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PRODUCT USER MANUAL
For Wind product
WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004
Issue: 1.3
Contributors: Abderrahim Bentamy
Approval Date : March 2019
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CHANGE RECORD
Issue Date § Description of Change Author Validated By
1.0
27 April
2018
All
Creation of the document
Abderrahim Bentamy
Jean François Piollé
Cedric Prevost
Abderrahim Bentamy
1.1 24 August
2018
Rebranded to Wind TAC M. Belmonte
1.2 10
January
2019
Adapted to CMEMS April
2019 Release
M. Belmonte
1.3 07 March
2019
Adaptation to netCDF4
format convertion
Cedric Prevost
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TABLE OF CONTENTS
I 5
II HOW TO DOWNLOAD A PRODUCT6
6
6
III 7
7
8
8
8
8
III.5 Upstream data used to build this product9
III.5.1 Scatterometer inputs10
III.5.2 ECMWF12
III.5.3 In-Situ12
III.5.4 Collocated Data13
I.1.1 Missing data13
III.5.5 References14
IV 15
V 16
VI 17
VI.1 NETCDF17
17
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GLOSSARY AND ABBREVIATIONS
KNMI Royal Netherlands Meteorological Institute
IFREMER Institut Français pour la Recherche et l’Exploitation de la MER
NetCDF Network Common Data Form
CF Climate Forecast (convention for NetCDF)
NRT Near Real-Time
PC Production Center
PU Production Unit
Wind Meridional Component West to East component of wind-to vector
Wind Zonal Component South to North component of the wind-to vector
ftp Protocol to download files
OpenDAP Open-Source Project for a Network Data Access Protocol. Protocol to
download subset of data from a n-dimensional gridded dataset (ie: 4
dimensions: lon-lat,depth,time)
Subsetter CMEMS service tool to download a NetCDF file of a selected
geographical box using values of longitude an latitude, and time range
Directgetfile CMEMS service tool (FTP like) to download a NetCDF file
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I INTRODUCTION
This guide describes the near-real-time (NRT) L4 product files from the CMEMS Ifremer
Centre, what data services are available to access them, and how to use the files and services.
The product is produced by IFREMER and distributed by Copernicus/CMEMS.
See also News flash. More detailed information can be obtained from http://marine.copernicus.eu/services-portfolio/contact-us/
This CMEMS product is composed of global 6-hourly averaged fields of surface 10m wind
speed, wind zonal component, wind meridional component, wind stress amplitude, wind
stress zonal component, wind stress meridional component, and of the associated errors.
The main change with respect to previous version is the use of stress-equivalent wind vector
(U10S) estimated from ECMWF 10m wind vector operational forecasts as background winds.
The latter are provided by KNMI. Moreover, SSMIS F18 and F19 are used, in addition to
SSMIS F16 and F17, as ancillary data aiming at the enhancement of the remotely sensed wind
observation spatial and temporal sampling. The third main change is the introduction of the
new variables wind vector curl and divergence, and wind stress curl and divergence. They are
available at each grid point (0.25°x0.25°) and synoptic times (00h:00, 06h:00, 12h:00, and
18h:00 UTC).
File nomenclature is the following:
YYYYMMDDHH-IFR-L4-EWSB-BlendedWind-GLO-025-6H-NRTv6-yyyymmddThhmnsc-
fv1.0.nc
Where
YYYY, MM, DD, and HH are year, month, day, and hour respectively. yyyymmddThhmnsc
indicates the wind field date production.
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II HOW TO DOWNLOAD A PRODUCT
II.1 Download a product through the CMEMS Web Portal Subsetter Service
You first need to register. Please find below the registration steps:
http://marine.copernicus.eu/web/56-user-registration-form.php
Once registered, the CMEMS FAQ http://marine.copernicus.eu/web/34-products-and-
services-faq.php will guide you on How to download a product through the CMEMS Web
Portal Subsetter Service.
Remark: Downloading via subsetter generates data in netCDF3 format
II.2 Download a product through the CMEMS Web Portal CMEMS FTPService
You first need to register. Please find below the registration steps:
http://marine.copernicus.eu/web/56-user-registration-form.php
Once registered, the CMEMS http://marine.copernicus.eu/web/34-products-and-services-
faq.php will guide you on How to download a product through the CMEMS Web Portal
CMEMS FTP Service.
