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Marine Monitoring
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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
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 ?
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
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 ?
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
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
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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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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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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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
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
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
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 ?
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
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 ?
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 ?
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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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
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]