Low-Level Atmospheric Jets And Inversions Over The Western Weddell Sea

Andreas, Edgar L.; Claffy, Kerry J.; Makshtas, A.

doi:10.1023/a:1002793831076

Cited by 190 publications

(216 citation statements)

References 41 publications

Supporting

Mentioning

202

Contrasting

Unclassified

Order By: Relevance

“…The experimental studies of LLJs that accompany long-lived wintertime inversions over snow-covered surfaces are few. The LLJs over snow surfaces were studied in the Antarctic (Andreas et al 2000;Anderson 2003;King et al 2008) and in the Arctic (Vihma and Brümmer 2002;Brümmer and Thiemann 2002;Vihma et al 2005). The main parameters of LLJs obtained in the latter studies are similar to those of nocturnal summertime LLJs.…”

mentioning

confidence: 74%

“…There is no commonly accepted criterion to identify the LLJs. In this study we used a visual inspection of wind profiles in a similar manner to that done by Coulter (1981), Andreas et al (2000) and Banta et al (2002). The wind-speed profiles that have a local maximum exceeding by 1 m s −1 the wind speed above it were considered as jets.…”

Section: Measurement Sites Equipment and Data Processingmentioning

confidence: 99%

“…The wind-speed profiles that have a local maximum exceeding by 1 m s −1 the wind speed above it were considered as jets. Note, that different threshold criteria can be found in the literature: 6 m s −1 (Bonner 1968), 2 m s −1 (Andreas et al 2000;Baas et al 2009), 0.5 m s −1 (Banta et al 2002;Conangla and Cuxart 2006). The choice of the jet criterion in these studies substantially depended on the resolution of the equipment used.…”

Section: Measurement Sites Equipment and Data Processingmentioning

confidence: 99%

“…Andreas et al 2000;Milionis and Davies 2002). It is probably caused by poor accuracy in Z inv derived from the temperature profiles.…”

Section: Nocturnal Lljs and The Geostrophic Windmentioning

confidence: 99%

“…The main parameters of LLJs obtained in the latter studies are similar to those of nocturnal summertime LLJs. However, we have found only one study (Andreas et al 2000), where the statistical data on LLJs over snow-covered surface are given. The measurements over the Arctic are few since they were performed by means of aircraft.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Low-Level Jets in the Moscow Region in Summer and Winter Observed with a Sodar Network

Kallistratova

Kouznetsov

2011

Boundary-Layer Meteorol

View full text Add to dashboard Cite

We evaluate the statistical properties of low-level jets (LLJs) observed by means of a network of Doppler sodars in the Moscow region, Russia. Continuous long-term measurements of the echo-signal intensity and wind-velocity profiles were carried out in July 2005 and in 2008-2010 synchronously in the centre of Moscow and at a rural site. The summertime nocturnal LLJs have a very clear diurnal cycle and exhibit features predicted by the Blackadar mechanism. In contrast, the long-lasting wintertime jets do not have any clear diurnal variability. The urban environment strongly influences LLJs in both seasons: above the city LLJs are higher, weaker and observed more rarely than at the rural site. In very cold periods (air temperature below −8 • C) no LLJs were observed over the city, instead convection emerged in the urban boundary layer. The results are based on observations made in

show abstract

mentioning

confidence: 74%

Section: Measurement Sites Equipment and Data Processingmentioning

confidence: 99%

Section: Measurement Sites Equipment and Data Processingmentioning

confidence: 99%

“…Andreas et al 2000;Milionis and Davies 2002). It is probably caused by poor accuracy in Z inv derived from the temperature profiles.…”

Section: Nocturnal Lljs and The Geostrophic Windmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Low-Level Jets in the Moscow Region in Summer and Winter Observed with a Sodar Network

Kallistratova

Kouznetsov

2011

Boundary-Layer Meteorol

View full text Add to dashboard Cite

show abstract

The low-level jet dust emission mechanism in the central Sahara: Observations from Bordj-Badji Mokhtar during the June 2011 Fennec Intensive Observation Period

