Http://ghrsst.nodc.noaa.gov GHRSST Data Access Tutorial GHRSST Data Access How to Access GODAE High Resolution SST Products from the GDAC and LTSRF Kenneth.

http://ghrsst.nodc.noaa.gov

GHRSST Data Access Tutorial

GHRSST Data AccessGHRSST Data AccessHow to AccessHow to Access

GODAE High Resolution SST GODAE High Resolution SST Products from the GDAC and LTSRF Products from the GDAC and LTSRF

Kenneth S. Casey, Ph.D.Kenneth S. Casey, Ph.D.Long Term Stewardship and Reanalysis FacilityLong Term Stewardship and Reanalysis Facility

NOAA National Oceanographic Data Center, USANOAA National Oceanographic Data Center, USAUpdated: July 2007Updated: July 2007



Regional/Global Task SharingRegional/Global Task Sharing

EUMETSAT

GHRSST data access is possible from all levels of the Regional/Global Task Sharing Framework.

This tutorial covers the basic data access mechanisms from the GDAC at NASA PO.DAAC and the LTSRF at NOAA NODC.

Individual data providers - the RDACs at the top of this framework, also provide their data in a variety of ways. Access to data from the RDACs is not discussed here.



Current StatusCurrent Status

As of July 2007, GHRSST provides integrated As of July 2007, GHRSST provides integrated Level 2 Preprocessed (L2P) SST observations Level 2 Preprocessed (L2P) SST observations from the following sensors:from the following sensors:– AMSR-E, AVHRR-16, AVHRR-17, AVHRR-18 AMSR-E, AVHRR-16, AVHRR-17, AVHRR-18

(GAC,LAC,HRPT), MODIS Aqua and Terra, SEVIRI, (GAC,LAC,HRPT), MODIS Aqua and Terra, SEVIRI, AATSR, TMI, GOES-11, and GOES-12AATSR, TMI, GOES-11, and GOES-12

In addition, gap-free Level 4 (L4) SST In addition, gap-free Level 4 (L4) SST products are available from the following products are available from the following analysis systems:analysis systems:– OSTIA: global, daily, 5 kmOSTIA: global, daily, 5 km– Daily OI: global, daily, 25 km Daily OI: global, daily, 25 km – Mediterranean: daily, 2.2 kmMediterranean: daily, 2.2 km



Current StatusCurrent Status

All data files are in netCDF file formatAll data files are in netCDF file format

All data files contain COARDS/CF compliant All data files contain COARDS/CF compliant file level metadatafile level metadata

All data files have a corresponding DIF All data files have a corresponding DIF metadata record, and once in the LTSRF, metadata record, and once in the LTSRF, FGDC metadata as wellFGDC metadata as well

All data are free and openly available All data are free and openly available to everyoneto everyone

(only OSTIA requires use of a Crown copyright statement)(only OSTIA requires use of a Crown copyright statement)



Example L2P and L4 DataExample L2P and L4 Data

GOES-11 L2PGOES-11 L2PAATSR L2PAATSR L2P SEVIRI L2PSEVIRI L2P

OSTIA L4 - gap-free OSTIA L4 - gap-free analysis productanalysis product

((©© Crown Copyright 2007, data supplied Crown Copyright 2007, data supplied by the Met Office).by the Met Office).

Shown above are Shown above are example L2P images example L2P images (each image may have (each image may have been generated using been generated using several separate L2P several separate L2P files from the same day) files from the same day) and to the right is an and to the right is an example L4, blended, example L4, blended, gap-free analysis gap-free analysis productproduct



GHRSST Access OverviewGHRSST Access Overview

Due to the enormity of the task, GHRSST data Due to the enormity of the task, GHRSST data management is achieved through a partnership management is achieved through a partnership between the NASA Physical Oceanography Distributed between the NASA Physical Oceanography Distributed Active Archive Center (PO.DAAC) and the NOAA Active Archive Center (PO.DAAC) and the NOAA National Oceanographic Data Center (NODC)National Oceanographic Data Center (NODC)PO.DAAC operates the GHRSST Global Data Assembly PO.DAAC operates the GHRSST Global Data Assembly Center (GDAC) and provides SST data within 30 days of Center (GDAC) and provides SST data within 30 days of observationobservationNODC operates the GHRSST Long Term Stewardship NODC operates the GHRSST Long Term Stewardship and Reanalysis Facility (LTSRF), where GHRSST SST and Reanalysis Facility (LTSRF), where GHRSST SST data older than 30 days are available in perpetuitydata older than 30 days are available in perpetuityGHRSST is working toward making access to these GHRSST is working toward making access to these data as seamless as possible across the two centersdata as seamless as possible across the two centers



