An approximation to boundary layer wind profiles

Abstract Detailed observations of boundary layer structure were acquired on 14 September 2001, prior to and during the landfall of Tropical Storm Gabrielle. The Mobile Integrated Profiling System (MIPS) and the Shared Mobile Atmospheric Research and Teaching Radar (SMART-R) were collocated at the western Florida coastline near Venice, very close to the wind center at landfall. Prior to landfall, the boundary layer was rendered weakly stable by a long period of evaporational cooling and mesoscale downdrafts within extensive stratiform precipitation that started 18 h before landfall. The cool air mass was expansive, with an area within the 23°C surface isotherm of about 50 000 km2. East-northeasterly surface flow transported this cool air off the west coast of Florida, toward the convergent warm core of the Gabrielle, and promoted the development of shallow warm and cold fronts that were prominent during the landfall phase. Airflow properties of the boundary layer around the coastal zone are examined using the MIPS and SMART-R data. Wind profiles exhibited considerable temporal variability throughout the period of observations. The stable offshore flow within stratiform precipitation exhibited a modest jet that descended from about 600 to 300 m within the 20-km zone centered on the coastline. In contrast, the onshore flow on the western side of the wind center produced a more turbulent boundary layer that exhibited a well-defined top varying between 400 and 1000 m MSL. The horizontal variability of each boundary layer is examined using high-resolution Doppler radar scans at locations up to 15 km on either side of the coastline, along the mean flow direction of the boundary layer. These analyses reveal that transitions in boundary layer structure for both the stable and unstable regimes were most substantial within 5 km of the coastline.

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Characteristics of wind profiles in the landfalling typhoon boundary layer

Journal of Wind Engineering and Industrial Aerodynamics ◽

10.1016/j.jweia.2015.11.008 ◽

2016 ◽

Vol 149 ◽

pp. 77-88 ◽

Cited By ~ 20

Author(s):

Lili Song ◽

Wenchao Chen ◽

Binglan Wang ◽

Shiqun Zhi ◽

Aijun Liu

Keyword(s):

Boundary Layer ◽

Wind Profiles ◽

Landfalling Typhoon

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Wind profile correction algorithm based on Atmospheric Boundary Layer stability profile

10.5194/ems2021-341 ◽

2021 ◽

Author(s):

Francisco Albuquerque Neto ◽

Vinicius Almeida ◽

Julia Carelli

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Wind Profile ◽

Horizontal Wind ◽

Boundary Layer Stability ◽

Correction Algorithm ◽

Horizontal Wind Speed ◽

Study Region ◽

Profile Correction ◽

Wind Profiles

In recent years, the use of radar wind profilers (RWP) at airports has grown significantly with the aim of supporting decision makers to maintain the safety of aircraft landings and takeoffs.The RWP provide vertical profiles of averaged horizontal wind speed and direction and vertical wind velocity for the entire Atmospheric Boundary Layer (ABL) and beyond. In addition, RWP with Radio-Acoustic Sounding System (RASS) are able to retrieve virtual temperature profiles in the ABL.RWP data evaluation is usually based on the so-called Doppler Beam Swinging method (DBS) which assumes homogeneity and stationarity of the wind field. Often, transient eddies violate this homogeneity and stationarity requirement. Hence, incorrect wind profiles can relate to transient eddies and present a problem for the forecast of high-impact weather phenomena in airports. This work intends to provide a method for removing outliers in such profiles based on historical data and other variables related to the Atmospheric Boundary Layer stability profile in the study region.For this study, a dataset of almost one year retrieved from a RWP LAP3000 with RASS Extension is used for a wind profile correction algorithm development.The algorithm consists of the detection of outliers in the wind profiles based on the thermodynamic structure of the ABL and the generation of the corrected profiles.Results show that the algorithm is capable of identifying and correcting unrealistic variations in speed caused by transient eddies. The method can be applied as a complement to the RWP data processing for better data reliability.&#160;Keywords: atmospheric boundary layer; stability profile; wind profile

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A Simple Method for Simulating Wind Profiles in the Boundary Layer of Tropical Cyclones

Boundary-Layer Meteorology ◽

10.1007/s10546-016-0207-0 ◽

2016 ◽

Vol 162 (3) ◽

pp. 475-502 ◽

Cited By ~ 16

Author(s):

George H. Bryan ◽

Rochelle P. Worsnop ◽

Julie K. Lundquist ◽

Jun A. Zhang

Keyword(s):

Boundary Layer ◽

Tropical Cyclones ◽

Simple Method ◽

Wind Profiles

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Assimilation of Surface-Based Boundary Layer Profiler Observations during a Cool-Season Weather Event Using an Observing System Simulation Experiment. Part I: Analysis Impact

Monthly Weather Review ◽

10.1175/2011mwr3622.1 ◽

2011 ◽

Vol 139 (8) ◽

pp. 2309-2326 ◽

Cited By ~ 19

Author(s):

Jason A. Otkin ◽

Daniel C. Hartung ◽

David D. Turner ◽

Ralph A. Petersen ◽

Wayne F. Feltz ◽

...

