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1.
Summary The temporal variability of thermal turbulence and vertical velocity derived from sodar measurements during periods of atmospheric
free convection is studied using both spectral and wavelet analysis. A promising approach to analyse atmospheric processes,
an advanced high-resolution spectrum estimation technique is described. Variance spectra of meteorological and turbulent parameters
are shown to have their specific comb shape at a low-frequency range. Spectra and wavelet transforms of the data obtained
at different sites both indicate the existence of some representative predominant temporal scales in time variations of the
convective boundary layer structure. The most evident temporal scales revealed are centered around 7–9 and 18–22 minutes.
Received October 16, 1998 Revised April 15, 1999 相似文献
2.
An investigation into high Reynolds number turbulent flow over a ridge top in New Zealand is described based on high-resolution
in-situ measurements, using ultrasonic anemometers for two separate locations on the same ridge with differing upwind terrain
complexity. Twelve 5-h periods during neutrally stratified and weakly stable atmospheric conditions with strong wind speeds
were sampled at 20 Hz. Large (and small) turbulent length scales were recorded for both vertical and longitudinal velocity
components in the range of 7–23 m (0.7–3.3 m) for the vertical direction and 628–1111 m (10.5–14.5 m) for the longitudinal
direction. Large-scale eddy sizes scaled to the WRF (Weather Research and Forecasting) numerical model simulated boundary-layer
thickness for both sites, while small-scale turbulent features were a function of the complexity of the upwind terrain. Evidence
of a multi-scale turbulent structure was obtained at the more complex terrain site, while an assessment of the three-dimensional
isotropy assumption in the inertial subrange of the spectrum showed anisotropic turbulence at the less complex site and evidence
of isotropic turbulence at the more complex site, with a spectral ratio convergence deviating from the 4/3 or unity values
suggested by previous theory and practice. Existing neutral spectral models can represent locations along the ridge top with
simple upwind complexity, especially for the vertical wind spectra, but sites with more orographic complexity and strong vertical
wind speeds are often poorly represented using these models. Measured spectra for the two sites exhibited no significant diurnal
variation and very similar large-scale and small-scale turbulent length scales for each site, but the turbulence energy measured
by the variances revealed a strong diurnal difference. 相似文献
3.
4.
Nikki Vercauteren Elie Bou-Zeid Marc B. Parlange Ulrich Lemmin Hendrik Huwald John Selker Charles Meneveau 《Boundary-Layer Meteorology》2008,128(2):205-228
We examine the dynamics of turbulence subgrid (or sub-filter) scales over a lake surface and the implications for large-eddy
simulations (LES) of the atmospheric boundary layer. The analysis is based on measurements obtained during the Lake-Atmosphere
Turbulent EXchange (LATEX) field campaign (August–October, 2006) over Lake Geneva, Switzerland. Wind velocity, temperature
and humidity profiles were measured at 20 Hz using a vertical array of four sonic anemometers and open-path gas analyzers.
The results indicate that the observed subgrid-scale statistics are very similar to those observed over land surfaces, suggesting
that the effect of the lake waves on surface-layer turbulence during LATEX is small. The measurements allowed, for the first
time, the study of subgrid-scale turbulent transport of water vapour, which is found to be well correlated with the transport
of heat, suggesting that the subgrid-scale modelling of the two scalars may be coupled to save computational resources during
LES. 相似文献
5.
Observations of Coherent Turbulence Structures in the Near-Neutral Atmospheric Boundary Layer 总被引:1,自引:1,他引:0
Mitsuaki Horiguchi Taiichi Hayashi Hiroyuki Hashiguchi Yoshiki Ito Hiromasa Ueda 《Boundary-Layer Meteorology》2010,136(1):25-44
Turbulence structures of high Reynolds number flow in the near-neutral atmospheric boundary layer (ABL) are investigated based
on observations at Shionomisaki and Shigaraki, Japan. A Doppler sodar measured the vertical profiles of winds in the ABL.
Using the integral wavelet transform for the time series of surface wind data, the pattern of a descending high-speed structure
with large vertical extent (from the surface to more than 200-m level) is depicted from the Doppler sodar data. Essentially
this structure is a specific type of coherent structure that has been previously shown in experiments on turbulent boundary-layer
flows. Large-scale high-speed structures in the ABL are extracted using a long time scale (240 s) for the wavelet transform.