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III DESCRIPTION OF THE PRODUCT SPECIFICATION
I.1 General Information
Table1 L4 6-hourly blended wind Product Specification
Product Line WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004
Geographical coverage Global
Variables wind_speed
eastward_wind
northward_wind
wind_vector_curl
wind_vector_divergence
wind_stress
surface_downward_eastward_stress
surface_downward_northward_stress
wind_stress_curl
wind_stress_divergence
wind_speed_rms
eastward_wind_rms
northward_wind_rms
sampling_length
height
Analysis yes
Available time series from Jan 2018 to present
Temporal resolution 6-hourly (00h:00, 06h:00, 12h:00, 18h:00 UTC) averaged field
Target delivery time daily
Delivery mechanism CMEMS Information System: SUBSETTER, FTP
Horizontal resolution 1/4°
Number of vertical levels 1 (surface)
Format Netcdf CF1.7
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Detailed information on the systems and products are on CMEMS web site:
http://marine.copernicus.eu/Production Subsystem description
III.1 Grid
L4 wind products are available on regular grid in longitude and latitude over global ocean.
The grid point is 0.25° 0.25°.
III.2 Domain coverage
L4 wind products are calculated over global ocean. The associated longitudes and latitudes
vary between -179.875 and 179.875, and between -79.875 and 80.125, respectively.
III.3 Update Time
The surface wind analyses estimated as 6-hourly wind fields, and calculated from
scatterometer retrievals in combination with radiometer retrievals (time series), will be
updated yearly if needed.
III.4 Details of datasets
Table 2: List of the wind dataset (column 1) and their names in the NetCDF files (column 2)
Dataset name Associated variables
WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004 wind_speed
eastward_wind
northward_wind
wind_vector_curl
wind_vector_divergence
wind_stress
surface_downward_eastward_stress
surface_downward_northward_stress
wind_stress_curl
wind_stress_divergence
surface_typewind_speed_rms
eastward_wind_rms
northward_wind_rms
sampling_length
height
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III.5 Upstream data used to build this product
The estimation and calibration of the near-real-time (NRT) 6-hourly wind product
makes use of remotely sensed surface wind derived from scatterometers on board ASCAT-A
and ASCAT-B as observation inputs for the objective method dealing with the calculation of
daily wind fields over global oceans with 0.25°×0.25° spatial resolution. The scatterometer
retrievals are ASCAT coastal winds from the OSI SAF. Ancillary remotely sensed data are
from SSMIS radiometers onboard F16, F17, F18, and F19 satellites. The latter are processed
and provided by Remote Sensing Systems (RSS) as L2b products. Wind speed and direction
from WindSat radiometer onboard the Department of Defense Coriolis satellite are also used
as provided by RSS (V7). The model background winds are stress equivalent winds from the
ECMWF operational forecasts, used as input into The L4 NRT product is complemented by
the newly reprocessed L4 REP 6-hourly product extended back in time from January 1992
through October 2018 using the latest version of the L4 NRT processing chain, i.e., the
objective method described in (Bentamy et al., 2016) and (Desbiolles et al., 2017).