GHRSST Access OverviewGHRSST Access Overview

The GDAC will typically be the place you should go to The GDAC will typically be the place you should go to begin searching for GHRSST data and toolsbegin searching for GHRSST data and toolsHowever, if the data you are looking for are more than However, if the data you are looking for are more than 30 days old, you can also begin your search at the 30 days old, you can also begin your search at the LTSRFLTSRFThis tutorial will begin at the GDAC, and walk you This tutorial will begin at the GDAC, and walk you through some of the basic search and access through some of the basic search and access techniquestechniquesAfter that, the tutorial will walk you through the search After that, the tutorial will walk you through the search and access mechanisms available at the LTSRFand access mechanisms available at the LTSRF



GDAC Access: Getting Started GDAC Access: Getting Started

Typically, to begin Typically, to begin looking for GHRSST looking for GHRSST data, a user should start data, a user should start at the GDAC: at the GDAC: http://ghrsst.jpl.nasa.govhttp://ghrsst.jpl.nasa.govGeneral information is General information is available hereavailable hereClick on “Data Access” Click on “Data Access” to access data and toolsto access data and tools



GDAC Access: Getting Data and InfoGDAC Access: Getting Data and Info

Here on the GDAC Data Access Here on the GDAC Data Access Page, clicking on “Data” will Page, clicking on “Data” will take you straight to the FTP take you straight to the FTP directories, where you can directories, where you can access the data directly. If you access the data directly. If you are familiar with GHRSST are familiar with GHRSST products and conventions, this products and conventions, this is a good way to get right to the is a good way to get right to the data you wantdata you wantClicking on “Software” or Clicking on “Software” or “Documentation” will take you “Documentation” will take you to example code (currently in C to example code (currently in C and IDL, with Matlab available and IDL, with Matlab available soon) and documents soon) and documents describing GHRSST productsdescribing GHRSST productsClicking on “Data Search” will Clicking on “Data Search” will take you to the GHRSST search take you to the GHRSST search tooltool



GDAC Access: Data SearchGDAC Access: Data Search

Here on the GDAC Data Here on the GDAC Data Search Page, you can Search Page, you can look for GHRSST data by look for GHRSST data by geographic region, time, geographic region, time, by Sensor/Product Level, by Sensor/Product Level, and by RDAC and by RDAC As an example, select As an example, select 2007-Jan-13 as both start 2007-Jan-13 as both start and stop dates, select and stop dates, select AMSR-E as the Sensor, AMSR-E as the Sensor, and select “Detailed” as and select “Detailed” as the search results format the search results format to find all AMSR-E data to find all AMSR-E data from that date.from that date.Then click on “Submit”Then click on “Submit”



GDAC Access: Data SearchGDAC Access: Data Search

Here are some of the results. Here are some of the results. Notice that FTP (and Notice that FTP (and OPeNDAP links if available) OPeNDAP links if available) are provided for the relevant are provided for the relevant data, and that the links point data, and that the links point to the data both at the GDAC to the data both at the GDAC and the originating RDAC (if and the originating RDAC (if available). available). Eventually, if your search Eventually, if your search query returns data older than query returns data older than 30 days, then links to the 30 days, then links to the LTSRF holdings will also be LTSRF holdings will also be providedprovidedYou can click on a file to You can click on a file to download it, or you can use download it, or you can use your favorite FTP client to your favorite FTP client to access the dataaccess the data



LTSRF Access: Getting StartedLTSRF Access: Getting Started

If you know you want data If you know you want data that are more than 30 days that are more than 30 days old, or if you want to find out old, or if you want to find out more about the stewardship more about the stewardship and reanalysis activities in and reanalysis activities in GHRSST, you can go straight GHRSST, you can go straight to the LTSRF at to the LTSRF at http://ghrsst.nodc.noaa.govhttp://ghrsst.nodc.noaa.govNear the bottom of every page Near the bottom of every page you will find the same set of you will find the same set of informational links, and you informational links, and you can also click on the image on can also click on the image on the left to return you to the the left to return you to the LTSRF home pageLTSRF home pageClick on “Access GHRSST Click on “Access GHRSST Data” to get to the GHRSST Data” to get to the GHRSST LTSRF archivesLTSRF archives



