J2-XGDR - OSTM/Jason-2: Level-2 Geophysical Data Records

Cycle

The ~10 day repeat period of the satellite's orbit. It comprises 254 pole-to-pole passes.

For searching, the user may specify cycle as a positive number or a range of numbers, such as "1-10", "20,40,60", "20-22,30-32", "5,10,15-16,20". 

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Data Usage Guidance/Restrictions

Access restrictions on the Operational Geophysical Data Records were lifted on 15 December, 2008. Restrictions on the Interim Geophysical Data Records were lifted on 15 January, 2009. Restrictions on the Geophysical Data Records will be lifted after the June 2009 Ocean Surface Topography Science Team meeting, which serves as the final Jason-2/OSTM product verification workshop.

All members of the Ancillary data family (J2-ANC), Orbital Information family (J2-ORBINFO), and Quality Assurance reports family (J2-QA) were made unrestricted on 15 December, 2008.

Filetypes in the Auxiliary data family (J2-AUX), which are produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), are restricted by ECMWF to the Jason-2 project team. All telemetry data (J2-TEL) are restricted to the project team, per the mission's 4-partner Memorandum of Understanding. For these restricted data families, users will only see listed those datatypes upon which they can search.

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Dataset Name

File-naming Convention

The naming conventions for the files in this family are as follows:

OGDR:  JA2_OPN_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

OGDR-SSHA: JA2_OPR_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

OGDR-BUFR: JA2_OPB_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

IGDR: JA2_IPN_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

IGDR-SSHA: JA2_IPR_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

S-IGDR:  JA2_IPS_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

GDR:  JA2_GPN_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

GDR-SSHA:  JA2_GPR_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

S-GDR:  JA2_GPS_2PvSccc_ppp_yyyymmdd_hhnnss_yyyymmdd_hhnnss

 

Where fields in caps are fixed per datatype with:

Characters 1 through 3 set to “JA2” to indicate the data is from the Jason-2 platform;

The 5th character of the file name standing for the product type with:

O = OGDR
I  = IGDR
G = GDR;

The 6th character of the file name is a constant “P”;

The 7th character of the file name standing for the type of file:

N = Native
R = Reduced SSHA
S = Sensor
B = BUFR;

The 8th and 9th characters of the file name are constant “2P”;

The 12th character of the file name is set to a constant “S”;

and those in lower case are as follows:

v = Version of the file. Length: 1 char. Domain: "T" for Test during pre-operational phase, “a” initially and “b”, “c” etc. through “z” as needed during operational phase.

ccc = Cycle number. Note: for IGDR and GDR datatypes, the file will contain data from just one cycle. For OGDR datatypes, the file may contain data from multiple cycles but this field will only indicate the starting cycle number. Length: 4 char. Domain: “000”, “001” etc. as needed for the life of the mission. Note that pre-operational data utilized cycle numbers 998 and 999 since these cycles will not be reached operationally.

ppp = Pass number. Note: for IGDR and GDR datatypes, the file will contain data from just one pass. For OGDR datatypes, the file may contain data from multiple passes but this field will only indicate the starting pass number. Length: 4 char (a preceding underscore followed by a 3-digit indication of the pass). Domain: “_001” to “_254”.

yyyymmdd = Sensing Start Date – the starting date of observations. Length: 9 char. (8 characters for the date string, plus one for the preceding underscore). Domain: "_yyyymmdd" where the variable components of date strings are: "yyyy" = 4-digit year (e.g. 2007), "mm" = 2-digit month (01-12), "dd" = 2-digit day of month (01-31).

hhnnss = Sensing Start Time – the starting UTC time of observations. Length: 7 char. (6 characters for the time string, plus one for the preceding underscore). Domain: "_hhnnss" where the variable components of time strings are:

"hh" = hour (00-23), "nn" = minute (00-59), "ss" = second (00-59).

yyyymmdd = Sensing End Date – the ending date of observations. Length: 9 char. (8 characters for the date string, plus one for the preceding underscore). Domain: "_yyyymmdd" where the variable components of date strings are: "yyyy" = 4-digit year (e.g. 2007), "mm" = 2-digit month (01-12), "dd" = 2-digit day of month (01-31).

hhnnss = Sensing End Time – the ending UTC time of observations. Length: 7 char. (6 characters for the time string, plus one for the preceding underscore). Domain: "_hhnnss" where the variable components of time strings are:

"hh" = hour (00-23), "nn" = minute (00-59), "ss" = second (00-59).

Total Filename Length: 51 char.

Filename example: 

JA2_OPN_2PaS143_217_20100322_211754_20100322_231846

Each file will be paired with a corresponding XML-Formatted metadata file whose naming convention is simply the data file name with a .xml extension.

Total Filename Length: 55 char.

Filename example: 

JA2_OPN_2PaS143_217_20100322_211754_20100322_231846.xml

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Datatype

J2GDR
J2GDRSSHA
J2IGDR
J2IGDRSSHA
J2OGDR
J2OGDRBUFR
J2OGDRSSHA
J2SGDR
J2SIGDR

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End Cycle

The cycle corresponding to the last data point in the file.

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End Pass

The pass corresponding to the last data point in the file.

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End Time

The UTC date and time corresponding to the end of the coverage of the given dataset.
Format is yyyy-mm-dd hh:mm:ss.fff where fff is the fraction of a second in milliseconds.

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Inventory ID

A unique numerical ID assigned to the data set for CLASS inventory purposes.

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Node

The ascending node refers to that portion of the orbit during which the satellite is heading northward.
Descending refers to the southbound portion.

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Pass

Half of an orbital revolution, running from southern-most latitude to northern-most for ascending passes, which are odd numbered; or from northern-most latitude to southern-most for descending passes, which are even numbered.

For searching, the user may specify pass as a positive number or a range of numbers from 1 to 254, such as "10-20", "250,254", "10-20,40", "10-20,40-42", "5,8-10,12". 

The following is commercial freeware Pass Locator Tool is provided by Aviso, as part of the SSALTO ground processing segment. CLASS does not endorse any commercial packages or vendors.

This link is outside of the CLASS domain. You may wish to check their privacy policy.

Pass Locator Tool by Aviso. 

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Satellite

The satellite that acquired the data.

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Start Cycle

The cycle corresponding to the first data point in the file.

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Start Pass

The pass corresponding to the first data point in the file.

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Start Time

The UTC date and time corresponding to the beginning of the coverage of the given dataset.
Format is yyyy-mm-dd hh:mm:ss.fff where fff is the fraction of a second in milliseconds.

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Temporal

The user may specify a time interval for searching using either date and time, OR a range of cycles.  To search by date and time, click on the "Date" radio button, then enter the desired Start Date, Start Time, End Date, and End Time.  To search by cycle, click on the "Cycle" radio button, then enter the cycle number or range of numbers.  Only one of these temporal search methods can  be used per search. 

The user may also specify a set of passes to search for within the time interval, for either a date and time search or a cycle range search. If no specific passes are  requested, all 254 passes per cycle will be included in the search.

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UTC

Coordinated Universal Time (UTC) is the international time standard. It is the current term for what was referred to as Greenwich Meridian Time (GMT). Zero (0) hours UTC is midnight in Greenwich England, which lies on the zero longitudinal meridian. Universal time is based on a 24 hour clock, therefore, afternoon hours such as 4 pm UTC are expressed as 16:00 UTC (sixteen hours, zero minutes).

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