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III.5.1 Scatterometer inputs
Scatterometer wind retrievals are primary inputs for daily-averaged calculations. Two
scatterometers, ASCAT-A and ASCAT-B, are available and both used for 6-hourly wind field
Product Upstream Satellite data Time Range Data source NWP
model data
L4 REP
ERS-1
Aug 1991 –
May 1996 ESA ASPS2
(reprocessed Ifremer) ERA
Interim
ERS-2 Apr 1995 –
Jan 2001 ESA ASPS2
(reprocessed Ifremer)
ADEOS-1
(MIDORI1/NSCAT)
Oct 1996 – Jul
1997 JPL/PODAAC V2
QuikScat (SeaWinds) Jul 1999 –
Nov 2009 JPL/PODAAC V3 (w/
Ifremer SST bias
correction)
ADEOS-2
(MIDORI2/SeaWinds) Dec 2002 – Jul
2003 JPL/PODAAC V2
OceanSat2 OSCAT Dec 2009 –
Jan 2014 KNMI
ASCAT-A/B Oct 2006 –
Oct 2018 OSI-SAF NRT (w/
Ifremer bias correction)
RapidScat Dec 2014 –
Nov 2016 JPL/PODAAC
Coriolis (WindSat) Feb 2003 –
Oct 2018 RSS V7
SSM/I (F10 – F15) Mar 1992 –
Mar 2012 RSS V7
SSMIS (F16 – F18) Dec 2007 –
Oct 2018 RSS V7
GCOM (AMSR2) May 2012 –
Oct 2018 RSS V7
AQUA (AMSR-E) May 2002 –
Sep 2011 RSS V7
L4 NRT
Coastal ASCAT-A/B Jan 2016 –
present OSI-SAF NRT ECMWF
operational
forecasts SSMIS (F16 – F19) RSS V7
Windsat RSS V7
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determinations. They are onboard METOP-A and METOP-B, respectively. Scientific and
technical documentation related to ASCAT physical measurements as well as to ASCAT
derived products may be found under EUMETSAT web site
http://www.eumetsat.int/Home/Main/Publications/Technical_and_Scientific_Documentation/
Technical_Notes/ and under SAF OSI web site http://www.knmi.nl/scatterometer/. Metop is
in circular orbit (near synchronous orbit) for a period of about 101 minutes, at an inclination
of 98.59° and at a nominal height of 800 km with a 29-day repeat cycle. ASCAT has two
swaths 550 km wide, located on each side of the satellite track, separated by 700km. It
operates at 5.3 GHz (C band). Its fore-beam and aft-beam antennas point at 45° and 135° to
each side of the satellite track, respectively. The mid-beam antennas point at 90°. The fore
and aft-beams provide backscatter coefficient measurements at incidence angle varying
between 34° and 64°. The mid-beams provide 0
measurements at incidence angle varying
between 25° and 53°. Backscatter coefficients are provided with two spatial resolutions of
25km and 12.5km over the global ocean.
All ASCAT products used in this study correspond to near real time data provided by
EUMETSAT and by KNMI as wind component of the Ocean Sea Ice Satellite Application
Facility (OSI SAF) (http://www.osi-saf.org/)). Only high spatial resolution ASCAT wind
retrievals, available on Wind Vector Cell (WVC) of 0.125°×0.125° across the two ASCAT
scatterometer swaths of 600km width each, are used for the calculation of L4 wind products.
The quality of ASCAT retrieval has been assessed through comprehensive comparisons with
buoy wind measurements (Verhoef et al, 2013). The findings indicate that ASCAT high
resolution products have quite similar accuracy than lower resolution data. The root mean
square differences of wind speed and direction are of 1 m/s and 18°, respectively
.Special Sensor Microwave Imager Sounder (SSMIS)
The SSMIS radiometers are used as ancillary data for the calculation of L4 wind fields.
They are onboard the Defense Meteorological Satellite Program (DMSP) F16, F17, F18 and
F19. They provide measurements of the surface brightness temperatures (TB) at frequencies
of 19.35, 22.235, 37, and 85 GHz (hereafter referred to as 19, 22, 37, and 85 GHz),
respectively. Horizontal and vertical polarization measurements are taken at 19, 37, and 85
GHz. Only vertical polarization is available from 22 GHz. Due to the choice of the channels
operating at frequencies outside strong absorption lines [for water vapor] (50-70 GHz), the
radiation observed by the antennae is a mixture of radiation emitted by clouds, water vapor in
the air and the sea surface, as well as radiation emitted by the atmosphere and reflected at the
sea surface.
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Only surface wind speed at 10m height can be derived from SSMIS TB based on the use
of an empirical model fitting the relationship between surface wind speed and TB through the
radiative transfer equation (RTE). SSMIS winds used in this study are from remote sensing
system (RSS) (Wentz, 2013). Full details related to SSMIS data as well as to geophysical
parameter retrievals may be found in (http://www.remss.com/). To meet the project
requirements, near real time SSMIS winds are used. They are extracted based on ftp
downloading procedure. V7 products, available over swath (1400 km width) at wind cell of
0.25° in latitude and longitude over global oceans, are used.
III.5.2 ECMWF
The calculation of L4 wind analyses, based on the objective method described in
(Bentamy et al., 2011), (Bentamy et al, 2016) and (Desbiolles, 2017), requires the use of
NWP surface winds. The L4 NRT stream uses the European Centre for Medium-range
Weather Forecasts (ECMWF) operational forecasts. They are available at synoptic times
(00h:00, 06h:00, 12h:00, 18h:00 UTC) and at grid point of 0.25° in longitude and latitude.
