Terrain gravity wave drag parameterization method considering horizontal transmission factor

A technique for propagating factors, gravitational waves, applied in the field of atmospheric science research

Active Publication Date: 2017-06-20
NANJING UNIV
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Problems solved by technology

In addition, Eckerman et al. found that the horizontal propagation of orographic gravity waves can cause the wave amplitude to decrease with height, thereby preventing the formation of orographic gravity wave fragmentation and dragging of orographic gravity waves

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  • Terrain gravity wave drag parameterization method considering horizontal transmission factor
  • Terrain gravity wave drag parameterization method considering horizontal transmission factor
  • Terrain gravity wave drag parameterization method considering horizontal transmission factor

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Embodiment Construction

[0039] Taking the gravity wave excited by the topography of Hainan Island in July 2014 as an example, the drag parameterization method of terrain gravity wave considering the horizontal propagation factor proposed by the present invention is described in detail.

[0040] The first step is the preprocessing of terrain and ambient atmosphere. According to the global high-resolution terrain data provided by the National Atmospheric and Oceanic Administration of the United States, the terrain distribution of Hainan Island with a resolution of 5km can be obtained, see Figure 4 . According to the 2.5° reanalysis data provided by the European Center for Mesoscale Weather Forecasting, the vertical profile of wind speed and buoyancy frequency in Hainan Island in July 2014 can be obtained with 35 vertical layers, from the surface to about 31km height, as shown in Figure 5 shown. For simplicity, the horizontal wind speed is used here instead of the east-west wind, while the north-sou...

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Abstract

The invention discloses a terrain gravity wave drag parameterization method considering a horizontal transmission factor. The method comprises the steps of calculating a block altitude when airflow passes a terrain; obtaining spectral distribution of the terrain, starting from the first model layer located above the block altitude, and conducting the following processing steps to calculate the amplitude of a terrain gravity wave; calculating a fluctuation Richardson number; calculating a saturation amplitude of the terrain gravity wave and a vertical flux of a horizontal momentum of the terrain gravity wave if the fluctuation Richardson number is smaller than a critical value; calculating a momentum flux absorbed by mean flow of the gravity wave; continuing to perform vertical transmission till a mode top is reached if the fluctuation Richardson number is larger than the critical value Rie. By means of the terrain gravity wave drag parameterization method considering the horizontal transmission factor, the horizontal transmission of the gravity wave is processed, the influence of the terrain gravity wave on atmospheric circulation can be better represented, and the simulating capability of a numerical mode is improved.

Description

technical field [0001] The invention relates to a parameterization method of terrain gravity wave dragging in numerical weather and climate models, especially for the parameterization method of dragging caused by three-dimensional propagating terrain gravity waves, and belongs to the field of atmospheric science research. Background technique [0002] Orographic gravity waves are common fluctuations in the Earth's atmosphere, which are generated by stratified stable air flow disturbed by terrain. When a terrain gravity wave breaks up, it can transfer the momentum it carries to the ambient airflow and cause it to slow down. This effect is known as terrain gravity wave drag. Palmer et al. found that the introduction of orographic gravity wave drag in numerical weather and climate models can effectively improve the simulation of the Earth's atmosphere. Since the horizontal scale of terrain gravity wave drag is usually small and cannot be directly resolved by the numerical mod...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F19/00
CPCG16Z99/00
Inventor 徐昕王元
Owner NANJING UNIV
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