204 research outputs found
Towards a solution of the closure problem for convective atmospheric boundary-layer turbulence
We consider the closure problem for turbulence in the dry convective atmospheric boundary
layer (CBL). Transport in the CBL is carried by small scale eddies near the surface and large
plumes in the well mixed middle part up to the inversion that separates the CBL from the
stably stratified air above. An analytically tractable model based on a multivariate Delta-PDF
approach is developed. It is an extension of the model of Gryanik and Hartmann [1] (GH02)
that additionally includes a term for background turbulence. Thus an exact solution is derived
and all higher order moments (HOMs) are explained by second order moments, correlation
coefficients and the skewness. The solution provides a proof of the extended universality
hypothesis of GH02 which is the refinement of the Millionshchikov hypothesis (quasi-
normality of FOM). This refined hypothesis states that CBL turbulence can be considered as
result of a linear interpolation between the Gaussian and the very skewed turbulence regimes.
Although the extended universality hypothesis was confirmed by results of field
measurements, LES and DNS simulations (see e.g. [2-4]), several questions remained
unexplained. These are now answered by the new model including the reasons of the
universality of the functional form of the HOMs, the significant scatter of the values of the
coefficients and the source of the magic of the linear interpolation. Finally, the closures
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predicted by the model are tested against measurements and LES data. Some of the other
issues of CBL turbulence, e.g. familiar kurtosis-skewness relationships and relation of area
coverage parameters of plumes (so called filling factors) with HOM will be discussed also
Hetonic quartets in a two-layer quasi-geostrophic flow : V-states and stability
M.A.S. and X.C. were supported by RFBR/CNRS (PRC Grant No. 16-55-150001/1069). M.A.S. was supported also by RFBR (Grant No. 16-05-00121), RSF (Grant No. 14-50-00095, geophysical applications) and MESRF (Grant No. 14.W.03.31.0006, numerical simulation, vortex dynamics).We investigate families of finite core vortex quartets in mutual equilibrium in a two- layer quasi-geostrophic flow. The finite core solutions stem from known solutions for discrete (singular) vortex quartets. Two vortices lie in the top layer and two vortices lie in the bottom layer. Two vortices have a positive potential vorticity anomaly while the two others have negative potential vorticity anomaly. The vortex configurations are therefore related to the baroclinic dipoles known in the literature as hetons. Two main branches of solutions exist depending on the arrangement of the vortices: the translating zigzag-shaped hetonic quartets and the rotating zigzag- shaped hetonic quartets. By addressing their linear stability, we show that while the rotating quartets can be unstable over a large range of the parameter space, most translating quartets are stable. This has implications on the longevity of such vortex equilibria in the oceans.PostprintPeer reviewe
On a Solution of the Closure Problem for Dry Convective Boundary Layer Turbulence and Beyond
We consider the closure problem of representing the higher-order moments (HOMs) in terms of lower-
order moments, a central feature in turbulence modeling based on the Reynolds-averaged NavierβStokes (RANS)
approach. Our focus is on models suited for the description of asymmetric, nonlocal, and semiorganized turbulence in the
dry atmospheric convective boundary layer (CBL). We establish a multivariate probability density function (PDF) describ-
ing populations of plumes that are embedded in a sea of weaker randomly spaced eddies, and apply an assumed delta-PDF
approximation. The main content of this approach consists of capturing the bulk properties of the PDF. We solve the clo-
sure problem analytically for all relevant HOMs involving velocity components and temperature and establish a hierarchy
of new non-Gaussian turbulence closure models of different content and complexity ranging from analytical to semianalyti-
cal. All HOMs in the hierarchy have a universal and simple functional form. They refine the widely used Millionshchikov
closure hypothesis and generalize the famous quadratic skewnessβkurtosis relationship to higher order. We examine the
performance of the new closures by comparison with measurement, LES, and DNS data and derive empirical constants for
semianalytical models, which are best for practical applications. We show that the new models have a good skill in predict-
ing the HOMs for atmospheric CBL. Our closures can be implemented in second-, third-, and fourth-order RANS turbu-
lence closure models of bi-, tri-, and four-variate levels of complexity. Finally, several possible generalizations of our
approach are discussed
A Package of Momentum and Heat Transfer Coefficients for the Stable Surface Layer Extended by New Coefficients over Sea Ice
