Testing the efficacy of atmospheric boundary layer height detection algorithms using uncrewed aircraft system data from MOSAiC

Abstract. During the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, meteorological conditions over the lowest 1 km of the atmosphere were sampled with the DataHawk2 (DH2) fixed wing uncrewed aircraft system (UAS). Of particular interest is the atmospheric boundary layer (ABL) height, as ABL structure can be closely coupled to cloud properties, surface fluxes, and the atmospheric radiation budget. The high temporal resolution of the UAS observations allows us to subjectively identify ABL height for 65 out of the total 89 flights conducted over the central Arctic Ocean between 23 March and 26 July 2020 by visually analyzing profiles of virtual potential temperature, humidity, and bulk Richardson number. Comparing this subjective ABL height with the ABL heights identified by various previously published objective methods allows us to determine which objective methods are most successful at accurately identifying ABL height in the central Arctic environment. The objective methods we use are the Liu-Liang, Heffter, virtual potential temperature gradient maximum, and bulk Richardson number methods. In the process of testing these objective methods on the DH2 data, numerical thresholds were adapted to work best for the UAS-based sampling. To determine if conclusions are robust across different measurement platforms, the subjective and objective ABL height determination processes were repeated using the radiosonde profile closest in time to each DH2 flight. For both the DH2 and radiosonde data, it is determined that the bulk Richardson number method is the most successful at identifying ABL height, while the Liu-Liang method is least successful.

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Comparisons of Planetary Boundary Layer Height from Ceilometer with ARM Radiosonde Data

10.5194/amt-2021-292 ◽

2021 ◽

Author(s):

Damao Zhang ◽

Jennifer Comstock ◽

Victor Morris

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Richardson Number ◽

Value Added ◽

Department Of Energy ◽

Radiosonde Data ◽

Polar Regions ◽

Atmospheric Conditions ◽

Bulk Richardson Number ◽

Stable Atmospheric Boundary Layer

Abstract. Ceilometer measurements of aerosol backscatter profiles have been widely used to provide continuous PBLHT estimations. To investigate the robustness of ceilometer-estimated PBLHT under different atmospheric conditions, we compared ceilometer- and radiosonde-estimated PBLHTs using long term U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) ceilometer and balloon-borne sounding data at three ARM fixed-location atmospheric observatories and from three ARM mobile observatories deployed around the world for various field campaigns, which cover from Tropics to Polar regions and over both ocean and land surfaces. Statistical comparisons of ceilometer-estimated PBLHTs from the Vaisala CL31 ceilometer data with radiosonde-estimated PBLHTs from the ARM PBLHT-SONDE Value-added Product (VAP) are performed under different atmospheric conditions including stable and unstable atmospheric boundary layer, low-level cloud-free, and cloudy conditions at these ARM observatories. Under unstable atmospheric boundary layer conditions, good comparisons are found between ceilometer- and radiosonde-estimated PBLHTs at ARM low- and mid-latitude land observatories. However, it is still challenging to obtain reliable PBLHT estimations over ocean surfaces even using radiosonde data. Under stable atmospheric boundary layer conditions, ceilometer- and radiosonde-estimated PBLHTs have weak correlations. Among different PBLHT estimations utilizing the Heffter, the Liu-Liang, and the bulk Richardson number methods in the ARM PBLHT-SONDE VAP, ceilometer-estimated PBLHTs have better comparisons with the Liu-Liang method under unstable and with the bulk Richardson number method under stable atmospheric boundary layer conditions.

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On the computation of planetary boundary-layer height using the bulk Richardson number method

Geoscientific Model Development ◽

10.5194/gmd-7-2599-2014 ◽

2014 ◽

Vol 7 (6) ◽

pp. 2599-2611 ◽

Cited By ~ 45

Author(s):

Y. Zhang ◽

Z. Gao ◽

D. Li ◽

Y. Li ◽

N. Zhang ◽

...

