;+
;
; .. _q2m_correction_ncdf.pro:
;
; =======================
; q2m_correction_ncdf.pro
; =======================
;
; DESCRIPTION
; ===========
;
; Correction of q2m on OAFLUX grid
;
; :file:`${PROJECT_OD}/erai_q2m_19890101_20091231_oafluxgrid.nc` have been
; produced by :ref:`d2m_to_q2m_erai.pro`.
;
; Corrected q2m on OAFLUX grid is written in
; :file:`${PROJECT_OD}/TropFlux_q2m_19890101_20091231.nc`
; if this file not already exists.
;
; This file will be used by :ref:`TropFlux_19890101_20091231.pro`.
;
;     .. graphviz::
;
;        digraph q2m_correction_ncdf {
;
;           file_in [shape=ellipse,fontname=Courier,label="${PROJECT_OD}/erai_q2m_19890101_20091231_oafluxgrid.nc"];
;           file_out [shape=ellipse,fontname=Courier,label="${PROJECT_OD}/TropFlux_q2m_19890101_20091231.nc"];
;
;           q2m_correction_ncdf [shape=box,
;           fontname=Courier,
;           color=blue,
;           URL="http://forge.ipsl.jussieu.fr/tropflux/browser/trunk/src/q2m_correction_ncdf.pro",
;           label="${PROJECT}/src/q2m_correction_ncdf.pro"];
;
;           {file_in} -> {q2m_correction_ncdf} -> {file_out}
;
;        }
;
; SEE ALSO
; ========
;
; :ref:`project_profile.sh`
;
; :ref:`mooring_corrections`
;
; :ref:`d2m_to_q2m_erai.pro`
;
; :func:`initncdf <saxo:initncdf>`
; :func:`read_ncdf <saxo:read_ncdf>`
; :func:`grossemoyenne <saxo:grossemoyenne>`
; :func:`julday <saxo:julday>`
; :func:`ncdf_quickwrite <saxo:ncdf_quickwrite>`
;
; EXAMPLES
; ========
;
; ::
;
;  IDL> q2m_correction_ncdf
;
; TODO
; ====
;
; work on cratos idl7 even if NaNf values in erai_q2m_19890101_20091231_oafluxgrid.nc written by
; d2m_to_q2m.pro.
; 
; No way ... NaNf also in this output !!
;
; coding rules
;
; EVOLUTIONS
; ==========
;
; $Id$
;
; $URL$
;
; - fplod 20110808T143129Z aedon.locean-ipsl.upmc.fr (Darwin)
;
;   * usage of ${PROJECT_OD}
;   * remove v20 in output filename
;
; - fplod 20101215T113945Z aedon.locean-ipsl.upmc.fr (Darwin)
;
;   * add graph in header
;
; - fplod 20101214T093615Z aedon.locean-ipsl.upmc.fr (Darwin)
;
;   * minimal header
;
; - pbk 2008
;
;   * creation
;
;-
pro q2m_correction_ncdf
;
@cm_4cal
@cm_4data
@cm_4mesh
@cm_4data
@cm_project
;
; test if ${PROJECT_OD} defined
CASE project_od_env OF
  '' : BEGIN
         msg = 'eee : ${PROJECT_OD} is not defined'
         ras = report(msg)
       STOP
       END
  ELSE: BEGIN
          msg = 'iii : ${PROJECT_OD} is ' + project_od_env
          ras = report(msg)
        END
 ENDCASE
;
; check if output data will be possible
iodirout = isadirectory(project_od_env)
;
; existence and protection for reading
IF (FILE_TEST(iodirout, /DIRECTORY, /EXECUTABLE, /READ) EQ 0) THEN BEGIN
   msg = 'eee : the directory' + iodirout  + ' is not accessible.'
   ras = report(msg)
   STOP
ENDIF
;
; existence and protection for writing
IF (FILE_TEST(iodirout, /DIRECTORY, /WRITE) EQ 0) THEN BEGIN
    msg = 'eee : the directory' + iodirout  + ' was not found.'
    ras = report(msg)
    STOP
ENDIF
;
da1=19880101 & da2=20101231
;
; build data filename
filename='erai_q2m_19890101_20091231_oafluxgrid.nc'
;
; check if this file exists
msg='iii : looking for ' + filename
ras = report(msg)
fullfilename = isafile(iodirout + filename, NEW=0, /MUST_EXIST)
IF fullfilename[0] EQ '' THEN BEGIN
   msg = 'eee : the file ' + fullfilename + ' was not found.'
   ras = report(msg)
   STOP
ENDIF
;
; build output filename
filename_out = 'TropFlux_q2m_19890101_20091231.nc'
fullfilename_out = iodirout + filename_out
; in order to avoid unexpected overwritten
IF (FILE_TEST(fullfilename_out) EQ 1) THEN BEGIN
   msg = 'eee : the file ' + fullfilename_out  + ' already exists.'
   ras = report(msg)
   STOP
ENDIF
;
initncdf, fullfilename
q2m=read_ncdf('q2m',da1,da2,file=fullfilename,/nostr)
help, q2m

q2m_mean=grossemoyenne(q2m,'t',/nan)
help, q2m_mean

tt=time & jpt=n_elements(time)
caldat, time,mon,day,yea
q2m_m=q2m*0.

for jt=0,jpt-1 do begin
  jtt=(time(jt)-julday(1,1,yea(jt))) < 364
  q=reform(q2m_mean(*,*))
  q2m_m(*,*,jt)=q
endfor
help, q2m_m

q2m_ano=q2m-q2m_m

;; correction for mean based on scatter
;q2m_m=q2m_m+0.815445  ;;  (2000-2008)
q2m_m=q2m_m+0.792717   ;;  (2000-2009)
help, q2m_ano

;; applying the correction for variability based on the scatter
;q2m_ano=q2m_ano*(1/0.919333)  ;;  (2000-2008)
q2m_ano=q2m_ano*(1/0.924674)   ;;  (2000-2009)

q2m_new=q2m_m+q2m_ano
help, q2m_new

;writing field
lat=reform(gphit(0,0:jpj-1))
lon=reform(glamt(0:jpi-1,0))
time=timegen(7670, units='days', start=julday(1,1,1989,0)) & jpt=n_elements(time)

cda0=string(jul2date(time(0)),format='(i8.8)')
cda1=string(jul2date(time(jpt-1)),format='(i8.8)')

time=time-julday(1,1,1950) & jpt=n_elements(time)

ncfile='!' + fullfilename_out
lon_attr={units:'degrees_east',long_name:'Longitude'}
lat_attr={units:'degrees_north',long_name:'Latitude'}
time_attr={units:'days since 1950-01-01 00:00:00',long_name:'Time axis',time_origin:'1950-JAN-01 00:00:00'}
q2m_attr={units:'g/kg',missing_value:1.e20,long_name:'Specific humidity at 2m height',short_name:'q2m',axis:'TYX'}
globattr={source:'Basic data obtained from ERAI.  Mean correction for bias and correction for variability are applied',timerange:cda0+' - '+cda1}

ncfields = 'q2m[longitude,latitude,time]=q2m_new:q2m_attr; ' $
                      + 'longitude[]=lon:lon_attr; ' $
                      + 'latitude[]=lat:lat_attr; ' $
                      + 'time[*time]=time:time_attr ' $
                      + ' @ globattr'

@ncdf_quickwrite

end