An Analysis of Near-Surface Optical Turbulence and Aerosol Concentration Coupling during a Solar Eclipse

2018 ◽  
Author(s):  
Steven Fiorino ◽  
Kevin Keefer ◽  
Lee Burchett ◽  
Aaron Archibald
Keyword(s):  
Solar Eclipse ◽  
Aerosol Concentration ◽  
Optical Turbulence ◽  
Near Surface ◽  
Surface Optical

The Use of Weather Forecasts to Characterise Near-Surface Optical Turbulence

2010 ◽  
Vol 138 (3) ◽  
pp. 453-473 ◽  
Author(s):  
S. Cheinet ◽  
A. Beljaars ◽  
K. Weiss-Wrana ◽  
Y. Hurtaud
Keyword(s):  
Optical Turbulence ◽  
Near Surface ◽  
Weather Forecasts ◽  
Surface Optical

Daytime Reduction in Near-Surface Optical Turbulence due to Black Carbon Aerosols

2021 ◽  
Author(s):  
N. Anand ◽  
K. Sunilkumar ◽  
S. K. Satheesh ◽  
K. Krishna Moorthy
Keyword(s):  
Black Carbon ◽  
Optical Turbulence ◽  
Near Surface ◽  
Surface Optical ◽  
Carbon Aerosols ◽  
Black Carbon Aerosols

Probing bulk and near-surface optical properties of phantoms and human skin using a probe with small source-detector distances

2002 ◽  
Author(s):  
Omar S. Khalil ◽  
Johannes S. Kanger ◽  
Xiaomao Wu ◽  
Rene A. Bolt ◽  
Shu-Jen Yeh ◽  
...  
Keyword(s):  
Optical Properties ◽  
Human Skin ◽  
Near Surface ◽  
Surface Optical

scholarly journals Unmanned aerial vehicles reveal the impact of a total solar eclipse on the atmospheric surface layer

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190212 ◽  
Author(s):  
Sean C. C. Bailey ◽  
Caleb A. Canter ◽  
Michael P. Sama ◽  
Adam L. Houston ◽  
Suzanne Weaver Smith
Keyword(s):  
Surface Layer ◽  
Unmanned Aerial Vehicles ◽  
Solar Eclipse ◽  
Atmospheric Surface Layer ◽  
Small Scale ◽  
Stable Layer ◽  
Holistic View ◽  
Near Surface ◽  
Aerial Vehicles ◽  
The Impact

We use unmanned aerial vehicles to interrogate the surface layer processes during a solar eclipse and gain a comprehensive look at the changes made to the atmospheric surface layer as a result of the rapid change of insolation. Measurements of the atmospheric surface layer structure made by the unmanned systems are connected to surface measurements to provide a holistic view of the impact of the eclipse on the near-surface behaviour, large-scale turbulent structures and small-scale turbulent dynamics. Different regimes of atmospheric surface layer behaviour were identified, with the most significant impact including the formation of a stable layer just after totality and evidence of Kelvin–Helmholtz waves appearing at the interface between this layer and the residual layer forming above it. The decrease in surface heating caused a commensurate decrease in buoyant turbulent production, which resulted in a rapid decay of the turbulence in the atmospheric surface layer both within the stable layer and in the mixed layer forming above it. Significant changes in the wind direction were imposed by the decrease in insolation, with evidence supporting the formation of a nocturnal jet, as well as backing of the wind vector within the stable layer.

An unknown maximum lag-correlation between rainfall and aerosols at 140-160 minutes

2021 ◽  
Author(s):  
Pinhas Alpert ◽  
Haim Shafir ◽  
Emily Elhacham
Keyword(s):  
Time Series ◽  
Time Scales ◽  
Atmospheric Chemistry ◽  
Numerical Study ◽  
Aerosol Concentration ◽  
Hygroscopic Growth ◽  
Plain Language ◽  
Geophysical Research ◽  
Near Surface ◽  
The Earth