Keyword(s):

Boundary Layer ◽

Boundary Layers ◽

Planetary Boundary Layer ◽

Richardson Number ◽

Potential Temperature ◽

Bulk Richardson Number ◽

Stable Boundary Layers ◽

Stable Boundary ◽

Field Campaigns ◽

Weakly Stable

Abstract. Experimental data from four field campaigns are used to explore the variability of the bulk Richardson number of the entire planetary boundary layer (PBL), Ribc, which is a key parameter for calculating the PBL height (PBLH) in numerical weather and climate models with the bulk Richardson number method. First, the PBLHs of three different thermally stratified boundary layers (i.e., strongly stable boundary layers, weakly stable boundary layers, and unstable boundary layers) from the four field campaigns are determined using the turbulence method, the potential temperature gradient method, the low-level jet method, and the modified parcel method. Then for each type of boundary layer, an optimal Ribc is obtained through linear fitting and statistical error minimization methods so that the bulk Richardson method with this optimal Ribc yields similar estimates of PBLHs as the methods mentioned above. We find that the optimal Ribc increases as the PBL becomes more unstable: 0.24 for strongly stable boundary layers, 0.31 for weakly stable boundary layers, and 0.39 for unstable boundary layers. Compared with previous schemes that use a single value of Ribc in calculating the PBLH for all types of boundary layers, the new values of Ribc proposed by this study yield more accurate estimates of PBLHs.

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Climatology of the Boundary Layer Height and of the Wind Field over Greece

Atmosphere ◽

10.3390/atmos11090910 ◽

2020 ◽

Vol 11 (9) ◽

pp. 910

Author(s):

Nikolaos A. Bakas ◽

Angeliki Fotiadi ◽

Sophia Kariofillidi

Keyword(s):

Boundary Layer ◽

Gradient Method ◽

Seasonal Variability ◽

Wind Field ◽

Richardson Number ◽

Potential Temperature ◽

Bulk Richardson Number ◽

Layer Height ◽

Boundary Layer Height ◽

General Preference

In this study, a climatology of two key boundary layer features, the Planetary Boundary Layer Height (PBLH) and the wind field over Greece is derived. The climatology is based on daily soundings collected in Athens, Thessaloniki and Heraklion and spanning a 32-year period. The PBLH is estimated using a method based on the gradient of potential temperature and a method based on the bulk Richardson number. The wind field is analyzed by calculating the wind shear and the turning angle of the wind vector between the surface and the top of the boundary layer. The PBLH of the daytime boundary layer over Athens and Thessaloniki is found to exhibit seasonal variability with summer maxima and winter minima and has annual median values in the range of 1.4–1.7 km estimated using the gradient method. The PBLH over Heraklion is found to exhibit weak seasonal variability with a lower median value of 1.2 km. The nighttime boundary layer over all three sites is found to be much shallower with PBLH values in the range of 150–200 m with no seasonal variations. In addition, the bulk Richardson number method is found to systematically underestimate the PBLH compared to the gradient method. The wind field in the daytime boundary layer at all three sites is found to have small shear of the order of 1 ms−1 and wind turning angles that are lower than 15 degrees, while in the nocturnal boundary layer it has larger shear of the order of 5–10 ms−1 with turning angles lower than 20 degrees. In addition, for both the daytime and the nighttime boundary layer there is no general preference for veering or backing.

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The Characteristics of Spatial and Temporal Variations in the PBL during the Landfall of Tropical Cyclones across East China

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-18-0131.1 ◽

2019 ◽

Vol 58 (7) ◽

pp. 1557-1572 ◽

Cited By ~ 1

Author(s):

Yong Han ◽

Yiwen Zhou ◽

Jianping Guo ◽

Yonghua Wu ◽

Tijian Wang ◽

...

