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This directory contains Calgary Neutron Monitor Data at five
minute resolution. Each file is a gzipped tar archive that
contains files of uncorrected count rates and barometric
pressures at five minute intervals for one year. A file
named snm.calg.fmi.YYYY.tgz is an archive that holds five minute
data for the year YYYY. There is five minute data available for
the complete years 1980 through to the present, except for the
current year, and partial coverage of the year 1979.

Each tar archive contains files named calYYDDD.fmi, where
YY is the year and DDD is the day of the year, from 1 to 365
or 366. So a file named cal01030.fmi contains five minute
uncorrected data for year 2001 day 30 (which is Jan 30, 2001).

Occasionally, other files named calYYDDD.fmo are present. A
text file named note.txt is also usually present. These files arise
when anomalous data was recorded that cannot be be used for
neutron monitor work but which are kept for reasons of completeness
and interest. Generally this happens on the rare occasions when the
building housing the neutron monitor is covered with several feet
of wet snow, thus moderating the incoming neutrons. The files ending
in fmo are the original data, the corresponding files ending in fmi
are the valid data files with the anomalies removed. The text file
note.txt generally is present to explain what happened.

Each calYYDDD.fmi file contains a header followed by lines of data.
The header is always the same and consists of the five lines:
Calgary_Neutron_Monitor_Data
288
5.0
minutes
Date_and_Time_Pressure_ChanAcounts_ChanBcounts_ChanCcounts_ChanDcounts
Following this are 288 lines of data, one for each
five minute period in the given day. Each line of data
records the time of the data, the barometric pressure at
that time, and the recorded neutron counts at that time.
The detector is comprised of four banks of 3 nm-64 tubes.
The counts from each bank are recorded separately as
channel A, channel B, channel C, and channel D.

Each of these lines has the form
YYYYDDDHHMMSS PPPP AAAAA BBBBB CCCCC DDDDD
where
YYYY is the year
DDD is the day of the year (1 to 365 or 366)
HH is the hour (UT)
MM is the minute (UT)
SS is the seconds (UT)
PPPP is the pressure*10 in millibars
AAAAA is the counts/10 for channel A
BBBBB is the counts/10 for channel B
CCCCC is the counts/10 for channel C
DDDDD is the counts/10 for channel D

The time that is recorded in the file is the end
time of each five minute interval. So the first data
point in a day is at time 00:05:00 UT and the last
data point in the day is 24:00:00 UT.

The recorded pressure is the actual station barometric
pressure in millibars times ten. The pressure is not
normalized to a sea level value as is usually done for
weather observations.

The recorded counts from each channel are scaled by 10.

To obtain the total uncorrected counts for the Calgary neutron
monitor in a five minute period, the four channels are combined
together. To account for different efficiencies in each bank of
nm-64 tubes, each channel is scaled by a normalization factor first.
The normalization factors are:
efficiency_a = 0.99670 ;
efficiency_b = 0.99640 ;
efficiency_c = 0.99696 ;
efficiency_d = 0.99607 ;
So the total uncorrected counts are given by
the integer part (truncation) of
total_uncorrected_counts = 10.0*(efficiency_a*AAAAA+
efficiency_b*BBBBB+
efficiency_c*CCCCC+
efficiency_d*DDDDD)

For example, the line:
2001296001500 8723 2337 2325 2327 2336
states that this is data taken on year 2001, day 296
(which is October 23) for the interval from
00:10:00 UT to 00:15:00 UT. The pressure at that time
was 872.3 millibars. There were 23370 counts from channel A,
23250 counts from channel B, 23270 counts from channel C,
and 23360 counts from channel D. This yields a total
uncorrected count of 92926 counts in this five minute period.