CREX software

WMO BUFR training course Langen 17-20 April 2007

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CREX softwareMilan Dragosavac


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Requirements for CREX software

Suitable for small volume of observations

Building blocks for other applications

Encoding

Decoding

Conversion to BUFR

Low maintenance costs

Portable


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Programming languages used

Fortran 77

- All CREX subroutines and functions

C

- Reading/writing CREX data

- gbyte, sbyte routines unpack/pack bytes


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Ecmwf CREX software

How to get the software?

The software can be downloaded from Ecmwf web site

http://www.ecmwf.int/products/data/software/

Go to Free download and get crex_000320.tar.gz file

gunzip crex_000320.tar.gz

cd crex_000320

Read README file for explanations

Execute make command which will create libcrex.a

cd example

Running make will create number of executables


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Ecmwf CREX software

Content of crex_000310 directory

-rw-r----- 1 maa ma 450 Jul 5 2006 Makefile

-rw-r----- 1 maa ma 10758 Jul 5 2006 README

-rwxr----- 1 maa ma 3662 Jul 5 2006 build_library

drwxr-x--- 2 maa ma 4096 Jul 5 2006 config

drwxr-x--- 2 maa ma 4096 Feb 12 07:53 crexdc

drwxr-x--- 2 maa ma 4096 Feb 12 11:07 crextables

drwxr-x--- 2 maa ma 4096 Jul 5 2006 doc

drwxr-x--- 3 maa ma 4096 Feb 12 09:27 example

-


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Ecmwf CREX software

rwxr----- 1 maa ma 3107 Jul 5 2006 install

-rw-r----- 1 maa ma 1196 Jul 5 2006 licence

drwxr-x--- 2 maa ma 4096 Jul 5 2006 options

drwxr-x--- 2 maa ma 4096 Feb 12 07:53 pbio


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Ecmwf CREX software

config directory contains various configuration files

for different platforms and compilers

options directory contains various options for different platforms

You can make additional configurations and options if needed


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Ecmwf CREX software

pbio

pbio directory contain all c and fortran routines needed for BUFR and CREX IO

all routines are part of bufr and crex libraries

crexdc

crexdc directory contain all crex software source code routines which are written in fortran 77


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Ecmwf CREX software

example

bufr2crex.F

create_crex.F

crex2bufr.F

crextdexp.F

decode_crex.F

doc

doc directory contain CREX User’s Guide and Reference Manual in pdf format


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Ecmwf CREX software

Crex is table driven code form

- no need to transfer element names, units …

- no need to change CREX software for new observations

Crex table B – classification elements

- reference number

- element name

- element unit

- scale

- data width in bytes


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Ecmwf CREX software

Crex table D – list of common sequences to describe the data

- table B elements

- operators

- other table D descriptors

Crex table C – text and meaning of code/flag tables


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Ecmwf CREX software

CREX table naming convention

BXXYYZZ

DXXYYZZ

B - Crex table B

D - Crex table D

XX - Crex Master table used “00”

YY - Crex edition number used “01”

ZZ - Crex table version number “03”


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Ecmwf CREX software

PATH for CREX tables

export CREX_TABLES=/xxx/

setenv CREX_TABLES /xxx/

The path must end with back slash “/”

Check digit indicator

export USE_E=true

setenv USE_E true


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Ecmwf CREX software

Defaults

Integer missing value indicator

NVIND=2147483647

Real*8 missing value indicator

RVIND= 1.7E38


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Decoding CREX data

There are 4 steps in CREX data processing

Open crex input file

Read in one crex message at a time

Expand crex message

Use the data

Repeat last three steps until the end of file is reached


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PBIO routines

FORTRAN routines to handle products in an unblocked binary file

subroutine PBOPEN ( kunit, filename, mode, kerr )

Input arguments:

filename - character variable

mode - character variable ‘r’ read, ‘w’ write, ‘a’ append, ‘r+’ read and write

Output arguments:

kunit - integer unit number

kerr - integer status return code


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PBIO routines

kerr - 0, successful

-1, file does not exist

-2, invalid file name

-3, invalid open mode specified


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PBIO routines

subroutine PBCLOSE (kunit, kret)

Input argument is an integer:

kunit - unit number from PBOPEN

Output argument is an integer:

kret – status return code

0 - OK

-1 - error in handling the file


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PBIO routines

subroutine PBWRITE( kunit, karray, kount, kerr)

Input arguments are integers:

kunit – unit number from PBOPEN

karray- an integer array holding bytes for write

kount – number of bytes to write to the file

Output arguments:

kret – status return code

>= 0 number of bytes written to the file

-1 Error in writing to the file


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PBIO routines

Subroutine PBCREX( KUNIT, KARRAY, KINLEN,

KOUTLEN, KRET)

