HRDI data is available in several forms. We recommend using the level 3a data files for most purposes. These files contain the raw HRDI results interpolated at regular time (3AT files) or latitude (3AL files) locations, and are available on both altitude and pressure grids.

HRDI leve 3a data can be obtained in several different ways, depending on which nodes the user has access to. Users at the Space Physics Research Lab (SPRL) should log into the HRDI computer system (HRDRAC) to access the data. Users having an account on the UARS CDHF system should access the data there. Other potential users of the data should get access to it through the Goddard Space Flight Center (GSFC) Distributed Active Archive Center (DAAC). Data files can be obtained as follows:

For HRDRAC users:

Level 3a files are stored in the following locations, by level and subtype:

• L3at merwin data is in tmerwin
• L3al merwin data is in lmerwin
• L3at zonwin data is in tzonwin
• L3al zonwin data is in lzonwin

If a file cannot be found there (there is only room for a limited number of files online), the files can be promoted from the optical jukebox storage (where all level 3a files are available) using the 'arc/promote' or 'arc/fetch' commands. To promote the L3AT merwin_a file for day 800 (for example), you enter the DCL command:

ARC/FETCH/LEVEL=3AT/SUBTYPE=MERWIN_A/UARS=800

or you can use the command:

ARC/PROMOTE="HRDI_L3AT_SMERWIN_A_D0800.V0001_C01_PROD"

The file will then be promoted (it may take a couple of minutes, depending on how busy the archive system is) to the 'TMERWIN' area. The HRDI archive system will mail you a message with the status of your promotion request when it has finished, if you used the fetch command.

For a more detailed description of the archive system and software, see the archive system section in the HRDI Cookbook. For simple questions, there is also online help available by typing "help arc". Descriptions of the UARS/HRDI level 3a data file format can be obtained from the HRDI Cookbook.

For CDHF users:

Files can be copied from the optical storage area to a user's 'home' computer using the CDHF data transfer (DT) command, as in the following example:

DT/CDHF HRDRAC:: SELECT/LEVEL=3AT/TYPE=HRDI/SUBTYPE=MERWIN_A/DAY=800

(replacing 'HRDRAC' with your home computer's name, '3at', 'merwin_a', and '800' with the appropriate level, subtype, and uars day number for the data desired), or they can be transfered to the user's area on CDHF (by replacing 'HRDRAC::' with the area you desire).

The file will then be transfered to the appropriate area. It may take several minutes to complete this transfer. The UCSS (UARS CDHF Software System) will mail you a message with the status of your transfer request when it is complete. Online help is available on the CDHF for the DT command by typing 'help dt'.

The format of level 3a UARS files in general, and HRDI files in particular, can be obtained through the SFDU_REG menu system on the CDHF (just type sfdu_reg, select 'Req. Data Description Package', and request the 'generic level 3al data format', 'generic level 3at data format', 'hrdi level 3al data file description', and 'hrdi level 3at data file description' - the files are e-mailed to you, usually within a day).

More information about UARS and the CDHF is available through the UARS home page.

For DAAC users:

The first two years of HRDI level 3a stratospheric and mesospheric wind data are now on the GSFC DAAC. To transfer data from the GSFC DAAC to your system, follow the following steps:

1. telnet daac.gsfc.nasa.gov (telnet to the daac)
2. reply to username prompt with 'daacims' (log in as daacims)
3. reply to password prompt with 'gsfcdaac'

The menu-driven data ordering system will then start up, and guide the user towards requesting the data. You should note that this system requires that users be registered, and affiliated with some registered institution. If your version of Web software has a telnet capability, you can request data through the GSFC DAAC home page. Users should also keep in mind that the GSFC DAAC is a UNIX machine, and also a non-DEC machine, so that the data storage format for real*4 and integer*4 numbers may not be the same as for other machines (in our case, the data is stored byte reversed from our DEC system storeage, so that the four bytes of an integer (1,2,3,4) are stored and transfered in reverse order (4,3,2,1) on the DAAC, and much be reversed in the transfered data file before use here.

Documentation on the file format can be requested along with the data files.

Questions concerning access to data via the DAAC can be addressed to:

• GSFC DAAC User Services
• telephone (301) 286-3209
• or e-mail daacuso@eosdata.gsfc.nasa.gov

File Access Software

FORTRAN Software

A simple FORTRAN program to read a hrdi level 3 file and dump it as an ascii file is available in:

sprlj::hrd$prjroot:[l3.doc]new_read3_with_includes.for

It doesn't reference any external include files, to make it more portable to other systems. SPRLJ HRDI users can use:

hrdrac::hrd$prjroot:[l3.tools]new_read3.for

(and run its executable, hrdrac::hrd$prjroot:[l3.test]new_read3.exe)

instead, which is somewhat easier to look thru, but contains references to external include files.

The program prompts for two inputs, the name of the file to be read (which should include its location), and the name of the output ascii file to be created.

IDL Software

IDL routines to read level HRDI level 3 wind files exists in:

hrdrac::hrd$prjroot:[idl_lib.src]l3_extract.pro

This file contains a routine to read level 3 files into a structure for analysis. The routine prompts for the names of the input file, and places the wind profiles into the structure along with the profile times, the latitudes and longitudes, the solar zenith angles, the altitudes, and the measurement variances. For more information on these routines, check the HRDI Users Guide, IDL section.