c m e m s p r a c t i c a l s e s s i o n -...
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Marine Monitoring
Imp
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How to view CMEMS products with Ncview?
CMEMS ServiceDesk/ Véronique Landes
C M E M S P r a c t i c a l S e s s i o n
Brussels, September 28th
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Marine Monitoring • What is a numerical file in the CMEMS catalogue?
a Netcdf file
• How to visualize the data inside?
with Ncview
• How to manipulate a netcdf file?
with Ncdump & Nco tools
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
Viewing NetCDF: Ncview
• to quickly plot and view
the contents of a NetCDF file
• to allow selection and
quick view/plotting functionality
that can be useful
when working with data
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Marine Monitoring Ncview – getting started
Exemple: ncview global-analysis-forecast-phy-001-024.nc
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
To do the exercises: - Download the Ncview tool
Ncview (http://meteora.ucsd.edu/~pierce/ncview_home_page.html)
It’s easy to install on unix/linux platforms, possible on windows - Type in command line
ncview filepath/filename.nc
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
Ncview – getting started
You are presented with •An information panel •A control panel for visualization •A variable selection panel •Details of dimensions for the selected variable
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
ncview – select variable Select variable: in this case we have selected Sea Surface Temperature (“thetao"). Ncview: •displays information in the top panel •Populates the colour bar •Plots the first time step of the variable •Displays information about dimensions
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
ncview – animate
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
ncview –
other options
Edit: data edit
Edit: data edit
Postscript file .ps
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Marine Monitoring
Ncview Exemple
Other figure with ncview
It is possible to visualize
bathy vertical profiles like
these vertical temperature
profiles on the right.
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
ncview – other figures
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Marine Monitoring Other Operators
Ncea/ Ncdiff
To average data available in differents netcdf file
ncea ficin-1.nc … ficin-n.nc ficout.nc
To calculate the difference between two numeric values
ncdiff ficin-1.nc ficin-2.nc -o ficout.nc
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
September 15th, 2016, temperature anomaly compared with model climatology from 2007 to 2015
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Marine Monitoring After Hurricane Irma
on 17/09/10
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
September 10th, 2017, temperature anomaly compared with model climatology from 2007 to 2017
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Marine Monitoring Other Operator
Ncks
To extract only selected variable,
Selected dimension from the input netcdf file
Ncks –v variable –d dimension ficin.nc ficout.nc
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
Exemples Ncdiff/ Ncks/ Ncdump # Temperature anomalies compared with climatology on september 2016
ncdiff (-h) thetao_psy4v3r1_mean_20160915.nc
monthly_data/PSY4V3R1/mercatorpsy4v3r1_gl12_mean_2007_2016_m09.nc
-o anomaly_clim_1509.nc
# Extraction of 3 temperature levels
ncks -v thetao -d depth,1 -d depth,24 -d depth,33
mercatorpsy4v3r1_gl12_mean_20160915_R20160928.nc
thetao_psy4v3r1_mean_20160915.nc
# Area extraction
ncks -d latitude0.,65. -d longitude,-82.,0. anomaly_clim_1509.nc
zoom_anomaly_clim_1509.nc
# Time extraction ncks -d time,1,3 fic_in.nc fic_out.nc
# Time check ncdump –v time –t fic.nc
v: variable / d: dimension
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Marine Monitoring • Ncdump
Commandline tool for Unix To Visualize the variables available in a netcdf file ncdump -h fichier.nc
To See the variable var1 values ncdump fichier.nc -v var1
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
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Marine Monitoring Ncdump Example
ncdump -h global-analysis-forecast-phys-001-024.nc | more
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
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Marine Monitoring Annex 1 - Cnes Julian Days are used for Oceanography data
Number of days since January 1st, 1950
Exemple: 2016/10/11 24390
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
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Marine Monitoring
Annex 2 - Model physical variable name
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
Standard Name Former name Current name
sea_surface_height_above_geoid ssh zos
sea_ice_thickness hice sithick
sea_ice_area_fraction fice siconc
eastward_sea_ice_velocity uice usi
northward_sea_ice_velocity vice vsi
sea_water_potential_temperature temperature thetao
sea_water_salinity salinity so
eastward_sea_water_velocity u uo
northward_sea_water_velocity v vo
ocean_mixed_layer_thickness_defined_by_sigma_theta mlotst
sea_water_potential_temperature_at_sea_floor bottomT
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Marine Monitoring
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
Annex 3 – All generic variable name
CMEMS GLOSSARY http://marine.copernicus.eu/glossary/
…
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Marine Monitoring Thank you for attending this session!
H o w t o v i e w p r o d u c t s w i t h N c v i e w ?
Contact Us: CMEMS Service Desk [email protected]