Input arguments:

KUNIT - unit number returned by PBOPEN

KARRAY - integer array big enough to hold crex message

KINLEN - size in bytes of KARRAY

Output arguments:

KOUTLEN - size in bytes of the CREX product read

KRET - 0 if OK


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PBIO routines

KRET -1 if EOF is hit before CREX product is read

-2 if file read error is generated

-3 if size of KARRAY is not sufficient for the CREX product


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CREX software FORTRAN routines

CREX expansion

subroutine crexex( kbufl, ybuff, ksup, ksec0,ksec1, ksec3, kelem, cnames, cunits,

kvals, values, cvals, kerr)

Input arguments:

kbufl - length of bufr message in words

ybuff - character string containing crex message

kelem - expected number of expanded elements

kvals - the size of values array in words


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Output arguments:

ksup - an array containing supplementary information

ksec0 - integer array of 3 words containing CREX

section 0 information

ksec1 - integer array of at least 40 words containing

CREX section 1 information

ksec3 - integer array of 4 words

cnames – character*64 array of kelem containing element names

cunits - character*24 array of kelem containing element units


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values - real*8 array of kvals containing expanded data

cvals - character*80 array of kvals containing code table or CCITTIA5 CREX element entries

kerr - return error code


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KSUP array of 9 words

Array index

Word content

1 IDIM1, dimension of ksec1

2 Reserved

3 IDIM3, dimension of KSEC3

4 Reserved

5 M (number of elements in in values array, first index)

6 N (number of subsets)

7 JVC number of elements in CVALS array

8 Total length of the message in bytes

9 IDIM0, dimension of KSEC0


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KSEC0 array

Array index

Word content

1 Length of section 0 in bytes

2 Total length of CREX message in bytes

3 Reserved


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KSEC1 array

Array index

Word content

1 Reserved

2 CREX edition number

3 Originating centre (oooo)

4 Update sequence number (uu)

5 Number of subsets (sss)

6 CREX data category (nnn)

7 International sub-category (mmm)

8 Version number of local table used

9 Year (yyyy)


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KSEC1 array

Array index

Word content

10 Month (mm)

11 Day (dd)

12 Hour (hh)

13 Minute (nn)

14 CREX master table (tt)

15 Version number of master table used (vv)

16 Originating sub-centre (ppp)

17 Bufr master table version number

18 Bufr version number of local tables used

19-40 Reserved


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KSEC3 array

Array index

Word content

1 Reserved

2 Reserved

3 Number of subsets

4 Reserved


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Values array is of type real*8

If crex table B element is CCITTIA5, corresponding element contain a real number, when truncated to an integer represents

index*1000+length

where

index – subscript of the element in CVALS array where character strings are stored

length – number of characters in the string


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In the case of multi-subset data, one dimensional array

VALUES contains all subsets. Index to values array of

i-th element of observation is:

index=i+(nsub-1)*kelem


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CREX SOFTWARE fortran ROUTINES

CREX encoding

subroutine crexen (ksec0, ksec1, ksec3, ktdlen, crexktdlst, kdlen, kdata,

kelem, kvals, values, cvals, kbufl, kerr)

Input arguments:

ksec0 - an integer array containing section 0 information

ksec1 - an integer array containing section 1 information

ksec3 - an integer array of size 4 containing number of subsets


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ktdlen - an integer, number of data descriptors to be packed in section 1 of crex message

crexktdlst - an integer array containing ktdlen descriptors

kdlen - an integer, dimension of kdata array

kdata - an integer array containing delayed replication values

kelem - an integer containing expected number of expanded elements

kvals - an integer containing expected number of data values


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values - real*8 array of kvals words containing element values

cvals - character*80 array of kvals words containing CCITTIA5 elements

Output arguments:

kbufl - an integer containing the length of bufr message in words

kbuff - an integer array containing packed bufr message

kerr - integer, status return code


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Slide 35

KSEC0 array

Array index

Word content

1 Length of section 0 bytes

2 Total length of crex message

3 Reserved


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Slide 36

KSEC1 array

Array index

Word content

1 Reserved








9 Year (yyyy)


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Slide 37

KSEC1 array

Array index

Word content

10 Month (mm)

11 Day (dd)

12 Hour (hh)

13 Minute (nn)

14 CREX master table (tt)





19-40 Reserved


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Slide 38

KSEC3 array

Array index

Word content

1 Reserved

2 Reserved

3 Number of subsets

4 Reserved


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Printing routines

subroutine CREXPRS0 (ksec0)

