product user manual for wind product wind glo wind l4 nrt … · 2021. 2. 3. · through october...

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 /

PRODUCT USER MANUAL

For Wind product


Issue: 1.3

Contributors: Abderrahim Bentamy

Approval Date : March 2019




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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.




Date : March 2019

Issue : 1.3


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.

http://marine.copernicus.eu/web/34-products-and-services-faq.php







Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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).




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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.

http://www.eumetsat.int/Home/Main/Publications/Technical_and_Scientific_Documentation/Technical_Notes/

http://www.eumetsat.int/Home/Main/Publications/Technical_and_Scientific_Documentation/Technical_Notes/

http://www.knmi.nl/scatterometer/

http://www.osi-saf.org/)




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


.

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.




Date : March 2019

Issue : 1.3


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.




Date : March 2019

Issue : 1.3


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.




Date : March 2019

Issue : 1.3


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




Date : March 2019

Issue : 1.3


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 ;




Date : March 2019

Issue : 1.3


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" ;




Date : March 2019

Issue : 1.3


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)" ;




Date : March 2019

Issue : 1.3


: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" ;




Date : March 2019

Issue : 1.3


: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]" ;

}

product user manual for wind product wind glo wind l4 nrt … · 2021. 2. 3. · through october...

Documents