ingredients of numerical weather prediction and climatemodels. They are needed for the calculation of turbulent fluxes in the surface layer and often rely on the MoninβObukhov similarity theory requiring universal stability functions. The problem of a derivation of transfer coefficients based on different stability functions has been considered by many researchers over the years but it remains to this day. In this work, dedicated to the memory of S.S. Zilitinkevich, we also address this task, and obtain transfer coefficients from three pairs of theoretically derived stability functions suggested by Zilitinkevich and co-authors for stable conditios. Additionally, we construct non-iterative parametrizations of these transfer coefficients based on earlier work. Results are compared with state-of-the-art coefficients for land, ocean, and sea ice. The combined parametrizations form a package in a universal framework relying on a semi-analytical solution of the Monin-Obukhov similarity theory equations. A comparison with data of the Surface Heat Budget of the Arctic Ocean campaign (SHEBA) over sea ice reveals large differences between the coefficients for land conditions and the measurements over sea ice. However, two schemes of Zilitinkevich and co-authors show, after slight modification, good agreement with SHEBA although they had not been especially developed for sea ice. One pair of the modified transfer coefficients is superior and is compatible to earlier SHEBA-based parametrizations. Finally, an algorithm for practical use of all transfer coefficients in climate models is given
A package of momentum and heat transfer coefficientsfor the stable atmospheric surface layer
The polar atmospheric surface layer is often stably stratified, which strongly influences turbulent transport processes between the atmosphere and sea ice/ocean. Transport is usually parametrized applying Monin Obukhov Similarity Theory (MOST) which delivers transfer coefficients as a function of stability parameters (see below). In a series of papers (Gryanik and LΓΌpkes, 2018; Gryanik et al., 2020,2021; Gryanik and LΓΌpkes, 2022) it has been shown that differences between existing parametrizations are large, especially for strong stability. One reason is that they are based on different data sets, for which the origin of differences is still unclear. In this situation Gryanik et al. (2021) as well as Gryanik and LΓΌpkes (2022) proposed a numerically efficient method, which can be used for most of the existing data sets and their specific stability dependences. A package of parametrization resulted that is suitable for its application in weather prediction and climate models. Especially, calculation of fluxes over sea ice were improved. Combined with latest parametrizations of surface roughness it has a large impact on large scale fields as shown recently by Schneider et al. (2021) who applied some members of the package
Parametrization of Turbulent Fluxes over Leads in Sea Ice in a Non-Eddy-Resolving Small-Scale Atmosphere Model
Leads (open-water channels in sea ice) play an important role for surface-atmosphere interactions in the polar regions. Due to large temperature differences between the surface of leads and the near-surface atmosphere, strong turbulent convective plumes are generated with a large impact on the atmospheric boundary layer (ABL). Here, we focus on the effect of lead width on those processes, by means of numerical modeling and turbulence parametrization.
We use a microscale atmosphere model in a 2D version resolving the entire convective plume with grid sizes in the range of L/5 where L is the lead width. For the sub-grid scale turbulence, we developed a modified version of an already existing nonlocal parametrization of the lead-generated sensible heat flux including L as parameter. All our simulations represent measured springtime conditions with a neutrally stratified ABL capped by a strong temperature inversion at 300 m height, where the initial temperature difference between the lead surface and the near-surface atmosphere amounts to 20 K.
We found that our simulation results obtained with the new approach agree very well with time-averaged results of a large eddy simulation (LES) model for variable lead widths with L β₯ 1 km and different upstream wind speeds. This is a considerable improvement since results obtained with the previous nonlocal approach clearly disagree with the LES results for leads wider than 2 km. In conclusion, considering L as parameter in a nonlocal turbulence parametrization seems to be necessary to study the effect of leads on the polar ABL in non-eddy-resolving small-scale atmosphere models
On a solution of the closure problem for atmospheric convective boundary-layer turbulence
Π ΡΠ΅ΡΠ΅Π½ΠΈΡ ΠΏΡΠΎΠ±Π»Π΅ΠΌΡ Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΡ Π΄Π»Ρ ΡΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠ½Π²Π΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ Π°ΡΠΌΠΎΡΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ³ΡΠ°Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠ»ΠΎΡ.
ΠΡΡΠ½ΠΈΠΊ Π. Π. ΠΈ Π₯Π°ΡΡΠΌΠ°Π½Π½ Π.
ΠΠ½ΡΡΠΈΡΡΡ ΡΠΈΠ·ΠΈΠΊΠΈ Π°ΡΠΌΠΎΡΡΠ΅ΡΡ ΠΈΠΌ. Π.Π. ΠΠ±ΡΡ
ΠΎΠ²Π° Π ΠΠ, ΠΠΎΡΠΊΠ²Π°, Π ΠΎΡΡΠΈΡ
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
ΠΠΎΠ΄Π΅Π»ΠΈ Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΡ ΠΈΠ³ΡΠ°ΡΡ ΡΠ΅Π½ΡΡΠ°Π»ΡΠ½ΡΡ ΡΠΎΠ»Ρ Π² ΡΠ΅ΠΎΡΠΈΠΈ ΡΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΡΡΠΈ ΠΈ Π΅Ρ ΠΏΡΠΈΠ»ΠΎΠΆΠ΅Π½ΠΈΡΡ
.
