Boundary-layer depth and entrainment zone characterization with a boundary-layer profiler

Angevine, W. M.; White, Allen B.; Avery, S. K.

doi:10.1007/bf00706797

Cited by 214 publications

(190 citation statements)

References 7 publications

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“…It can be noticed that the sharp gradient in height profile of θ (gray line in 1st column panel of Fig. 5b), indicating the top of the boundary-layer (Angevine et al, 1994), shows a good correlation with the LLJ core height. The significant change in wind speed with a clear oscillation in the level of maximum wind during the course of the day can be seen in the right-most column panels of Fig.…”

Section: General Llj Characteristic Features Over Gadankimentioning

confidence: 91%

“…The sharp decrease in ε above the boundary layer indicates the diminishing of turbulent eddies of sizes comparable to half of radar wavelength above the boundary layer. So, the sharp gradient feature of these parameters observed around the boundary layer top can be used to estimate the boundary layer depth (Angevine et al, 1994;White, 1993;Sandra Jacoby-Koaly et al, 2002). Hence, this gradient feature, from here on, is utilized to find the boundary-layer depth/top from sole radar measurements.…”

Section: Site System and Data Descriptionmentioning

confidence: 99%

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Wind profiler observations of a monsoon low-level jet over a tropical Indian station

et al. 2007

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Abstract. Three-year high-resolution wind observations of the wind profiler have been utilized to characterize the diurnal and seasonal features of the monsoon Low-Level Jet (LLJ) over a tropical station, Gadanki (13.5 • N, 79.2 • E), with a focus on the diurnal variability of low-level winds. The Boreal summer monsoon winds show a conspicuously strong westerly LLJ with average wind speed exceeding 20 m s −1 . The L-band wind profiler measurements have shown an advantage of better height and time resolutions over the conventional radiosonde method for diurnal wind measurements. An interesting diurnal oscillation of LLJ core has been observed. It is varying in the height range of 1.8±0.6 km with the maximum and minimum intensity noticed during the early morning and afternoon hours, respectively. The jet core (wind maxima) height is observed to coincide with the inversion height. Strong wind shears are normally located beneath the LLJ core. The sole wind profiler observations are capable of identifying the monsoon phases, such as onset, break and active spells, etc. The mutual influence between the LLJ and the boundary layer has been discussed. One notices that the observed LLJ diurnal structures depend on the local convective activity, wind shears and turbulence activity associated with boundary layer winds. The day-to-day change in the LLJ structure depends on the latitudinal position of the LLJ core.

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Section: General Llj Characteristic Features Over Gadankimentioning

confidence: 91%

Section: Site System and Data Descriptionmentioning

confidence: 99%

Wind profiler observations of a monsoon low-level jet over a tropical Indian station

et al. 2007

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“…2c). Herein, a method proposed by Angevine et al (1994Angevine et al ( , 1998) is used. The distributed software from the manufacturer did not provide reasonable PBL heights and was therefore not further included in the analysis.…”

Section: Wind Profilermentioning

confidence: 99%

Investigation of the Planetary Boundary Layer in the Swiss Alps Using Remote Sensing and In Situ Measurements

Ketterer

Zieger

Bukowiecki

et al. 2014

Boundary-Layer Meteorol

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The development of the planetary boundary layer (PBL) has been studied in a complex terrain using various remote sensing and in situ techniques. The high-altitude research station at Jungfraujoch (3,580 m a.s.l.) in the Swiss Alps lies for most of the time in the free troposphere except when it is influenced by the PBL reaching the station, especially during the summer season. A ceilometer and a wind profiler were installed at Kleine Scheidegg, a mountain pass close to Jungfraujoch, located at an altitude of 2,061 m a.s.l. Data from the ceilometer were analyzed using two different algorithms, while the signal-to-noise ratio of the wind profiler was studied to compare the retrieved PBL heights. The retrieved values from the ceilometer and wind profiler agreed well during daytime and cloud-free conditions. The results were additionally compared with the PBL height estimated by the numerical weather prediction model COSMO-2, which showed a clear underestimation of the PBL height for most of the cases but occasionally also a slight overestimation especially around noon, when the PBL showed its maximum extent. Air parcels were transported upwards by slope winds towards Jungfraujoch when the PBL was higher than 2,800 m a.s.l. during cloud-free cases. This was confirmed by the in situ aerosol measurements at Jungfraujoch with a significant increase in particle number concentration, particle light absorption and scattering coefficients when PBL-influenced air masses reached the station in the afternoon hours. The continuous aerosol in situ measurements at Jungfraujoch were clearly influenced by the local PBL development but also by long-range transport phenomena such as Saharan dust or pollution from the south.

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“…For a boundary layer topped by boundary layer clouds, the cloud top coincides with the height at which turbulence stops, and boundary layer height detection is aided by the sensitivity to clouds. However, for clouds above the boundary layer, the cloud top is significantly different from the CBLH, and it is difficult to extract the information needed to define the CBLH from the backscatter profile [30].…”

Section: Convective Condensation Level Limitermentioning

confidence: 99%

“…In such conditions, the cloud layer can be regarded as the upper portion of the boundary layer [1,27]. However, for continental boundary layers topped by cumulus clouds, the CBLH is distinct from the elevated cloud layers above the cumulus [30,31]. In such situations, clouds are not part of the boundary layer, and determination of the CBLH requires further consideration if we are to separate boundary layer clouds from clouds that are not part of the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Application of Convective Condensation Level Limiter in Convective Boundary Layer Height Retrieval Based on Lidar Data

Yang

et al. 2017

Atmosphere

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Abstract:Micro pulse lidar is a promising tool for retrieving the convective boundary layer height (CBLH), but its application has been hindered by sharp extinction of the signal in high humidity conditions, e.g., clouds. To remedy this, we developed an effective and simple limiter to obtain more accurate estimates of the CBLH. The limiter is based on the algorithm for the convective condensation level (CCL) and is aimed at limiting the vertical extent of the lidar backscatter profile used in lidar methods to search for the CBLH. Four lidar methods (i.e., the gradient method, the idealized backscatter method, and two forms of the wavelet covariance methods) are used to calculate the CBLH with (or without) the limiter added. Compared to the CBLH calculated by the parcel method from microwave radiometer temperature data, more accurate retrieval of the CBLH is carried out with the limiter applied in four cloudy cases.

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Boundary-layer depth and entrainment zone characterization with a boundary-layer profiler

Cited by 214 publications

References 7 publications

Wind profiler observations of a monsoon low-level jet over a tropical Indian station

Wind profiler observations of a monsoon low-level jet over a tropical Indian station

Investigation of the Planetary Boundary Layer in the Swiss Alps Using Remote Sensing and In Situ Measurements

Application of Convective Condensation Level Limiter in Convective Boundary Layer Height Retrieval Based on Lidar Data

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