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NCL學習筆記(天氣分析圖)

一、風向風速向量圖

    先看一個風向風速的樣例圖片:

這裡與上一篇氣溫分佈圖的繪製方法基本相同,不同的地方在於

  wplot = gsn_csm_vector_map(wks,ddata1,vdata1,wres)           ; create plot

  ddata1是插值後的風向,vdata1是插值後的風速

由於wplot要和之前的map疊加,使用overlayhas函式,最後在顯示疊加後的map

  overlay(map,wplot)
  draw(map)
二、地面氣象要素天氣分析圖

  

改圖為繪製樣例,不是真實資料。

1.各要素分析圖示

  需要50char的字串用來顯示圖中左側的圖示,具體資料格式如下:

example:

imdat ="11721700181008020050300004983052026604007289086925"


A string (or array) of 50 characters encoded as per the WMO/NOAA(世界氣象組織/美國國家海洋大氣局) guidelines.
If an array, it must have the same shape as the x and y arrays.
In more detail (where the characters are numbered from left to right, starting at character number 0):

      character 0  =  iR  -  the precipitation data indicator  (冰雹資料指數)
      character 1  = iX  -  weather data and station type indicator(天氣資料和站點型別指數)
      character 2  = h  -  height above ground of base of lowest cloud
      characters 3-4  = VV  -  visibility in miles and fractions (能見度)
      character 5  = N  -  total amount of cloud cover (總雲量)
      characters 6-7  =  dd  -  direction from which wind is blowing (風向)
      characters 8-9  =  ff  -  wind speed in knots(風速)

If character 10 = "1", then

      character 11  = sn  - sign of temperature
      characters 12-14  =  TTT  - current air temperature

If character 15 = "2", then

      character 16  =  sn  - sign of temperature
      characters 17-19  =  Td  - dew point

If character 20 = "3", then

      characters 21-24  =  PO  - station pressure (not plotted)

If character 25 = "4", then

      characters 26-29  =  PPPP  - pressure reduced to sea level

If character 30 = "5", then

      character 31  =  a  - characteristic of barograph
      characters 32-34  =  ppp  - pressure change, last 3 hrs.

If character 35 = "6", then

      characters 36-38  =  RRR  - precipitation
      character 39  =  tR  - time duration of precipitation

If character 40 = "7", then

      characters 41-42  =  ww  - present weather
      character 43  =  W1  - most significant past weather
      character 44  =  W2  - 2nd most sig. past weather

If character 45 = "8", then

      character 46  =  Nh  - Fraction of sky cover
      character 47  =  CL  - cloud type, low clouds
      character 48  =  CM  - cloud type, medium clouds
      character 49  =  CH  - cloud type, high clouds
可以根據實際資料需要將資料轉換成50char,傳送給

     wmstnm(wks,lat_imdat,lon_imdat,imdat)   進行繪製


2.冷暖峰

  wmsetp("fro","warm")      ; Specify stationary front. ;cold or warm or stationary(interal)
  wmsetp("cfc",3)           ; Use blue for the triangles.
  wmsetp("wfc",2)           ; Use red for the bumps.
  wmsetp("swi",0.02)        ; Increase the size of the bumps and triangles.
  wmsetp("nms",2)           ; 設定峰的個數
  wmsetp("sig",0.005) 
  wmsetp("slf",0)            ;0 使用SL1和SL2 ,1 使用SL1 ,2 使用SL2  , 3 均不使用,預設值 
  wmsetp("sl1",90.)         ; 起始方向與X軸的夾角
  wmsetp("sl2",0.)          ; 終止方向與X軸的夾角
  xlat = (/  25.,   30./)   ; Latitudes.
  xlon = (/ 113., 116./)   ; Longitudes.
  wmdrft(wks, xlat, xlon)  

3.繪製高低氣壓中心

  以高氣壓為例,用紅色的"D"代表。

  gsn_text(wks,map,"D",123.,51.,tres)

三、高空氣象要素天氣分析圖

   就是等溫線和等壓線的疊加,使用函式map = gsn_csm_contour_map_overlay(wks,pdata,vdata,res,res2),即可,其他同地面氣象要素