Low-level mixing height detection in coastal locations with a scanning Doppler lidar

Vakkari, Ville; O’Connor, Ewan; Nisantzi, Argyro; Mamouri, Rodanthi-Elisavet; Hadjimitsis, Diofantos G.

doi:10.5194/amt-8-1875-2015

Cited by 63 publications

(70 citation statements)

References 33 publications

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“…Lee AIWs (or orographic waves) are one of the types of AGWs, which arise leeward of obstacles at the stable stratification of an incoming flow (Vel'tishchev and Stepanenko, 2006;Kozhevnikov, 1999;Makarenko and Maltseva, (Pearson et al, 2009). These lidars find expanding applications in studies of ABL (O'Connor et al, 2010;Sathe and Mann, 2012;van Dinther et al, 2015;Päschke et al, 2015;Smalikho and Banakh, 2015a, b;Smalikho et al, 2015a, b, c;Vakkari et al, 2015). The processing of all data measured by the lidar and the analysis of the processed data have revealed several cases of formation of atmospheric internal waves for the period of measurements.…”

Section: Introductionmentioning

confidence: 99%

Lidar observations of atmospheric internal waves in the boundary layer of the atmosphere on the coast of Lake Baikal

Banakh

Smalikho

2016

Atmos. Meas. Tech.

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Abstract. Atmospheric internal waves (AIWs) in the boundary layer of atmosphere have been studied experimentally with the use of Halo Photonics pulsed coherent Doppler wind lidar Stream Line. The measurements were carried out over 14-28 August 2015 on the western coast of Lake Baikal (51 • 50 47.17 N, 104 • 53 31.21 E), Russia. The lidar was placed at a distance of 340 m from Lake Baikal at a height of 180 m above the lake level.A total of six AIW occurrences have been revealed. This always happened in the presence of one or two (in five out of six cases) narrow jet streams at heights of approximately 200 and 700 m above ground level at the lidar location. The period of oscillations of the wave addend of the wind velocity components in four AIW events was 9 min, and in the other two it was approximately 18 and 6.5 min. The amplitude of oscillations of the horizontal wind velocity component was about 1 m s −1 , while the amplitude of oscillations of the vertical velocity was 3 times smaller. In most cases, internal waves were observed for 45 min (5 wave oscillations with a period of 9 min). Only once the AIW lifetime was about 4 h.

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Section: Introductionmentioning

confidence: 99%

Lidar observations of atmospheric internal waves in the boundary layer of the atmosphere on the coast of Lake Baikal

Banakh

Smalikho

2016

Atmos. Meas. Tech.

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“…Turbulent kinetic energy (TKE) dissipation rate was calculated from the Doppler lidar measurements according to the method by O'Connor et al (2010). A VAD-based proxy for turbulent mixing (σ 2 VAD) was calculated from the 30° elevation VAD scan according to the method by Vakkari et al (2015). MLH was determined from the TKE dissipation rate and the VAD scan 30 similar to Vakkari et al (2015).…”

Section: Complementary Measurementsmentioning

confidence: 99%

“…A VAD-based proxy for turbulent mixing (σ 2 VAD) was calculated from the 30° elevation VAD scan according to the method by Vakkari et al (2015). MLH was determined from the TKE dissipation rate and the VAD scan 30 similar to Vakkari et al (2015). Briefly, first a constant threshold of 10 -4 m 2 s -3 was applied to the TKE dissipation rate profile, (Vakkari et al, 2015).…”

Section: Complementary Measurementsmentioning

confidence: 99%

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Sesquiterpenes identified as key species for atmospheric chemistry in boreal forest by terpenoid and OVOC measurements

Hellén

Praplan

Tykkä

et al. 2018

Preprint

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Abstract. Concentrations of terpenoids (isoprene, monoterpenes, sesquiterpenes) and oxygenated volatile organic compounds (OVOCs, i.e. aldehydes, alcohols, acetates and volatile organic acids) were investigated during two years at a boreal forest site in Hyytiälä, Finland, using in situ gas chromatograph-mass spectrometers (GC-MS). Seasonal and diurnal variations of terpenoid and OVOC concentrations as well as their relationship with meteorological factors were studied.Of the studied VOCs, C2-C7 unbranched volatile organic acids (VOAs) were found to have the highest concentrations mainly 20 due to their low reactivity. Of the terpenoids, monoterpenes (MTs) had highest concentrations at the site, but also 7 different highly reactive sesquiterpenes (SQTs) were detected. Monthly and daily mean concentrations of most terpenoids, aldehydes and VOAs were found to be highly dependent on the temperature. Highest exponential correlation with temperature was found for a SQT (β-caryophyllene) in summer. The diurnal variations of the concentrations could be explained by sources, sinks and vertical mixing. Especially the diurnal variations of MT concentrations were strongly affected by vertical mixing. Based on 25 the temperature correlations and mixing layer height simple proxies were developed for estimating MT and SQT concentrations.To estimate the importance of different compound groups and compounds for the local atmospheric chemistry, reactivity with main oxidants (OH, NO3 and O3) and production rates of oxidation products (OxPR) were calculated. MTs dominated OH and NO3 radical chemistry, but SQTs had a major impact on ozone chemistry, even though concentrations of SQT were 30 times 30 lower than MT concentrations. SQTs were the most important also for the production of oxidation products. Since SQTs have high secondary organic aerosol (SOA) yields, results clearly indicate the importance of SQTs for local SOA production.Atmos. Chem. Phys. Discuss., https://doi

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“…Suomi et al, 2015). However, Doppler lidars can also provide high-resolution turbulent measurements, in both the vertical direction (O'Connor et al, 2010) and, potentially, the horizontal direction (Vakkari et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Untitled

2017

Quart J Royal Meteoro Soc

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A new methodology is proposed for scaling Doppler lidar observations of wind gusts to make them comparable with those observed at a meteorological mast. Doppler lidars can then be used to measure wind gusts in regions and heights where traditional meteorological mast measurements are not available. This novel method also provides estimates for wind gusts at arbitrary gust durations, including those shorter than the temporal resolution of the Doppler lidar measurements. The input parameters for the scaling method are the measured wind-gust speed as well as the mean and standard deviation of the horizontal wind speed. The method was tested using WindCube V2 Doppler lidar measurements taken next to a 100 m high meteorological mast. It is shown that the method can provide realistic Doppler lidar estimates of the gust factor, i.e. the ratio of the wind-gust speed to the mean wind speed. The method reduced the bias in the Doppler lidar gust factors from 0.07 to 0.03 and can be improved further to reduce the bias by using a realistic estimate of turbulence. Wind gust measurements are often prone to outliers in the time series, because they represent the maximum of a (moving-averaged) horizontal wind speed. To assure the data quality in this study, we applied a filtering technique based on spike detection to remove possible outliers in the Doppler lidar data. We found that the spike detection-removal method clearly improved the wind-gust measurements, both with and without the scaling method. Spike detection also outperformed the traditional Doppler lidar quality assurance method based on carrier-to-noise ratio, by removing additional unrealistic outliers present in the time series.

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Low-level mixing height detection in coastal locations with a scanning Doppler lidar

Cited by 63 publications

References 33 publications

Lidar observations of atmospheric internal waves in the boundary layer of the atmosphere on the coast of Lake Baikal

Lidar observations of atmospheric internal waves in the boundary layer of the atmosphere on the coast of Lake Baikal

Sesquiterpenes identified as key species for atmospheric chemistry in boreal forest by terpenoid and OVOC measurements

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