Keyword(s):

Remote Sensing ◽

Boundary Layer ◽

Simulation Experiment ◽

System Simulation ◽

Microwave Radiometer ◽

Lower Troposphere ◽

Moisture Profile ◽

Wind Profiles ◽

Observing System Simulation Experiment ◽

The Impact

AbstractIn this study, an Observing System Simulation Experiment was used to examine how the assimilation of temperature, water vapor, and wind profiles from a potential array of ground-based remote sensing boundary layer profiling instruments impacts the accuracy of atmospheric analyses when using an ensemble Kalman filter data assimilation system. Remote sensing systems evaluated during this study include the Doppler wind lidar (DWL), Raman lidar (RAM), microwave radiometer (MWR), and the Atmospheric Emitted Radiance Interferometer (AERI). The case study tracked the evolution of several extratropical weather systems that occurred across the contiguous United States during 7–8 January 2008. Overall, the results demonstrate that using networks of high-quality temperature, wind, and moisture profile observations of the lower troposphere has the potential to improve the accuracy of wintertime atmospheric analyses over land. The impact of each profiling system was greatest in the lower and middle troposphere on the variables observed or retrieved by that instrument; however, some minor improvements also occurred in the unobserved variables and in the upper troposphere, particularly when RAM observations were assimilated. The best analysis overall was achieved when DWL wind profiles and temperature and moisture observations from the RAM, AERI, or MWR were assimilated simultaneously, which illustrates that both mass and momentum observations are necessary to improve the analysis accuracy.

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Low-level wind profiles at an Antarctic coastal station

Antarctic Science ◽

10.1017/s095410208900026x ◽

1989 ◽

Vol 1 (2) ◽

pp. 169-178 ◽

Cited By ~ 35

Author(s):

J.C. King

Keyword(s):

Boundary Layer ◽

Temperature Profiles ◽

Pressure Gradients ◽

Synoptic Scale ◽

Layer Model ◽

Coastal Station ◽

One Dimensional ◽

Dimensional Boundary ◽

Sloping Surface ◽

Wind Profiles

Wind and temperature profiles in the lowest 2000 m of the atmosphere at Halley (75°35′S, 26°50′W) have been analysed. Surface winds blow most frequently from the sector 090° ± 45° but the 2000 m wind direction is much more evenly distributed and appears to be determined by synoptic-scale pressure gradients. A simple one-dimensional boundary layer model, which includes the effects of stably-stratified air overlying a sloping surface, is able to reproduce some of the features of the observed profiles.

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Influence of Aerosols on Atmospheric Gravity Waves at an Urban Tropical Location

10.21203/rs.3.rs-1121047/v1 ◽

2021 ◽

Author(s):

Soumyajyoti Jana ◽

Gargi Rakshit ◽

Animesh Maitra

Keyword(s):

Boundary Layer ◽

Gravity Waves ◽

Mass Movement ◽

Atmospheric Gravity Waves ◽

Monsoon Period ◽

Boundary Layer Height ◽

Absorbing Aerosols ◽

Wind Profiles ◽

Atmospheric Gravity ◽

Aerosol Extinction Coefficient

Abstract The elevated layer of heat-absorbing pollutant aerosols causes temperature perturbations in the pre-monsoon period above the boundary layer height (1.6-4 km) as observed over a polluted tropical urban location Kolkata (22°34' N, 88°22' E) during 2007-2016. Satellite observations of different types of aerosols show an increase in aerosol extinction coefficient around 1.6-4 km altitude, enhancing the perturbations in both temperature and wind profiles at that height. The opposing air mass movement within and above the boundary layer, which is strengthened by elevated heat-absorbing aerosols, is illustrated by height profiles of atmospheric vorticity and divergence. This results in higher Brunt-Vaisala frequencies indicating increased atmospheric oscillations. Consequently, atmospheric gravity waves, which manifest the temperature and wind profile perturbations, have enhanced energy in the upper troposphere (6-10 km). Based on multi- technique observations consisting of radiosonde, space-borne lidar and model data, this study reveals the interactions between aerosol and other atmospheric processes such as temperature variations and wind perturbations, which affect the atmospheric instability and increase gravity wave activities during the pre-monsoon period over a tropical metropolis.

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Observations of Boundary Layer Wind and Turbulence of a Landfalling Tropical Cyclone

10.21203/rs.3.rs-812123/v1 ◽

2021 ◽

Author(s):

Zhongkuo Zhao ◽

Ruiquan Gao ◽

Jun A. Zhang ◽

Yong Zhu ◽

Chunxia Liu ◽

...

