winds for fresh and seawater. Journal of Geophysical Research: Atmospheres, 124, 11,297–11,312.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.