Input arguments:

ksec0 – an array containing section 0 information

Array index

Word content

1 Length of section 0

2 Total length of crex message in bytes

3 Crex edition number


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subroutine crexprs1 ( ksec1,ksec3, ktdlen, ktdlst, ktdexl, ktdexp, kelem, cnames)

Input arguments:

ksec1 - an integer array containing CREX section 1

ksec3 - an integer array containing number of subsets

ktdlen - number of data descriptors in section 1

ktdlst- an array containing data descriptors in section 1

ktdexl - number of entries in the list of expanded data descriptors

ktdexp - an array containing expanded data descriptors


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kelem - expected number of expanded elements

cnames - character*64 array of kelem containing CREX section 1 information

KSEC1

Array index

Word content

1 Reserved






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CREX software FORTAN routines


7 International data sub-category (mmm)

8 Version number of local tables used

9 Year (yyyy)

10 Month (mm)

11 Day (dd)

12 Hour (hh)

13 Minute (nn)

14 CREX Master table (tt)

15 Version number of Master table used (vv)




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19-40 Reserved


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ksec3

Array index

Word content

1 Reserved

2 Reserved

3 Number of subsets

4 Reserved


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Subroutine crexsel2 (kbubset, kelem, ktdlen, ktdlst, ktdexl, ktdexp, cnames, cunits, kerr)

Input arguments:

ksubset - subset number

kelem - number of expected elements

Output arguments:

ktdlen - number of data descriptors in section 1

ktdlst - list of data descriptors in section 1


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ktdexl - number of expanded data descriptors

ktdexp - array containing expanded data descriptors

cnames- array containing element names

cunits - array containing element units

kerr - return error code


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Subroutine crexprt ( k, ksub1, ksub2, kelem, cnames, cunits, cvals, kvals, values, ksup, ksec1, kerr)

Input arguments:

k - switch to print with/without code tables content

0 – no code table content, 1 – code table content

ksub1 – starting subset

ksub2 – ending subset

kelem – dimension of cnames, cunits arrays

cnames- character*64 array containing element names


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cunits – character*24 array containing element units

kvals – dimension of values array

values – real*8 array ( expanded data values)

ksup – an array containing supplementary information

ksec1 – an integer array of 40 containing section 1


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KSUP

Array index

Word content


2 Reserved


4 Reserved

5 M ( number of elements in values array, first index)

6 N (number of subsets)

7 JVC (number of elements in CVALS array)

8 Total CREX message length in bytes



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KSEC1

Array index

Word content

1 Reserved







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CREX software FORTRAN routinesArray index

Word content



9 Year (yyyy)

10 Month (mm)

11 Day (dd)

12 Hour (hh)

13 Minute (nn)

14 CREX Master table (tt)



17 Bufr master table number


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Array index

Word content

18 Bufr version of local tables used

19-40 Reserved


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CREX template design

Basic idea is to know one to one correspondence between data descriptors expanded and the data values

To achieve that use:

subroutine CREXDES ( k, ksec1, ktdlen, crexktdlst, kdlen, kdata, kelem, ktdexl, crexktdexp, cnames, cunits, kerr)

Input arguments:

k - an integer, 0 no print; 1 – print


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ksec1 - an integer array containing section 1 information.

Set the following words

ksec1(2) – Bufr edition number

ksec1(3) – Originating centre

ksec1(8) – Version number of local tables used

ksec1(15) – version number of master table used

ktdlen – number of data descriptors

crexktdlst- list of data descriptors in section 1

kdlen – dimension of kdata array

kdata - an integer array containing delayed replications

kelem – expected number of expanded elements


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Output arguments:

ktdexl – number of expanded elements

crexktdexp – integer array containing list of expanded

elements

cnames – character *64 array containing element names

cunits – character*24 array containing element units

kerr – status return code


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Program to use for template design

…/crex_000320/example/crextdexp.F

Conversion CREX to BUFR

…/crex_000320/example/crex2bufr.F

Conversion BUFR to CREX

…/crex_000320/example/bufr2crex.F


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CREX software and pre-processing

What happens when crex data reach DPC

How to organize observation

Pre-process observations

- unpacking

- re-organization of data

- possible quality control

- grouping of observations which belong to

particular analysis cycle

- creating RDB key for further more efficient processing

- packing the data into BUFR format

- writing data into RDB


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Slide 58

CREX software and pre-processing

Alternatively

- unpack crex message

- write unpacked values into DB

- make decisions about archiving

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