;; Example HOPS script #6
;; reanal_z500: Analyze 500 hPa height in NMC re-analysis data

;; Open 23 years of monthly-mean NMC re-analysis data (1973-1995)
;; for selected variables
;; (This file is stored in fern/winterpark in the /tmp space)

hopen,"/tmp/svn/csm/REANAL/h23-1973.nc"

;; Extract the 500 hPa height field for all months
Z500= hget("ZA", z=500)
Z500.name= "Z500"

;; Fold time dimension to create an i-dimension corresponding
;; to the 12 calendar months
Z500= hfold( Z500, month1="jan")

;; Display all the date values
print, Z500.date

;; Plot height field for February 1981, using NH polar stereographic projection
hplot, hsub(Z500,t=810101,i="feb"), proj="nhp"

;; Compute time-average (for each month separately)
Z500AVG= hsub(Z500,t="avg")

;; Plot average height field for February
hplot, hsub(Z500AVG,i="feb"), proj="nhp"

;; Compute monthly height anomlies (by subtracting time average)
Z500ANOM= hop( Z500, "-", Z500AVG )

;; Compute standard deviation of height anomalies
Z500RMS= hsub(Z500ANOM,t="rms")

;; Plot height standard deviation for February
hplot, hsub(Z500RMS,i="feb"), proj="nhp"

;; Save mean, standard deviation, and anomaly time-series for height field
Z500AVG.name= "Z500AVG"
Z500RMS.name= "Z500RMS"
Z500ANOM.name= "Z500ANOM"

hsave, "z500y1973-95.nc", Z500AVG, Z500RMS, Z500ANOM

end