About NAM 12km file

[niuniu]

Hi,

We want to know more details about the NAM12KM files,coule you help me?

In the beginning of one NAM 12km file, the content is like the following:
METEOROLOGICAL DATA LISTING ...
Enter meteorological directory ...
Enter meteorological file name ...

File start time: 13 9 8 0 0
File ending time: 13 9 8 21 0

Last record number : 1688
Record length bytes: 262842
Meteo data model : NAM
Grid size x,y,z : 614 428 27
Vertical coordinate: 2
First forecast hour: 0
Last forecast hour : 3
Records per time : 211
Minutes between : 180

Pole pnt lat/lon : 90.0000 0.0000
Reference lat/lon: 25.0000 -95.0000
Grid size (km) : 12.1910
Orientation : 0.0000
Tang Lat / Cone : 25.0000
Synch pnt x,y : 1.0000 1.0000
Synch pnt lat/lon: 12.1900 -133.4600

Lower left corner: 12.1900 -133.4600
Upper right corner: 57.3290 -49.4167
Tangent point x,y: 1070.2968 333.3806

In our understanding,this file include the meteorological data from the lower point(12.1900 -133.4600) and upper point(57.3290 -49.4167). The width of this area is about 4700km and the length of this erea is about 5000km.

The the second part of the file is like this:
27 50.0000 7 UWND 186 VWND 212 HGTS 13 TEMP 52 WWND 37 RELH 130
TKEN 200
26 100.0000 7 UWND 213 VWND 35 HGTS 101 TEMP 105 WWND 134 RELH 18
TKEN 184
25 150.0000 7 UWND 81 VWND 25 HGTS 62 TEMP 94 WWND 189 RELH 162
TKEN 194
24 200.0000 7 UWND 238 VWND 46 HGTS 80 TEMP 125 WWND 243 RELH 57
TKEN 184

In our understaning, this is the records about the levels between the ground and the 1000hpa.

The third part of this file is :
0.0000 28 SHGT 211 MSLP 177 TPP3 0 CPP3 0 T02M 151 RH2M 156
U10M 10 V10M 232 PRSS 203 LHTF 207 SHTF 57 USTR 50
RGHS 149 DSWF 182 TMPS 233 SOLT 109 SOLW 149 WESD 184
CSNO 184 CICE 184 CFZR 184 CRAI 219 VSBY 9 TCLD 203
CAPE 58 CINH 255 LISD 121 LIB4 72

First question is : what exact meanings about these data? For example, USTR 50, what is the unit? is m/s? what height it is ? what location it is ? Because this area is about 4700km*5000km, and the file is 12km resolution, and in our understanding ,there will be many points in such a area, and these meteorological data should have parameters in many locations each 12km.

The final part of this file is:

1 13 9 8 0 0 099INDX 0 0.0000000E+00 0.0000000E+00
2 13 9 8 0 0 099SHGT 10 0.4031496E+01 0.7002258E-01
3 13 9 8 0 0 099MSLP 2 0.1574803E-01 0.1010241E+04
4 13 9 8 0 6 099TPP3 -5 0.1230315E-03 0.0000000E+00
5 13 9 8 0 6 099CPP3 -6 0.6151575E-04 0.0000000E+00
6 13 9 8 0 0 099T02M 4 0.6299213E-01 0.2999895E+03
7 13 9 8 0 0 099RH2M 6 0.2519685E+00 0.7732455E+02

According to some info from the web,the meanings of each column are as following,
# YYMMDDHHFHLLGG FLD EXP PRECISION VAR(1,1)


The second question is , all these records ,the GG is 99, that means these data is all described the no.99 grid? These all one location data?

13 13 9 8 0 0 099USTR 0 0.3937008E-02 0.1027537E+00

The meaning of the upper record is index=13, date=20130908, hour=00:00 UTC, FH(forecast hour)=0, LL=0(level=0 , height=?) GG=99(No.99 grid?)

precision OF USTR=0.3937008E-02 USTR=0.1027537E+00 M/S, is it right?


There are so many questions. Many and many thanks.

[ariel.stein]

Here is some information about the NAM12

NAM 12 km Forecast Data Archive
Revised: 10 January 2004

________________________________________________________________________________

Overview -


NOAA ARL began an archive of the first 3 hours of NAM 12km
meteorological data from NOAA NCEP in May 2007. An extraction procedure was implemented to
concatenate the initial field (+0 h forecast) and the +3 h forecast for each
cycle, four times daily, into daily files that can be accessed as a
pseudo analysis archive.
________________________________________________________________________________

Additional Data Set Details

12 km lambert conformal grid
614x428 points
Spatial domain: 12.19N 133.46W to 57.329N 49.4167W
31-day rotating archive with output every 3 hours
26 Levels (hPa): 1000,975,950,925,900,875,850,825,800,775,750,725,700,
650,600,550,500,450,400,350,300,250,200,150,100,50
Sfc Variables: 14 SHGT MSLP TPPT CPPT T02M RH2M U10M
V10M PRSS LHTF SHTF USTR RGHS DSWF
Upper Levels: 7 HGTS TEMP UWND VWND WWND RELH TKEN

MODEL TYPE: NAM
VERT COORD: 2
POLE LAT: 90.000
POLE LON: 0.0000
REF LAT: 25.000
REF LON: -95.00
REF GRID: 12.190
ORIENTATION: 0.
CONE ANGLE: 25.0
SYNC X: 1.
SYNC Y: 1.
SYNC LAT: 12.190
SYNC LON: -133.46
NUMB X: 614
NUMB Y: 428
NUMB LEVELS: 26