ΠΠ½ΠΈ ΡΠΈΡΠΎΠΊΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡΡΡΡ Π² ΠΌΠΎΠ΄Π΅Π»ΡΡ
ΠΊΠ»ΠΈΠΌΠ°ΡΠ°, ΠΎΠ±ΡΠ΅ΠΉ ΡΠΈΡΠΊΡΠ»ΡΡΠΈΠΈ, ΠΏΠΎΠ³ΡΠ°Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΠΈ ΠΏΡΠΈΠ·Π΅ΠΌΠ½ΠΎΠ³ΠΎ ΡΠ»ΠΎΠ΅Π²
Π°ΡΠΌΠΎΡΡΠ΅ΡΡ ΠΈ ΠΎΠΊΠ΅Π°Π½Π°.
ΠΠ°ΠΈΠ±ΠΎΠ»Π΅Π΅ ΠΏΠΎΠΏΡΠ»ΡΡΠ½Ρ, ΠΈΠ·-Π·Π° ΡΠ²ΠΎΠ΅ΠΉ ΠΏΡΠΎΡΡΠΎΡΡ, ΠΎΠ΄Π½ΠΎ-ΡΠΎΡΠ΅ΡΠ½ΡΠ΅ ΠΈ Π΄Π²ΡΡ
-ΡΠΎΡΠ΅ΡΠ½ΡΠ΅ (ΡΠΏΠ΅ΠΊΡΡΠ°Π»ΡΠ½ΡΠ΅) Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΡ.
ΠΠ΄Π½Π° ΠΈΠ· ΠΏΠ΅ΡΠ²ΡΡ
ΠΌΠΎΠ΄Π΅Π»Π΅ΠΉ Π±ΡΠ»Π° ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π° ΠΠ±ΡΡ
ΠΎΠ²ΡΠΌ Π² Π΅Π³ΠΎ Π·Π½Π°ΠΌΠ΅Π½ΠΈΡΠΎΠΉ ΡΠ΅ΠΉΡΠ°Ρ ΡΠ°Π±ΠΎΡΠ΅, Π³Π΄Π΅ Π²ΠΏΠ΅ΡΠ²ΡΠ΅ Π±ΡΠ» ΠΏΠΎΠ»ΡΡΠ΅Π½
Π·Π°ΠΊΠΎΠ½ ΠΏΡΡΠΈ ΡΡΠ΅ΡΠ΅ΠΉ Π΄Π»Ρ ΡΠΏΠ΅ΠΊΡΡΠ° ΠΎΠ΄Π½ΠΎΡΠΎΠ΄Π½ΠΎΠΉ ΠΈ ΠΈΠ·ΠΎΡΡΠΎΠΏΠ½ΠΎΠΉ ΡΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΡΡΠΈ.
Π’ΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΡΡΡ Π² Π°ΡΠΌΠΎΡΡΠ΅ΡΠ΅ ΠΈ ΠΎΠΊΠ΅Π°Π½Π΅ ΠΌΠΎΠΆΠ΅Ρ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΠΊΠ°ΠΊ ΠΎΠ΄Π½ΠΎΡΠΎΠ΄Π½Π°Ρ ΠΈ ΠΈΠ·ΠΎΡΡΠΎΠΏΠ½Π°Ρ ΡΠΎΠ»ΡΠΊΠΎ Π½Π° ΠΌΠ°Π»ΡΡ
ΠΌΠ°ΡΡΠ°Π±Π°Ρ
Π² ΡΠ°ΠΊ Π½Π°Π·ΡΠ²Π°Π΅ΠΌΠΎΠΌ ΠΈΠ½Π΅ΡΡΠΈΠΎΠ½Π½ΠΎΠΌ ΠΈΠ½ΡΠ΅ΡΠ²Π°Π»Π΅.
Π Π΄ΠΎΠΊΠ»Π°Π΄Π΅ ΠΏΡΠΎΠ±Π»Π΅ΠΌΠ° Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΡ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°Π΅ΡΡΡ Π΄Π»Ρ ΡΡΡ
ΠΎΠ³ΠΎ ΠΊΠΎΠ½Π²Π΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΠΏΠΎΠ³ΡΠ°Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠ»ΠΎΡ Π½Π°ΠΊΡΡΡΠΎΠ³ΠΎ ΠΈΠ½Π²Π΅ΡΡΠΈΠ΅ΠΉ.