Keyword(s):

Tropical Cyclones ◽

Eastern China ◽

Potential Temperature ◽

Ground Surface ◽

Temporal Variations ◽

Radiosonde Data ◽

Bulk Richardson Number ◽

Temperature Method ◽

Virtual Potential Temperature ◽

Temperature Gradient Method

AbstractThe planetary boundary layer (PBL) controls the exchange of momentum and energy between the ground surface and the free troposphere, but few studies have been involved in the connection of the PBL with the development and extinction of tropical cyclones (TCs). Studies on the PBL usually need high-resolution soundings in the lowest troposphere that are otherwise quite rare with traditional technology. Here, 1-s resolution L-band radiosonde data are acquired to study the variations in PBL characteristics associated with the development of TCs in eastern China. The strong variations in the vertical profiles of temperature, relative humidity, and wind speed in the PBL during the landfall of a TC are revealed. In addition, four typical methods, including the virtual potential temperature method, Holzworth method, bulk Richardson number method, and potential temperature gradient method, are applied to estimate the PBL height (PBLH). The results indicate that the PBLHs derived by these methods vary by several hundred meters, which may be related to their different definitions of kinetic or thermodynamic theories. Furthermore, the PBLH was found to display a slight upward tendency during the landfall of TC.

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Inference of Marine Atmospheric Boundary Layer Moisture and Temperature Structure Using Airborne Lidar and Infrared Radiometer Data

Journal of Applied Meteorology ◽

10.1175/1520-0450-37.3.308 ◽

1998 ◽

Vol 37 (3) ◽

pp. 308-324 ◽

Cited By ~ 10

Author(s):

Stephen P. Palm ◽

Denise Hagan ◽

Geary Schwemmer ◽

S. H. Melfi

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Potential Temperature ◽

Airborne Lidar ◽

Temperature Structure ◽

Marine Atmospheric Boundary Layer ◽

Space Technology ◽

Near Surface ◽

Surface Moisture ◽

Infrared Radiometer

Abstract A new technique for retrieving near-surface moisture and profiles of mixing ratio and potential temperature through the depth of the marine atmospheric boundary layer (MABL) using airborne lidar and multichannel infrared radiometer data is presented. Data gathered during an extended field campaign over the Atlantic Ocean in support of the Lidar In-space Technology Experiment are used to generate 16 moisture and temperature retrievals that are then compared with dropsonde measurements. The technique utilizes lidar-derived statistics on the height of cumulus clouds that frequently cap the MABL to estimate the lifting condensation level. Combining this information with radiometer-derived sea surface temperature measurements, an estimate of the near-surface moisture can be obtained to an accuracy of about 0.8 g kg−1. Lidar-derived statistics on convective plume height and coverage within the MABL are then used to infer the profiles of potential temperature and moisture with a vertical resolution of 20 m. The rms accuracy of derived MABL average moisture and potential temperature is better than 1 g kg−1 and 1°C, respectively. The method relies on the presence of a cumulus-capped MABL, and it was found that the conditions necessary for use of the technique occurred roughly 75% of the time. The synergy of simple aerosol backscatter lidar and infrared radiometer data also shows promise for the retrieval of MABL moisture and temperature from space.

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Soil Moisture-Boundary Layer Feedbacks on the Loess Plateau in China Using Radiosonde Data with 1-D Atmospheric Boundary Layer Model

Atmosphere ◽

10.3390/atmos12121619 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1619

Author(s):

Yingsai Ma ◽

Xianhong Meng ◽

Yinhuan Ao ◽

Ye Yu ◽

Guangwei Li ◽

...

Keyword(s):

Boundary Layer ◽

Soil Moisture ◽

Atmospheric Boundary Layer ◽

Loess Plateau ◽

Atmospheric Stability ◽

Heat Fluxes ◽

Radiosonde Data ◽

Atmospheric Conditions ◽

The Loess Plateau ◽

The Impact

The Loess Plateau is one land-atmosphere coupling hotspot. Soil moisture has an influence on atmospheric boundary layer development under specific early-morning atmospheric thermodynamic structures. This paper investigates the sensitivity of atmospheric convection to soil moisture conditions over the Loess Plateau in China by using the convective triggering potential (CTP)—humidity index (HIlow) framework. The CTP indicates atmospheric stability and the HIlow indicates atmospheric humidity in the low-level atmosphere. By comparing the model outcomes with the observations, the one-dimensional model achieves realistic daily behavior of the radiation and surface heat fluxes and the mixed layer properties with appropriate modifications. New CTP-HIlow thresholds for soil moisture-atmosphere feedbacks are found in the Loess Plateau area. By applying the new thresholds with long-time scales sounding data, we conclude that negative feedback is dominant in the north and west portion of the Loess Plateau; positive feedback is predominant in the south and east portion. In general, this framework has predictive significance for the impact of soil moisture on precipitation. By using this new CTP-HIlow framework, we can determine under what atmospheric conditions soil moisture can affect the triggering of precipitation and under what atmospheric conditions soil moisture has no influence on the triggering of precipitation.