The remotely sensed surface winds are estimated at 10m height in neutral conditions,
while the numerical model winds are provided as 10m real winds. Even though the
atmospheric boundary layer is almost neutrally stable over the global ocean, atmospheric
stability may have an impact on the consistency between scatterometer and ECMWF winds,
particularly in regions of strong currents and/or during winter seasons. Using a large number
of moored buoy data (see hereafter) the difference between 10 m winds and the equivalent
neutral winds both derived from anemometer wind measurements is investigated. About 78%
of total buoy data are measured in stable conditions. Except some few cases (less than 1%),
most of the difference values are between -0.5 m/s (unstable condition) and 0.5 m/s (stable
condition).
To enhance the correspondence between remotely sensed and NWP data, mass density
wind correction is applied on ECMWF winds (De Kloe et al, 2016). The resulting ECMWF
surface winds called stress-equivalent winds (W10s) are calculated and provided by KNMI.
They are available globally at (00h:00, 03h:00, 06h:00, 09h:00, 12h:00, 15h:00, 18h:00,
21h:00) over a map of about 0.30° in longitude and latitude. Since 8 April 2017, KNMI
provides the ECMWF stress equivalent winds to IFREMER.
III.5.3 In-Situ
The accuracy of L4 6-hourly wind estimates is investigated through comprehensive
comparisons with 6-hourly averaged winds estimated from mooring buoy measurements.
Buoy data come from the National Data Buoy Center (NDBC) located along the coast of
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United States of America, Météo-France and U.K. Met office (MFUK) located off the
English, Ireland, and French coasts, Tropical Atmosphere Ocean (TAO) array located in the
equatorial Pacific; and from Pilot Research Moored Array in the Tropical Atlantic (PIRATA)
network located in the equatorial Atlantic. The buoy data include wind speed at the
anemometer height, wind direction (or the corresponding zonal and meridional wind
components), sea surface and air temperatures, and relative humidity (or dew point). As L4
wind products correspond to wind observations at 10-m above the ocean surface, the buoy
winds are converted to 10-m equivalent neutral wind (ENW) using coare3.0 parameterisation
(Fairall et al, 2003)
III.5.4 Collocated Data
Buoys data are 6-houly averaged. They are arithmetically calculated from available and
valid raw measurements occurring within 3 hours of synoptic times (00h:00, 06h:00, 12h:00,
18h:00 UTC). The resulting 6-hourly buoy estimates are collocated with the time
corresponding L4 estimates available within 25 km of mooring locations.
I.1.1 Missing data
No missing data
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.
III.5.5 References
Desbiolles F., A. Bentamy, B. Blanke, C. Roy, A. Mestas-Nunez, S. A. Grodsky , S.
Herbette, G. Cambon, C. Maes, 2017 : Two Decades [1992-2012] of Surface Wind
Analyses based on Satellite Scatterometer Observations . Journal Of Marine Systems ,
168, p. 38-56
Bentamy A. S. A.Grodsk,A. Elyouncha, B. Chapron, F. Desbiolle, 2016 :
Homogenization of Scatterometer Wind Retrievals, Int. J. Climatol. doi:10.1002/joc.
Bentamy A., D. Croizé. Fillon, 2011: Gridded Surface Wind Fields from
Metop/ASCAT Measurements. International Journal of Remote Sensing, 33, pp
1729-1754
De Kloe, J., A. Stoffelen, and A., Verhoef, 2016: Improved Use of
Scatterometer Measurements by Using Stress-Equivalent Reference Winds.
IEEE JSTARS Vol 99, pp.1-8,doi: 10.1109/JSTARS.2017.2685242
Fairall CW, Bradley EF, Hare JE, Grachev AA, Edson JB. 2003. Bulk
parameterization of air–sea fluxes: updates and verification for the COARE
algorithm. Journal of Climate 16: 571–591, DOI:10.1175/1520-
0442(2003)016<0571:BPOASF>2.0.CO;2.
Verspeek, J.; A. Stoffelen, M, Portabella, H. Bonekamp, C. Anderson, and J.F.
Saldana, 2010: Validation and Calibration of ASCAT Using CMOD5.n, IEEE
Transactions on Geoscience and Remote Sensing, 48, 386-395, doi:
10.1109/TGRS.2009.2027896
Wentz, F. J and D. K. Smith, 1999: A model function for the ocean-normalized
radar cross section at 14 GHz derived from NSCAT observations. J. Geophys.
