Optical Properties Of The Marine Atmospheric Boundary Layer: Aerosol Profiles

Davidson, Kenneth L.; Fairall, C. W.

doi:10.1117/12.964211

Cited by 2 publications

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“…In view of the above, a model for the vertical structure of the marine aerosol is required to explain a wide range of processes in the MBL. Adequate descriptions of the particle size distributions under the ambient atmospheric conditions are not available, although good progress has been made recently for a model at ship deck level ( Leeuw, 1986a]. A comparison with profiles of particle concentrations, measured during the same and other campaigns with a rotating impaction sampler [de Leeuw, 1986b[de Leeuw, , c, 1987, shows that the predicted concentrations near the air-sea interface are too high for particles larger than about 10/•m in diameter.…”

Section: Introductionmentioning

confidence: 99%

“…The complexity of the problem [cf. Davidson and Fairall, 1986;Fairall and Davidson, 1986] and the lack of data to test the assumptions involved indicate the need for more [Mestayer et al, 1988] are expected to contribute substantially to the modeling of particle behavior after ejection at the sea surface. However, more field experiments are required to validate in oceanic conditions the conclusions derived from the laboratory experiments.…”

Section: Introductionmentioning

confidence: 99%

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Investigations on turbulent fluctuations of particle concentrations and relative humidity in the marine atmospheric surface layer

Leeuw¹

1989

J. Geophys. Res.

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Results are presented from measurements on the variation of sea spray concentrations and relative humidity (RH) in the lower 15 m of the marine atmospheric surface layer. Particle total area concentrations were determined from measurements of near‐forward scattering intensities with an optical device. Both time dependent variations and mean values were recorded as a function of height from 0.5 to 15 m. The profiles of particle total area concentrations and relative humidity show trends similar to previously published particle concentration profiles measured with a rotorod impaction sampler. Hence our previous results are confirmed by using a completely different technique, based on different physical principles. The time dependent measurements show that fluctuations in the particle total area concentrations are correlated with the motions of the waves under the sampler. Spectral analyses reveal a height dependent frequency, which may be due to the wind profile, to the wave‐induced turbulence structure, and to changes in the particle size distribution. Simultaneous time‐resolved measurements of RH do not reveal a distinct wave influence. This analysis indicates that water vapor is transported by turbulent diffusion on a time scale much faster than 1 s. The time scale for the response of the largest sea spray particles to the surface displacements is estimated to be longer than 5 s. Theoretical implications are indicated. The results have implications for humidity transport and the constant flux assumption in the surface layer and may be applied to study interaction between wind and waves in the open ocean.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigations on turbulent fluctuations of particle concentrations and relative humidity in the marine atmospheric surface layer

Leeuw¹

1989

J. Geophys. Res.

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<title>NOVAM evaluation from aerosol and lidar measurements in a tropical marine environment</title>

Leeuw¹,

Kunz²

1992

SPIE Proceedings

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NOVAM, the Naval Oceanic Vertical Aerosol Model, has been developed to predict the non-unifoni and nonlogarithinic extinction profiles that are often observed in the iarine atiospheric boundary layer. The kernel of NOVAN is the Navy Aerosol Model (NAN) that calculates the aerosol size distribution at 10 ii ASL froi meteorological paralueters. The aerosol profile is calculated from the surface layer size distribution with a physical model. Extinction profiles are calculated froi the aerosol profiles using a Mie code. NOVAM requires validation in different iaeteorological scenarios During the KEY9O experiient, July 1990 near Marathon (Fl), NOVAM was validated in a tropical marine environment. We ieasured the surface layer particle size distribution profile at levels froia 0.5 to 4 m ASL to evaluate the large particle end of NAN. The 110VA14 prediction of the aerosol profile in the fflixed layer was evaluated by lidar ieasurements of the 1.06 j backscatter profile. The timeserial lidar measurements show the convective pluiaes and the variability in both the aerosol content at higher levels in the boundary layer and in the boundary layer height itself. Consequences for application of NOVA?.! for slant path transmission are discussed. . INTRODUCTIONFor the assessiiient of electro-optical (EO) instruiaentation for vertical and slant path observations, knowledge on the vertical variation of electrouagnetic scattering and absorption at wavelengths froi the visible to the far infrared is important. Existing empirically derived expressions for the contribution of the aerosol to the EO propagation characteristics in the iaarine atmosphere were formulated for single levels. An exaiaple is the Navy Aerosol Model (NAN)1'2 as found in LOWTRAN VI.3 To extend the extinction prediction to higher levels, a physical model is required to calculate the vertical distribution of the aerosol. Eipirical iodels fail to predict the correct behavior see e.g., ref . 4 for a brief review) . Therefore the Naval Oceanic Vertical Aerosol Model (NOVAI4) has been developed. '' 'b, 7,t NOVAN uses neteorological profile information to account for the physical processes that influence the vertical aerosol structure and are thought to be responsible for the observed variety of profiles. NOVA!'! has been designed to describe the nonunifor but also non-logarithmic aerosol distributions that are often observed throughout the marine atiaospheric boundary layer (MABL).NOVAM is a mixture of empirical and dynamical models. The kernel for NOVAM is NAN which has been extensively updated from the original.1 NAM produces an aerosol size distribution at 10 m above the sea surface, from input data of wind speed (both current wind speed and the 24-hour average), visibility and relative hulaidity. The NANgenerated surfacelayer particle size distribution is mixed throughout the MABL by turbulent-controlled processes, further modified by humidity effects. The physics describing these processes are determined by the MABL vertical structure. Various models desc...

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Optical Properties Of The Marine Atmospheric Boundary Layer: Aerosol Profiles

Cited by 2 publications

References 4 publications

Investigations on turbulent fluctuations of particle concentrations and relative humidity in the marine atmospheric surface layer

Investigations on turbulent fluctuations of particle concentrations and relative humidity in the marine atmospheric surface layer

<title>NOVAM evaluation from aerosol and lidar measurements in a tropical marine environment</title>

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