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Corrections of Precipitation Particle Size Distribution Measured by a Parsivel OTT<sup>2</sup> Disdrometer under Windy Conditions in the Antisana Massif, Ecuador
oleh: Luis Felipe Gualco, Lenin Campozano, Luis Maisincho, Leandro Robaina, Luis Muñoz, Jean Carlos Ruiz-Hernández, Marcos Villacís, Thomas Condom
Format: | Article |
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Diterbitkan: | MDPI AG 2021-09-01 |
Deskripsi
Monitoring precipitation in mountainous areas using traditional tipping-bucket rain gauges (TPB) has become challenging in sites with strong variations of air temperature and wind speed (<i>Ws</i>). The drop size distributions (<i>DSD</i>), amount, and precipitation-type of a Parsivel OTT<sup>2</sup> disdrometer installed at 4730 m above sea level (close to the 0 °C isotherm) in the glacier foreland of the Antisana volcano in Ecuador are used to analyze the precipitation type. To correct the <i>DSDs</i>, we removed spurious particles and shifted fall velocities such that the mean value matches with the fall velocity–diameter relationship of rain, snow, graupel, and hail. Solid (<i>SP</i>) and liquid precipitation (<i>LP</i>) were identified through −1 and 3 °C thresholds and then grouped into low, medium, and high <i>Ws</i> categories by k-means approach. Changes in <i>DSDs</i> were tracked using concentration spectra and particle’s contribution by diameter and fall velocity. Thus, variations of concentration/dispersion and removed hydrometeors were linked with <i>Ws</i> changes. Corrected precipitation, assuming constant density (1 g cm<sup>−3</sup>), gives reliable results for <i>LP</i> with respect to measurements at TPB and overestimates <i>SP</i> measured in disdrometer. Therefore, corrected precipitation varying density models achieved fewer differences. These results are the first insight toward the understating of precipitation microphysics in a high-altitude site of the tropical Andes.