The non-dimensional interval of time between structures is evaluated as 3.0–6.2 in most cases. These structures make a large
contribution to downward momentum transfer in the surface layer. Quadrant analyses of the turbulent motion measured by the
sonic anemometer (20-m height) suggest that the sweep motion (high-speed downward motion) plays a substantial role in the
downward momentum transfer. In general, the contribution of sweep motions to the momentum flux is nearly equal to that of
ejection motions (low-speed upward motions). This contribution of sweep motions is related to the large-scale high-speed structures. 相似文献
6.
A nocturnal gravity wave was detected over a south-western Amazon forest during the Large-Scale Biosphere–Atmosphere experiment
in Amazonia (LBA) in the course of the dry-to-wet season campaign on October 2002. The atmospheric surface layer was stably
stratified and had low turbulence activity, based on friction velocity values. However, the passage of the wave, an event
with a period of about 180–300 s, caused negative turbulent fluxes of carbon dioxide (CO2) and positive sensible heat fluxes, as measured by the eddy-covariance system at 60 m (≈30 m above the tree tops). The evolution
of vertical profiles of air temperature, specific humidity and wind speed during the wave movement revealed that cold and
drier air occupied the sub-canopy space while high wind speeds were measured above the vegetation. The analysis of wind speed
and scalars high frequency data was performed using the wavelet technique, which enables the decomposition of signals in several
frequencies allowed by the data sampling conditions. The results showed that the time series of vertical velocity and air
temperature were −90° out of phase during the passage of the wave, implying no direct vertical transport of heat. Similarly,
the time series of vertical velocity and CO2 concentration were 90° out of phase. The wave was not directly associated with vertical fluxes of this variable but the mixing
induced by its passage resulted in significant exchanges in smaller scales as measured by the eddy-covariance system. The
phase differences between horizontal velocity and both air temperature and CO2 concentration were, respectively, zero and 180°, implying phase and anti-phase relationships. As a result, the wave contributed
to positive horizontal fluxes of heat and negative horizontal fluxes of carbon dioxide. Such results have to be considered
in nocturnal boundary-layer surface-atmosphere exchange schemes for modelling purposes. 相似文献
7.
During the SABLES2006 (Stable Atmospheric Boundary Layer Experiment in Spain 2006) field campaign, a gravity-wave episode
was observed on the night of July 11 by the microbarometers deployed at the surface and on the 100-m tower. The high-amplitude,
low-frequency periodic pressure fluctuations were very well correlated with the wind speed and direction. Data from neighbouring
automatic stations showed that the gravity wave was not local, but long-lived and mesoscale. The propagation of the wave over
the experimental site had significant effects on the structure of the weakly-stratified nocturnal boundary layer that developed
that night: the stability increased, turbulent vertical motions were suppressed, the nocturnal low-level jet was disrupted,
and periodic temperature fluctuations of amplitude up to 3–4 K were observed. In this work we analyse the different available
data sources (tower data, RASS-SODAR, microbarometric, satellite imagery, automatic stations) to describe the phenomena in
depth and to find a suitable explanation for the generation and propagation of the wave. The linear wave theory explains remarkably
well most of the observations, and the wave parameters could be estimated by applying a wavelet-based technique to surface
microbarometric measurements. We also analyse the vertical structure of the wave and find wave ducting conditions above the
surface. Finally, by means of the multi-resolution flux decomposition, we analyse in detail the changes in vertical turbulent
fluxes and the spectra of turbulent motions produced by the interaction between the gravity wave and the local flow. 相似文献
8.
Impact of Sea-Spray on the Atmospheric Surface Layer 总被引:1,自引:0,他引:1
The feedback effects of sea-spray on the heat and momentum fluxes under equilibrium conditions associated with winds of tropical
cyclones are investigated using a one-dimensional coupled sea-spray and atmospheric surface-layer (ASL) model. This model
is capable of simulating the microphysical aspects of the evaporation of saline water droplets of various sizes and their
dynamic and thermal interaction with the turbulence mixing that is simulated by the Mellor–Yamada 1.5-order closure scheme.
