A simple thermodynamical model to estimate the rate of depletion of nocturnal low level inversion layer

The low level inversion, be it that of ground based or elevated, plays a significant role in the dispersion of polluted particles and in aviation meteorology. The rate of rise of the ground based inversion top and the base of elevated inversion causes the decrease of inversion strength and thereby permits vertical mixing of pollutants as the stability of the atmosphere is reduced. A simple thermodynamical model using the global radiation and vertical temperature profile has been proposed to estimate the rate of rise of (i) the ground based inversion top and (ii) the base of the elevated inversion. The depth of inversion thus estimated can be used in the pollution/fog dispersion models. The model is simple and operationally practicable. The limitations of the model are also discussed.

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LONG-TERM VARIABILITY IN THE LOW-LEVEL INVERSION LAYER OVER THE ARCTIC OCEAN

International Journal of Climatology ◽

10.1002/(sici)1097-0088(199611)16:11<1297::aid-joc86>3.0.co;2-t ◽

1996 ◽

Vol 16 (11) ◽

pp. 1297-1313 ◽

Cited By ~ 35

Author(s):

JONATHAN D. W. KAHL ◽

DEWAYNE A. MARTINEZ ◽

NINA A. ZAITSEVA

Keyword(s):

Arctic Ocean ◽

Inversion Layer ◽

The Arctic ◽

Low Level ◽

The Arctic Ocean ◽

Level Inversion

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Kelvin-Helmholtz waves observed by aircraft at different stages of their life-cycle in a low-level inversion

Boundary-Layer Meteorology ◽

10.1007/bf00165504 ◽

1978 ◽

Vol 15 (1) ◽

pp. 31-55 ◽

Cited By ~ 2

Author(s):

P. Mascart ◽

H. Isaka ◽

B. Guillemet

Keyword(s):

Life Cycle ◽

Low Level ◽

Level Inversion

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The Breakdown of a Low-level Inversion Studied by Means of Detailed Soundings with a Modified Radiosonde

Bulletin of the American Meteorological Society ◽

10.1175/1520-0477-33.9.373 ◽

1952 ◽

Vol 33 (9) ◽

pp. 373-379 ◽

Cited By ~ 8

Author(s):

Frank Gifford

Keyword(s):

Minimum Temperature ◽

Low Level ◽

Short Series ◽

Pilot Balloon ◽

Level Inversion

A short series of unusually detailed temperature, humidity, and wind soundings to a height of about 750 mb., made at Silver Hill, Md. on the night of October 30th and 31st, 1950, and consisting of eight flights of specially modified radiosondes and 26 double-theodolite pilot balloon runs, is presented. The nocturnal breakdown of the ground inversion with steep wind gradients, a phenomenon first remarked by Durst in 1933, is here observed apparently to be associated with the sudden lowering of an upper (turbulence or subsidence) inversion. Alternative explanations for this are advanced, and implications for minimum temperature and stratus forecasting noted. The accuracy of the observations is discussed.

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A Hydrodynamical Model for Calculating the Vertical Temperature Profile in Lakes During Cooling

Hydrology Research ◽

10.2166/nh.1983.0019 ◽

1983 ◽

Vol 14 (4) ◽

pp. 239-254 ◽

Cited By ~ 6

Author(s):

Jörgen Sahlberg

Keyword(s):

Heat Flux ◽

Temperature Profile ◽

Vertical Mixing ◽

Hydrodynamical Model ◽

Measured Temperature ◽

Vertical Temperature ◽

Mixing Rate ◽

Mixing Processes ◽

Vertical Temperature Profile ◽

Radiation Fluxes

A one-dimensional hydrodynamical model is used for simulating the vertical temperature profile in a lake during cooling conditions. The vertical mixing rate is calculated by solving the equations for turbulent kinetic energy, k, and dissipation of energy, ε. The heat exchange between the water and atmosphere consists of the radiation fluxes, sensible and latent heat flux. Temperature measurements from Lake Väsman during November-December, 1981, were used in the verification study. The agreement between calculated and measured temperature profiles is very good. This indicates that both the mixing processes and the net heat flux are well described in the model.

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The impact of London on a low-level jet

10.5194/egusphere-egu21-11307 ◽

2021 ◽

Author(s):

Aristofanis Tsiringakis ◽

Natalie Theeuwes ◽

Janet Barlow ◽

Gert-Jan Steeneveld

Keyword(s):

Urban Area ◽

Prediction Models ◽

Weather Prediction ◽

Vertical Mixing ◽

Forecasting Model ◽

Low Level ◽

Low Level Jet ◽

The Difference ◽

The Impact ◽

Numerical Weather Prediction Models

<p>The low-level jet (LLJ) is an important phenomenon that can affect (and is affected by) the turbulence in the nocturnal urban boundary layer (UBL). We investigate the interaction of a regional LLJ with the UBL during a 2-day period over London. Observations from two Doppler Lidars and two numerical weather prediction models (Weather Research & Forecasting model and UKV Met Office Unified Model) are used to compared the LLJ characteristics (height, speed and fall-off) between a urban (London) and a rural (Chilbolton) site. We find that LLJs are elevated (70m) over London, due to the deeper UBL, an effect of the increased vertical mixing over the urban area and the difference in the topography between the two sites. Wind speed and fall-off are slightly reduced with respect to the rural LLJ. The effects of the urban area and the surrounding topography on the LLJ characteristics over London are isolated through idealized sensitivity experiments. We find that topography strongly affects the LLJ characteristics (height, falloff, and speed), but there is still a substantial urban influence.</p>

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Loss of consciousness reduces the stability of brain hubs and the heterogeneity of brain dynamics

Communications Biology ◽

10.1038/s42003-021-02537-9 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Ane López-González ◽

Rajanikant Panda ◽

Adrián Ponce-Alvarez ◽

Gorka Zamora-López ◽

Anira Escrichs ◽

...

Keyword(s):

Brain Injuries ◽

Brain Activity ◽

Structural Connectivity ◽

Conscious State ◽

Brain Dynamics ◽

Disorder Of Consciousness ◽

Low Level ◽

States Of Consciousness ◽

The Stability ◽

Different Levels

AbstractLow-level states of consciousness are characterized by disruptions of brain activity that sustain arousal and awareness. Yet, how structural, dynamical, local and network brain properties interplay in the different levels of consciousness is unknown. Here, we study fMRI brain dynamics from patients that suffered brain injuries leading to a disorder of consciousness and from healthy subjects undergoing propofol-induced sedation. We show that pathological and pharmacological low-level states of consciousness display less recurrent, less connected and more segregated synchronization patterns than conscious state. We use whole-brain models built upon healthy and injured structural connectivity to interpret these dynamical effects. We found that low-level states of consciousness were associated with reduced network interactions, together with more homogeneous and more structurally constrained local dynamics. Notably, these changes lead the structural hub regions to lose their stability during low-level states of consciousness, thus attenuating the differences between hubs and non-hubs brain dynamics.

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Axially and Helically Chiral Cationic Radical Bicarbazoles: SOMO–HOMO Level Inversion and Chirality Impact on the Stability of Mono- and Diradical Cations

Journal of the American Chemical Society ◽

10.1021/jacs.0c08948 ◽

2020 ◽

Vol 142 (48) ◽

pp. 20409-20418

Author(s):

Sitthichok Kasemthaveechok ◽

Laura Abella ◽

Marion Jean ◽

Marie Cordier ◽

Thierry Roisnel ◽

...

Keyword(s):

Homo Level ◽

The Stability ◽

Level Inversion

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Measurement of scattering and absorption properties of dust aerosol in a Gobi farmland region of northwest China — a potential anthropogenic influence

10.5194/acp-2017-165 ◽

2017 ◽

Author(s):

Jianrong Bi ◽

Jianping Huang ◽

Jinsen Shi ◽

Zhiyuan Hu ◽

Tian Zhou ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Source Region ◽

Inversion Layer ◽

Vertical Mixing ◽

Northwest China ◽

Single Scattering ◽

Dust Aerosol ◽

Dust Particles ◽

Valley Wind ◽

Average Mass

Abstract. We conducted a comprehensive field campaign on exploring the optical characteristics of mineral dust in Dunhuang farmland nearby the Gobi deserts of northwest China during spring of 2012. The day-to-day and diurnal variations of dust aerosol showed prominent features throughout the experiment, primarily attributable to frequent dust events and local anthropogenic emissions. The overall average mass concentration of the particulate matter with an aerodynamic diameter less than 10 μm (PM10), light scattering coefficient (σsp,670), absorption coefficient (σap,670), and single-scattering albedo (SSA670) were 113±169 μgm-3, 53.3 ± 74.8 Mm-1, 3.2± 2.4 Mm-1, and 0.913 ± 0.05, which were comparable to the background levels in southern United States, but smaller than that in the eastern and other northwestern China. The anthropogenic dust produced by agricultural cultivations (e.g., land planning, plowing, and disking) exerted a significant superimposed effect on high dust concentrations in Dunhuang farmland prior to the growing season (i.e., from 1 April to 10 May). Strong south valley wind and vertical mixing in daytime scavenged the pollution and weak northeast mountain wind and stable inversion layer at night favorably accumulated the air pollutants near the surface. In the afternoon (13:00–18:00 LT), mean SSA670 was 0.945 ± 0.04 that was predominant by dust particles, whereas finer particles and lower SSA670 values (~ 0.90–0.92) were measured at night, suggesting the potential influence by the mixed dust-pollutants. During a typical biomass burning event on 4 April 2012, σap,670 changed from ~ 2.0 Mm-1 to 4.75 Mm-1 and SSA670 changed from ~ 0.90 to ~ 0.83, implying remarkable modification of aerosol absorptive properties induced by human activities. The findings of this study would help to advance an in-depth understanding of the interaction among dust aerosol, atmospheric chemistry, and climate change in desert source region.

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Effects of Low Level Graded I-Layer Doping on the Stability of A-SI:H Solar Cells

MRS Proceedings ◽

10.1557/proc-258-887 ◽

1992 ◽

Vol 258 ◽

Cited By ~ 6

Author(s):

D. Fischer ◽

N. Pellaton ◽

H. Keppner ◽

A. Shah ◽

C. M. Fortmann

Keyword(s):

Numerical Modeling ◽

Solar Cells ◽

Electric Field ◽

Conversion Efficiency ◽

Red Light ◽

Degradation Behavior ◽

Low Level ◽

Carrier Collection ◽

The Stability ◽

Light Conversion Efficiency

ABSTRACTThis work reports on attempts to tailor the electric field of a-Si:H solar cells by the graded low-level doping of the intrinsic layer to optimize conversion efficiency in the degraded state. Based on wavelength dependent collection measurements and numerical modeling, the degradation behavior of doped and undoped cells is explained in terms of the interaction of dopants and the light-induced space-charge. Low level doping is shown to shift the electric field away from the p/i interface towards the bulk of the i-layer. This results in a better carrier collection from the back part of the solar cell, and solar cells with improved stabilized red light conversion efficiency can be realized. These cells can be readily applied as bottom cells of stacked solar cells.

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