Aerosol light scattering dependency on wind speed in marine air

Aerosol light scattering measurements were carried out using a TSI 3563 Nephelometer at the Mace Head Atmospheric Research Station, on the west coast of Ireland from year 2001–2010. A strong seasonal trend in the aerosol light scattering coefficient at 550 nm (), for clean marine air masses, is observed with a high value, [average (geometric mean)] of 35.3 Mm−1(29.5 Mm−1), in January and a low value of 13.7 Mm−1(10.2 Mm−1), in July. This near threefold increase in the value during the winter season is because of the large contribution of wind-speed generated sea-salt particles in the marine boundary layer. A high positive correlation coefficient of 0.82 was found between the percentage occurrence of relatively large Ångström exponent (Å) values (>1.2) and the percentage occurrence of lower values (5–15 Mm−1) in the summer season. and wind-speed have a high positive correlation coefficient of 0.88 whereas Å and wind-speed have a negative correlation coefficient of −0.89. Å values during the summer months indicate the dominance of sub-m particles thus indicating the contribution of non-sea-salt sulphate and organics towards the as these species show an enhanced concentration during the summer months.

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Transport of Atmospheric Aerosol by Gap Winds in the Columbia River Gorge

Journal of Applied Meteorology and Climatology ◽

10.1175/2007jamc1561.1 ◽

2008 ◽

Vol 47 (1) ◽

pp. 15-26 ◽

Cited By ~ 2

Author(s):

Mark C. Green ◽

Jin Xu ◽

Narendra Adhikari

Keyword(s):

Light Scattering ◽

Wind Speed ◽

Atmospheric Aerosol ◽

Columbia River ◽

Pressure Gradients ◽

Gap Flow ◽

Westerly Winds ◽

Gap Winds ◽

Diurnal Wind ◽

The City

Abstract Typical diurnal wind patterns and their relationship to transport of atmospheric aerosol in the Columbia River gorge of Oregon and Washington are addressed in this paper. The measurement program included measurements of light scattering by particles (bsp) with nephelometers, and wind speed and direction, temperature, and relative humidity at seven locations in the gorge. Winds are shown to respond to along-gorge pressure gradients, and five common patterns were identified: strong, moderate, and light westerly (west to east), light easterly, and winter easterly. The strong westerly and winter easterly patterns were the most common summer and winter patterns, respectively, and represented strong gap flow. The light westerly and light easterly patterns occurred most frequently in spring and autumn transition periods. Winter easterly had the highest light scattering and indicated sources east of the gorge mainly responsible for haze. During summer, as westerly winds increased diurnally, a pulse of hazy air from the Portland, Oregon, metropolitan area is transported eastward into the gorge, arriving later with distance into the gorge. During light easterly flow impacts to haze from the city of The Dalles, Oregon, are noted as the wind shifts direction diurnally.

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Local thermal gradient and large-scale circulation impacts on turbine-height wind speed forecasting over the Columbia Basin

10.5194/wes-2021-72 ◽

2021 ◽

Author(s):

Ye Liu ◽

Yun Qian ◽

Larry K. Berg

Keyword(s):

Wind Speed ◽

Thermal Gradient ◽

Large Scale ◽

Forecast Accuracy ◽

Columbia River ◽

Self Organizing Map ◽

Weather System ◽

Large Scale Circulation ◽

Thermal Anomalies ◽

Marine Air

Abstract. We investigate the sensitivity of turbine-height wind speed forecast to initial condition (IC) uncertainties over the Columbia River Gorge (CRG) and Columbia River Basin (CRB) for two typical weather phenomena, i.e., local thermal gradient induced marine air intrusion and a cold frontal passage. Four types of turbine-height wind forecast anomalies and their associated IC uncertainties related to local thermal gradients and large-scale circulations are identified using the self-organizing map (SOM) technique. The four SOM types are categorized into two patterns, each accounting for half of the ensemble members. The first pattern corresponds to IC uncertainties that alter the wind forecast through modulating weather system, which produces the strongest wind anomalies in the CRG and CRB. In the second pattern, the moderate local thermal gradient and large-scale circulation uncertainties jointly contribute to wind forecast anomaly. We analyze the cross-section of wind and temperature anomalies through the gorge to explore the evolution of vertical features of each SOM type. The turbine-height wind anomalies induced by large-scale IC uncertainties are more concentrated near the front. In contrast, turbine-height wind anomalies induced by the local IC thermal uncertainties are found above the surface thermal anomalies. Moreover, the wind forecast accuracy in the CRG and CRB are limited by IC uncertainties in a few specific regions, e.g., the 2-m temperature within the basin and large-scale circulation over the northeast Pacific around 140° W.

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Speciation of Organic Aerosols in the Tropical Mid-Pacific and Their Relationship to Light Scattering

Journal of the Atmospheric Sciences ◽

10.1175/jas3284.1 ◽

2004 ◽

Vol 61 (21) ◽

pp. 2544-2558 ◽

Cited By ~ 23

Author(s):

Kathleen K. Crahan ◽

Dean A. Hegg ◽

David S. Covert ◽

Haflidi Jonsson ◽

Jeffrey S. Reid ◽

...

Keyword(s):

Light Scattering ◽

Principal Component ◽

Mass Gain ◽

Organic Component ◽

Research Platform ◽

Marine Air ◽

The Relationship ◽

Aerosol Hygroscopicity

Abstract Although the importance of the aerosol contribution to the global radiative budget has been recognized, the forcings of aerosols in general, and specifically the role of the organic component in these forcings, still contain large uncertainties. In an attempt to better understand the relationship between the background forcings of aerosols and their chemical speciation, marine air samples were collected off the windward coast of Oahu, Hawaii, during the Rough Evaporation Duct project (RED) using filters mounted on both the Twin Otter aircraft and the Floating Instrument Platform (FLIP) research platform. Laboratory analysis revealed a total of 17 species, including 4 carboxylic acids and 2 carbohydrates that accounted for 74% ± 20% of the mass gain observed on the shipboard filters, suggesting a possible significant unresolved organic component. The results were correlated with in situ measurements of particle light scattering (σsp) at 550 nm and with aerosol hygroscopicities. Principal component analysis revealed a small but ubiquitous pollution component affecting the σsp and aerosol hygroscopicity of the remote marine air. The Princeton Organic-Electrolyte Model (POEM) was used to predict the growth factor of the aerosols based upon the chemical composition. This output, coupled with measured aerosol size distributions, was used to attempt to reproduce the observed σsp. It was found that while the POEM model was able to reproduce the expected trends when the organic component of the aerosol was varied, due to large uncertainties especially in the aerosol sizing measurements, the σsp predicted by the POEM model was consistently higher than observed.

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