WORLD METEOROLOGICAL ORGANIZATION
______
COMMISSION FOR BASIC SYSTEM
OPAG ON
INFORMATION SYSTEMS & SERVICES
EXPERT TEAM MEETING ON DATA-COMMUNICATION SYSTEMS AND TECHNIQUES
GENEVA, 27-30 SEPTEMBER 1999 / ISS/ET-DCST 99/Doc. 21
(23.IX.1999)
______
ITEM 4.2
ENGLISH only

FILE NAMING ISSUES

Submitted by the delegate of Germany

The purpose of this document is to communicate the experiences at RTH Offenbach with file naming issues

  1. File naming situation in the RTH Offenbach

The file exchange in the German Weather Service (DWD) started to a greater extent in the beginning of the nineties. First an application specific invention of different file naming came up. Due to the increasing connectivity in the LAN a central concept was missed painful.

To avoid these disadvantages, e.g. the need to have "translators" between different file naming, a central file naming convention of the DWD was developed in 1995 by a small team of experts concerned with file exchange.

The developing goals have been contradictory. So the result is a compromise in several directions.

The developing goals were:

  • to guarantee a unique file naming
  • relative short file names with 80 characters length maximum
  • short but readable description of the file contents
  • content description bound to defined positional parameters to ease machine readability
  • no descriptive parts to be placed in the directory path to set no preconditions for the directory structure of the destination site (in push regime)

The concept is widely proofed in practice, accepted and increasingly in use.
(please find the concept included below)

  1. File naming for GTS file exchange

For the advantage of the GTS file exchange in 1997 a file naming convention was adopted. (see final report ICM on the MTN 1997 and "Guide on the use of TCP/IP on the GTS") This naming convention meets its purpose if it is used for file exchange on the GTS. It is assumed that the file exchange takes place between centres having MSS systems on both sides of the connection. The sending side compiles the bulletins into files and the destination side unpacks it at once after arrival. That means, the files are restricted to transport GTS bulletins.

This concept fails to achieve a unique file naming in special cases if we have several instances in a centre that compile bulletins into files (by chance using the same name but different content) and send them to a destination centre.

These files possibly meet each other in the same directory there with the risk to overwrite each other.

As solution is proposed to open the definition of the second two of the first four letters in the file name for free use by the file originating centre (naming its instances) to provide an unique file naming.

  1. File/directory naming in server/database issue

It is an useful and adequate solution to organise meteorological information in well formed directory trees. This implies to use the metadata in directory naming structuring the data hierarchy to ease the access by applications.

  1. Proposal

GTS data exchange and server/ database concepts are connected by complex applications. Therefore the DWD concept connects properties useful for file exchange and data storage in directory systems by files with readable filenames, which allow much less to elaborate applications for the handling of the information.

Therefore we recommend it for widespread use in heterogeneous environments which require both, communication and data- storage activities.

File naming convention in DWD

The basic issue is the following which has to be detailed step by step:

filetype-filespec-time-producer-free-free-format(max. 80 characters)

filetypeis compiled from a recognition code of three letters and two figures for further discrimination (Table 1).

filespecthe format of this field depends on the file type (ergo not context free). "filespec" is combined from several parameters separated from each other by "_" (underscore). The length of the parameters may vary within a limit. The maximum length is 30 characters.

For graphic products (satellite pictures, facsimile charts, radar charts, ...) are the following parameters mandatory:

MOD_MET_LOC_P_yyyyyy_zzzzzz

MOD- kind of data respectively the originating model[1-3 char](see table 2)

MET- meteorological parameter[1-3 char](see table 3)

LOC- location indicator [1-6 char](see table 4)

P- projection type[1 char](see table 5)

yyyyyy - prediction time/ prediction interval[1 resp. 2 * 3 chars]

zzzzzz - level/ layer boundaries [1 resp. 2 * 3 chars]

e.g. zzz999, 999zzz or 999999 (no level applicable)

In case of GTS- Bulletins the fields of the abbreviated bulletin header serve as file specification :

e.g. TTAAii_CCCC_YYhhmm[_BBB]

timeYYMMDDhhmm

YYMMDD-year, month, day

hhmmhour, minute (e.g. model output)

producerproducing system (e.g. hostname of the computer)

freefree for future use

formatdescribes the format the file is stored in.