Res., 104, 11 499–11 514
Verhoef, A. and A. Stoffelen, ASCAT Wind Product User Manual. Document
external project: 2013, SAF/OSI/CDOP/KNMI/TEC/MA/126, EUMETSAT,
2013. Available in www.knmi.nl./scatterometer, Complete text
Wentz, F. J., (2013), SSM/I Version-7 Calibration Report, report number
011012, Remote Sensing Systems, Santa Rosa, CA, 46pp.
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IV NOMENCLATURE OF FILES
YYYYMMDDHH-IFR-L4-EWSB-BlendedWind-GLO-025-6H-NRTv6-yyyymmddThhmnsc-
fv1.0.nc
Where
YYYY, MM, DD, and HH are year, month, day, and synoptic hour respectively.
yyyymmddThhmnsc indicates wind field date production.
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V VALIDATION AND ASSESSMENT QUALITY CONTROL DONE ON
PRODUCTS
Detailed information on the calibration and validation, including accuracy determination, of
blended wind product may be found in CMS-OSI-ScCP Scientific Calibration Plan and CMS-
OSI-ScVP Scientific Validation Plan documents.
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VI FILE FORMAT
VI.1 NETCDF
The products are stored using the NetCDF4 format.
NetCDF (network Common Data Form) is an interface for array-oriented data access and a
library that provides an implementation of the interface. The netCDF library also defines a
machine-independent format for representing scientific data. Together, the interface, library,
and format support the creation, access, and sharing of scientific data. The netCDF software
was developed at the Unidata Program Center in Boulder, Colorado. The netCDF libraries
define a machine-independent format for representing scientific data.
Please see Unidata netCDF pages for more information, and to retrieve netCDF software
package.
NetCDF data is:
* Self-Describing. A netCDF file includes information about the data it contains.
* Architecture-independent. A netCDF file is represented in a form that can be accessed by
computers with different ways of storing integers, characters, and floating-point numbers.
* Direct-access. A small subset of a large dataset may be accessed efficiently, without first
reading through all the preceding data.
* Appendable. Data can be appended to a netCDF dataset along one dimension without
copying the dataset or redefining its structure. The structure of a netCDF dataset can be
changed, though this sometimes causes the dataset to be copied.
* Sharable. One writer and multiple readers may simultaneously access the same netCDF
file.
VI.2 STRUCTURE OF NETCDF FILE
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netcdf \2019020100-IFR-L4-EWSB-BlendedWind-GLO-025-6H-NRTv6-20190203T034939-fv1.0 {
dimensions:
time = UNLIMITED ; // (1 currently)
lat = 641 ;
lon = 1440 ;
variables:
float time(time) ;
time:long_name = "time" ;
time:standard_name = "time" ;
time:authority = "CF-1.7" ;
time:units = "hours since 1900-01-01 00:00:00" ;
time:valid_min = 1043880.f ;
time:valid_max = 1043880.f ;
time:axis = "T" ;
float lat(lat) ;
lat:long_name = "latitude" ;
lat:standard_name = "latitude" ;
lat:authority = "CF-1.7" ;
lat:units = "degrees_north" ;
lat:valid_min = -80.f ;
lat:valid_max = 80.f ;
lat:axis = "Y" ;
float lon(lon) ;
lon:long_name = "longitude" ;
lon:standard_name = "longitude" ;
lon:authority = "CF-1.7" ;
lon:units = "degrees_east" ;
lon:valid_min = -180.f ;
lon:valid_max = 180.f ;
lon:axis = "X" ;
double wind_speed(time, lat, lon) ;
wind_speed:_FillValue = 9.96920996838687e+36 ;
wind_speed:least_significant_digit = 3LL ;
wind_speed:long_name = "wind speed" ;
wind_speed:standard_name = "wind_speed" ;
wind_speed:authority = "CF-1.7" ;
wind_speed:units = "m s-1" ;
wind_speed:coverage_content_type = "physicalMeasurement" ;