Π’ΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΠ΅ ΠΏΠ΅ΡΠ΅ΠΌΠ΅ΡΠΈΠ²Π°Π½ΠΈΠ΅ Π² ΡΠ»ΠΎΠ΅ ΡΠ²ΡΠ·Π°Π½ΠΎ Ρ Π²ΠΈΡ
ΡΡΠΌΠΈ ΠΌΠ°Π»ΡΡ
ΠΌΠ°ΡΡΡΠ°Π±ΠΎΠ² Π²Π±Π»ΠΈΠ·ΠΈ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΈ Π² Π·ΠΎΠ½Π΅ Π²ΠΎΠ²Π»Π΅ΡΠ΅Π½ΠΈΡ, Π° ΡΠ°ΠΊΠΆΠ΅ Ρ
ΠΊΡΡΠΏΠ½ΠΎΠΌΠ°ΡΡΡΠ°Π±Π½ΡΠΌΠΈ ΠΊΠΎΠ³Π΅ΡΠ΅Π½ΡΠ½ΡΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ - ΠΏΠ»ΡΠΌΠ°ΠΌΠΈ - ΠΏΡΠΎΠ½ΠΈΠ·ΡΠ²Π°ΡΡΠΈΠΌΠΈ Π²ΡΡ ΡΠΎΠ»ΡΡ ΠΏΠΎΠ³ΡΠ°Π½ΡΠ»ΠΎΡ.
Π’ΡΠ°Π΄ΠΈΡΠΈΠΎΠ½Π½ΡΠ΅ Π³ΠΈΠΏΠΎΡΠ΅Π·Ρ Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΡ ΠΏΠ»ΠΎΡ
ΠΎ ΡΠ°Π±ΠΎΡΠ°ΡΡ Π² ΡΡΠΈΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
:
1) ΠΏΠΎΡΠΎΠΊΠΈ ΡΠ΅ΠΏΠ»Π°, ΠΊΠΈΠ½Π΅ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΈ ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ ΡΠ½Π΅ΡΠ³ΠΈΠΉ
ΠΈ ΠΌΠΎΠΌΠ΅Π½ΡΠΎΠ² ΡΡΠ°ΡΡΠ΅Π³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ° Π½Π΅ ΠΎΠΏΠΈΡΡΠ²Π°ΡΡΡΡ ΠΎΠ±ΡΡΠ½ΡΠΌΠΈ Π·Π°ΠΊΠΎΠ½Π°ΠΌΠΈ Π΄ΠΈΡΡΡΠ·ΠΈΠΈ,
2) Π³ΠΈΠΏΠΎΡΠ΅Π·Π° ΠΠΈΠ»Π»ΠΈΠΎΠ½ΡΠΈΠΊΠΎΠ²Π° ΠΎ Π³Π°ΡΡΡΠΎΠ²ΠΎΡΡΠΈ ΠΌΠΎΠΌΠ΅Π½ΡΠΎΠ² ΡΠ΅ΡΠ²Π΅ΡΡΠΎΠ³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ°
ΠΏΡΠΎΡΠΈΠ²ΠΎΡΠ΅ΡΠΈΡ Π΄Π°Π½Π½ΡΠΌ Π½Π°Π±Π»ΡΠ΄Π΅Π½ΠΈΠΉ ΠΈ ΡΠΈΡΠ»Π΅Π½Π½ΠΎΠ³ΠΎ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ,
3) ΡΠΊΠΎΡΠΎΡΡΡ Π΄ΠΈΡΡΠΈΠΏΠ°ΡΠΈΠΈ ΡΠ½Π΅ΡΠ³ΠΈΠΈ ΠΈ ΠΏΠΎΡΠΎΠΊΠ° ΡΠ΅ΠΏΠ»Π° (ΠΈ ΡΡΠ°ΡΡΠΈΡ
ΠΌΠΎΠΌΠ΅Π½ΡΠΎΠ²)
Π½Π΅ ΠΎΠΏΠΈΡΡΠ²Π°Π΅ΡΡΡ Π³ΠΈΠΏΠΎΡΠ΅Π·ΠΎΠΉ Π ΠΎΡΡΠ°-ΠΠΎΠ½ΠΈΠ½Π° ΠΎΠ± ΠΎΠ΄Π½ΠΎΡΠΎΠ΄Π½ΠΎΠΉ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΈ.
