F E R R E T

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F E R R E T

• OPeNDAP client for data analysis and visualization

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What is Ferret?

• Command line application
• Developed for large, gridded model output
• Provides analysis and visualization
• Popular in ocean modeling community
• Customizable graphics
• Customizable analysis (external functions)
• Delayed evaluation environment

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What is delayed evaluation?

• Data access occurs when data is needed.
• Lets you create variable definitions.
• Lets you think mathematically instead of
  programmatically
• Perfect for data access with network latency.

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Delayed Evaluation

• use tmpu_winter8586.cdf
• let g 9.81
• let p0 1000
• let omega 7.292e-5
• let deg2rad 3.14159/180.
• let f 2 omega sin(deg2radygtmpu)
• let/qui theta tmpu((p0/zgtmpu)0.286)
• set var/title"Potential Temp"/unitK theta
• shade/z850 theta ! data access

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Ferret use of OPeNDAP

• Local file access through NetCDF
• use coads_climatology
• Remote file access through OPeNDAP
• use OPeNDAP URL
• OPeNDAP provides data translation into the NetCDF
  API.

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Ferret tour

• yes? use coads_cliamtology
• yes? SHADE/L1 SST
• yes? GO fland

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Ferret tour

• yes? SHADE/L1 AIRT-SST
• yes? GO fland

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Ferret tour

• yes? SHADE/LINE SSTL112_at_AVE

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Ferret tour

• yes? SHADE/PALETTEcentered SSTL1
  - SSTL112_at_AVE

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Ferret capabilities

• Section plot (with split Z axis)

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Ferret capabilities

• Map projections

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Ferret capabilities

• Time series analasys

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Ferret capabilities

• Support for curvilinear model grids

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Ferret Documentation

• http//ferret.pmel.noaa.gov/Ferret/

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Tutorial opening a dataset

• promptgt ferret
• yes? use coads_climatology
• yes? show data
• yes? show grid sst
• yes? shade sstl9

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Tutorial opening remote data

• yes? cancel data/all
• yes? use http//www.ferret.noaa.gov/cgi-bin/dods/
  nph-dods/data/coads_climatology
• yes? show data
• yes? show grid sst
• yes? shade sstl9

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Tutorial regions

• Ferret converts world coordinate bounds into
  OPeNDAP index bounds
• yes? set region/x100w0e/y10n60n
• yes? set region/t15-sep
• yes? shade sst
• yes? can region
• yes? set region/i120170/y5075/l9
• yes? shade sst

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Tutorial strides

• Ferret and OPeNDAP understand how to use NetCDF
  strides.
• Create images from a fraction of the data.
• Greatly reduces network traffic.
• yes? can region
• yes? shade ssti11804,j1904,l9

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Tutorial tranformations

• Ferret can perform axis transormations
• min, max, ave, var, sum, ngd
• yes? shade sstl_at_var
• yes? shade sstl_at_ngd
• yes? can data/all
• yes? use http//www.ferret.noaa.gov/cgi-bin/dods/n
  ph-dods/data/coads_sst.nc
• yes? show grid
• yes? plot sstx180w80w_at_ave,y5s5n_at_ave

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Tutorial regridding

• Ferret can regrid data
• yes? use levitus_climatology
• yes? show data
• yes? shade sstd1 tempd2
• yes? let sst_on_levitus sstd1,gxytempd2
• yes? set region/k1/l1
• yes? shade sst_on_levitus tempd2

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Tutorial putting it all together

• yes? use "http//dods.jpl.nasa.gov/dods-bin/nph-hd
  f/pub/sea_surface_temperature/buoy/gostaplus/hdf/D
  ata/atlas8/A803sn1d.hdf
• yes? show data
• yes? show grid GISST22_NOR1DG_6190
• yes? shade GISST22_NOR1DG_6190k1

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Tutorial putting it all together

• yes? use climatological_axes
• yes? define axis/x1805401/modulo/edge/unitdegr
  ee x_1deg
• yes? define axis/y-90901/edge/unitdegree
  y_1deg
• yes? define grid/xx_1deg/yy_1deg/tmonth_reg
  g_1deg_clim
• yes? use "http//dods.jpl.nasa.gov/dods-bin/nph-hd
  f/pub/sea_surface_temperature/buoy/gostaplus/hdf/D
  ata/atlas8/A803sn1d.hdf"
• yes? let my_gisst if GISST22_NOR1DG_6190d2
  GT -300 then GISST22_NOR1DG_6190d2

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Tutorial putting it all together

• yes? let reverse_j181-jgyg_1deg_clim
• yes? let gisst_rev_j samplej(my_gisst,reverse_j)
  
• yes? let grid_var 0 igxg_1deg_clim 0
  jgyg_1deg_clim 0 lgtg_1deg_clim
• yes? let gisst reshape(gisst_rev_j,grid_var)
• yes? set var/title"GISST temperature"/units"Deg
  C" gisst

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Tutorial putting it all together

• yes? shade gisstl3
• yes? use coads_climatology
• yes? show grid gisst
• yes? show grid sst
• yes? let coads_1deg_sst sstdcoads_climatology,g
  gisst
• yes? show grid coads_1deg_sst
• yes? shade/l3 gisst-coads_1deg_sst