1. Rain Detection & Attenuation for Remote sensing; & auxiliary sensors
Dr. Sandra Cruz-Pol
INEL 5995
DCAS –network weather radars

3. Total number of drops per unit volume
in units of mm-3

4. Reflectivity in other books

6. For Rayleigh approximation
The cross sectional areas of a scatterer.
D=2r =diameter of drop

7. Observe scattering in Visible EM; forward scattering vs. backscattering
Mie scattering by dust particles and aerosols
Rayleigh scattering by water vapor molecules and gases.

9. Mie forward scattering nos impide ver bien a menos que haya alto contraste.

12. Volume extinction from clouds
Total attenuation is due to gases,cloud, and rain
cloud volume extinction is (eq.5.98)
Liquid Water Content LWC or mv )
water density = 106 g/m3

13. Raindrops symmetry
polarimetric radars

14. Volume backscattering from Clouds
Many applications require the modeling of the radar return.
For a single drop
For many drops (cloud)

15. Reflectivity Factor, Z Is defined as so that
and sometimes expressed in dBZ to cover a wider dynamic range of weather conditions.
Z is also used for rain and ice measurements.

16. Reflectivity in other books

17. Reflectivity & Reflectivity Factorh
Z (in dB)
Reflectivity, h [cm-1]
dBZ for 1g/m3
Reflectivity and reflectivity factor produced by 1g/m3 liquid water
Divided into drops of same diameter. (from Lhermitte, 2002).

18. Precipitation (Rain) Volume extinction where Rr is rain rate in mm/hr
[dB/km] and b define an algorithm and can depend on polarization since large drops are not spherical but ~oblong.
[dB/km]
Mie coefficients

19. Rain Rate [mm/hr]
If know the rain drop size distribution, each drop has a liquid water mass of
total mass per unit area and time
rainfall rate is depth of water per unit time
a useful formula

20. W-band UMass CPRS radar

21. Volume Backscattering for Rain
For many drops in a volume, if we use Rayleigh approximation
Marshall and Palmer developed
but need Mie for f>10GHz.

22. Rain retrieval Algorithms
Several types of algorithms used to retrieve rainfall rate with polarimetric radars; mainly
R(Zh),
R(Zh, Zdr)
R(Kdp)
R(Kdp, Zdr)
where
R is rain rate,
Zh is the horizontal co-polar radar reflectivity factor,
Zdr is the differential reflectivity
Kdp is the differential specific phase shift a.k.a. differential propagation phase, defined as

23. 2-Dimensional video disdrometer
X-band polarimetric radar simulation -estimator R(KDP) - less sensitive to natural variations in DSD
2-Dimensional video disdrometer
R-Z relation

24. Also called Distrometers
$80K $25K

25. Rain Gauges
Tipping bucket mm (0.007 in) falls the lever tips and an electrical signal is sent to the recorder
Weighing rain gauge-storage bin atop a pen recording the changes of weight on a rotating drum . More expensive than Tipping buckets.
Optical -These have a row of collection funnels. In an enclosed space below each is a laser diode and a phototransistor detector. When enough water is collected to make a single drop, it drips from the bottom, falling into the laser beam path. The sensor is set at right angles to the laser so that enough light is scattered to be detected as a sudden flash of light. The flashes from these photodetectors are then read and transmitted or recorded.

26. Water spout at Mayaguez, Sept 2005

27. Calibrated R-Z for 3 regions
Rain gauge data
R-Z calibration
NEXrad data
Leonid Tolstoy, UPRM-CSU Collaborative Ph.D. student

28. Puerto Rico Testbed IP3
Update:1st radar is here