wind_speed:coordinates = "time lon lat" ;
double eastward_wind(time, lat, lon) ;
eastward_wind:_FillValue = 9.96920996838687e+36 ;
eastward_wind:least_significant_digit = 3LL ;
eastward_wind:long_name = "eastward wind speed" ;
eastward_wind:standard_name = "eastward_wind" ;
eastward_wind:authority = "CF-1.7" ;
eastward_wind:units = "m s-1" ;
eastward_wind:coverage_content_type = "physicalMeasurement" ;
eastward_wind:coordinates = "time lon lat" ;
double northward_wind(time, lat, lon) ;
northward_wind:_FillValue = 9.96920996838687e+36 ;
northward_wind:least_significant_digit = 3LL ;
northward_wind:long_name = "northward wind speed" ;
northward_wind:standard_name = "northward_wind" ;
northward_wind:authority = "CF-1.7" ; northward_wind:units = "m s-1" ;
northward_wind:coverage_content_type = "physicalMeasurement" ;
northward_wind:coordinates = "time lon lat" ;
double wind_vector_curl(time, lat, lon) ;
wind_vector_curl:_FillValue = 9.96920996838687e+36 ;
wind_vector_curl:least_significant_digit = 9LL ;
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wind_vector_curl:long_name = "wind vector curl" ;
wind_vector_curl:standard_name = "atmosphere_relative_vorticity" ;
wind_vector_curl:authority = "CF-1.7" ;
wind_vector_curl:units = "s-1" ;
wind_vector_curl:coverage_content_type = "physicalMeasurement" ;
wind_vector_curl:coordinates = "time lon lat" ;
double wind_vector_divergence(time, lat, lon) ;
wind_vector_divergence:_FillValue = 9.96920996838687e+36 ;
wind_vector_divergence:least_significant_digit = 7LL ;
wind_vector_divergence:long_name = "wind vector divergence" ;
wind_vector_divergence:standard_name = "divergence_of_wind" ;
wind_vector_divergence:authority = "CF-1.7" ;
wind_vector_divergence:units = "s-1" ;
wind_vector_divergence:coverage_content_type = "physicalMeasurement" ;
wind_vector_divergence:coordinates = "time lon lat" ;
double wind_stress(time, lat, lon) ;
wind_stress:_FillValue = 9.96920996838687e+36 ;
wind_stress:least_significant_digit = 5LL ;
wind_stress:long_name = "wind stress" ;
wind_stress:standard_name = "magnitude_of_surface_downward_stress" ;
wind_stress:authority = "CF-1.7" ;
wind_stress:units = "Pa" ;
wind_stress:coverage_content_type = "physicalMeasurement" ;
wind_stress:coordinates = "time lon lat" ;
double surface_downward_eastward_stress(time, lat, lon) ;
surface_downward_eastward_stress:_FillValue = 9.96920996838687e+36 ;
surface_downward_eastward_stress:least_significant_digit = 5LL ;
surface_downward_eastward_stress:long_name = "eastward wind stress" ;
surface_downward_eastward_stress:standard_name = "surface_downward_eastward_stress" ;
surface_downward_eastward_stress:authority = "CF-1.7" ;
surface_downward_eastward_stress:units = "Pa" ;
surface_downward_eastward_stress:coverage_content_type = "physicalMeasurement" ;
surface_downward_eastward_stress:coordinates = "time lon lat" ;
double surface_downward_northward_stress(time, lat, lon) ;
surface_downward_northward_stress:_FillValue = 9.96920996838687e+36 ;
surface_downward_northward_stress:least_significant_digit = 5LL ;
surface_downward_northward_stress:long_name = "northward wind stress" ;
surface_downward_northward_stress:standard_name = "surface_downward_northward_stress" ;
surface_downward_northward_stress:authority = "CF-1.7" ;
surface_downward_northward_stress:units = "Pa" ;
surface_downward_northward_stress:coverage_content_type = "physicalMeasurement" ;
surface_downward_northward_stress:coordinates = "time lon lat" ;
double wind_stress_curl(time, lat, lon) ;
wind_stress_curl:_FillValue = 9.96920996838687e+36 ;
wind_stress_curl:least_significant_digit = 9LL ;
wind_stress_curl:long_name = "wind stress curl" ;
