GlobColour / Medspiration User Consultation, November 20-22, 2007, Oslo, Norway Session 2 –...

GlobColour / Medspiration User Consultation, November 20-22, 2007, Oslo, NorwaySession 2 – GlobColour Products – Processing and Data Access

GlobColour ProductsProcessing and Data Access

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Gilbert Barrot, Julien DemariaACRI-ST



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1 The GlobColour products

3 Data access

2 Processing status

Where and how to get the data ?

What are the GlobColour parameters ?FPS, DDS and DDS_insitu productsGrids and files format

Which products are currently available ?



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The GlobColour Parameters

Not all parameters areavailable for all merging

methods

Methods selected at WS1Weighted average+GSM for CHL1

All products includeerror bars and flags

Parameters andmerging methods



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CHL1 weighted average pre-processing

Inverse formulation is available in the Product User Guide


CHL1AVW2003

Jan Feb Mar Apr

May Jun Jul Aug

Sep Oct Nov Dec



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CDM(m-1)

2003/05 CDM_MERIS monthly mean

2002/07 CDM_GSM monthly mean

CDM is the coloured dissolved and detrital organic materials (m-1). Two GlobColour products are generated for FPS:

A merged CDM concentration is generated using the GSM model from the daily L3 radiance products of the 3 instruments if available.The other one comes from the MERIS products.

MERIS-derived CDM productGSM-derived CDM product




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BBP(m-1)

2003/05

bbp is the particulate back-scattering coefficient (in m-1) at λ0 = 443nm.

The merged bbp concentration is generated using the GSM model.

From the initial GlobColour bbp merged product, we have therefore the

possibility of generating the following products:bp (m-1) = bbp/0.015 TSM (g.m-3) = 1.73*bp = 1.73*bbp/0.015

GSM-derived bbp product


2003/05



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Kd(490) is the diffuse attenuation coefficient at 490 nm (m-1). It is one indicator

of the turbidity of the water column. The merged Kd(490) is computed directly

from the merged CHL1, using the following equation:

with: Kw(490) = 0.0166 m-1

= 0.08349

e(490) = 0.63303

)(ewd chl)()(K)(K

490(Morel, 2006)


May 2003

Nov. 2003



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Lxxx is the fully normalised water leaving radiances at xxx nm (in mW/cm²/µm/sr).

Spectral values are: 412, 443, 490, 510, 531, 550-565, 620, 665-670, 681 and 709 nm.

MERIS reflectances (L2 products) are converted into fully normalised water leaving radiances (normalisation is not applied to the MERIS 681 nm fluorescence band and to the 709 nm band.). MODIS-only - MERIS-only - Preprocessing




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The 550-565 bands are submitted to a specific processing just before averagingto prepare a more consistent merging between the instruments.First of all, all bands are spectrally re-affected to 555 nm, using inter-spectralconversion rules, which are functions of the CHL1 concentration.


L555July 2002

Weighted average

2002/05



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EL555 is the relative (%) excess of radiance at 555 nm, above a given threshold.The EL555 parameter is computed from the L555 fully normalised water leaving radiance and the CHL1 products.The daily products are computed for each instrument using the associated dailywater leaving radiance and daily CHL1, while the merged product is computedfrom the merged L555 and the merged CHL1 concentration.

Details in User Guide




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CFJuly 2002

CF is the “cloud fraction” (expressed in %).

daily products: percentage of input pixels per bin flagged as cloudy in the original L2 products

8-days and monthly products: percentage of merged days per bin where the daily cloudfraction is greater than a specified threshold (50% in current processor conf.)