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Integrated System for Atmospheric Boundary Layer Height Estimation (ISABLE) using a ceilometer and microwave radiometer

Atmospheric Measurement Techniques ◽

10.5194/amt-13-6965-2020 ◽

2020 ◽

Vol 13 (12) ◽

pp. 6965-6987

Author(s):

Jae-Sik Min ◽

Moon-Soo Park ◽

Jung-Hoon Chae ◽

Minsoo Kang

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Layer Structure ◽

Microwave Radiometer ◽

Accurate Determination ◽

Integrated System ◽

Lapse Rate ◽

High Temporal Resolution ◽

Near Surface ◽

Boundary Layer Structure

Abstract. Accurate boundary layer structure and height are critical in the analysis of the features of air pollutants and local circulation. Although surface-based remote sensing instruments provide a high temporal resolution of the boundary layer structure, there are numerous uncertainties in terms of the accurate determination of the atmospheric boundary layer heights (ABLHs). In this study, an algorithm for an integrated system for ABLH estimation (ISABLE) was developed and applied to the vertical profile data obtained using a ceilometer and a microwave radiometer in Seoul city, Korea. A maximum of 19 ABLHs were estimated via the conventional time-variance, gradient, wavelet, and clustering methods using the backscatter coefficient from the ceilometer. Meanwhile, several stable boundary layer heights were extracted through near-surface inversion and environmental lapse rate methods using the potential temperature from the microwave radiometer. The ISABLE algorithm can find an optimal ABLH from post-processing, such as k-means clustering and density-based spatial clustering of applications with noise (DBSCAN) techniques. It was found that the ABLH determined using ISABLE exhibited more significant correlation coefficients and smaller mean bias and root mean square error between the radiosonde-derived ABLHs than those obtained using the most conventional methods. Clear skies exhibited higher daytime ABLH than cloudy skies, and the daily maximum ABLH was recorded in summer because of the more intense radiation. The ABLHs estimated by ISABLE are expected to contribute to the parameterization of vertical diffusion in the atmospheric boundary layer.

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How is the marine atmospheric boundary layer turbulence organized in the trades ?

10.5194/egusphere-egu21-12339 ◽

2021 ◽

Author(s):

Pierre-Etienne Brilouet ◽

Marie Lothon ◽

Sandrine Bony

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Vertical Velocity ◽

Large Scale ◽

Layer Structure ◽

Potential Temperature ◽

Surface Wind ◽

Cloud Amount ◽

Velocity Spectrum ◽

Marine Atmospheric Boundary Layer

Tradewind clouds can exhibit a wide diversity of mesoscale organizations, and the turbulence of marine atmospheric boundary layer (MABL) can exhibit coherent structures and mesoscale circulations. One of the objectives of the EUREC4A (Elucidating the role of cloud-circulation coupling in climate) field experiment was to better understand the tight interplay between the mesoscale organization of clouds, boundary-layer processes, and the large-scale environment.During the experiment, that took place East of Barbados over the Western Tropical Atlantic Ocean in Jan-Feb 2020, the French ATR-42 research aircraft was devoted to the characterization of the cloud amount and of the subcoud layer structure. During its 17 research flights, it sampled a large diversity of large scale conditions and cloud patterns. Multiple sensors onboard the aircraft measured high-frequency fluctuations of potential temperature, water vapour mixing ratio and wind , allowing for an extensive characterization of the turbulence within the subcloud layer. A quality-controled and calibrated turbulence dataset was produced on the basis of these measurements, which is now available on the EUREC4A AERIS data portal.The MABL turbulent structure is studied using this dataset, through a spectral analysis of the vertical velocity. Vertical profiles of characteristic length scales reveal a non-isotropic structure with a stretching of the eddies along the mean wind. The organization strength of the turbulent field is also explored by defining a diagnostic based on the shape of the vertical velocity spectrum. The structure and the degree of organization of the subcloud layer are characterized for different types of mesoscale convective pattern and as a function of the large-scale environment, including near-surface wind and lower-tropospheric stability conditions.&#160;