Allen

Washington

2014

J. Geophys. Res. Atmos.

View full text Add to dashboard Cite

This paper presents the first detailed analysis of low-level jets (LLJs) in the central Sahara from ground-based observations at Bordj-Badji Mokhtar, Algeria, and addresses their operation as a dust emission mechanism. On LLJ mornings, composite wind speeds in the core (300 m aboveground level) reach 13.5 m s À1 at 0400. Surface temperatures increase from 0545 (30 min after sunrise), and jet decay begins around 0600. Ten meter winds lag those in the core by 5 h; peak 10 m wind speed, 7.5 m s À1 , occurs at 0900. Only the deepest and strongest LLJs lead to dust emission. At 0600, these five LLJs have core wind speeds ≥16 m s À1 , below-core wind shear ≥ 0.6 m s À1 /30 m, and wind shear between the core and 500 m above the core ≤À1.8 m s À1 . On these occasions, momentum mixes down from the LLJ after surface heating, leading to emission. On nondusty LLJ mornings, the convective boundary layer is 100 m shallower, and the LLJ is too weak to provide enough momentum to be mixed down for emission. LLJs are most frequently embedded in the monsoon flow or in the Harmattan; there is a clear association with the Saharan Heat Low. ERA-Interim reanalysis underestimates both Harmattan and monsoon LLJ core winds (by 4 m s À1 and 6 m s À1 , respectively). The Met Office Africa Limited Area Model underestimates Harmattan LLJ core winds by only 0.2 m s À1 . Monsoon LLJ core winds, however, are underestimated by 8.5 m s À1 . Surface winds at 0900 are underestimated in both cases by up to 6 m s À1 .

show abstract

Time evolution of monsoon low-level jet observed over an Indian tropical station during the peak monsoon period from high-resolution Doppler wind lidar measurements

Ruchith

Raj

Kalapureddy

et al. 2014

J. Geophys. Res. Atmos.

View full text Add to dashboard Cite

Doppler wind lidar measurements of horizontal winds at an Indian tropical station, Mahbubnagar (16.73°N, 77.98°E, 445 m above mean sea level), were used to investigate the time evolution of the monsoon low-level jet (MLLJ) during the southwest monsoon season. Vertical profiles of zonal wind in the altitude range of 100 to 3000 m above surface (at every 50 m height interval and 5 min time averaged) obtained during the period 25 July to 23 August 2011 are considered for the analysis. The zonal winds in the altitude up to 3000 m above ground are predominantly westerly throughout the period and on almost all the days there is a westerly wind speed maximum around 500 m above ground during nighttime. Soon after local sunrise, the core of this wind speed maximum (jet) gets lifted up and by afternoon, the westerly wind maximum is shifted to a higher altitude of 2000 m-2500 m without much change in its magnitude. Analysis of the high-resolution lidar data strongly indicates that the same nocturnal LLJ seems to be moving up and evolving into a daytime westerly MLLJ reported in several previous studies. Wind speed and direction derived from the wind lidar agree reasonably well with simultaneously observed GPS upper air sounding wind measurements. Further analysis shows that the time-height evolution of the jet core is closely associated with daytime convection and boundary layer growth. The presence of clouds over the region seems to inhibit this type of time evolution.

show abstract

Low-Level Atmospheric Jets And Inversions Over The Western Weddell Sea

Cited by 190 publications

References 41 publications

Low-Level Jets in the Moscow Region in Summer and Winter Observed with a Sodar Network

Low-Level Jets in the Moscow Region in Summer and Winter Observed with a Sodar Network

The low-level jet dust emission mechanism in the central Sahara: Observations from Bordj-Badji Mokhtar during the June 2011 Fennec Intensive Observation Period

Time evolution of monsoon low-level jet observed over an Indian tropical station during the peak monsoon period from high-resolution Doppler wind lidar measurements

Contact Info

Product

Resources

About