本文關(guān)鍵詞： 海霧 黃海 WRF模式 YSU邊界層方案 MYNN邊界層方案　出處：《中國海洋大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：海霧是發(fā)生在海上大氣邊界層內(nèi)的一種天氣現(xiàn)象，邊界層方案所描述的湍流過程是影響海霧數(shù)值模擬的關(guān)鍵因素之一。本文旨在基于WRF（Weather Researchand Forecasting）模式，研究其YSU與MYNN邊界層方案對黃海海霧的模擬效果，以便加深對它們的認(rèn)識并試圖對其不足加以改進(jìn)。 本文選取2次典型的黃海海霧個例為研究對象，它們分別是發(fā)生在2006年3月的一次濃厚海霧與發(fā)生在2012年3月一次較為淡薄的海霧。首先利用MTSAT衛(wèi)星反演數(shù)據(jù)、再分析數(shù)據(jù)與常規(guī)觀測數(shù)據(jù)，對海霧演變特征、海霧天氣形勢與邊界層特征進(jìn)行了詳細(xì)的觀測分析。然后設(shè)計并實(shí)施了一系列WRF數(shù)值試驗(yàn)，細(xì)致地對比分析了YSU與MYNN方案對黃海海霧的模擬效果。結(jié)果表明：1）對于2006年海霧個例，海霧邊界層內(nèi)湍流較強(qiáng)，湍流動量交換系數(shù)（Km）約為10m2/s，YSU模擬效果明顯優(yōu)于MYNN；因?yàn)镸YNN邊界層方案模擬的近海面湍流過強(qiáng)，Km達(dá)到了40m2/s，導(dǎo)致海霧逐漸脫離地面，不利于海霧的發(fā)展與維持，而YSU方案刻畫的湍流強(qiáng)度適合海霧發(fā)展與維持。2）對于2012年海霧個例，海霧邊界層內(nèi)湍流較弱，霧區(qū)Km約為5m2/s，YSU的模擬效果明顯不如MYNN；MYNN邊界層方案刻畫的湍流強(qiáng)度適合海霧發(fā)展與維持；而YSU方案則不能體現(xiàn)弱湍流，其給出的Km約1m2/s，導(dǎo)致模擬失敗。3）YSU方案適合濃厚海霧的模擬，而MYNN方案適合淡薄海霧的模擬；適合海霧發(fā)生發(fā)展的湍流交換系數(shù)的平均值約為5m2/s左右。 針對MYNN方案在強(qiáng)湍流的情況下模擬的近海面湍流過強(qiáng)導(dǎo)致海霧消散，而YSU方案在弱湍流的情況下對海霧的模擬效果不佳的問題，本文對MYNN與YSU方案進(jìn)行了一系列的敏感性試驗(yàn)。我們試圖改進(jìn)MYNN方案對Case-2006與YSU方案對Case-2012的模擬效果，得到如下結(jié)果：1）對于Case-2006，MYNN湍流交換系數(shù)過大的情況下設(shè)計的敏感試驗(yàn)表明，直接將MYNN方案的湍流交換系數(shù)降低之后，對Case_2006模擬得到的非接海霧區(qū)雖然較原來有所減小，但是接海霧區(qū)有所改進(jìn)；通過減小MYNN方案中與浮力項(xiàng)相關(guān)的系數(shù)降低湍流交換系數(shù)的試驗(yàn)，模擬得到的霧區(qū)明顯增大，霧區(qū)改進(jìn)顯著；而對其他閉合參數(shù)修改的試驗(yàn)，模擬得到的霧區(qū)改變不大，不能提高海霧的模擬效果。2）對于Case_2012，YSU湍流交換系數(shù)過小的情況下設(shè)計的敏感性試驗(yàn)表明，直接將YSU方案交換系數(shù)增大后對Case_2012進(jìn)行模擬，雖然霧區(qū)內(nèi)的交換系數(shù)增大且接近模擬較好的MYNN方案的數(shù)值，但是霧區(qū)外的交換系數(shù)比MYNN增大一倍，導(dǎo)致海霧消散，模擬效果并沒有得到改善；修改YSU方案中湍流交換系數(shù)的p指數(shù)雖然能夠使得湍流交換系數(shù)增大，但對霧區(qū)模擬并沒有改進(jìn)，模擬得到的霧區(qū)幾乎沒有變化。
[Abstract]:Sea fog is a weather phenomenon occurring in the boundary layer of the sea atmosphere. The turbulent process described by the boundary layer scheme is one of the key factors affecting the numerical simulation of sea fog. Weather Researchand forecasting) mode. This paper studies the simulation effect of Huang Hai sea fog by its YSU and MYNN boundary layer schemes in order to deepen their understanding and try to improve their shortcomings. In this paper, two typical examples of Huang Hai sea fog are selected as the research object. They were a dense sea fog in March 2006 and a lighter one in March 1st 2012. First, the data were retrieved by MTSAT satellite. The characteristics of sea fog evolution, sea fog weather situation and boundary layer are analyzed in detail. Then a series of WRF numerical experiments are designed and implemented. The simulation results of Huang Hai sea fog by YSU and MYNN schemes are compared and analyzed in detail. The results show that the turbulence in the sea fog boundary layer is stronger for the case of 2006 sea fog. The turbulent momentum exchange coefficient (Km) is about 10 m ~ (2 / s) and the simulation effect of YSU is obviously better than that of MYNN. Because the MYNN boundary layer scheme