Solid Precipitation and Visibility Measurements at the Centre for Atmospheric Research Experiments in Southern Ontario and Bratt’s Lake in Southern Saskatchewan

Abstract

Accurate measurement of solid precipitation ((Formula presented.)) has a critical importance for proper understanding of the Earth’s hydrological cycle, validation of emerging technologies and weather prediction models, and developing parameterizations of severe weather elements such as visibility ((Formula presented.)). However, measuring (Formula presented.) is still a challenging problem, due mainly to wind effects. The wind effects are normally mitigated by using a Double-Fence Automated Reference (DFAR) system to reduce the wind speed ((Formula presented.)). To contribute towards addressing some of these problems, we have analyzed datasets collected at two sites, Center for Atmospheric Research Experiments (CARE) and Bratt’s Lake, located in southern Ontario and southern Saskatchewan, Canada, respectively, using several instruments. The instruments at CARE include two Geonor gauges, one placed inside a DFAR ((Formula presented.) and the other inside a double Alter shield ((Formula presented.)), a Pluvio2 gauge inside a single Alter shield ((Formula presented.)), a HotPlate, a PARSIVEL2 disdrometer that measures S and fall velocity ((Formula presented.)), and an FD12P senor that measures S and type and Vis. The instruments deployed in Bratt’s Lake includes a similar DFAR system and DAS Pluvio2 gauge. The results show that for the (Formula presented.) observed in this study ((Formula presented.) < 6 ms−1), both (Formula presented.) and (Formula presented.) have similar collection efficiency (CE) of near 70%. The transfer functions (TF) for (Formula presented.) and (Formula presented.) as a function of (Formula presented.) and also (Formula presented.), and (Formula presented.) were derived. The TF developed for the (Formula presented.) that includes both (Formula presented.) and (Formula presented.) showed better agreement with observation than just (Formula presented.) alone. The TF developed for (Formula presented.) at CARE site was tested using the data collected in Bratt’s Lake and correlated well (R = 0.86), but slightly overestimated the S accumulation by about 12%. The S measured at CARE site using all the other instruments were correlated well with (Formula presented.) (R = 0.9), but the PARSIVEL2 and FD12P overestimated and underestimated the snow amount, respectively, as compared the (Formula presented.). However, the HotPlate captured similar amount of (Formula presented.) as the (Formula presented.). According to this study, the (Formula presented.) showed good correlation with Vis.