LTSRF Access: Data AccessLTSRF Access: Data Access

On the “Access GHRSST On the “Access GHRSST Data” page you will see a link Data” page you will see a link directly to the four main ways directly to the four main ways you can get GHRSST data you can get GHRSST data from the NODC LTSRF:from the NODC LTSRF:– HTTPHTTP– FTPFTP– OPeNDAPOPeNDAP– NODC Ocean Archive SystemNODC Ocean Archive System

HTTP and FTP access HTTP and FTP access mechanisms are very mechanisms are very straightforward… you may straightforward… you may click through to those click through to those directories and download data directories and download data files directly. The next slide files directly. The next slide shows an example of what the shows an example of what the L2P directory looks like… L2P directory looks like…



LTSRF Access: HTTP and FTPLTSRF Access: HTTP and FTP

Here is the example GHRSST Here is the example GHRSST L2P directory structure as seen L2P directory structure as seen using HTTP. Up one level higher using HTTP. Up one level higher in the parent directory at in the parent directory at http://data.nodc.noaa.gov/ghrssthttp://data.nodc.noaa.gov/ghrsst you can you can also see the L2P_GRDIDED and also see the L2P_GRDIDED and L4 directories. Note that when L4 directories. Note that when additional data streams enter the additional data streams enter the LTSRF, additional directories will LTSRF, additional directories will be shown.be shown.The FTP directory structure is The FTP directory structure is identical and can be examined identical and can be examined using your browser or favorite using your browser or favorite ftp client. Just point them at ftp client. Just point them at ftp://data.nodc.noaa.gov/pub/data.nodc/ghrsstftp://data.nodc.noaa.gov/pub/data.nodc/ghrsst..



LTSRF Access: OPeNDAPLTSRF Access: OPeNDAP

The OPeNDAP structure is also The OPeNDAP structure is also identical, but it has a different identical, but it has a different base URL: base URL: http://data.nodc.noaa.gov/cgi-binhttp://data.nodc.noaa.gov/cgi-bin/nph-dods/ghrsst/nph-dods/ghrsstTo the left is what one example To the left is what one example L4 product looks like in the L4 product looks like in the OPeNDAP directoryOPeNDAP directoryThe next several slides will The next several slides will demonstrate how to select a demonstrate how to select a particular file and look at its particular file and look at its contents using OPeNDAP and contents using OPeNDAP and your web browseryour web browserFrom the listing for L4 MED From the listing for L4 MED (Mediterranean area) data from (Mediterranean area) data from the EUR (European) RDAC, the EUR (European) RDAC, select day 304…select day 304…




After selecting day 304, After selecting day 304, you’ll see the files on the you’ll see the files on the leftleft– The *.nc.bz2 is the bzip2-The *.nc.bz2 is the bzip2-

compressed netCDF data compressed netCDF data filefile

– The FDGC*.xml file is the The FDGC*.xml file is the corresponding FGDC corresponding FGDC metadata recordmetadata record

– The FR*.xml file is the The FR*.xml file is the original DIF-formatted original DIF-formatted metadata record (which metadata record (which contains much less contains much less information than the FGDC information than the FGDC record)record)

Now click on the *.nc.bz2 Now click on the *.nc.bz2 file to open the OPeNDAP file to open the OPeNDAP web form…web form…




Here is the OPeNDAP web Here is the OPeNDAP web form, which shows the form, which shows the attributes and variables attributes and variables contained in the GHRSST contained in the GHRSST netCDF files. You can netCDF files. You can select any of the select any of the parameters and then click parameters and then click on “Get ASCII” to see the on “Get ASCII” to see the data in plain text - you data in plain text - you would not want to do this would not want to do this to download significant to download significant amounts of data but it can amounts of data but it can be useful for quickly be useful for quickly browsing some of the browsing some of the contents.contents.There is one more way to There is one more way to search for and access search for and access GHRSST data at the GHRSST data at the LTSRF… LTSRF…