Examples:

  • gka -GKS- file in ASCII (Graphical Kernel System)
  • gkb-GKS- file binary
  • cgm-CGM coded file
  • asc -plain ASCII
  • bin -binary coded
  • tiff -TIFF coded file
  • wp51-Word Perfect (Version 5.1 widespread used in DWD)
  • tar.gz- tar- archives compressed by ZIP

Release:01.10.1996

Table 1: <FILETYPE>

<FILETYPE>Description

berXXreport as text

bufXXfields of grid points, BUFR- format

czbXXCGM-module of weather charts for newsletters

czwXXCGM-weather chart for newsletters

dawXXservice message

fx3XXfax charts formatted for DIN A3 (TIFF)

fx4XXfax charts formatted for DIN A4 (TIFF)

gkdXXGKS- (Germany model) chart format

gmeXXGKS- meteogramme

grbXXfields of grid points, GRIB- format

grdXXfields of grid points, GRID- format

gtrXXGKS- trajectories

gtsXXGTS- bulletins

gveXXGKS- vertical cut

rabXXradar chart,BUFR- coded

radXXradar chart, TIFF- palettes format

sacXXcloud classification,TIFF- palettes format

sadXXsatellite picture,TIFF- "dithered"

safXXsatellite picture,TIFF- "true Colour"

sapXXsatellite picture,TIFF- palettes format

satXXsatellite picture,TIFF- grey levels

tkaXXweather charts,PC- format (TIFF)

...

Table2: <FILESPEC>MOD - kind of data resp. model [1-3 characters]

MODDescription

anaanalyses worked out manually

bkfold DWD- model

c00COST- RADAR

dmmodel covering Germany

dm3model covering Germany (DWD)

ecmEZMW model

egrEGRR model

emmodel covering Europe

em3model covering Europe (DWD)

emvmodel covering Europe V

gmglobal model

gmsGMS (Japan)

goeGOES (USA)

gomGOMS (Russia)

metMETEOSAT (Europe)

n11routine NOAA

n12routine NOAA

n14routine NOAA

noaNOAA

obsobservations

p00DWD- RADAR

p10global model (DWD)

promanually worked out forecast

wafWAFS- products (model of UKMO)

...

Table 3 : <FILESPEC>MET - meteorological parameters [1-3 characters]

METDescription

am1WAFC amendments

am2WAFC amendments

bhvsurface- upper level forecast

bwksurface weather chart (analysis)

catCAT- index

cbtCB- heights (lower and upper boundaries)

cclcloud classification

clmcloud coverage with clouds of medium heights [0 ... 1]

cthclouds heights

eisicing (lower and upper boundaries)

enhenhanced

fqndivergence of the Q- vector component vertically to the isobars

fqqforcing FQs | forcing FQn

fqsgeostr. Div. - Qs

frosurface- frontiers

frs omega- forcing

gtageostr. temperature advection

gvageostr. vorticity advection

gvogeostr. vorticity

hdfgeopotential, wind vectors

hgpgeopotential

hjtjet- heights

hoemessage plot upper air chart [station model]

hsygeopotential | station plots

htpgeopotential | temperature | pressure

htrtropopauses

httgeopotential | temperature

hwvgeopotential | wind speed

hwxmax.-wind ISO : isotaches

ic5analysis of the ice coverage

insinstability

ipvisentrope potential vorticity

irinfrared

iswwind isentrope

k1...k5channel 1 ... channel5

koiKO- index

kovKO- stability field | classified vertical velocity

metmeteogramme

nfqdiv. Qn

nggzero grad boundary

nqvfrontogenesis parameter

omevertical motion (OMEGA)

p00surface pressure

pde3 hourly surface pressure variation

pispressure at isentrope levels

pwisurface pressure | wind vectors

qdfQ-vectorv divergence | frontogenesis parameter

qdigeostr. divergence Q

qdpdivergence Q

qffgeostr. frontogenesis function

qfpfrontogenesis function

qvngeostr. frontogenesis parameter

qvsgeostr. Qs- vector

r1212- hourly sum of precipitation

r2424- hourly sum of precipitation

radRADAR

ramRADAR- composit plus Meteosat

rarkind of precipitation

rferelative humidity

rftrelative humidity / temperature

rrtphase of precipitation, thunderstorm and black ice

rs1amount of precipitation (rain and snow) - raster

rsaamount of precipitation (rain and snow)