<p>Keywords:</p><p>Scavenging process, Rainfall, Aerosols, Lag correlation, Rainfall-aerosol processes</p><p>Abstract</p><p>Rainfall and aerosols play major roles in the Earth climate system and substantially influence our life. Here, the focus is on the local near-surface aerosol/rainfall correlations with time-scales of minutes to days. We investigated 29 experiments including 14 specific rain events, with time resolutions of daily and 60, 30, 10 minutes at ten stations in Israel and California. The highest negative correlations were consistently at a positive lag of about 140-160 minutes where a positive lag means that the aerosol time-series follows that of the rain. The highest negative value is suggested to be the probable outcome of immediate scavenging along with the rise in aerosol concentration after rain depending on aerosol sources, hygroscopic growth and transport. The scavenging dominance is expressed by the mostly negative lag-correlation values in all experiments. In addition, the consistent lack of significant correlation found at negative lags suggest a weak aerosol effect on precipitation (Gryspeerdt et al., 2015).</p><p>Plain Language Summary: Rainfall and atmospheric particles (aerosols) play significant roles in the Earth atmosphere and largely influence our weather and climate. The relations between near-surface aerosol and rainfall on time scales of minutes to days are studied, employing correlations in 10 meteorological stations in Israel and California. The highest negative correlations were consistently at a positive lag of about 140-160 minutes. A positive lag means that the aerosol time-series follows that of the rain. The highest negative correlation value is suggested to be the outcome of scavenging along with the rise in aerosol concentration after rain depending on the sources of aerosols, hygroscopic growth and transport. <strong>Furthermore, our approach provides a more fundamental insight into the local, near-surface rain-aerosol interactions, in contrast to many aerosol-rainfall studies that are climatological and with the tele-connection approach (Alpert et al., 2008), which involves other processes over distances of a few km up to even large synoptic scales.</strong></p><p>            </p><p><strong>Relevant References:</strong></p><p>Alpert, P., Halfon, N., & Levin, Z. (2008). Does Air Pollution Really Suppress Precipitation in Israel? Journal of Applied Meteorology and Climatology. https://doi.org/10.1175/2007jamc1803.1</p><p>Barkan, J., & Alpert, P. (2020). Red Snow occurrence in Eastern Europe - A case study. Weather. https://doi.org/10.1002/wea.3644</p><p>Gryspeerdt, E., Stier, P., White, B. A., & Kipling, Z. (2015). Wet scavenging limits the detection of aerosol effects on precipitation. Atmospheric Chemistry and Physics, 15(13), 7557–7570.</p><p>Tsidulko, M., Krichak, S. O., Alpert, P., Kakaliagou, O., Kallos, G., & Papadopoulos, A. (2002). Numerical study of a very intensive eastern Mediterranean dust storm, 13-16 March 1998. Journal of Geophysical Research: Atmospheres. https://doi.org/10.1029/2001jd001168</p>

scholarly journals Effects of vernal equinox solar eclipse on temperatures and wind directions in Switzerland

2017 ◽  
Author(s):  
Werner Eugster ◽  
Carmen Emmel ◽  
Sebastian Wolf ◽  
Nina Buchmann ◽  
Joseph P. McFadden ◽  
...  
Keyword(s):  
Air Temperature ◽  
Solar Eclipse ◽  
Wind Direction ◽  
Temperature Drop ◽  
Swiss Alps ◽  
Maximum Temperature ◽  
Small Scale ◽  
Near Surface ◽  
Vernal Equinox ◽  
Cold Air

Abstract. The vernal equinox total solar eclipse of 20 March 2015 produced a maximum occultation of 65.8 to 70.1 % over Switzerland during the morning hours (09:22 to 11:48 CET). Skies were generally clear over the Swiss Alps due to a persistent high-pressure band between the UK and Russia associated with a rather weak pressure gradient over the continent. To assess the effects of penumbral shading on near-surface meteorology across Switzerland, air temperature data measured at 10-minute intervals at 184 MeteoSwiss weather stations that reported air temperature at 10-minute intervals were used. Wind speed and direction data were available from 165 of these stations. Additionally, six Swiss FluxNet eddy covariance flux (ECF) sites provided turbulent measurements at 20 Hz resolution. During maximum occultation the temperature drop was up to 5.8 K at a mountain site where cold air can pool in the topographic depression of the weather station. The bootstrapped average of the maximum temperature drops of all 184 MeteoSwiss sites during the solar eclipse was 1.51 ± 0.02 K (mean ± SE). A detailed comparison with literature values since 1834 showed a temperature decrease by 2.6 ± 1.7 K (average of all reports) with extreme values up to 11 K. On fair weather days under weak larger scale pressure gradients, local thermo-topographic wind systems develop that are driven by small-scale pressure and temperature gradients. At one ECF site, the penumbral shading delayed the morning transition from down-valley to up-valley wind conditions, and at another site, it prevented this transition from occurring at all. Data from the 165 MeteoSwiss sites measuring wind direction did not show a consistent pattern of wind direction response to the passing of the penumbral shadow. These results suggest that the local topographic setting had an important influence on the temperature drop and the wind flow patterns during the eclipse. Still, results tend to lend support to a recent theory that the anticyclonic cold-air outflow from the center of the eclipse only extends ≈ 1600 km outwards, with cyclonic flow beyond that distance. This contrasts with an earlier theory that the anticyclonic outflow should reach as far as ≈ 2400 km from the center of the eclipse, which would have included all of Switzerland during the 2015 eclipse. Nevertheless, a significant cyclonic effect of the passing penumbral shadow was found in the elevation range ≈ 1700–2700 m a.s.l., but not at lower elevations of the Swiss Plateau. Thus, measurable effects of penumbral shading on the local wind system could be even found at ≈ 2000 km from the path of the eclipse (that is, Switzerland during the 2015 eclipse).

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