RAINGAIN Kick-Off Meeting Benefits of High Spatial and Temporal Resolution for Urban Catchments from existing Radars
UK Met Office Work Package <ul><li>Table of Contents </li></ul><ul><li>UK Network </li></ul><ul><li>Spatial Resolution </l...
Location of radars  5km resolution  coverage 2km resolution  coverage 1km resolution coverage UK Weather Radar Network
UK Weather Radar Network <ul><li>C-Band Siemens-Plessey Radars  </li></ul><ul><ul><li>Oldest  ~ 30 years old  </li></ul></...
Expected benefits of increased spatial resolution
Benefits of increased spatial resolution
Azimuthal Resolution improvement  *  Design considerations for improved tornado detection using super-resolution data on t...
Range Resolution improvement   <ul><li>Building on work by Sebastian Torres et al. </li></ul><ul><li>Oversample data and p...
Expected Benefits of Improved Temporal Resolution
Demands on Weather Radars  <ul><li>Different users place different (and increasing!) demands on weather radar time resourc...
A problem of temporal resolution 5 km  1 km Not noticeable  Highly noticeable  15 min accumulation for Crug-y-Gorllwyn, 07...
Threshold wind velocities for stroboscopic banding to occur  <ul><li>5 km radar resolution </li></ul><ul><ul><li>60  km/h ...
<ul><li>New Transmitter has novel control interface  </li></ul><ul><ul><li>Trigger pulse from DSP controls pulse length an...
Goals <ul><li>Currently producing 500m composite over London </li></ul><ul><ul><li>Determine limits of this with current C...
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RainGain : Benefits of High Spatial and Temporal resolution for urban catchments from existing radars

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Benefits of High Spatial and Temporal resolution for urban catchments from existing radars

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  • The problem of pixel jumping is applicable to the basic method of accumulation at all scales, however the wind velocities required for its manifestation at 5 km resolution are physically unrealistic in the UK. Threshold velocity = velocity required to move &gt; 1 pixel length in 5 minutes between scan intervals.
  • RainGain : Benefits of High Spatial and Temporal resolution for urban catchments from existing radars

    1. 1. RAINGAIN Kick-Off Meeting Benefits of High Spatial and Temporal Resolution for Urban Catchments from existing Radars
    2. 2. UK Met Office Work Package <ul><li>Table of Contents </li></ul><ul><li>UK Network </li></ul><ul><li>Spatial Resolution </li></ul><ul><ul><li>Benefits </li></ul></ul><ul><ul><li>Planned Work </li></ul></ul><ul><li>Increased Temporal Resolution </li></ul><ul><ul><li>Benefits </li></ul></ul><ul><ul><li>Planned Work </li></ul></ul>
    3. 3. Location of radars 5km resolution coverage 2km resolution coverage 1km resolution coverage UK Weather Radar Network
    4. 4. UK Weather Radar Network <ul><li>C-Band Siemens-Plessey Radars </li></ul><ul><ul><li>Oldest ~ 30 years old </li></ul></ul><ul><ul><li>Mechanically sound but control systems & transmitters increasingly facing obsolescence issues </li></ul></ul><ul><li>Renewal project installing new modern Motors, Drive systems and Transmitters – keeping pedestals and antennas – upgraded to Dual Pol. </li></ul><ul><li>In-house signal processing and control system </li></ul><ul><ul><li>Cyclops </li></ul></ul><ul><ul><ul><li>Currently 14 bit ADC @ 100MHz </li></ul></ul></ul><ul><ul><ul><li>Move to 16 bit ADC @ 200MHz </li></ul></ul></ul><ul><ul><ul><li>Allows access to whole of signal processing chain </li></ul></ul></ul>
    5. 5. Expected benefits of increased spatial resolution
    6. 6. Benefits of increased spatial resolution
    7. 7. Azimuthal Resolution improvement * Design considerations for improved tornado detection using super-resolution data on the NEXRAD network Sebastian Torres, Christopher Curtis Effective antenna patterns corresponding to legacy- and super-resolution processing for a Gaussian intrinsic antenna beam pattern with a two-way 6-dB beam width of 0.89 deg. * <ul><li>Beam width usually degraded by scanning motion of antenna </li></ul><ul><li>Beam sharpening by applying suitable weighting function </li></ul><ul><li>Degrades data due to effectively fewer samples – can possibly compensate by range oversampling </li></ul>
    8. 8. Range Resolution improvement <ul><li>Building on work by Sebastian Torres et al. </li></ul><ul><li>Oversample data and process to de-convolve effects of transmitter pulse and receiver </li></ul><ul><ul><li>Can be used to increase range resolution </li></ul></ul><ul><ul><li>Or </li></ul></ul><ul><ul><li>Can be used to increase number of independent samples available to reduce measurement variance in averaging stage </li></ul></ul><ul><ul><ul><li>Scan speed could then be increased with reduced degradation of measurement error </li></ul></ul></ul>
    9. 9. Expected Benefits of Improved Temporal Resolution
    10. 10. Demands on Weather Radars <ul><li>Different users place different (and increasing!) demands on weather radar time resources </li></ul><ul><li>Hydrological users want best rainfall estimate </li></ul><ul><li>NWP community want Volume Reflectivity, Radial Velocity and relative humidity </li></ul><ul><li>Forecasters want a combination of the two </li></ul>
    11. 11. A problem of temporal resolution 5 km 1 km Not noticeable Highly noticeable 15 min accumulation for Crug-y-Gorllwyn, 07-04-2009 (2130) Prevailing wind ( ~ 19 mph) (~ 30 km/h) Prevailing wind ( ~ 19 mph) (~ 30 km/h)
    12. 12. Threshold wind velocities for stroboscopic banding to occur <ul><li>5 km radar resolution </li></ul><ul><ul><li>60 km/h ( ~ 37 mph, ~ 32 knots ) – Rarely observed. </li></ul></ul><ul><li>2 km radar resolution </li></ul><ul><ul><li>24 km/h ( ~ 15 mph, ~ 13 knots ) – Observed fairly frequently and sometimes causes banding. </li></ul></ul><ul><li>1 km radar resolution </li></ul><ul><ul><li>12 k m/h ( ~ 7.5 mph, ~ 6 knots) – Regularly observable and frequently causes pixel jumping even in non-extreme precipitation events. </li></ul></ul>
    13. 13. <ul><li>New Transmitter has novel control interface </li></ul><ul><ul><li>Trigger pulse from DSP controls pulse length and repetition frequency simultaneously </li></ul></ul><ul><ul><li>Possibility of Mixed pulse lengths and PRFs </li></ul></ul><ul><li>Can we use this to maximise transmitted power (for best reflectivity) at same time as having high PRF (for best Doppler) within the duty cycle of the Tx? </li></ul><ul><li>Takes advantage of the fact that the rain does not fully de-correlate between pulses </li></ul>Can we combine Doppler and reflectivity scans/please everyone? t Pulse Gate PW 1 PW 2 PW 3 PRF1 PRF2 PRF n
    14. 14. Goals <ul><li>Currently producing 500m composite over London </li></ul><ul><ul><li>Determine limits of this with current C band hardware </li></ul></ul><ul><li>Decrease current volume scan times by factor of two </li></ul><ul><li>Maintain operational network with diverse user requirements </li></ul>
    15. 15. Questions and answers

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