>From: Owen Cooper <address@hidden>
>Organization: Aeronomy Laboratory/NOAA
>Keywords: 200406080008.i5808gtK000586 McIDAS SCHEMA Flexpart
Hi Owen,
>Last year you helped me contour pollution data onto GOES imagery using
>the SCHEMA below, which was applied to a text file containing 3 columns,
>latitude longitude and carbon monoxide concentration.
I actually remember :-)
>The SCHEMA has worked great but the one thing it's lacking is the time
>stamp of the data.
I believe I made a comment about this at the time...
>I'd like to create a large data set for one month with a separate MD
>file (containing carbon monoxde data for the USA) for each 3-hour time
>period. So there would be 8 files per day.
Why split the observations into different files for 3 hour chunks?
The most common approach would be to create a single file for each
day.
>I would then like to use
>PTCON to display the data, but have a SELECT clause set up so that the
>data can be retrieved by day and hour.
OK.
>Seeing as my MD files contain
>point data at each 1x1 degree grid cell, does this mean each data point
>has to have a day and time (which would make the files much larger)
No. It could, but it doesn't have to.
>or
>can I simply add the day and time to a header within the MD file that
>applies to all data points?
Yes.
Your objective is to essentially create an MD file that has a lot of
similarities with a surface (METAR) MD file. To illustrate my point,
here is a listing for the schema (ISFC) for a surface MD file:
LSCHE ISFC
NAME: ISFC VERSION: 7 DATE: 1999085 TEXTID: "SURFACE HOURLY OBSERVATIONS
---- -------
DEFAULT NUMBER OF ROWS: 72 INTEGER ID: 0
COLS: 3500 MISSING DATA VALUE:
-2139062144
REPEAT GROUP: NUMBER OF REPETITIONS: 1
STARTING POSITION: 11
SIZE: 25
NUMBER OF KEYS IN ROW HEADER: 4
COL HEADER: 6 STARTING AT POSITION 5
DATA RECORD: 25 STARTING AT POSITION 11
----
35 TOTAL
KEY SCALE UNIT KEY SCALE UNIT KEY SCALE UNIT
---- ----- ---- ---- ----- ---- ---- ----- ----
TYPE 0 DAY 0 CYD TIME 0 HMS
NREC 0 ID 0 CHAR LAT 4 DEG
LON 4 DEG ZS 0 M ST 0 CHAR
CO 0 CHAR MOD 0 HMS 0 HMS
CIGC 0 CC1 0 CC2 0
CIGH -2 FT ZCL1 -2 FT ZCL2 -2 FT
VIS 1 MI WX1 0 CHAR WX2 0 CHAR
T 2 K TD 2 K DIR 0 DEG
SPD 1 MPS GUS 1 MPS PSL 2 MB
PCP 2 IN SNO 0 IN PRE 2 MB
P24 2 IN WXC1 0 CODE WXC2 0 CODE
WXC3 0 CODE WXC4 0 CODE
LSCHE: DONE
Notice the following about the ISFC schema (located in the file DCISFC):
- there are 4 keys per row: TYPE, DAY, TIME, NREC
- there are 6 keys per column: ID, LAT, LON, ZS, ST, CO
- there are 25 keys for data
(Here CO is COuntry, not Carbon diOxide)
What you are proposing to create could look very similar to this:
- 2 keys per row: DAY, TIME
- 0 keys per column
- 3 data keys: LAT, LON, CO
(Here CO is Carbon diOxide, not COuntry)
If your data is hourly, the schema would have 24 rows. If your data is
3-hourly, your schema would have 8 rows.
I think the schema would end up looking something like:
" NAME VSN DATE ID TEXTID
" ---- --- ---- -- ------
SCHEMA FLXP 2 04160 0 "FLEXPART CO CONCENTRATIONS
"KEY SCALE UNITS DESCRIPTION
"--- ----- ----- -----------
ROWS 24 "24 ROWS 1 PER HOUR
DAY CYD "YEAR AND JULIAN DAY (CCYYDDD)
TIME HMS "NOMINAL TIME (HH0000)
COLUMNS 360 "DEFAULT # OF COLS
DATA "START OF DATA SECTION
LAT 4 DEG "LATITUDE (DECIMAL DEG)
LON 4 DEG "LONGITUDE (DECIMAL DEG)
CO 2 CON "CO2 CONCENTRATION
ENDSCHEMA
>Thank you in advance for any ideas you can send my way.
You may have to play a little with the setup to get TXT2MD to work with
your input file.
Please let me know if anything is not clear.
Cheers,
Tom
--
NOTE: All email exchanges with Unidata User Support are recorded in the
Unidata inquiry tracking system and then made publically available
through the web. If you do not want to have your interactions made
available in this way, you must let us know in each email you send to us.
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.