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MRMS/HalfDegGauge

Comparisons of rainrates from gauges and MRMS over HalfDeg Gauge Network, MD-VA

Gauge data

A network of 20 indvidual gauge sites was deployed in an approximately 0.5-degree grid area over Delmarva Peninsula near Maryland-Virgina boundary. Three tipping-bucket gauges were equipped at each of Sites 01-09,18,19,29, and two at each of Sites 10-14. Here is a list of these gauge sites and their locations as well as their deployment dates.
    SiteID         Lat(N)        Lon(W)       Installation Date
    0001         38.03231      75.39695   Fri, 21 February 2014
    0002         38.33289      75.70567   Wed, 26 February 2014
    0003         38.19720      75.69918   Thu, 29 December 2011
    0004         38.16560      75.39945   Thu, 05 January 2012
    0005         37.93716      75.46634   Fri, 20 August 2004 (Gauges A&B),Gauge C was installed on Fri, 30 May 2008
    0006         37.92781      75.72054   Fri, 16 December 2011
    0007         38.01686      75.82676   Thu, 22 December 2011
    0008         38.34092      75.51331   Tue, 24 August 2004 (Gauges A&B),Gauge C was installen on Tue, 03 June 2008
    0009         38.19685      75.36974   Mon, 24 March 2014, In addition,
                  NASA38 (A&B) was moved to Site09 on 06 May 2015. So, 5 gauges at Site09.
    0010         38.36982      75.65482   Wed, 04 Jun  2014 (NASA0012)
    0011         38.01403      75.52278   Mon, 21 July 2014 (NASA0019)
    0012         38.26268      75.34166   Thu, 21 Aug  2014 (NASA0025),moved from (37.93456  -75.47101) on 21 Aug 2014,
                   then moved to Site0016 (38.05473, -75.40990) on 2015-Apr-14
    0013         38.33173      75.40291   Thu, 16 Oct  2014 (NASA0022)
    0014         38.12071      75.73399   Thu, 05 Feb  2015 (NASA0005)
    0015	     38.012383     75.455125  Mon, 09 Mar  2015 (NASA0017)
    0016	     38.054728     75.409900  Tue, 14 Apr  2015 (NASA0025)
    0017	     38.36986      75.31886   Mon, 08 Jun  2015 (NASA0006)
    0018         38.09558      75.43140   Thu, 11 Feb  2016
    0019         38.21044      75.58657   Wed, 09 Mar  2016
    0029         37.97574      75.50856   Wed, 25 Aug  2016 
    

All these gauges measure rainfall in increments of 0.01 inch (0.254 mm).

Collocated gauge comparisons

Comparisons with MRMS

The following figure shows the areal map of HalfDegGrid Gauge Networks along with 0.1o grids. The dots denote locations of the individual gauge sites with their identification numbers indicated on the right.

The rain tip data from each gauge are QCed, and compared with the MRMS rainrates at each 0.01-degree pixel where the gauge locates. The comparisons are conducted at hourly and daily resolutions for each matched pixel, as well as for averaged pixel from all matched data.

Two sets of MRMS files, hourly and half-hourly are available for this study. Hourly MRMS files are available from 01 Feb 2013 to 06 Jun 2016, and half-hourly files from 01 Jun 2014 to 01 Jun 2017 with a lof of missing (Jan-May 2016 are completely missing) as of this writing. Since most gauges started to report rain tips from Mar 2014 and some are only updated to Aug 2015, both the MRMS and gauge data from Mar 2014 (or Jun 2014 for half-hourly MRMS) to Dec 2015 are included in this study.

Following is a complete list of the gauges used in the comparisons.
	   SiteID     Lat(N)        Lon(W)    Start    End          Missing
	   0001	     38.03231      75.39695  20140221 20150821 20140727 20141124
	   0002	     38.33289      75.70567  20140226 20150802
	   0003	     38.19720      75.69918  20140310 20150823 
	   0004	     38.16560      75.39945  20140310 20151231
	   0005	     37.93716      75.46634  20140311 20151231 20141017 20141231
	   0006	     37.92781      75.72054  20140311 20151120 20140803 20141231
	   0007	     38.01686      75.82676  20140312 20151231
	   0008      38.34092      75.51331  20140314 20151231 20140803 20150518
	   0009	     38.19685      75.36974  20140324 20151231
	   0010      38.36982      75.65482  20140604 20151231
	   0011	     38.01403      75.52278  20140721 20151231
	   0014	     38.12071      75.73399  20150205 20151231 20150922 20151014
	   0015	     38.012383     75.455125 20150309 20151231 20150922 20151014
	   0016	     38.054728     75.409900 20150414 20151231
	   0017	     38.36986      75.31886  20150608 20151231
     

Below is the comparison using hourly MRMS data (Mar 2014 - Dec 2015)

  • Cumulative rainfall

  • Scatter plot

  • Mean difference and relative error

  • PDF by occurrence and volume
    In the PDF plot, rainrate thresholds are set to 0.1, 0.2 and 0.5 mm/h.

    The inserted "Agreement" in the PDF plot is defined as the fraction of both MRMS and gauge report the same rain category: rain ( rainrate >threshold), no rain (rainrate <=threshold) among all available observations.

    Agreement=N[(r>T & g>T) + (r<=T & g<=T)] / N(r>=T & g>=T)
    where T is rain threshold (0.1,0.2 0r 0.5 mm/h), N is sample size, r is MRMS rainrate, and g is gauge rainrate. Be definition, Agreement is between 0 (worst) and 1 (best).


Below is the comparison using QCed half-hourly MRMS files (Jun 2014 - Dec 2015)

The half-hourly MRMS data are QCed using following filters, and then accumulated to hourly and daily rainrates.
RQI>=80; 0.5<=ratio<=2. and ratio=0.; liquid precipitation only
  • Scatter plot

  • Mean difference and relative error

  • PDF by occurrence and volume

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