Main program to produce pseudo SST observations
in ice-covered areas. Pseudo SST observations are needed
to prevent the propagation of analysis increments to
the ice-covered areas, that may result in undesirable sea-ice melting.
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Algorithm
Pseudo SST observations are assigned to the ice-covered
water points.
First, a global sea-ice analysis is read.
The sea-ice analysis file contains a mandatory sea-water
fraction field.
The grid and land-ocean mask are read
from the analysisgrid file.
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Second, the number of ice-covered water points, including
concerned inland water points, are computed.
If the number of ice-covered water points is zero,
an empty observation SQLite file is created.
If not, the computation of pseudo observations starts.
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First, the index array of ice-covered water points are
randomly shuffled to prevent the insertion of pseudo
observations at the same locations
that would lead to spatial correlation of observations.
Second, the pseudo observations of sea surface temperature \(T\)
are inserted at every ice-covered inland water point \(k\),
where the value of observations is computed as follows:
\(T(k)=(1 - w(k)) * T_{fw} + w(k) * T_{s}\),
where \(w(k)\) is the sea-water fraction at the point \(k\),
\(T_{fw}\) is the temperature of fresh water below the ice,
\(T_{s}\) is a temperature of the sea water below the ice.
The pseudo observations are inserted into every \(N\)-th point
of sea water ice-covered points,
where the value of observation is defined as
\(T_{s}\).
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The computed observation values along with the corresponding
coordinates are put into obsSpaceData.
Finally, output SQLite files are created.