Sea-spray droplet generation is described by a state-of-the-art parametrization that predicts the size spectrum of sea-spray
droplets for a given surface forcing. The results from a series of simulations indicate the way in which evaporating droplets
of various sizes modify the turbulence mixing near the surface, which in turn affects further droplet evaporation. All these
results are direct consequences of the effects of sea-spray on the balance of turbulent kinetic energy in the spray-filled
surface layer. In particular, the overall impact of sea-spray droplets on the mean wind depends on the wind speed at the level
of sea-spray generation. When the wind speed is below 40 m s−1, the droplets are small in size and tend to evaporate substantially and thus cool the spray-filled layer, while for wind
speeds above 50 m s−1, the size of the droplets is so large that they do not have enough time to evaporate much before falling back into the sea.
The sensible heat carried by the droplets is released to the ambient air, increasing the buoyancy of the surface layer and
enhancing the turbulent mixing. The suspension of sea-spray droplets reduces the buoyancy and makes the surface layer more
stable, decreasing the friction velocity and the downward turbulent mixing of momentum. The results from the numerical experiments
also suggest that, in order not to violate the constant flux assumption critical to the Monin–Obukhov similarity theory, a
displacement equal to the mean wave height should be included in the logarithmic profiles of the wind and thermal fields. 相似文献
9.
A time series of microwave radiometric profiles over Arctic Canada’s Cape Bathurst (70°N, 124.5°W) flaw lead polynya region
from 1 January to 30 June, 2008 was examined to determine the general characteristics of the atmospheric boundary layer in
winter and spring. A surface based or elevated inversion was present on 97% of winter (January–March) days, and on 77% of
spring (April–June) days. The inversion was the deepest in the first week of March (≈1100 m), and the shallowest in June (≈250 m).
The mean temperature and absolute humidity from the surface to the top of the inversion averaged 250.1 K (−23.1°C), and 0.56 × 10−3 kg m−3 in winter, and in spring averaged 267.5 K (−5.6°C), and 2.77 × 10−3 kg m−3. The median winter atmospheric boundary-layer (ABL) potential temperature profile provided evidence of a shallow, weakly
stable internal boundary layer (surface to 350 m) topped by an inversion (350–1,000 m). The median spring profile showed a
shallow, near-neutral internal boundary layer (surface to 350 m) under an elevated inversion (600–800 m). The median ABL absolute
humidity profiles were weakly positive in winter and negative in spring. Estimates of the convergence of sensible heat and
water vapour from the surface that could have produced the turbulent internal boundary layers of the median profiles were
0.67 MJ m−2 and 13.1 × 10−3 kg m−2 for the winter season, and 0.66 MJ m−2 and 33.4 × 10−3 kg m−2 for the spring season. With fetches of 10–100 km, these accumulations may have resulted from a surface sensible heat flux
of 15–185 W m−2, plus a surface moisture flux of 0.001–0.013 mm h−1 (or a latent heat flux of 0.7–8.8 W m−2) in winter, and 0.003–0.033 mm h−1 (or a latent heat flux of 2–22 W m−2) in spring. 相似文献
10.
John Kochendorfer Tilden P. Meyers John Frank William J. Massman Mark W. Heuer 《Boundary-Layer Meteorology》2012,145(2):383-398
Sonic anemometers are capable of measuring the wind speed in all three dimensions at high frequencies (10–50 Hz), and are relied upon to estimate eddy-covariance-based fluxes of mass and energy over a wide variety of surfaces and ecosystems. In this study, wind-velocity measurement errors from a three-dimensional sonic anemometer with a non-orthogonal transducer orientation were estimated for over 100 combinations of angle-of-attack and wind direction using a novel technique to measure the true angle-of-attack and wind speed within the turbulent atmospheric surface layer. Corrections to the vertical wind speed varied from −5 to 37% for all angles-of-attack and wind directions examined. When applied to eddy-covariance data from three NOAA flux sites, the wind-velocity corrections increased the magnitude of CO2 fluxes, sensible heat fluxes, and latent heat fluxes by ≈11%, with the actual magnitude of flux corrections dependent upon sonic anemometer, surface type, and scalar. A sonic anemometer that uses vertically aligned transducers to measure the vertical wind speed was also tested at four angles-of-attack, and corrections to the vertical wind speed measured using this anemometer were within ±1% of zero. Sensible heat fluxes over a forest canopy measured using this anemometer were 15% greater than sensible heat fluxes measured using a sonic anemometer with a non-orthogonal transducer orientation. These results indicate that sensors with a non-orthogonal transducer orientation, which includes the majority of the research-grade three-dimensional sonic anemometers currently in use, should be redesigned to minimize sine errors by measuring the vertical wind speed using one pair of vertically aligned transducers. 相似文献
11.