wind_stress_curl:standard_name = "vertical_component_of_surface_downward_stress_curl" ;
wind_stress_curl:authority = "CF-1.7" ;
wind_stress_curl:units = "N m-3" ;
wind_stress_curl:coverage_content_type = "physicalMeasurement" ;
wind_stress_curl:coordinates = "time lon lat" ;
double wind_stress_divergence(time, lat, lon) ;
wind_stress_divergence:_FillValue = 9.96920996838687e+36 ;
wind_stress_divergence:least_significant_digit = 7LL ; wind_stress_divergence:long_name = "wind stress divergence" ;
wind_stress_divergence:standard_name = "divergence_of_surface_downward_stress" ;
wind_stress_divergence:authority = "CF-1.7" ;
wind_stress_divergence:units = "N m-3" ;
wind_stress_divergence:coverage_content_type = "physicalMeasurement" ;
wind_stress_divergence:coordinates = "time lon lat" ;
PUM for Wind product
WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004
Ref: CMEMS-WIND-PUM-012-004
Date : March 2019
Issue : 1.3
© EU Copernicus Marine Service – Public Page /
double wind_speed_rms(time, lat, lon) ;
wind_speed_rms:_FillValue = 9.96920996838687e+36 ;
wind_speed_rms:least_significant_digit = 2LL ;
wind_speed_rms:long_name = "wind speed root mean square" ;
wind_speed_rms:units = "m s-1" ;
wind_speed_rms:coverage_content_type = "auxiliaryMeasurement" ;
wind_speed_rms:coordinates = "time lon lat" ;
double eastward_wind_rms(time, lat, lon) ;
eastward_wind_rms:_FillValue = 9.96920996838687e+36 ;
eastward_wind_rms:least_significant_digit = 2LL ;
eastward_wind_rms:long_name = "eastward wind speed root mean square" ;
eastward_wind_rms:units = "m s-1" ;
eastward_wind_rms:coverage_content_type = "auxiliaryMeasurement" ;
eastward_wind_rms:coordinates = "time lon lat" ;
double northward_wind_rms(time, lat, lon) ;
northward_wind_rms:_FillValue = 9.96920996838687e+36 ;
northward_wind_rms:least_significant_digit = 2LL ;
northward_wind_rms:long_name = "northward wind speed root mean square" ;
northward_wind_rms:units = "m s-1" ;
northward_wind_rms:coverage_content_type = "auxiliaryMeasurement" ;
northward_wind_rms:coordinates = "time lon lat" ;
byte sampling_length(time, lat, lon) ;
sampling_length:_FillValue = -127b ;
sampling_length:long_name = "sampling length" ;
sampling_length:units = "1" ;
sampling_length:coverage_content_type = "auxiliaryMeasurement" ;
sampling_length:coordinates = "time lon lat" ;
byte surface_type(time, lat, lon) ;
surface_type:_FillValue = -127b ;
surface_type:long_name = "flag - 0:ocean - 1:earth/ice" ;
surface_type:units = "1" ;
surface_type:flag_meanings = "sea land_or_ice" ;
surface_type:coverage_content_type = "auxiliaryMeasurement" ;
surface_type:flag_values = 0b, 1b ;
surface_type:coordinates = "time lon lat" ;
float height ;
height:long_name = "height" ;
height:standard_name = "height" ;
height:authority = "CF-1.7" ;
height:units = "m" ;
// global attributes:
:_NCProperties = "version=1|netcdflibversion=4.6.1|hdf5libversion=1.10.2" ;
:Conventions = "CF-1.7, ACDD-1.3, ISO 8601" ;
:netcdf_version_id = "4.6.1 of Sep 8 2018 17:21:01 $" ;
:date_created = "2019-03-12T15:53:34" ;
:date_modified = "2019-03-12T15:53:34" ;
:id = "WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004_V6.0" ;
:naming_authority = "fr.ifremer.cersat" ;
:Metadata_Conventions = "Unidata Dataset Discovery v1.0" ;
:standard_name_vocabulary = "NetCDF Climate and Forecast (CF) Metadata Convention" ;
:institution = "Institut Francais de Recherche pour l\'Exploitation de la mer / CERSAT" ;
:institution_abbreviation = "Ifremer/Cersat" ;
:title = "Global Ocean - Wind Analysis - Blended Sensors - 6 hourly - NRT" ;
:summary = "Multi-sensor blended winds over a 0.25 degree resolution grid , 6-hourly" ;
