Effects of spatial resolution on radar-based precipitation estimation using sub-kilometer X-band radar measurements

Known for the ability to observe precipitation at spatial resolution higher than rain gauge networks and
satellite products, weather radars allow us to measure precipitation at spatial resolutions of 1 kilometer
(typical resolution for operational radars) and a few hundred meters (often used in research activities).
In principle, we can operate a weather radar at resolution higher than 100m and the expectation is that
radar data at higher spatial resolution can provide more information. However, there is no systematic
research about whether the additional information is noise or useful data contributing to the quantitative
precipitation estimation. In order to quantitatively investigate the changes, as either benefits or drawbacks,
caused by increasing the spatial resolution of radar measurements, we set up an X-band radar
field experiment from May to October in 2017 in the Stuttgart metropolitan region. The scan strategy
consists of two quasi-simultaneous scans with a 75-m and a 250-m radial resolution respectively. They
are named as the fine scan and the coarse scan, respectively. Both scans are compared to each other in
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terms of the radar data quality and their radar-based precipitation estimates. The primary results from
these comparisons between the radar data of these two scans show that, in contrast to the coarse scan, the
fine scan data are characterized with losses of weak echoes, are more subjected to external signals and
second-trip echoes (drawback), are more effective in removing non-meteorological echoes (benefit), are
more skillful in delineating convective storms (benefit), and show a better agreement with the external
reference data (benefit).