We utilize experimental data collected in 2002 over an open field in Hanford, Washington, USA, to investigate the turbulent
kinetic energy (TKE) budget in the atmospheric surface layer. The von Kármán constant was determined from the near-neutral
wind profiles to be 0.36 ± 0.02 rather than the classical value of 0.4. The TKE budget was normalized and all terms were parameterized
as functions of a stability parameter z/L, where z is the distance from the ground and L is the Obukhov length. The shear production followed the Businger–Dyer relation for −2 < z/L < 1. Contrary to the traditional Monin–Obukhov similarity theory (MOST), the shear, buoyancy and dissipation terms were found
to be imbalanced due to a non-zero vertical transport over all stabilities. Motivated by this local imbalance, modified parameterizations
of the dissipation and the turbulent transport were attempted and generated good agreement with the experimental data. Assuming
stationarity and horizontal homogeneity, the pressure transport was estimated from the residual of the TKE budget. 相似文献
12.
Structure functions are used to study the dissipation and inertial range scales of turbulent energy, to parametrize remote turbulence measurements, and to characterize ramp features in the turbulent field. Ramp features are associated with turbulent coherent structures, which dominate energy and mass fluxes in the atmospheric surface layer. The analysis of structure functions to identify ramp characteristics is used in surface renewal methods for estimating fluxes. It is unclear how commonly observed different scales of ramp-like shapes (i.e., smaller ramps and spikes embedded in larger ramps) influence structure function analysis. Here, we examine the impact of two ramp-like scales on structure function analysis using artificially generated data. The range of time lags in structure function analysis was extended to include time lags typically associated with isotropic turbulence to those larger than the ramp durations. The Van Atta procedure (Arch Mech 29:161–171, 1977) has been expanded here to resolve the characteristics of two-scale ramp models. This new method accurately, and in some cases, exactly determines the amplitude and duration of both ramp scales. Spectral analysis was applied to the structure functions for a broad range of time lags to provide qualitative support for the expanded Van Atta procedure results. The theory reported here forms the foundation for novel methods of analyzing turbulent coherent structures. 相似文献
13.
Marieta Cristina Castillo Atsushi Inagaki Manabu Kanda 《Boundary-Layer Meteorology》2011,140(3):453-469
A large-eddy simulation of the atmospheric boundary layer, large enough to contain both an urban surface layer and a convective
mixed layer, was performed to investigate inner-layer and outer-layer scale motions. The objective was to determine the applicability
of Monin–Obukhov similarity theory to inner-layer motions, to investigate the influence of outer-layer motions on surface-layer
structure, as well as to assess the interaction of the two scales of motion. The urban surface roughness consisted of square-patterned
cubic buildings of dimension H (40 m). A spatial filter was used to decompose the two scales in the inertial sublayer. The horizontal square filter of size
10H was effective in separating the inner-layer (surface-layer height ≈ 2 H) and outer-layer scales (boundary-layer height δ ≈ 30H), where the Reynolds stress contribution of the inner layer dominates in the logarithmic layer (depth 2H). Similarity coefficients for velocity fluctuations were successfully determined for inner-layer motions in the surface layer,
proving the robustness of Monin–Obukhov similarity for surface-layer turbulence. The inner-layer structures exhibit streaky
structures that have similar streamwise length but narrower spanwise width relative to the streamwise velocity fluctuation
field, consistent with observations from an outdoor scale model. The outer-layer motions to some extent influence the location
of ejections and sweeps through updraft and downdraft motions, respectively, thus, disturbing the homogeneity and similarity
of inner-layer motions. Although the horizontal averages of the variances and covariance of motions reveal that the Reynolds
stresses are dominated by inner-layer structures, the localized influence of the interaction of outer-layer horizontal and
inner-layer vertical motions on the Reynolds stress is not insignificant. 相似文献
14.
G. A. Meehl P. R. Gent J. M. Arblaster B. L. Otto-Bliesner E. C. Brady A. Craig 《Climate Dynamics》2001,17(7):515-526
Historically, El Nino-like events simulated in global coupled climate models have had reduced amplitude compared to observations.