LTSRF Access: OASLTSRF Access: OAS

http://www.nodc.noaa.gov/cgi-bin/search/prod/http://www.nodc.noaa.gov/cgi-bin/search/prod/accessionsView.pl/prefaccessionsView.pl/pref

Here is the general NODC Here is the general NODC Ocean Archive System Ocean Archive System (OAS), which you can use to (OAS), which you can use to find GHRSST datasetsfind GHRSST datasetsFollowing the link below, Following the link below, you can then select various you can then select various fields to search on… to limit fields to search on… to limit the searches to only the searches to only GHRSST data, make sure GHRSST data, make sure you set Contributing you set Contributing Projects equal to “GHRSST-Projects equal to “GHRSST-PP”PP”The example here further The example here further limits the search to only limits the search to only GHRSST AATSR data (use GHRSST AATSR data (use instrument type = “AATSR-instrument type = “AATSR-NR”) since 14 October 2006.NR”) since 14 October 2006.Click on “search”…Click on “search”…




Here are the results of that Here are the results of that search… when this search… when this example was generated, 18 example was generated, 18 records (each record records (each record consists of all of the files consists of all of the files from a given RDAC, for a from a given RDAC, for a given sensor, on a given given sensor, on a given day) matched the search day) matched the search criteria.criteria.You can click on “details” You can click on “details” for more metadata for more metadata information or on the information or on the accession number to go accession number to go right to the archive right to the archive directory if you wish to directory if you wish to access the dataaccess the data




Important note:Important note: the OAS the OAS geographic search capability is geographic search capability is counter-intuitive, and works counter-intuitive, and works basically opposite to how you basically opposite to how you might expectmight expectTo use geographic searches, set To use geographic searches, set your preferences to include the your preferences to include the four boundary elements, and again four boundary elements, and again remember to set Contributing remember to set Contributing Projects equal to “GHRSST-PP”Projects equal to “GHRSST-PP”Click on “Continue” at the bottom Click on “Continue” at the bottom of the page (not shown here)of the page (not shown here)




As an example, search for As an example, search for GHRSST data that include Cook GHRSST data that include Cook Inlet, Alaska. A box that bounds Inlet, Alaska. A box that bounds this region spans 58 to 64º North, this region spans 58 to 64º North, and -156 to -144º West (Remember and -156 to -144º West (Remember West longitudes and South West longitudes and South latitudes are negative).latitudes are negative).In most search tools, you’d simply In most search tools, you’d simply use 58 as South, 64 as North, -156 use 58 as South, 64 as North, -156 as West, and -144 as the East as West, and -144 as the East BoundaryBoundaryHOWEVER, the OAS is different. HOWEVER, the OAS is different. See how this example is See how this example is implemented in the image on the implemented in the image on the left. It would take several pages left. It would take several pages to try to explain this in words… so to try to explain this in words… so follow this example. At the time follow this example. At the time this presentation was created, this presentation was created, 2911 records were returned. 2911 records were returned.



GHRSST Data AccessGHRSST Data Access

We hope this simple tutorial helps, but We hope this simple tutorial helps, but please remember…please remember…

There are many people ready to assist you - at There are many people ready to assist you - at the RDACs, at the GDAC, and at the LTSRF. the RDACs, at the GDAC, and at the LTSRF. Don’t hesitate to call or email!Don’t hesitate to call or email!More sophisticated access and browse More sophisticated access and browse mechanisms exist at many RDACs (for example, mechanisms exist at many RDACs (for example, Live Access Servers) and are being developed Live Access Servers) and are being developed for the GDAC and LTSRF. This presentation is for the GDAC and LTSRF. This presentation is intended to focus only on the basic GDAC and intended to focus only on the basic GDAC and LTSRF access techniques like FTP, OPeNDAP, LTSRF access techniques like FTP, OPeNDAP, and the Ocean Archive System (OAS).and the Ocean Archive System (OAS).



For More Information:For More Information:

[email protected]@noaa.gov

http://ghrsst.nodc.noaa.govhttp://ghrsst.nodc.noaa.gov

Http://ghrsst.nodc.noaa.gov GHRSST Data Access Tutorial GHRSST Data Access How to Access GODAE High Resolution SST Products from the GDAC and LTSRF Kenneth.

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basic data access mechanisms

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