An Aerosol Model of the Marine and Coastal Atmospheric Surface Layer

Abstract

We present a microphysical model for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01-100 µm particles. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of ASDF and its dependence on meteorological parameters, height above sea level (H), fetch (X), wind speed (U) and relative humidity (RH), are investigated. At present, the model covers the ranges H = 0-25 m, U = 3-18 km s −1 , X ≤ 120 km and RH = 40-98%.The latest version of the Marine Aerosol Extinction Profiles model (MaexPro) is described and applied to the computation and analysis of the spectral profiles of aerosol extinction coefficients α(λ) in the wavelength band λ = 0.2-12 µm. MaexPro is based on the aforementioned aerosol model assuming spherically shaped aerosol particles and the well-known Mie theory.The spectral profiles of α(λ) calculated by MaexPro are in good agreement with observational data and the numerical results obtained from the Navy Aerosol Model (NAM) and the Advanced Navy Aerosol Model (ANAM). Moreover, MaexPro was found to be an accurate and reliable tool for investigating the optical properties of atmospheric aerosols.RÉSUMÉ [Traduit par la rédaction] Nous présentons un modèle microphysique pour les aérosols atmosphériques marins et côtiers de la couche de surface, basé sur les observations à long terme des distributions granulométriques pour les particules de 0,01-100 µm. La caractéristique fondamentale du modèle est une paramétrisation des amplitudes et des largeurs pour les modes d'aérosols de la fonction de distribution granulométrique des aérosols (ASDF) comme des fonctions du fetch et de la vitesse du vent. Nous étudions la forme de l'ASDF et sa dépendance à l'égard des paramètres météorologiques : hauteur au-dessus du niveau de la mer (H), fetch (X), vitesse du vent (U) et humidité relative (HR). À ce moment-ci, le modèle couvre les intervalles H = 0 -25 m, U = 3 -18 km s −1 , X ≤ 120 km et HR = 40 -98 %.Nous décrivons la dernière version du modèle Marine Aerosol Extinction Profiles (MaexPro) et l'appliquons pour le calcul et l'analyse des profils spectraux des coefficients d'extinction α(λ) dans la bande de longueurs d'onde λ = 0,2-12 µm. MaexPro est basé sur le modèle d'aérosols mentionné ci-dessus pour des particules d'aérosol de forme sphérique et la théorie bien connue de Mie.Les profils spectraux de α(λ) calculés par MaexPro s'accordent bien avec les données d'observation et avec les résultats numériques obtenus du Navy Aerosol Model (NAM) et du Advanced Navy Aerosol Model (ANAM). Qui plus est, MaexPro s'est avéré un outil précis et fiable pour étudier les propriétés optiques des aérosols atmosphériques.

Detection Performance Analysis of Marine Wind by Lidar and Radar under All-Weather Conditions

“…The threshold of 1 µm may not fully represent reality, but it should provide a reasonable approximation for the simulation of the aerosol particle size distribution given the extensive data analysis of the ANAM. Additionally, both Lewis et al and Kaloshin et al also mentioned that the influence of gravity and the vertical concentration gradient on SSA particles smaller than 1 µm were negligible [23,28]. Figure 2 shows the variations in σ bsca and σ ext with different wind speeds and altitudes.…”

“…Numerous investigations on the size distribution models of SSA were conducted as a result of the significant impact of SSA on various remote sensing and environmental monitoring applications [26][27][28][29]. Among these models, the Advanced Navy Aerosol Model (ANAM) [29], which was derived from the Navy Aerosol Model [30], has been widely used after years of data validation since 1983.…”

“…As suggested above, the SSA particle size distribution model N aerosol (r 80 ) on sunny days was based on the ANAM and the range of r 80 in simulations was set from 0.01 to 100 µm [28,29,55]. According to Section 2, N aerosol (r 80 ) was mainly determined by the sea surface wind and the altitude from the sea surface.…”

Modeling of microphysics and optics of aerosol particles in the marine environments

“…for the radiative transfer simulations. For the wave band the optical activity of the particles beyond the size range 0.01 -100 m is negligible [4].…”

A Model for Predicting Coastal Aerosol Size Distributions in Chinese Seas

“…Since the radius range of the particles in observation data is from 0.248 to 12.633 μm, the fitting results of A 1 and C 1 cannot be obtained. The expressions of A 1 and C 1 used here are from the work of Kaloshin and Grishin (2011). Due to the lack of observed data of particles with radius of 0.24, 2, and 10 μm, the particles with similar radius of 0.248, 1.973, and 9.796 μm are selected for present analysis.…”