| In order to estimate the rainfall fields over an entire basin raingauge,
pointwise measurements need to be interpolated and the small-scale
variability of rainfall fields can lead to biases in the rain rate
estimation over an entire basin, above all for small or medium size
mountainous and urban catchments.
For these reasons, several raingauges should be installed in different
places in order to determine the spatial rainfall distribution during the
evolution of the natural phenomena over the selected area.
In technical applications, many empirical relations are used in order to
deduce heavy areal rainfall, when just one raingauge is available.
In this work, we studied the areal reduction factor (ARF) using radar
reflectivity maps collected with the Polar 55C, a C-band Doppler dual
polarized coherent weather radar with polarization agility and with a 0.9° beamwidth.
The radar rainfall estimates, for an area of 1 km2, were integrated for
heavy rainfall with an upscaling process, until we had rainfall estimate for
an area of 900 km2.
The results obtained for a significant amount of data by using this
technique are compared with the most important relations of the areal
reduction factor reported in the literature. |