Quantitative Precipitation Estimation over Antarctica Using Different Ze-SR Relationships Based on Snowfall Classification Combining Ground Observations

Abstract

Snow plays a crucial role in the hydrological cycle and energy budget of the Earth, and remote sensing instruments with the necessary spatial coverage, resolution, and temporal sampling are essential for snowfall monitoring. Among such instruments, ground-radars have scanning capability and a resolution that make it possible to obtain a 3D structure of precipitating systems or vertical profiles when used in profiling mode. Radars from space have a lower spatial resolution, but they provide a global view. However, radar-based quantitative estimates of solid precipitation are still a challenge due to the variability of the microphysical, geometrical, and electrical features of snow particles. Estimations of snowfall rate are usually accomplished using empirical, long-term relationships between the equivalent radar reflectivity factor (Ze) and the liquid-equivalent snowfall rate (SR). Nevertheless, very few relationships take advantage of the direct estimation of the microphysical characteristics of snowflakes. In this work, we used a K-band vertically pointing radar collocated with a laser disdrometer to develop Ze-SR relationships as a function of snow classification. The two instruments were located at the Italian Antarctic Station Mario Zucchelli. The K-band radar probes the low-level atmospheric layers, recording power spectra at 32 vertical range gates. It was set at a high vertical resolution (35 m), with the first trusted range gate at a height of only 100 m. The disdrometer was able to provide information on the particle size distribution just below the trusted radar gate. Snow particles were classified into six categories (aggregate, dendrite aggregate, plate aggregate, pristine, dendrite pristine, plate pristine). The method was applied to the snowfall events of the Antarctic summer seasons of 2018–2019 and 2019–2020, with a total of 23,566 min of precipitation, 15.3% of which was recognized as showing aggregate features, 33.3% dendrite aggregate, 7.3% plates aggregate, 12.5% pristine, 24% dendrite pristine, and 7.6% plate pristine. Applying the appropriate Ze-SR relationship in each snow category, we calculated a total of 87 mm water equivalent, differing from the total found by applying a unique Ze-SR. Our estimates were also benchmarked against a colocated Alter-shielded weighing gauge, resulting in a difference of 3% in the analyzed periods.

[Retracted] A Spatial Spectrum Estimation Method for Optimization and Improvement of Resource Allocation and Management of Public Sport and Health Facilities

“…In formula ( 2 ), θ ii represents the relationship between sport infrastructure and uncertain factors in various regions, and p ij is the result of the Jaro algorithm to judge the similarity between n j public sport facility resources and NJ public sport facility resources [ 22 ]. The higher the similarity, the lower the level of resource allocation and management, and corresponding optimization is needed.…”

A Network of X-Band Meteorological Radars to Support the Motorway System (Campania Region Meteorological Radar Network Project)

“…Future work should be primarily devoted to improving the performance of the developed meteorological products. In this respect, our main aims can be synthetized in the following key-points: (i) the design of a hail detection tool that incorporates additional information, such as the appearance of high reflectivity core above the melting layer; (ii) the test of a precipitation type product relying on thermo-hygrometric conditions observed within the planetary boundary layer, in order to strengthen its affordability in discriminating between liquid and solid precipitation; (iii) the enhancement of radar-based real time snowfall rate estimates through a real time calibration involving disdrometric measurements, following the strategy proposed by [60]. The achievement of this goal presupposes the establishment, in the study areas, of a laser-disdrometer network, as well as the deployment of ultrasonic snow depth sensors in strategic sites (such as the A16 highway passes).…”

“…For this reason, some recent works have proposed the use of Kdp alone or in combination with Zh for radarbased snowfall estimation (e.g., [55,58,59]). Very recently, in [60] an interesting approach for snowfall rate estimation, based on colocated Parsivel disdrometer and K-band micro rain radar measurements collected in Antarctica during two austral summer seasons, has been proposed. More specifically, the authors of this study proposed a continue…”

“…For this reason, some recent works have proposed the use of K dp alone or in combination with Z h for radarbased snowfall estimation (e.g., [55,58,59]). Very recently, in [60] an interesting approach for snowfall rate estimation, based on colocated Parsivel disdrometer and K-band micro rain radar measurements collected in Antarctica during two austral summer seasons, has been proposed. More specifically, the authors of this study proposed a continue adaptation (on 10 min basis) of the equivalent reflectivity factor to snowfall rate relationship depending on six different snow categories, in order to account for the extreme variability of snow microphysical features.…”

Consistency test of precipitating ice cloud retrieval properties obtained from the observations of different instruments operating at Dome C (Antarctica)

“…Different studies pointed out that the total downwelling radiative flux in the internal regions of Antarctica, including Dome C, varies from 50 to 220 W m −2 (Bromwich et al, 2013;Di Natale et al, 2020a) because of the cloud forcing. In particular, the FIR component (below 667 cm −1 ) reaches the 75 % of the total flux for optically thin clouds and reduces to 55 % for the optically thick clouds, since the longwave radiative fluxes (LRFs) strongly depend on the ice/liquid water content (IWC/LWC) of the cloud (Di Natale et al, 2020a).…”