Format for University of Wisconsin GOES
Effective Cloud Amount (i.e.,
Sky-Cover) data
Each line (record) contains 83 characters and
is a complete "report" in the folllowing ASCII format:
1X,I4,I3,1X,I2.2,I2.2,I2.2,1X,F8.4,1X,F9.4,3X,F6.2,3X,F6.2,2X,F7.2,1X,I2,A1,2X,F7.2,3X,F6.2
Parameters are as follows:
I4 -- GOES image year (YYYY)
I3 -- GOES image day of year (JJJ)
I2.2 -- GOES image hour (HH)
I2.2 -- GOES image minute (mm)
I2.2 -- GOES image second (ss)
F8.4 -- GOES field-of-view latitude (to nearest 0.0001 degree
-- N+, S-)
F9.4 -- GOES image field-of-view longitude [to nearest 0.0001
degree -- either 0-360 W or W+, E- (cannot tell
because observations appear only in Western Hemisphere)]
F6.2 -- Pixel-averaged (see *) IR cloud emissivity (effective
cloud amount) centered on the GOES field-of-view (to nearest 0.01 %)
F6.2 -- GOES field-of-view IR cloud emissivity (effective cloud
amount) (to nearest 0.01 %)
F7.2 -- GOES field-of-view cloud top pressure (to nearest 0.01 mb)
I2 -- GOES satellite number (currently either "15" for
GOES-W or
"16" for GOES-E)
A1 -- hardwired to "i" (GOES imager)
F7.2 -- Pixel-averaged (see *) cloud top pressure centered on the
GOES field-of-view (to nearest 0.01 mb)
F6.2 -- GOES field-of-view visible cloud transmission (albedo) (to
nearest 0.01 %)
* - Take a given GOES Imager pixel somewhere, and call it location
(Y,X), where Y = a line (N-S) coordinate,
and X = an element (E-W)
coordinate. For a given image, there can be literally
millions of these pixels,
as you can imagine. Then for
that pixel, we determine the # of pixels (using great circle distance)
one must
travel N, E, S and W to arrive at a
location 25km distant from pixel (Y,X). This forms essentially a
4-sided
polygon surrounding pixel (Y,X).
In other words, we will have a 2-d matrix of pixels that surround pixel
(Y,X).
Then for each pixel that lies within this
polygon/matrix, the great circle distance gets computed, and ONLY those
pixels
whose great circle distance is
<= 25.0km get used to compute the quantities
FINAL_AVG_CLOUD_EMISSIVITY
and AVG_CLOUDTOP_PRESSURE. The point
here is that we are attempting to only include those pixels in the
computations of these two quantities that an
earth-based observer would see if they were looking up and around
in all directions (the
"celestial dome").
For example:
-- start of file contents --
2015160 010000 19.9312
69.1336 67.26 91.00
894.00 13i 868.06 100.00
2015160 010000 19.9312
69.0883 69.07 91.00
896.00 13i 878.92 100.00
2015160 010000 19.9312
69.0429 66.55 92.00
902.00 13i 886.83 100.00
2015160 010000 19.9312
68.9990 62.67 93.00
906.00 13i 894.39 100.00
2015160 010000 19.9312
68.9550 55.88 93.00
905.00 13i 899.53 100.00
2015160 010000 19.9305
68.9097 52.52 93.00
908.00 13i 903.01 100.00
2015160 010000 19.9298
68.8644 49.32
0.00 0.00 13i 905.25
100.00
2015160 010000 19.9291
68.8205 44.63
0.00 0.00 13i 906.10
100.00
2015160 010000 19.9284
68.7765 38.90
0.00 0.00 13i 901.26
100.00
2015160 010000 19.9312
68.7312 36.29
0.00 0.00 13i 892.37
100.00
2015160 010000 19.9339
68.6859 33.95 94.00
895.00 13i 843.36 100.00
2015160 010000 19.9442
68.6378 33.43 93.00
909.00 13i 760.11 100.00
2015160 010000 19.9545
68.5897 36.74
7.00 216.00 13i 707.20 100.00
2015160 010000 19.9669
68.5403 35.88
0.00 196.00 13i 648.80 100.00
2015160 010000 19.9792
68.4909 30.83 15.00
228.00 13i 546.00 100.00
2015160 010000 19.9772
68.4483 24.93 20.00
247.00 13i 409.89 100.00
2015160 010000 19.9751
68.4057 21.11 24.00
262.00 13i 270.81 100.00
<snip>
-- end of file contents --