radar derived precipitation part 4
Download
Skip this Video
Download Presentation
Radar-Derived Precipitation Part 4

Loading in 2 Seconds...

play fullscreen
1 / 19

Radar-Derived Precipitation Part 4 - PowerPoint PPT Presentation


  • 124 Views
  • Uploaded on

Radar-Derived Precipitation Part 4. I. Radar Representation of Precipitation II. WSR-88D, PPS III. PPS Adjustment, Limitations IV. Effective Use. COMET Hydrometeorology 00-1 Matt Kelsch Tuesday, 19 October 1999 [email protected] V. Effective Use Stage I PPS Strengths.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Radar-Derived Precipitation Part 4' - marcos


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
radar derived precipitation part 4

Radar-Derived Precipitation Part 4

I. Radar Representation of Precipitation

II. WSR-88D, PPS

III. PPS Adjustment, Limitations

IV. Effective Use

COMET Hydrometeorology 00-1

Matt Kelsch

Tuesday, 19 October 1999

[email protected]

v effective use stage i pps strengths
V. Effective UseStage I PPSStrengths
  • Numerous quality control steps to minimize limitations both in the radar estimate of precipitation, and the rain gauge representation of precipitation.
  • Spatial and temporal resolution are excellent for the mesoscale detail of precipitation systems.
    • Spatial detail over a large area
    • Monitor evolution of events between gauge sites
    • Real time information
stage 1 pps strengths cont
Stage 1 PPS:Strengths (cont.)
  • Opportunity for important rainfall information in remote, poorly instrumented areas.
  • Adaptation parameters provide some flexibility for different locations and climate regimes.
  • Has the versatility to evolve into a better algorithm that can effectively account for variability on a geographic, seasonal, and even hourly basis.
  • Offers important input for a comprehensive, multi-sensor system.
radar derived precip when changing z r coefficients is not the real solution
Radar-Derived Precip:When changing Z-R coefficients is not the real solution:
  • Range degradation, overshooting low-levels
    • Problem associated with propagation of beam, not Z-R.
  • Snowfall
    • More complexity than liquid hydrometeors.
    • Phase changes and mixed phases exist over small space/time scales.
    • Range degradation often co-exists.
  • Phase change: hail, melting snow
    • Radical storm-scale changes in Z to R relationship.
    • Minimal proof that hail correction can be done with Z-R.
    • Inconsistent relationship between Z-R and hail occurrence.
radar derived precip when changing z r may help
Radar-Derived Precip:When changing Z-R may help:
  • Consistently different average DSD (climate)
    • Tropical versus mid-latitude (warm vs. cold process)
    • Maritime versus continental
  • Consistently different average DSD (season)
    • Convective versus stratiform
  • Precip System character
    • Identify Convective versus Stratiform signature
    • Identify warm versus cold rain signature
    • Identify maritime versus continental
why can t the adaptation parameters and bias adjustment procedure solve all the limitations
Why can’t the adaptation parameters and bias adjustment procedure solve all the limitations?
  • Radar bias adjustment is only one uniform adjustment. It depends on adequate representation of precip by the local gauge network.
  • Adaptation parameters can greatly help the algorithm performance for a given site and/or season. The parameters “tune” the algorithm for the typical scenario. Atypical events, such as unusually high rainfall rates, may not be diagnosed well.
  • The most effective use of PPS is to make it a function of meteorology, not the “normal” climatology.
slide14
Can we account for the important atypical events without degrading the guidance for the more common typical events?
  • Meteorological information from soundings, profilers, and surface reports are a few examples of data sources that can assist with real-time adjustment of adaptation parameters.
  • Information from other NEXRAD algorithms, such as HAIL or VIL, may provide some guidance.
  • The most effective use of PPS is to make it a function of meteorology, not the “normal” climatology.
radar derived precipitation a summary of major points
Radar-derived Precipitation:A Summary Of Major Points
  • Radar provides one of several useful methods for sampling precipitation
  • Quantitative reliability issues are related to the fact that radar is sampling some volume at some elevation to estimate precipitation at the ground
  • Radar-derived precipitation is most reliably modeled for liquid hydrometeors; hail and snow add complexity
  • The above two points are not effectively corrected by changing Z-R coefficients; Z-R changes should be related to Drop Size Distribution knowledge.
  • Radars and rain gauges do not measure equal samples
  • Rain gauges do not provide a good representation of precipitation distribution, especially convective precip.
  • Radar provides excellent information about the spatial and temporal evolution of precipitation systems.
ad