simulates the strong turbulence over 40 m2 / s, the sea fog is gradually detached from the ground, which is not conducive to the development and maintenance of sea fog. The turbulence intensity described by the YSU scheme is suitable for the development and maintenance of sea fog. For the case of sea fog in 2012, the turbulence in the sea fog boundary layer is relatively weak, and km in the fog region is about 5 m2 / s. The simulation effect of YSU is obviously inferior to that of MYNN. The turbulent intensity described by the MYNN boundary layer scheme is suitable for the development and maintenance of sea fog. But the YSU scheme can not reflect the weak turbulence. The km of the scheme is about 1m2 / s, which leads to the failure of simulation. 3YSU scheme is suitable for the simulation of thick sea fog, while the MYNN scheme is suitable for the simulation of light sea fog. The average turbulent exchange coefficient suitable for sea fog development is about 5m2 / s. In view of the problem that the near sea turbulence simulated by the MYNN scheme is too strong in the case of strong turbulence, the sea fog dissipates, but the simulation effect of the YSU scheme on the sea fog is not good in the case of weak turbulence. In this paper, a series of sensitivity tests on MYNN and YSU schemes are carried out. We try to improve the simulation effect of Case-2006 and YSU schemes on Case-2012. The following results are obtained as follows: 1) the sensitive experiments designed for Case-2006 MYNN show that the turbulent exchange coefficient of the MYNN scheme is reduced directly. Although the non-sea fog area obtained by Case_2006 simulation is smaller than the original one, the sea fog zone is improved. By reducing the coefficients related to buoyancy in the MYNN scheme and reducing the turbulent exchange coefficient, the simulated fog region is obviously increased, and the fog zone is improved significantly. But for the other closed parameter modification test, the simulated fog area is not changed much, which can not improve the simulation effect of sea fog. 2) for Case_2012. The sensitivity experiments designed under the condition that the YSU turbulence exchange coefficient is too small show that the Case_2012 is simulated by increasing the exchange coefficient of the YSU scheme directly. Although the exchange coefficient in the fog region increases and is close to that of the simulated MYNN scheme, the exchange coefficient outside the fog zone is twice that of MYNN, resulting in the dissipation of sea fog, and the simulation effect is not improved. The modified p exponent of the turbulent exchange coefficient in the YSU scheme can increase the turbulent exchange coefficient, but there is no improvement on the simulation of the fog zone, and there is almost no change in the fog region obtained by the simulation.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：P732

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