Inproceedings,
Study of effective distances for interpolation schemes in meteorology
XXVII Annual Assembly, European Geophysical Society, (2002)
Abstract
This work explores the possibility of integrating the geographical
elements such as orography and presence of water bodies as well as
the latitudinal effects into an effective distance when interpolating
meteorological fields. This effective distance may then be used in
any interpolation methods instead of the standard geodetic distance.
Several hundreds of sites are used in Europe to assess the benefits
of several effective distances. The meteorological parameters under
concern are ten-years averages of monthly means of daily sum of horizontal
global irradiation, daily sum of sunshine duration, daily extremes
of air temperature, atmospheric pressure and water vapor pressure,
and of monthly sums of precipitation. This work demonstrates that
taking into account the latitudinal effects in the distance increases
the accuracy in interpolation. Such effects have been seldom mentioned
in previous publications. The orographic effects may be partly corrected
by adding the weighted difference in elevation to the geodetic distance.
The following effective distance between the point P and each of
the measuring sites Xi for all parameters, is found to give better
results than the others: deff 2 = fNS 2 (dgeo 2 + foro 2 dh2) with
fNS = 1 + 0.3 Â?FP -FXÂ? 1+ (sinFP + sinFX) / 2, where dgeo is
the geodetic distance in km, latitudes FP and FX are expressed in
degrees, dh is the difference in elevation between P and Xi (expressed
in km) and foro is set to 500.
