Rain gauges are often considered ground truth for radar QPE. The QVS ingests many networks and provides for statistical results and manual quality control. See this link for statistical formulas. Stats are updated when gauges are quality controled. Gauge-radar data can be exported for additional use.
TIP: Most CoCoRaHS gauges report at 7am local time, which varies in UTC across the country. Some CoCoRaHS report on surrounding hours.
Q2 [Radar Only] vs gauges
Radar-based precipitation rate and accumulations over various time periods (1- to 72-hour). The rate is derived from the hybrid scan reflectivity using convective, stratiform and tropical Z-R relations identified by the precip_flags (that are in turn identified by VPRs). Note the additional optional Z-Rs used by the NWS.
An objective analysis of all gauges from NCEP with a 3 hr delay.
Q2 with a local gauge adjustment that includes a gauge-radar bias QC application
Local gauge corrected radar QPE fields. The local gauge correction is applied onto the 1-h Q2RAD_HSR precipitation field. It runs hourly and uses hourly rain gauge observations from the HADS (Hydrometeorological Automated Data System) data sets at NCEP. In the local gauge correction scheme, radar-gauge biases are calculated at each gauge site and then interpolated onto the MRMS grid using an inverse distance weighted (IDW) mean scheme. The two parameters in the IDW scheme, exponent and radius of influence, are determined through a cross-validation procedure. The interpolated radar-gauge bias field is applied back to the Q2RAD_HSR 1-h precipitation field and a local gauge bias corrected 1-h precipitation field is obtained. Longer-term accumulations are computed by aggregating the 1-h local gauge corrected precipitation fields.
Legacy PPS refers to conventional products from the Precipitation Proccessing System (PPS) computed in the ORPG and have resolution 1 km by 1 degree.
Instantaneous rates, 1 hr and 24 hr accumulations are displayed.
Various networks can be selected and carry over to the Dual-pol area.
Data can be scaled and output for further use.
Lookup Mode allows an average of surrounding radar pixels and the data range of the pixels is shown by the whiskers in the plot.
Completeness controls plotting of gauge data that may have missing time periods (currently 1-hr periods).
Click Initial Text File Output and a pop-up window will contain all the radar- gauge pairs and stats.
Text Output Current Selections opens a new browser tab and displays current radar-gauge pairs. Editing data will update information in the new tab.
Gauge data can be quality controlled by clicking on the
point in the plot. Updates are displayed in new tab if that option is selected on
the "Scatter" tab. Zooming on the region (lower left) will control number of points
in the plot. Hover over "Label All" to see all gauge IDs.
Note: the number of gauges meeting thresholds is displayed at the top.
Various masks can be applied to filter data.