Turbulent transport of electric charge in the marine atmospheric boundary layer

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Abstract
Sensible heat, water vapor, aerosols, gaseous pollutants, and electric charge are transported vertically in the marine boundary layer by turbulent processes. The standard eddy correlation method for measuring fluxes from aircraft requires inertial navigation systems, considerable computer power, and large aircraft with gust probes on specially engineered booms to correct for aircraft motions. Only a few laboratories can afford to operate aircraft systems of the required complexity. The development of a method for obtaining routine, high quality, relatively inexpensive measurements of at least one boundary‐layer flux profile from light aircraft (specifically not requiring an inertial platform or angular motion data) could permit enhancement of boundary‐layer research on a new statistical scale. The flux of electric charge (called the eddy current) can be inferred from simple dc measurements of electric field intensity and conductivity from a light aircraft. Recent aircraft measurements off the California coast show good correlation of surface layer eddy current peak values with the surface water vapor flux and the convective mixed layer velocity, w*. The electrical technique also appears to have exceptional sensitivity exceeding that of the eddy correlation technique. It is suggested that the eddy current could be used to infer the flux profiles of other passive scalars. Because space charge undergoes a decay in time, the space charge density does not tend to be well mixed (constant with altitude) in the planetary boundary layer. The ease of measuring space charge density gradient allows accurate determination of the passive scalar eddy diffusion coefficient, K, a parameter that has been difficult to measure in the past. Thus, atmospheric electrical measurements from aircraft have the potential for providing important new information for pollution modeling and studies of boundary‐layer meteorology.