rswsum of precipitation | snow height | water temperature

rtprelative topography

rxnsum of precipitation | temperature max | temperature min

sfqdiv. Qs

sgaroughness of sea analysis

sgvroughness of sea forecast

shwsnow thickness and water temperature

snhsnow thickness

sqvQs- vector

sttcloud height (lower and upper boundaries) non cumuloform clouds

swcSWC`s [graphic]

swxsurface station plots: significant weather

synsurface station plots: complete

taeequivalent- potential temperature

tafthickness of advection layers | frontogenese parameter

tappotential equivalent temperature

tavtemperature advection

tcntrue- colour- night

tcttrue- colour- day

te0zero grad boundary within the soil

tersoil temperature in depth 5 cm

tkbsurface forecast chart with frontiers

tmpTEMP / RAWIN

tpgthermopluviogramme

trrbackward trajectories (no forecast)

trvforward trajectories

trxtropopause | max wind

ttctemperature

ttwtemperature | wind vectors

tw6water temperature (6 days average)

txn temperature max | temperature min

vadprimitive advection of absolute vorticity

visvisible

vorvorticity

winwind vectors on grid points

wixmax wind (10m height)

wvwater vapour

wvowind vectors | vorticity

zwknewspaper weather chart

Table 4 : <FILESPEC> location indicator [1-6 characters]

LocationDescription

dNorth Atlantic

gCentral Europe

euEurope and slightly differing cuts

weeastern Europe

eeeastern Europe

ceCentral Europe

geGermany and slightly differing cuts

alAlps

naNorth Atlantic

nhNorthern Hemisphere

ceuWAFS- Central Europe

eurWAFS- Europe

natWAFS- North Atlantic

midWAFS- Asia

eursamWAFS- Europe-South America

eurafiWAFS- Europe-Africa

erd0full disc (for Sat- picture) 0

erd75Wfull disc (for Sat- picture) 75W

erd75Efull disk (for Sat- picture) 75E

asienAsia, North India, Western Pacific

npolArctic, northern Pacific, North America

spolAntarctica, Australia, South Africa, Eastern South America, South Atlantic, South India

Location indicators for presentation of trajectories:

harwHamburg, Rostock

lzpdLeipzig, Potsdam

ofemOffenbach, Essen

mssuMunich, Stuttgart

Location indicators for TEMP/RAWIN - presentations:

dlnlNetherlands, Germany(1. stations group)

dlswSwitzerland, Germany(2. Stations group)

ukUnited Kingdom(3. Stations group)

iefrFrance, Ireland(4. Stations group)

nosnNorway, Sweden(5. Stations group)

eusoSouth Europe(6. Stations group)

euseSouth Europe(7. Stations group)

euswSouth West Europe(8. Stations group)

dlGermany(9. Stations group)

dlewGermany, British Isles(10. Stations group)

Location indicator for DM - Meteogramme:

hnedhaHanover, Emden, Hamburg

lzbrgwLeipzig, Berlin, Greifswald

frcsemFrankfurt, Kassel, Essen

msnbmeMunich, Nürnberg, Meiningen

fgumsuFreiburg, Ulm, Stuttgart

Location indicator for GM - Meteogramme:

haHamburg

emEssen

lzLeipzig

msMunich

Location Indicators for EM - Meteogramme:

brBerlin

eggrLondon

ekchKopenhagen

emEssen

fgFreiburg

frFrankfurt/Main

gwGreifswald

haHamburg

lfpwParis

liibMilan

lowmVienna

lsswGeneva

lybmBelgrade

lzLeipzig

msMunich

nbNuremberg

okprPrague

sowrWarsaw

umUlm

...

Tabelle 5: <FILESPEC>P - projection [1 character]

PDescription

pprojection polarstereographic (A4 - Format)

qprojection polarstereographic (A3 - Format)

wsatellite projection

mmercator projection

ggraphic presentation

P,Q,W,M,Gorientation:portrait

...