Proposed: An ARM Precipitation Data Product

 

Authors

Mary Jane Bartholomew — Brookhaven National Laboratory
Jenni Kyrouac — Argonne National Laboratory
Adam Theisen — Argonne National Laboratory

Category

General Topics

Description

DROPS  Drop Size Distribution of Rainfall; Observations and Properties At any given ARM site, ground level precipitation observations are now made by multiple sensors. In addition to the tried and true MET tipping buckets and optical rain gauges, rainfall amount/rain rate is reported by weighing buckets (RAIN datastream) and acoustic rain gauges (AOSMET and MWR3C datstreams) . The suite of instruments is not consistent from site to site and each different sensor has strengths and weaknesses. More detailed rainfall characterization is collected by impact, laser and video disdrometers (DISD, PARS2 and VDIS datastreams) due to the disdrometer’s capability of measuring the drop size distribution. Furthermore, precipitation type is also available from some of the instruments. In hopes of providing a more useful, single datastream where researchers can find all of the rainfall results for each site, a precipitation best estimate data product is being considered. This product can significantly benefit from the rain gauge inter-comparison studies being carried out by the ARM Data Quality Office and others previously published (Vuerich et al., 2009, Tokay et al., 2013). Quality assessments can be provided for each observation. Most importantly, the suspicious observations reported by each instrument could be flagged on a minute by minute basis. Low rainfall is a particularly difficult observation to make with high accuracy and each device has a different threshold for observing low rain rates. The same is also true for very high rain rates. The DROPS data product can also produce the higher order derived values from the disdrometer data that pertain to radar validation and precipitation processes. Equivalent radar reflectivity mean Doppler velocity and attenuation can be calculated as a function of wavelength from the observed drop size distribution. While this does not provide a true radar calibration, it can provide a tool to help monitor radar performance. Tokay A., W. A. Petersen, P. Gatlin, and M. Wingo, 2013: Comparison of Raindrop Size Distribution Measurements by Collocated Disdrometers. J. Atmos. Oceanic Technol., 30, 1672–1690. doi: http://dx.doi.org/10.1175/JTECH-D-12-00163.1 Vuerich E., C. Monesi, L.G. Lanza, L. Stagi, and E. Lanzinger, 2009. WMO field intercomparison of rainfall intensity gauges. WMO/TD- No. 1504.