ΠΠ»Π°Π²Π½Π°Ρ ΠΏΡΠΈΡΠΈΠ½Π° Π² ΡΠΎΠΌ, ΡΡΠΎ ΠΏΡΠ΅Π΄ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠ΅ ΠΎ ΡΠ»Π°Π±ΠΎΠΌ ΠΎΡΠΊΠ»ΠΎΠ½Π΅Π½ΠΈΠΈ ΡΡΠ½ΠΊΡΠΈΠΈ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΡΠ»ΡΠΊΡΡΠ°ΡΠΈΠΉ ΡΠΊΠΎΡΠΎΡΡΠΈ ΠΈ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΡ ΠΎΡ Π³Π°ΡΡΡΠΎΠ²ΠΎΠΉ
Π½Π΅ Π²ΡΠΏΠΎΠ»Π½ΡΠ΅ΡΡΡ.
Π§ΡΠΎΠ±Ρ ΠΏΡΠΎΡΡΠ½ΠΈΡΡ ΡΠΈΡΡΠ°ΡΠΈΡ, ΠΌΡ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°Π΅ΠΌ ΡΠΏΡΠΎΡΡΠ½Π½ΡΡ ΠΌΠΎΠ΄Π΅Π»Ρ ΠΊΠΎΠ½Π²Π΅ΠΊΡΠΈΠ²Π½ΠΎΠΉ ΡΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΡΡΠΈ, ΠΏΡΠΈΠ½ΡΠ² Π³ΠΈΠΏΠΎΡΠ΅Π·Ρ ΡΡΠΎ Π½Π΅-Π³Π°ΡΡΡΠΎΠ²ΠΎΡΡΡ ΡΡΠ½ΠΊΡΠΈΠΈ
ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΠΎΠΏΠΈΡΠ°Π½Π° Π² ΡΠ°ΠΊ Π½Π°Π·ΡΠ²Π°Π΅ΠΌΠΎΠΌ Delta-PDF ΠΏΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½ΠΈΠΈ, ΠΊΠΎΡΠΎΡΠΎΠ΅ ΠΏΡΠ΅Π΄ΠΏΠΎΠ»Π°Π³Π°Π΅Ρ Π°ΠΏΠΏΡΠΎΠΊΡΠΈΠΌΠ°ΡΠΈΡ ΡΠ΅Π°Π»ΡΠ½ΠΎΠΉ
ΡΡΠ½ΠΊΡΠΈΠΈ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΡΡΠΌΠΌΠΎΠΉ ΠΠ΅Π»ΡΠ°-ΡΡΠ½ΠΊΡΠΈΠΉ.
ΠΠ½ΠΎ Π½Π°ΠΈΠ»ΡΡΡΠΈΠΌ ΠΎΠ±ΡΠ°Π·ΠΎΠΌ ΠΏΡΠΈΡΠΏΠΎΡΠΎΠ±Π»Π΅Π½ΠΎ Π΄Π»Ρ ΠΎΠΏΠΈΡΠ°Π½ΠΈΡ Π²Π»ΠΈΡΠ½ΠΈΡ Π°Π½ΡΠ°ΠΌΠ±Π»Π΅ΠΉ ΠΊΠΎΠ³Π΅ΡΠ΅Π½ΡΠ½ΡΡ
ΡΡΡΡΠΊΡΡΡ.
ΠΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½ΠΈΠ΅ Π½Π΅ Π½ΠΎΠ²ΠΎ ΠΈ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π»ΠΎΡΡ ΡΠ°Π½Π΅Π΅ Π² ΡΠ°Π±ΠΎΡΠ°Ρ
[1].
ΠΠ»Π°Π²Π½ΠΎΠ΅ ΠΎΡΠ»ΠΈΡΠΈΠ΅ Π½ΠΎΠ²ΠΎΠΉ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΡΠΎΡΡΠΎΠΈΡ
Π²ΠΎ Π²ΠΊΠ»ΡΡΠ΅Π½ΠΈΠΈ Π² ΡΡΠ½ΠΊΡΠΈΡ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ Π²ΠΊΠ»Π°Π΄Π° Π² ΠΎΡ ΠΏΠΎΠΏΡΠ»ΡΡΠΈΠΉ Π²ΠΈΡ
ΡΠ΅ΠΉ ΠΌΠ°Π»ΡΡ
ΠΌΠ°ΡΡΠ°Π±ΠΎΠ², ΠΏΠΎΠΌΠΈΠΌΠΎ Π²ΠΊΠ»Π°Π΄Π° ΠΎΡ ΠΊΠΎΠ³Π΅ΡΠ΅Π½ΡΠ½ΡΡ
ΡΡΡΡΠΊΡΡΡ.