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Radial Distance ◽

Flux Measurement ◽

Eddy Diffusivity ◽

Multiple Level ◽

A Value ◽

Momentum Fluxes ◽

Speed Range ◽

Wind Profiles

Abstract This study analyzed the atmospheric boundary layer characteristics based on the multiple level observations by a 350-m height tower during the landfall of Super Typhoon Mangkhut (1822). Mean wind profiles showed logarithmic wind profiles at different wind speed ranges suggesting nearly constant flux layers. The height of the constant layer increased with the wind speed and deceased with the radial distance from the storm centre. This behaviour was supported by flux observations. Momentum fluxes and turbulent kinetic energy increased with the wind speed at all flux measurement levels. The drag coefficient (surface roughness) estimated was nearly a constant with a value of 8´10-3 (0.09 m). Both the estimated eddy diffusivity and mixing length varied with height. The eddy diffusivity also varied with the wind speed. Our results supported that the eddy diffusivity is larger over land than over ocean in a same wind speed range.

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Twenty-Four-Hour Observations of the Marine Boundary Layer Using Shipborne NOAA High-Resolution Doppler Lidar

Journal of Applied Meteorology ◽

10.1175/jam2296.1 ◽

2005 ◽

Vol 44 (11) ◽

pp. 1723-1744 ◽

Cited By ~ 27

Author(s):

Volker Wulfmeyer ◽

Tijana Janjić

Keyword(s):

Boundary Layer ◽

High Resolution ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Wind Shear ◽

Marine Boundary Layer ◽

Sea Surface ◽

Doppler Lidar ◽

Sensible Heat ◽

Wind Profiles

Abstract Shipborne observations obtained with the NOAA high-resolution Doppler lidar (HRDL) during the 1999 Nauru (Nauru99) campaign were used to study the structure of the marine boundary layer (MBL) in the tropical Pacific Ocean. During a day with weak mesoscale activity, diurnal variability of the height of the convective MBL was observed using HRDL backscatter data. The observed diurnal variation in the MBL height had an amplitude of about 250 m. Relations between the MBL height and in situ measurements of sea surface temperature as well as latent and sensible heat fluxes were examined. Good correlation was found with the sea surface temperature. The correlation with the latent heat flux was lower, and practically no correlation between the MBL height and the sensible heat and buoyancy fluxes could be detected. Horizontal wind profiles were measured using a velocity–azimuth display scan of HRDL velocity data. Strong wind shear at the top of the MBL was observed in most cases. Comparison of these results with GPS radiosonde data shows discrepancies in the wind intensity and direction, which may be due to different observation times and locations as well as due to multipath effects at the ship’s platform. Vertical wind profiles corrected for ship’s motion were used to derive vertical velocity variance and skewness profiles. Motion compensation had a significant effect on their shape. Normalized by the convective velocity scale and by the top of the mixed layer zi, the variance varied between 0.45 and 0.65 at 0.4z/zi and decreased to 0.2 at 1.0z/zi. The skewness ranged between 0.3 and 0.8 in the MBL and showed in almost all cases a maximum between 1.0z/zi and 1.1z/zi. These profiles revealed the existence of another turbulent layer above the MBL, which was probably driven by wind shear and cloud condensation processes.

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Invented Forces in Supercell Models

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-21-0082.1 ◽

2021 ◽

Author(s):

Robert Davies-Jones

Keyword(s):

Boundary Layer ◽

Kinetic Energy ◽

Planetary Boundary Layer ◽

Degrees Of Freedom ◽

Wind Profile ◽

Equation Of Motion ◽

Force Balance ◽

Frictional Loss ◽

Hydrostatic Equation ◽

Wind Profiles

AbstractThis paper examines methods used in supercell models to maintain a steady, sheared, horizontally uniform environment with a three-force balance in the planetary boundary layer (PBL) and a two-force balance above it. Steady environments are maintained while ignoring the thermal-wind balance that permits large shear above the PBL. The Taylor-Proudman theorem indicates that wind profiles above the PBL must be unidirectional for balanced environments. In principle, supercell models that do not accommodate thermal advection should not support balanced steady environments with veering horizontally uniform winds.Recent methods add a permanent, pervasive, horizontal external force that varies only with height. By adding two more degrees of freedom, this force circumvents the Taylor-Proudman theorem and enables a static, horizontally uniform environment for any wind profile. It succeeds by adding spurious energy in lieu of flow towards low pressure to offset frictional loss of kinetic energy. However, the artificial force has downsides. It decouples the environmental horizontal equation of motion from the hydrostatic equation and the thermodynamics from the dynamics. It cancels environmental friction and the part of the Coriolis force that acts on the environmental wind. Within the storm, its curl can speciously generate significant horizontal vorticity near the ground. Inaccuracies arise in circulations around material circuits because of modifications by the artificial force and resulting miscalculations of parcel trajectories. Doubt is cast on conclusions about tornadogenesis drawn from recent simulations that contain an invented force.

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