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SONG-YOU HONG, JIMY DUDHIA, SHU-HUA CHEN

A Revised Approach to Ice Microphysical Process for the Bulk Parameterization of Clouds and Precipitation. SONG-YOU HONG, JIMY DUDHIA, SHU-HUA CHEN. 學生：陳文彬 指導老師：楊明仁老師. Introduction. CRMs(cloud-resolving models) 、 CEMs(cumulus ensemble models) 跟 GCM 的合併使用

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SONG-YOU HONG, JIMY DUDHIA, SHU-HUA CHEN

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  1. A Revised Approach to Ice Microphysical Process for the Bulk Parameterization of Clouds and Precipitation SONG-YOU HONG, JIMY DUDHIA, SHU-HUA CHEN 學生：陳文彬 指導老師：楊明仁老師

  2. Introduction • CRMs(cloud-resolving models)、CEMs(cumulus ensemble models)跟GCM的合併使用 • RH83(Rutledge and Hobbs)、D89(Dudhia 1989) • 本篇文章即是介紹修正模式中的微物理計算過程，並探討其影響。

  3. Modifications of microphysical process introduce to a commonly used bulk cloud scheme • 利用WRF simple ice and mixing phase 來修改 • 利用D89和RH83更正模組

  4. a.Sedimentation of falling ice crystal HD90(Heymsfield and Donner 1990) ρ空氣密度，qI雲冰混和比 New velocity-diameter formula HI2000(Heymsfiled and Iaquinta)

  5. b.Ice mass, diameter, and number concentration relationship (Fletcher 1962)

  6. 取single bullet來修正模式

  7. 利用single bullet的粒子數濃度求出來各項的數值

  8. c.Intercept parameter for snow Note : 最大值為2*108(m-4) Houze et al.1979 From Marshall and Palmer, 1948

  9. d.Initiation of cloud ice crystal qsi:冰的飽和混合比 q=water vapor mixing ratio qI0=NI0MI0/ρ

  10. (-43,1) (a)Ice nuclei number concentration (b)Initial ice crystal amount

  11. e.Vapor deposition of a small ice crystal(PIsd) SI=qSI/q AI、BI熱力和動力函數 RH83、D89 This study

  12. f.Accretion of cloud ice by snow (Pacr)

  13. g.Conversion of ice crystals to snow(PautI) qIcrit(MImaxNI/ρ)為autoconversion 的門檻值 Fletcher : D89, RH83 qicrit has small range of T : 0.1 and 1 gkg-1 for –27 and –32C This study qicrit :18gkg-1, at T=-40C, P=300 mb

  14. h.Sublimation and deposition grower of snow/evaporation of rain(Pres) μ=動力黏滯係數

  15. i.Autoconversion of cloud water to rain (Pautc) qc0 = critical liquid water content for cloud water (Kessler 1969) 在Tripoli and Cotton 1980(TC80)對參數qC0、α做了物理上的定義

  16. 3. Numerical experiments Two sets of experiments are carried out : • An idealized 2D thunderstorm case • A 3D real-data simulation of a heavy rain event KF cumulus parameterization for subgrid scale precipitation process

  17. An idealized 2D thunderstorm case • 2-D domain • 在x方向有201點，間距為250m • 垂直分80層 • 積分一小時，time step=3s • 初始值，在模式中心有一半徑4km的暖胞，最大溫度擾動為3K • 地表風速12ms-1，遞減到2.5km時風速為零 • 為開放邊界，沒有科氏力和摩擦力

  18. qci qrs

  19. 細實線(Exp1) 點線(Exp2) 虛線(Exp3) 粗實線 (Exp4) 1 4 3 2 3、4 1、2

  20. A 3D real-data simulation of a heavyrain event 目的：利用新的參數模擬降水和上層大氣大尺度系統特徵 時間：25 Jun.1997(Korea) 降水特徵：在西部有一個降水最大值，在南端也有數個不連續的大降水 大尺度特色：在黃海有一個低壓系統(中緯度氣旋)

  21. A 3D real-data simulation of a heavyrain event

  22. The simulation of the real case(setting) • 初始和邊界條件來自NCEP • 利用MM5來加強其高層的探空資料並讓WRF model使用 • 48小時的模擬時間(1200 UTC 25 Jun. 1997) • 水平網格間距45km共80點，中心位於Korea peninsula • 使用Lambert-conformal conic projection • 垂直分23層

  23. The simulation of the real case

  24. 2 3 4 1 1 3 2 4 Vertical profiles, at 0000 UTC 25 Jun 1997

  25. The 24-h accumulated precipitation (mm) (a)Exp1 and (b) Exp4.

  26. 平均1小時累積降水(domain-average) (a) subgrid-scale (implicit) rain and (b) grid-resolvable (explicit) rain

  27. 垂直積分cloud ice/water混合比(1200UTC 25 Jun.1997) (a) is Exp1, (b) is Exp4

  28. 1 2 Exp1~Exp4間的cloud ice/water的濃度、300hpa平均溫度 Exp1 (thin solid),Exp2(dotted),Exp3(dashed),and Exp4(thick solid) and the analyses (solid line with open circles). 1 3 2 4 3 4

  29. Conclusion Ideal case • 相對於雲微物理過程，考慮冰晶沉降作用對於降水和雲的模擬，影響較小。 • 冰晶沉降造成了anvil ice的減少，雪花增加 • 可以產生類似有graupel的雲結構產生 Heavy rain fall • 雲微物理和沉降作用改善了雲和溫度的模擬 • 模式在較冷的環境中產生較少的冰晶(接近觀測)

  30. Exp1(實線) • NORA=no radiation(點線) • NOSW=no short wave radiation(點虛線) • NOLW=no long wave radiation(長虛線)

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