ΠΡΠΎΡΠΎΠ΅ ΠΎΡΠ»ΠΈΡΠΈΠ΅ Π² ΡΠΎΠΌ, ΡΡΠΎ ΡΠ°Π½Π΅Π΅ Π² [1] Π°Π½Π°Π»ΠΈΠ· ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΡΡ Π°ΡΠΈΠΌΠΏΡΠΎΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΌΠ΅ΡΠΎΠ΄Π°ΠΌΠΈ, Π½ΠΎΠ²Π°Ρ ΠΆΠ΅ ΠΌΠΎΠ΄Π΅Π»Ρ ΡΠ΅ΡΠ΅Π½Π° ΡΠΎΡΠ½ΠΎ.
ΠΡΠ΅ ΠΌΠΎΠΌΠ΅Π½ΡΡ Π²ΡΡΡΠΈΡ
ΠΏΠΎΡΡΠ΄ΠΊΠΎΠ² Π²ΡΡΠ°ΠΆΠ΅Π½Ρ ΡΠ΅ΡΠ΅Π· Π½Π΅ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΠΌΡΠ΅, ΡΡΠ΅Π΄ΠΈ ΠΊΠΎΡΠΎΡΡΡ
ΡΠΎΠ΄Π΅ΡΠΆΠΈΡΡΡ ΡΠΎΠ»ΡΠΊΠΎ ΠΎΠ΄ΠΈΠ½ ΠΌΠΎΠΌΠ΅Π½Ρ ΡΠ΅ΡΠ²Π΅ΡΡΠΎΠ³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ° -
ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½Ρ ΠΊΠΎΡΡΠ΅Π»ΡΡΠΈΠΈ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½Ρ ΡΠΊΠΎΡΠΎΡΡΠΈ ΠΈ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΡ. ΠΠΎΠ»ΡΡΠ΅Π½Ρ ΡΠ²Π½ΡΠ΅ Π°Π½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΈΠ·Π°ΡΠΈΠΈ Π΄Π»Ρ Π½Π΅-Π΄ΠΈΡΡΡΠ·ΠΈΠΎΠ½Π½ΡΡ
ΠΏΠΎΡΠΎΠΊΠΎΠ² ΠΈΠΌΠΏΡΠ»ΡΡΠ°, ΡΠ΅ΠΏΠ»Π°, ΠΊΠΈΠ½Π΅ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΈ ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ ΡΠ½Π΅ΡΠ³ΠΈΠΈ. Π ΡΠ°ΡΡΠ½ΠΎΠΌ ΡΠ»ΡΡΠ°Π΅ ΠΌΠΎΠΌΠ΅Π½ΡΠΎΠ² ΡΠ΅ΡΠ²Π΅ΡΡΠΎΠ³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ° Π½ΠΎΠ²ΡΠ΅ Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΡ
ΠΎΠ±ΠΎΠ±ΡΠ°ΡΡ Π³ΠΈΠΏΠΎΡΠ΅Π·Ρ ΠΠΈΠ»Π»ΠΈΠΎΠ½ΡΠΈΠΊΠΎΠ²Π° Π½Π° ΡΠ»ΡΡΠ°ΠΉ ΡΠΈΠ»ΡΠ½ΠΎ Π°ΡΡΠΈΠΌΠ΅ΡΡΠΈΡΠ½ΠΎΠΉ ΡΡΡΠ±ΡΠ»Π΅Π½ΡΠ½ΠΎΡΡΠΈ.
Π’Π΅ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΠΉ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ Π΄Π°Π½Π½ΡΡ
ΡΠ°ΠΌΠΎΠ»ΡΡΠ½ΡΡ
ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠΉ (ARTIST), LES ΠΈ DNS ΠΏΠΎΠΊΠ°Π·Π°Π»ΠΎ Ρ
ΠΎΡΠΎΡΠ΅Π΅ ΡΠΎΠ³Π»Π°ΡΠΈΠ΅ ΠΌΠ΅ΠΆΠ΄Ρ ΡΠ΅ΠΎΡΠΈΠ΅ΠΉ ΠΈ
Π΄Π°Π½Π½ΡΠΌΠΈ. Π ΠΏΡΠ΅Π΄Π΅Π»ΡΠ½ΡΡ
ΡΠ»ΡΡΠ°ΡΡ
Π½ΠΎΠ²ΡΠ΅ Π·Π°ΠΌΡΠΊΠ°Π½ΠΈΡ ΡΠΎΠ²ΠΏΠ°Π΄Π°ΡΡ Ρ ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΠΌΠΈ Π² [1], ΠΈ ΡΠΆΠ΅ ΠΏΡΠΎΠ²Π΅ΡΠ΅Π½Π½ΡΠΌΠΈ Π² [2-4].
