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RadioSonde: A discussion of the data format
Most of this data was collected by a radiosonde which was carried aloft by a
weather balloon. This data was collected as part of a special field
program, but the instrument and data formats are very common
in the atmospheric community.
Fundamentally; temperature, pressure, and humidity sensors are bundled
with a radio transmitter and are either sent aloft on a balloon
(rawindsonde) or tied to a small parachute and dropped from a plane
(dropsonde). Either way, the location of the sonde is observed
(either visually or with GPS), the data from the radio transmitter
recorded, and the result is an ascii file that contains a header
(of varying length) with descriptive information followed by a
table of observational data and derived quantities.
For rawindsondes, the first entry for the table is actually the
surface data from the weather station, but the remaining entries
are from the sonde. Also, the wind is inferred from the position
of the balloon. Since this is real data, there are missing
values which arise all the time. If you get a profile
without missing values, you can be sure it is synthetic or interpolated.
The datastreme ends when the operator calls it quits. This happens when
a) the balloon breaks, or b) the radio reception has so many dropouts that
is is not worth it anymore. Different fields have different
The nominal format and is a mixture of ancillary data (contained in
the first ???? lines of the file), and the instrument measures and
some derived fields that follow in a fixed-format table with an
unknown number of lines. Part of the formatting of the table is that
each column has a whitespace-separated column name. This line is crucial
to the proper function of the RadioSonde package. If the datafile does not
contain information as to which column is what variable ...
you will have to modify
Fields 16 through 21 contain the Quality Control information (flags)
generated at JOSS. These flags are based on the automated or
visual checks made.
The JOSS QC flag codes are as follows: