Some effects of deforestation on nocturnal drainage flow and local climate ? A numerical study

Groß, Günter

doi:10.1007/bf00120851

Cited by 39 publications

(31 citation statements)

References 18 publications

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“…[]). Furthermore, the findings regarding the weaker magnitude and upward displacement of the jet, relative to downslope flows over bare ground, are consistent with observational and numerical modeling studies [e.g., Gross , ; Froelich and Schmid , ; Sun et al ., ; Belcher et al ., ]. Note that away from the sidewalls, winds are weak (±0.75 m s −1 ).…”

Section: Resultsmentioning

confidence: 99%

The effect of sidewall forest canopies on the formation of cold‐air pools: A numerical study

Kiefer

Zhong

2013

JGR Atmospheres

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[1] While the evolution and dynamics of cold-air pools in basins and valleys continue to be an active area of research, the influence of vegetation cover on cold-air pools remains largely unexamined. Recently, the Advanced Regional Prediction System (ARPS) atmospheric model has been modified to allow simulation of flow through a multilayer canopy (ARPS-CANOPY). In this study, two-dimensional numerical simulations are performed with ARPS-CANOPY to examine the impact of sidewall forest cover on diurnal cold-air pool formation inside an idealized valley. A cold-air pool develops regardless of the presence or absence of sidewall vegetation. However, the strength of the temperature inversion and the overall cooling appear to be substantially modified by sidewall vegetation. The coldest overall valley temperature occurs with no sidewall vegetation cover while the warmest occurs when the valley sidewalls are fully covered with vegetation. In simulations with partial forest cover, the nocturnal cooling in approximately the upper two thirds (lower one third) of the valley atmosphere is shown to be most sensitive to forest cover along the upper half (lower half) of the sidewall. The sidewall forest cover also affects downslope flows through a combination of weaker surface cooling beneath the forest canopy and increased drag on air flowing down the sidewalls. Finally, the strength of downslope flow is shown to be highly sensitive to the presence or absence of trees farther up the slope.Citation: Kiefer, M. T., and S. Zhong (2013), The effect of sidewall forest canopies on the formation of cold-air pools: A numerical study,

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Section: Resultsmentioning

confidence: 99%

The effect of sidewall forest canopies on the formation of cold‐air pools: A numerical study

Kiefer

Zhong

2013

JGR Atmospheres

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“…If not, the model is reduced to a "numerical laboratory" to study possible effects of such properties, that the sub-model simulates, on mesoscale circulations. One may then argue that, if this should be the aim, it might have been better to simplify the mesoscale model, for instance to use only the 2D version, and implement an even more sophisticated vegetation model with explicit resolution of the canopy, according to Gross (1987) or Yamada (1982), or wait until proper computer resources becomes available, using a simpler formulation in the meantime for routine use in the full mesoscale model.…”

Section: Discussionmentioning

confidence: 99%

“…The simplest way may be to use some kind of "Penman-Monteith"-like formulation with a specified overall resistance to evaporation and thus take the vegetation into account (Grandin, 1984;Schoeffler, 1982). A more complex way is to resolve the in-canopy air with a number of gridpoints and add source/sink terms in the thermodynamic equations for the transfer of sensible and latent heat and in the dynamic equations for the drag of the plants (Yamada, 1982 andGross, 1987). A way "in-between" has been described in Deardorff (1978).…”

Section: Introductionmentioning

confidence: 99%

Some tests with a surface energy balance scheme, including a bulk parameterisation for vegetation, in a mesoscale model

Tjernström

1989

Boundary-Layer Meteorol

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The problem of generating realistic boundary values of temperature and humidity in mesoscale models is discussed as well as the importance of allowing for non-linear interactions between the state of the surface and the atmosphere. An energy balance scheme, based on a bulk parameterisation of vegetation and simple prognostic equations for temperature and humidity of the soil interface, is presented. It is implemented in a hydrostatic, higher order closure model for the meso-y-scale. Some tentative results are presented and critically evaluated. The presented parameterisation is very simple in its description of the interaction between plant and atmosphere, but shows the importance of such effects. Regarded as a building block in a mesoscale model, however, it is concluded that the present scheme is rather complicated. It is concluded that, although the results presented are realistic and show the importance of variable soil and vegetation types, it is highly doubtful if the presented parameterisation is useful in a wider perspective. Some of the parameterisations are less well founded from a physical point of view, and even if it were not so, the modeller will be hard put to specify all specifiable parameters and initialize all variables for any arbitrary area and event. It is thus concluded that this problem may still have to be dealt with in a simpler fashion. The question is raised if it should not be possible to obtain comparatively good results, similar to those in this paper, by simpler means.

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“…However, Garrett (1983) made a sensitivity analysis of a one-dimensional drainage flow as it related to humidity, cloud height and forest cover. Also, Gross (1987) showed the influence of deforestation on the air flow and on the production of cold air over an actual valley. Most climatological researches on nocturnal cooling and drainage flow appear to be descriptive in nature (e.g.…”

Section: Introductionmentioning

confidence: 99%

The Sensitivities of Nocturnal Cooling and Drainage Flow over an Inclined Topography to Meteorological, Ground Surface, and Topographic Conditions

Sato

1989

Journal of the Meteorological Society of Japan

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On the basis of results of slope and valley drainage flow models Sato and Kondo, 1988), a simple method is presented for the simultaneous evaluation of nocturnal cooling and drainage flow over slopes and in valleys under weak ambient wind conditions.Evaluations are made of the sensitivities of nocturnal cooling, drainage flow characteristics (velocity and thickness), and sensible heat transport by the drainage flow to the following conditions: meteorological conditions, thermal constant of the ground, surface aerodynamic properties and topographic features.Due to the enhancement of sensible heat transport by the drainage flow, surface cooling of an inclined topography is smaller than that of a horizontal plain. The velocity of the drainage flow is sensitive to the conditions mentioned above, but its thickness is dependent only on the surface aerodynamic properties and the topographic features. The side-slope flow plays an essential role in the energy exchange between the atmosphere and a valley.Available observations of nocturnal cooling and drainage flow support the present method.

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Some effects of deforestation on nocturnal drainage flow and local climate ? A numerical study

Cited by 39 publications

References 18 publications

The effect of sidewall forest canopies on the formation of cold‐air pools: A numerical study

The effect of sidewall forest canopies on the formation of cold‐air pools: A numerical study

Some tests with a surface energy balance scheme, including a bulk parameterisation for vegetation, in a mesoscale model

The Sensitivities of Nocturnal Cooling and Drainage Flow over an Inclined Topography to Meteorological, Ground Surface, and Topographic Conditions

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