[1] Gryanik V.M. and J. Hartmann, 2002: J. Atmos. Sci., 59, 2729;
Gryanik, V.M., J. Hartmann, S. Raasch and M. SchrΓΆter, 2005: J. Atmos. Sci., 62, 2632.
[2] Kupka F. and F. Robinson 2007: Mon. Not. Roy. Astron. Soc. 374, 305, 79.
[3] Lenschow, D.H., M. Lothon, S.D. Mayor,
P.P. Sullivan and G. Canut, 2011: Boundary-Layer Meteorol. 143, 107.
[4] Waggy S., A. Hsieh and S. Biringen, 2016: Geophys. Astrophys. Fluid Dyn.
doi: 10.1080/03091929.2016.1196202
Turbulent Heat Exchange Over Polar Leads Revisited: A Large Eddy Simulation Study
Sea ice leads play an important role in energy exchange between the ocean and atmosphere in polar regions, and therefore must be considered in weather and climate models. As sea ice leads are not explicitly resolved in such models, lead-averaged surface heat flux is of considerable interest for the parameterization of energy exchange. Measurements and numerical studies have established that the lead-averaged surface heat flux depends not only on meteorological parameters, but also on lead width. Nonetheless, few studies to date have investigated the dependency of surface heat flux on lead width. Most findings on that dependency are based on observations with lead widths smaller than a few hundred meters, but leads can have widths from a few meters to several kilometers. In this parameter study, we present the results of three series of large-eddy simulations of turbulent exchange processes above leads. We varied the lead width and air temperature, as well as the roughness length. As this study focused on conditions without background wind, ice-breeze circulation occurred, and was the main driver of the adjustment of surface heat flux. A previous large-eddy simulation study with uncommonly large roughness length found that lead-averaged surface heat flux exhibited a distinct maximum at lead widths of about 3Β km, while our results show the largest heat fluxes for the smallest leads simulated (lead width of 50Β m). At more realistic roughness lengths, we observed monotonously increasing heat fluxes with increasing lead width. Further, new scaling laws for the ice-breeze circulation are proposed
Turbulent heat exchange over polar leads revisited: A large eddy simulation study
Sea ice leads play an important role in energy exchange between the ocean and atmosphere
in polar regions, and therefore must be considered in weather and climate models. As sea ice leads are
not explicitly resolved in such models, lead-averaged surface heat flux is of considerable interest for
the parameterization of energy exchange. Measurements and numerical studies have established that
the lead-averaged surface heat flux depends not only on meteorological parameters, but also on lead width.
Nonetheless, few studies to date have investigated the dependency of surface heat flux on lead width. Most
findings on that dependency are based on observations with lead widths smaller than a few hundred meters, but
