<div dir="ltr"><div>Dear all NCL users,<br class="gmail-Apple-interchange-newline"><br></div><div>I visited this link:<span style="background-color:rgb(255,242,204)"> <a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/calcMonAnomTLL.shtml" target="_blank">https://www.ncl.ucar.edu/Document/Functions/Contributed/calcMonAnomTLL.shtml</a> </span>, which is about monthly anomalies. But I could not understand the way it calculates the anomalies. <span style="color:rgb(51,51,51);font-family:verdana,sans-serif;font-size:13.3333px"></span></div><p style="font-variant-numeric:normal;font-variant-east-asian:normal;margin:10px 0px 20px;padding:0px;color:rgb(51,51,51);font-family:verdana,sans-serif;font-size:13.3333px;line-height:12pt"></p><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;font-size:13.3333px;line-height:12pt;font-family:courier;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)">_____________________________________________________________________________________________</pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;font-size:13.3333px;line-height:12pt;font-family:courier;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)">Example 1</pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;font-size:13.3333px;line-height:12pt;font-family:courier;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)"><br></pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;font-size:13.3333px;line-height:12pt;font-family:courier;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)">  fa     = <a href="https://www.ncl.ucar.edu/Document/Functions/Built-in/addfile.shtml" target="_blank" style="color:rgb(0,64,255);margin:0px;padding:0px;text-decoration-line:none;font-family:verdana,sans-serif"><strong style="margin:0px;padding:0px">addfile</strong></a>("<a href="http://air.mean.nc/" target="_blank">air.mean.nc</a>","r")
  fb     = <a href="https://www.ncl.ucar.edu/Document/Functions/Built-in/addfile.shtml" target="_blank" style="color:rgb(0,64,255);margin:0px;padding:0px;text-decoration-line:none;font-family:verdana,sans-serif"><strong style="margin:0px;padding:0px">addfile</strong></a>("<a href="http://air.nobs.nc/" target="_blank">air.nobs.nc</a>","r")
 
  air  = <a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml" target="_blank" style="color:rgb(0,64,255);margin:0px;padding:0px;text-decoration-line:none;font-family:verdana,sans-serif"><strong style="margin:0px;padding:0px">short2flt</strong></a>( fa->air)                           ; air temp        
  nobs = <a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml" target="_blank" style="color:rgb(0,64,255);margin:0px;padding:0px;text-decoration-line:none;font-family:verdana,sans-serif"><strong style="margin:0px;padding:0px">short2flt</strong></a>( fb->air)                           ; # obs for air
; filter out geographic locations that have < nMin observations
  nMin   = 2                                           ; min # obs
  air    = <a href="https://www.ncl.ucar.edu/Document/Functions/Built-in/mask.shtml" target="_blank" style="color:rgb(0,64,255);margin:0px;padding:0px;text-decoration-line:none;font-family:verdana,sans-serif"><strong style="margin:0px;padding:0px">mask</strong></a>(air,nobs.ge.nMin,True)

;---Compute the climatology using a function in contributed.ncl
  yrStrt = 1950
  yrLast = 1979
  moStrt = <span style="background-color:rgb(217,210,233)">(yrStrt-1800)*12     </span>         ; start subscript
  moLast = (yrLast-1800)*12 + 11         ; last  subscript
  clm = <a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/clmMonTLL.shtml" target="_blank" style="color:rgb(0,64,255);margin:0px;padding:0px;text-decoration-line:none;font-family:verdana,sans-serif"><strong style="margin:0px;padding:0px">clmMonTLL</strong></a> (air(moStrt:moLast,:,:)) ; monthly climatology

;---Compute the anomalies from the climatology just computed
  xAnom = <strong style="margin:0px;padding:0px">calcMonAnomTLL</strong> (air,clm)</pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;font-size:13.3333px;line-height:12pt;font-family:courier;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)">_________________________________________________________________</pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;line-height:12pt;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)"><font face="arial, sans-serif">May I ask you please explain subscript method? Why using 1800 and then multiply 12?</font></pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;line-height:12pt;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)"><font face="arial, sans-serif">what do moStrt and moLast show?</font></pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;line-height:12pt;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)"><font face="arial, sans-serif">I appriciate any advse</font></pre><pre style="white-space:pre-wrap;margin-top:0px;margin-bottom:0px;padding:0px;line-height:12pt;border-style:solid;border-width:0px 0px 15px;border-color:transparent;color:rgb(0,0,0)"><font face="arial, sans-serif">All the best,</font></pre></div>