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TRMM GMIN Data Format


File name

HAR1720_01.gmin

HAR            rain gauge network (in this case HAR=Harris County) 
1720           rain gauge ID 
01             Year 2001  
gmin           product ID 

File header

GMIN HSTN HAR 1720 Q100_Cedar TIP 1.0 29.76944 -94.91750 KHGX 36.72 25.29 83 92 -99.9

GMIN HAR 1720:   same as in file name 
HSTN             GV site 
Q100_Cedar       name of rain gauge location 
TIP              rain gauge type: tipping bucket 
1.0              resoultion: 1 minute 
29.76944         latitude in degree
-94.91750        longitude in degree
KHGX             primary radar
36.72            range, i.e. distance between primary radar and gauge
25.29            azimuth between primary radar and gauge
                 Azimuth is a direction in terms of the 360 degree compass;
                 north at 0, east at 90, south at 180, west at 270, etc.
83               gauge coordinate in pixel at X axis
92               gauge coordinate in pixel at Y axis
                 Radar location is at center pixel (75,75);
                 Pixel (0,0) is at the SW corner. One pixel is 2kmX2km.
-99.99           radar elevation above sea level. (-99.9 not available)

Data format

......................................
01 160 05 52 00  -18.67  3 1.11    10
01 160 05 53 00  -12.47  3 1.11    10
01 160 05 54 00   -7.57  3 1.11    10
01 160 05 55 00   -3.96  3 1.11    10
01 160 05 56 00   -1.64  3 1.11    10
01 160 05 57 00   -0.62  3 1.11    10
01 160 05 58 00   -0.84  3 1.11    10
01 160 05 59 00   -1.57  3 1.11    10
......................................

There are 9 data fields. 
1) year 
2) Julian Day 
3) hour in UTC 
4) minute 
5) second (always zero) 
6) rain rate in mm/hr
    negative indicates low data quality due to interpolation for Type 1,2,3 as defined in 7) 
    e.g. Rain rate is 18.67 mm/hr from 5:51:00 to 5:51:59 on Julian day 160, 2001. 
7) Type of Event 
     event: series of tips in which each tip in the series is temporally related 
            to the an antecedant or subsequent tip by 30 minutes or less 
     0 = normal spline interpolation, no "-" sign, good data quality; 
     1 = single isolated tip event; 
     2 = two single tip event (non-mulitple tip) or one isolated double tip event; 
     3 = multiple tip event ( >=3 tips in the event, at least one record has 2 or more tips) 
8) Rainfall bias by event 
   Bias = Raw Event Accumulation/Integrated Rain Rates (as derived from spline interpolation) 
9) Number of tips in a given rain event (as defined in 7) 

Since Mar 7, 2003, we have released version-4 2A56 files. The definition of rain event is changed from 30 minutes to 15 minutes. The format for version-4 2A56 files is the same as version 3. But the format for new version GMIN files is different.
e.g.

...............................................
2003 02 21 052 10 58 00  -12.01  1  1.00     1
2003 02 21 052 10 59 00  -12.01  1  1.00     1
2003 02 21 052 18 52 00   28.64  0  1.05     9
2003 02 21 052 18 53 00   28.64  0  1.05     9
2003 02 21 052 18 54 00   27.18  0  1.05     9
2003 02 21 052 18 55 00   24.27  0  1.05     9
2003 02 21 052 18 56 00   19.90  0  1.05     9
2003 02 21 052 18 57 00   14.07  0  1.05     9
...............................................

There are 11 data fields. 
1) year 
2) month 
3) Day of the month 
4) Julian Day 
5) hour in UTC 
6) minute 
7) second 
8) rain rate in mm/hr
    negative indicates low data quality due to interpolation for 1-minute rain event. 
9) Type of interpolation for different rain events
    event: series of tips in which each tip in the series is temporally related to the an antecedant or subsequent tip by 15 minutes or less
    0 = normal spline interpolation for event duration > 1 min; 
    1 = evenly spread 1-minute event rain into 5-min interval, flagged with "-" for one-minute rain event;
    2 = linear interpolation when spline interpolation bias>1.5 or <0.5. 
10)Rainfall bias by event 
    Bias = Integrated Rain Rates (as derived from above interpolation)/Raw Event Accumulation 
11) Number of tips in a given rain event (as defined in 9)