leads can have widths from a few meters to several kilometers. In this parameter study, we present the results
of three series of large-eddy simulations of turbulent exchange processes above leads. We varied the lead width
and air temperature, as well as the roughness length. As this study focused on conditions without background
wind, ice-breeze circulation occurred, and was the main driver of the adjustment of surface heat flux. A
previous large-eddy simulation study with uncommonly large roughness length found that lead-averaged surface
heat flux exhibited a distinct maximum at lead widths of about 3 km, while our results show the largest heat
fluxes for the smallest leads simulated (lead width of 50 m). At more realistic roughness lengths, we observed
monotonously increasing heat fluxes with increasing lead width. Further, new scaling laws for the ice-breeze
circulation are proposed
ΠΠΈΠ½Π°ΠΌΠΈΠΊΠ° Π±Π°ΡΠΎΠΊΠ»ΠΈΠ½Π½ΡΡ Π²ΠΈΡ ΡΠ΅ΠΉ Ρ Π½ΡΠ»Π΅Π²ΠΎΠΉ ΡΡΠΌΠΌΠ°ΡΠ½ΠΎΠΉ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΡΡ (Ρ Π΅ΡΠΎΠ½ΠΎΠ²)
ΠΡΠΈΠ²ΠΎΠ΄ΠΈΡΡΡ ΠΎΠ±Π·ΠΎΡ ΡΠ°Π±ΠΎΡ, ΠΏΠΎΡΠ²ΡΡΠ΅Π½Π½ΡΡ
ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΡΠ²ΠΎΠΉΡΡΠ² Π²ΠΈΡ
ΡΠ΅Π²ΡΡ
Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠΉ Π² ΡΡΡΠΎΠΉΡΠΈΠ²ΠΎ ΡΡΡΠ°ΡΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ Π±ΡΡΡΡΠΎ Π²ΡΠ°ΡΠ°ΡΡΠ΅ΠΉΡΡ ΠΆΠΈΠ΄ΠΊΠΎΡΡΠΈ ΠΈ ΠΎΠΏΠΈΡΡΠ²Π°Π΅ΠΌΡΡ
ΡΡΠ°Π²Π½Π΅Π½ΠΈΠ΅ΠΌ ΡΠ²ΠΎΠ»ΡΡΠΈΠΈ ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»ΡΠ½ΠΎΠ³ΠΎ Π²ΠΈΡ
ΡΡ Π² ΠΊΠ²Π°Π·ΠΈΠ³Π΅ΠΎΡΡΡΠΎΡΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΏΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½ΠΈΠΈ. ΠΡΠ½ΠΎΠ²Π½ΠΎΠ΅ Π²Π½ΠΈΠΌΠ°Π½ΠΈΠ΅ ΡΠ΄Π΅Π»Π΅Π½ΠΎ Π²ΠΈΡ
ΡΡΠΌ Ρ Π½ΡΠ»Π΅Π²ΠΎΠΉ ΡΡΠΌΠΌΠ°ΡΠ½ΠΎΠΉ ΡΠΈΡΠΊΡΠ»ΡΡΠΈΠ΅ΠΉ β ΡΠ°ΠΊ Π½Π°Π·ΡΠ²Π°Π΅ΠΌΡΠΌ Ρ
Π΅ΡΠΎΠ½Π°ΠΌ. Π Π°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ Π·Π°Π΄Π°ΡΠΈ ΡΠ°ΠΌΠΎΠ΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ Π΄ΠΈΡΠΊΡΠ΅ΡΠ½ΡΡ
Ρ
Π΅ΡΠΎΠ½ΠΎΠ², ΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ Π΅Π΄ΠΈΠ½ΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Π½ΠΎΠ³ΠΎ Ρ
Π΅ΡΠΎΠ½Π°, Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ Π΄Π²ΡΡ
Ρ
Π΅ΡΠΎΠ½ΠΎΠ² ΠΊΠΎΠ½Π΅ΡΠ½ΡΡ
ΡΠ°Π·ΠΌΠ΅ΡΠΎΠ². ΠΡΠΈΠ²ΠΎΠ΄ΡΡΡΡ ΡΠ°ΠΊΠΆΠ΅ Π½ΠΎΠ²ΡΠ΅ ΡΠ΅ΡΠ΅Π½ΠΈΡ Π·Π°Π΄Π°Ρ ΠΎ ΡΡΠ΅Ρ
ΠΈ Π±ΠΎΠ»Π΅Π΅ Π΄ΠΈΡΠΊΡΠ΅ΡΠ½ΡΡ
Π²ΠΈΡ
ΡΡΡ
Ρ
Π΅ΡΠΎΠ½Π½ΠΎΠΉ ΡΡΡΡΠΊΡΡΡΡ. ΠΠ°ΡΡΡΡ ΠΏΡΠΈΠΌΠ΅ΡΡ Π²ΠΎΠ·Π½ΠΈΠΊΠ½ΠΎΠ²Π΅Π½ΠΈΡ Ρ
Π°ΠΎΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ΅ΠΆΠΈΠΌΠΎΠ². ΠΠ±ΡΡΠΆΠ΄Π°ΡΡΡΡ ΠΎΠ±Π»Π°ΡΡΡ ΠΏΡΠΈΠΌΠ΅Π½ΠΈΠΌΠΎΡΡΠΈ Ρ
Π΅ΡΠΎΠ½Π½ΠΎΠΉ ΡΠ΅ΠΎΡΠΈΠΈ ΠΈ ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²ΡΠ΅Π΅ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΡΡ
ΠΏΡΠΈΠ»ΠΎΠΆΠ΅Π½ΠΈΠΉ, Π² ΡΠ°ΡΡΠ½ΠΎΡΡΠΈ, β Π΄Π»Ρ Π°Π½Π°Π»ΠΈΠ·Π° Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΡΠ°Π΄ΠΈΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ Π³Π»ΡΠ±ΠΎΠΊΠΎΠΉ ΠΊΠΎΠ½Π²Π΅ΠΊΡΠΈΠΈ Π² ΠΎΠΊΠ΅Π°Π½Π΅
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