Here, El Nino-like phenomena are compared in ten sensitivity experiments using two recent global coupled models. These models
have various combinations of horizontal and vertical ocean resolution, ocean physics, and atmospheric model resolution. It
is demonstrated that the lower the value of the ocean background vertical diffusivity, the greater the amplitude of El Nino
variability which is related primarily to a sharper equatorial thermocline. Among models with low background vertical diffusivity,
stronger equatorial zonal wind stress is associated with relatively higher amplitude El Nino variability along with more realistic
east–west sea surface temperature (SST) gradient along the equator. The SST seasonal cycle in the eastern tropical Pacific
has too much of a semiannual component with a double intertropical convergence zone (ITCZ) in all experiments, and thus does
not affect, nor is it affected by, the amplitude of El Nino variability. Systematic errors affecting the spatial variability
of El Nino in the experiments are characterized by the eastern equatorial Pacific cold tongue regime extending too far westward
into the warm pool. The time scales of interannual variability (as represented by time series of Nino3 SSTs) show significant
power in the 3–4 year ENSO band and 2–2.5 year tropospheric biennial oscillation (TBO) band in the model experiments. The
TBO periods in the models agree well with the observations, while the ENSO periods are near the short end of the range of
3–6 years observed during the period 1950–94. The close association between interannual variability of equatorial eastern
Pacific SSTs and large-scale SST patterns is represented by significant correlations between Nino3 time series and the PC
time series of the first EOFs of near-global SSTs in the models and observations.
Received: 17 April 2000 / Accepted: 17 August 2000 相似文献
15.
Mitsuaki Horiguchi Taiichi Hayashi Ahoro Adachi Shigeru Onogi 《Boundary-Layer Meteorology》2012,144(2):179-198
Large-scale turbulence structures in the near-neutral atmospheric boundary layer (ABL) are investigated on the basis of observations made from the 213-m tall meteorological tower at Tsukuba, Japan. Vertical profiles of wind speed and turbulent fluxes in the ABL were obtained with sonic anemometer-thermometers at six levels of the tower. From the archived data, 31 near-neutral cases are selected for the analysis of turbulence structures. For the typical case, event detection by the integral wavelet transform with a large time scale (180 s) from the streamwise velocity component (u) at the highest level (200 m) reveals a descending high-speed structure with a time scale of approximately 100 s (a spatial scale of 1 km at the 200-m height). By applying the wavelet transform to the u velocity component at each level, the intermittent appearance of large-scale high-speed structures extending also in the vertical is detected. These structures usually make a large contribution to the downward momentum transfer and induce the enhancement of turbulent kinetic energy. This behaviour is like that of “active” turbulent motions. From the analysis of the two-point space–time correlation of wavelet coefficients for the u velocity component, the vertical extent and the downward influence of large-scale structures are examined. Large fluctuations in the large-scale range (wavelet variance at the selected time scale) at the 200-m level tend to induce the large correlation between the higher and lower levels. 相似文献
16.
We present results of a technique for examining the scale-dependence of the gradient Richardson number, Ri, in the nighttime residual layer. The technique makes use of a series of high-resolution, in situ, vertical profiles of wind
speed and potential temperature obtained during CASES-99 in south-eastern Kansas, U.S.A. in October 1999. These profiles extended
from the surface, through the nighttime stable boundary layer, and well into the residual layer. Analyses of the vertical
gradients of both wind speed, potential temperature and turbulence profiles over a wide range of vertical scale sizes are
used to estimate profiles of the local Ri and turbulence structure as a function of scale size. The utility of the technique lies both with the extensive height range
of the residual layer as well as with the fact that the sub-metre resolution of the raw profiles enables a metre-by-metre
‘sliding’ average of the scale-dependent Richardson number values over hundreds of metres vertically. The results presented
here show that small-scale turbulence is a ubiquitous and omnipresent feature of the residual layer, and that the region is
dynamic and highly variable, exhibiting persistent turbulent structure on vertical scales of a few tens of metres or less.
Furthermore, these scales are comparable to the scales over which the Ri is less than or equal to the critical value of Ri
c of 0.25, although turbulence is also shown to exist in regions with significantly larger Ri values, an observation at least consistent with the concept of hysteresis in turbulence generation and maintenance. Insofar
as the important scale sizes are comparable to or smaller than the resolution of current models, it follows that, in order
to resolve the observed details of small Ri values and the concomitant turbulence generation, future models need to be capable of significantly higher resolutions. 相似文献
17.