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Modulation of Small-Scale Turbulence by Ducted Gravity Waves in the Nocturnal Boundary Layer

Journal of the Atmospheric Sciences ◽

10.1175/2007jas2359.1 ◽

2008 ◽

Vol 65 (4) ◽

pp. 1414-1427 ◽

Cited By ~ 28

Author(s):

Y. P. Meillier ◽

R. G. Frehlich ◽

R. M. Jones ◽

B. B. Balsley

Keyword(s):

Boundary Layer ◽

Gravity Waves ◽

Richardson Number ◽

Potential Temperature ◽

Nocturnal Boundary Layer ◽

Small Scale ◽

Temperature Structure ◽

Turbulence Measurements ◽

Gradient Richardson Number ◽

Scale Turbulence

Abstract Constant altitude measurements of temperature and velocity in the residual layer of the nocturnal boundary layer, collected by the Cooperative Institute for Research in Environmental Sciences (CIRES) Tethered Lifting System (TLS), exhibit fluctuations identified by previous work (Fritts et al.) as the signature of ducted gravity waves. The concurrent high-resolution TLS turbulence measurements (temperature structure constant C2T and turbulent kinetic energy dissipation rate ɛ) reveal the presence of patches of enhanced turbulence activity that are roughly synchronized with the troughs of the temperature and velocity fluctuations. To investigate the potentially dominant role ducted gravity waves might play on the modulation of atmospheric stability and therefore, on turbulence, time series of the wave-modulated gradient Richardson number (Ri) and of the vertical gradient of potential temperature ∂θ/∂z(t) are computed numerically and compared to the TLS small-scale turbulence measurements. The results of this study agree with the predictions of previous theoretical studies (i.e., wave-generated fluctuations of temperature and velocity modulate the gradient Richardson number), resulting in periodic enhancements of turbulence at Ri minima. The patches of turbulence observed in the TLS dataset are subsequently identified as convective instabilities generated locally within the unstable phase of the wave.

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Effects of Boundary Layer Vertical Mixing on the Evolution of Hurricanes over Land

Monthly Weather Review ◽

10.1175/mwr-d-16-0421.1 ◽

2017 ◽

Vol 145 (6) ◽

pp. 2343-2361 ◽

Cited By ~ 7

Author(s):

Feimin Zhang ◽

Zhaoxia Pu ◽

Chenghai Wang

Keyword(s):

Boundary Layer ◽

Positive Impact ◽

Potential Temperature ◽

Vertical Mixing ◽

Vertical Wind Shear ◽

Vertical Gradient ◽

Weather Research And Forecasting ◽

Virtual Potential Temperature ◽

Dynamic Structures ◽

Hurricane Boundary Layer

Abstract After a hurricane makes landfall, its evolution is strongly influenced by its interaction with the planetary boundary layer (PBL) over land. In this study, a series of numerical experiments are performed to examine the effects of boundary layer vertical mixing on hurricane simulations over land using a research version of the NCEP Hurricane Weather Research and Forecasting (HWRF) Model with three landfalling hurricane cases. It is found that vertical mixing in the PBL has a strong influence on the simulated hurricane evolution. Specifically, strong vertical mixing has a positive impact on numerical simulations of hurricanes over land, with better track, intensity, synoptic flow, and precipitation simulations. In contrast, weak vertical mixing leads to the strong hurricanes over land. Diagnoses of the thermodynamic and dynamic structures of hurricane vortices further suggest that the strong vertical mixing in the PBL could cause a decrease in the vertical wind shear and an increase in the vertical gradient of virtual potential temperature. As a consequence, these changes destroy the turbulence kinetic energy in the hurricane boundary layer and thus stabilize the hurricane boundary layer and limit its maintenance over land.

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