:cdm_data_type = "grid" ;
:keywords = "Oceans > Ocean Winds > Surface Winds, Oceans > Ocean Winds > Wind Stress" ;
:keywords_vocabulary = "NASA Global Change Master Directory (GCMD) Science Keywords" ;
:project = "Copernicus - Marine environment monitoring service (CMEMS)" ;
PUM for Wind product
WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004
Ref: CMEMS-WIND-PUM-012-004
Date : March 2019
Issue : 1.3
© EU Copernicus Marine Service – Public Page /
:acknowledgment = "Please acknowledge the use of these data with the following statement:
These data were provided by th
e Centre de Recherche et d Exploitation Satellitaire (CERSAT), at IFREMER, Plouzane (France) and
CMEMS" ;
:license = "These data are available free of charge under the CMEMS data policy, refer to
http://marine.copernicus.eu/se
rvices-portfolio/service-commitments-and-licence/" ;
:format_version = "v1.0" ;
:processing_software = "Ifremer blended wind NRT processing chain v6.0" ;
:product_version = " 1.0" ;
:uuid = "0c626477-c7dc-4060-afa1-a3614c1c32b7" ;
:processing_level = "L4" ;
:history = "analysis originally produced by Ifremer/Cersat with blended wind processor 6.0" ;
:publisher_name = "CMEMS" ;
:publisher_url = "marine.copernicus.eu" ;
:publisher_email = "[email protected]" ;
:creator_name = "CERSAT" ;
:creator_url = "http://cersat.ifremer.fr" ;
:creator_email = "[email protected]" ;
:references = "Product User Manual for Wind Product
WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004, v1.3, January 2019" ;
:metadata_link = "" ;
:source = "Ifremer blended wind NRT processor" ;
:source_version = "6.0" ;
:platform = "Metop-A Metop-B DMSP_F-16 DMSP_F-17 CORIOLIS" ;
:platform_type = "low_earth_orbit_satellite low_earth_orbit_satellite low_earth_orbit_satellite
low_earth_orbit_satellit
e low_earth_orbit_satellite" ;
:instrument = "ASCAT ASCAT SSM/IS SSM/IS WindSat" ;
:instrument_type = "scatterometer scatterometer microwave_radiometer microwave_radiometer
microwave_radiometer" ;
:geospatial_lat_min = -80.f ;
:geospatial_lat_max = 80.f ;
:geospatial_lat_units = "degrees_north" ;
:geospatial_lat_resolution = 0.25f ;
:geospatial_lon_min = -180.f ;
:geospatial_lon_max = 179.75f ;
:geospatial_lon_units = "degrees_east" ;
:geospatial_lon_resolution = 0.25f ;
:geospatial_vertical_min = 10. ;
:geospatial_vertical_max = 10. ;
:geospatial_vertical_units = "meters above mean sea level" ;
:geospatial_vertical_positive = "up" ;
:time_coverage_start = "20190201T000000Z" ;
:time_coverage_end = "20190201T000000Z" ;
:time_coverage_resolution = "P6H" ;
:cmems_product_id = "WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004_V6.0" ;
:creator_institution = "Ifremer / CERSAT" ;
:creator_type = "Ifremer / CERSAT" ;
:date_issued = "2019-03-12T15:53:34" ;
:date_metadata_modified = "2019-03-01T00:00:00" ;
:featureType = "grid" ;
:geospatial_bounds = "POLYGON ((-180.0 -80.0, 180.0 -80.0, 180.0 80.0, -180.0 80.0, -180.0 -
80.0))" ; :geospatial_bounds_crs = "WGS84" ;
:geospatial_bounds_vertical_crs = "EPSG:5831" ;
:instrument_vocabulary = "CEOS" ;
:objective_method = "kriging" ;
:platform_vocabulary = "CEOS" ;
:polar_sea_ice_mask_date = "2019-01-27" ;
PUM for Wind product
WIND_GLO_WIND_L4_NRT_OBSERVATIONS_012_004
Ref: CMEMS-WIND-PUM-012-004
Date : March 2019
Issue : 1.3
© EU Copernicus Marine Service – Public Page /
:program = "CMEMS" ;
:publisher_institution = "CMEMS" ;
:scientific_support_contact = "[email protected]" ;
:source_data = "ASCAT_WIND_METOP_A-L2B-v1.0 ASCAT_WIND_METOP_B-L2B-v1.0
SSMIS_DMSP_F16_REMSS-L2-v7.0 SSMIS_DMSP_F17_REMS
S-L2-v7.0 SSMIS_CORIOLIS_REMSS-L2-v7.01" ;
:technical_support_contact = "[email protected]" ;
}