A three-dimensional numerical meteorological model is used to perform large-eddy simulations of the upslope flow circulation
over a periodic ridge-valley terrain. The subgrid-scale quantities are modelled using a prognostic turbulence kinetic energy
(TKE) scheme, with a grid that has a constant horizontal resolution of 50 m and is stretched along the vertical direction.
To account for the grid anisotropy, a modified subgrid length scale is used. To allow for the response of the surface fluxes
to the valley-flow circulation, the soil surface temperature is imposed and the surface heat and momentum fluxes are computed
based on Monin–Obukhov similarity theory. The model is designed with a symmetrical geometry using periodic boundary conditions
in both the x and y directions. Two cases are simulated to study the influence of along-valley geostrophic wind forcing with different intensities.
The presence of the orography introduces numerous complexities both in the mean properties of the flow and in the turbulent
features, even for the idealized symmetric geometry. Classical definitions for the height of the planetary boundary layer
(PBL) are revisited and redefined to capture the complex structure of the boundary layer. Analysis of first- and second-moment
statistics, along with TKE budget, highlights the different structure of the PBL at different regions of the domain. 相似文献
18.
The processes influencing turbulence in a deciduous forest and the relevant length and time scales are investigated with spectral and cross-correlation analysis. Wind velocity power spectra were computed from three-dimensional wind velocity measurements made at six levels inside the plant canopy and at one level above the canopy. Velocity spectra measured within the plant canopy differ from those measured in the surface boundary layer. Noted features associated with the within-canopy turbulence spectra are: (a) power spectra measured in the canopy crown peak at higher wavenumbers than do those measured in the subcanopy trunkspace and above the canopy; (b) peak spectral values collapse to a relatively universal value when scaled according to a non-dimensional frequency comprised of the product of the natural frequency and the Eulerian time scale for vertical velocity; (c) at wavenumbers exceeding the spectral peak, the slopes of the power spectra are more negative than those observed in the surface boundary layer; (d) Eulerian length scales decrease with depth into the canopy crown, then increase with further depth into the canopy; (e) turbulent events below crown closure are more correlated with turbulent events above the canopy than are those occurring in the canopy crown; and (f) Taylor's frozen eddy hypothesis is not valid in a plant canopy. Interactions between plant elements and the mean wind and turbulence alter the processes that produce, transport and remove turbulent kinetic energy and account for the noted observations. 相似文献
19.
Measurements of concentration fluctuation intensity, intermittency factor, and integral time scale were made in a water channel
for a plume dispersing in a well-developed, rough surface, neutrally stable, boundary layer, and in grid-generated turbulence
with no mean velocity shear. The water-channel simulations apply to full-scale atmospheric plumes with very short averaging
times, on the order of 1–4 min, because plume meandering was suppressed by the water-channel side walls. High spatial and
temporal resolution vertical and crosswind profiles of fluctuations in the plume were obtained using a linescan camera laser-induced
dye tracer fluorescence technique. A semi-empirical algebraic mean velocity shear history model was developed to predict these
concentration statistics. This shear history concentration fluctuation model requires only a minimal set of parameters to
be known: atmospheric stability, surface roughness, vertical velocity profile, and vertical and crosswind plume spreads. The
universal shear history parameter used was the mean velocity shear normalized by surface friction velocity, plume travel time,
and local mean wind speed. The reference height at which this non-dimensional shear history was calculated was important,
because both the source and the receptor positions influence the history of particles passing through the receptor position. 相似文献
20.
K.-P. Wittich 《Boundary-Layer Meteorology》1991,55(1-2):47-66
The stable boundary layer which evolved over the lowland of Northern Germany during a clear night with moderate geostrophic winds is studied. Because of the lack of turbulence measurements, a vertical flux-profile of heat and momentum is derived from a mean wind and temperature profile using an integral method. The stability parameter h/L
*
= 17 indicates that turbulence was sporadic during this particular night. This result is confirmed by the observed inertial oscillations, which occur not only in the residual layer but also in the boundary layer below.The case study shows that turbulent cooling overrules radiational cooling in the lower part of the surface inversion layer. Additionally, warm-air advection occurs. In the upper part, cold-air advection and radiational cooling dominate, while turbulent cooling is reduced. Subsidence warming can be neglected throughout the boundary layer during this particular night. 相似文献