Takes into account clouds, ice andhigh aerosol load contamination




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The

fla

gsThe GlobColour Parameters



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Information stored in the products

(1): stdev is not computed in the nearest neighbour interpolation process(2): before merging step, error is not provided pixel-wise, but the global relative error (%) coming from the characterisation is saved in metadata(3): stdev is not defined at the output of the merging module. Only error is estimated.(4): error is the output of the weighted average merging model. Only products merged using this method contain the error pixel-wise field; other products does not contain this field.(5): for merged daily, 8-days and monthly products, count is not the number of L2 binned pixels, but the number of days contributing to the bin. So for merged daily products, it is always set to 1.(6): computed from the quadratic sum of the inverse errors of the parents products.(7): quicklook product does not contain any geophysical variable

Complete details are available in the GlobColour

Product User Guide




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FPS, DDS and DDS_insitu

FPS, DDS and DDS_insitu

FPS: global productsone parameter per file

DDS: local products on specific areas (100x100 km2)all parameters in a single filesystematic production

DDS_insitu: local products on specific areasall parameters in a single fileproduction linked to in-situ data availability



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GlobColour products are netCDF files

Grids and Files Format

CDL representationin the PUG



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GlobColour grids

Plate-Carré Integerised Sinusoidal

1 km

0.25° 1.00°4.6 km

All bins Only valid bins

Easy geolocation More complex




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The row(), col(), center_lat(), center_lon() and lon_step() arrays allow an easier conversion of the bin index into geographical coordinates.

Equations to compute center longitude and latitude for a bin b:

index = row(b) – first_row (first_row is a global attribute) lat(b) = center_lat( index ) lon(b) = center_lon( index ) + col(b) * lon_step( index )




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and any external tools using netCDF reader and ISIN / PC grid definition

Tools to browse/plot ISIN and PC productsare available on the GlobColour web site




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3 Data access

2 Processing status


What are the GlobColour parameters ?FPS, DDS and DDS_insitu productsGrids and file formats




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MODIS 1.1

SeaWiFS 5.1

MERIS 2.0/Q

Level 2 products

1997 … 2006

PC - 1kmISIN – 4km

Track

Not mergedDDS

ISIN - 4kmDay

Not mergedDDS

ISIN - 4kmDay

MergedDDS

PC - 1kmISIN – 4km

Track

Not mergedDDS in-situ

ISIN - 4kmDay

Not mergedDDS in-situ

ISIN - 4kmDay

MergedDDS in-situ

GlobColour processor

Processing Status



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ISIN – 4km8-daysMonthly

MergedFPS

ISIN - 4kmDay

MergedFPS

GlobColour processor

PC – 25kmPC – 100 km

Day

MergedFPS

PC – 25kmPC – 100km

8-daysMonthly

MergedFPS

Diskstorage

Archive

ftp server

web server

Processing Status



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L3b 68491 1/24°

L3m 136982 0.25° & 1.00°

png 68491 0.25°

L3m TR 99934 1 km

L3b TR 101541 1/24°

L3b DAY 280028 1/24°

L3m TR 6691 1 km

L3b TR 6769 1/24°

L3b DAY 16229 1/24°

fps

dds

dds_

insi

tuProcessing Status



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MERIS data 04/2002 – end 2006

MODIS data 06/2002 – end 2006

FPS 1.0

SeaWiFS data 09/1997 – end 2002

Merged products3 instrumentsonly for 2002

Processing Status



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Extention to end 2006on distribution servers

before Xmas



FPS 1.1


Processing Status



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FPS 2.0


Available in 2008

Start of NRTservice demonstration

Processing Status



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3 Data access

2 Processing status



What are the GlobColour parameters ?FPS, DDS and DDS_insitu productsGrids and file formats



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Data Access

ftp web (*)

All products All products

Tree structure Selection (GUI)

No extraction Extraction

GlobColour web site Available early 2008

Data Access



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Any ftp client

Data Access

ftp data access2 ways… at least…

WgetUnix command

wget -r -l10 -t10 -A "L3m*_25_*CHL1_MO*.gz" -w3 -Q1000m \ftp://globcolour_data:[email protected]/FPS/CHL1 ./

All CHL1 monthly quicklooks at 25 km resolution

GlobColour products filenames are described in the PUG



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Thank youfor yourattention

GlobColour / Medspiration User Consultation, November 20-22, 2007, Oslo, Norway Session 2 –...

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