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RADAR METEOROLOGY

RADAR METEOROLOGY. Yrd. Doç. Dr. Ali DENİZ. OUTLINE. INTRODUCTION. RADAR HARDWARE. ELECTROMAGNETİC WAVES. RADAR EQUATION FOR POINT TARGETS. METEOROLOGICAL TARGETS. DISCUSSIONS. REFERENCES. INTRODUCTION. RA dio D etection A nd R anging. wawelength.

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RADAR METEOROLOGY

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  1. RADAR METEOROLOGY Yrd. Doç. Dr. Ali DENİZ

  2. OUTLINE INTRODUCTION RADAR HARDWARE ELECTROMAGNETİC WAVES RADAR EQUATION FOR POINT TARGETS METEOROLOGICAL TARGETS DISCUSSIONS REFERENCES

  3. INTRODUCTION RAdio Detection And Ranging wawelength LIght Detection And Ranging RADAR RADIO Buderi – 1996 : THE INVENTION THAT CHANGED THE WORLD Young and Taylor – 1934 : PULSES OF ENERGY

  4. power Doppler Radars speed RADAR DATA AUTOMATIC WARNINGS KINDS SHAPES POLARIZATION SIZES

  5. RADAR HARDWARE reflector transmitter receiver display modulator Master Clock antenna waveguide duplexer

  6. How Does Radar Work? single antenna Return back target send short pulses of energy The antenna rotates about a vertical axis, scanning the horizon in all directions To determine how high a storm is, met. radars can also aim their antennas above the horizon 10 to 20 elevation angles + 4 to 6 minutes DATA ...DISPLAY Whole cycle

  7. TYPES OF RADARS Monostatic and Bistatic radar CW and pulsed radar Doppler radar FM-CW radar Wind profilers and aircraft radars Airborn radar Shipboard radar Weather radar Dual-wavelength radar Polarization-diversity radar

  8. RADARS USED IN AVIATION L-band, =20 cm Detect aircraft ARSR : Provide information on the position of aircrafts ASR : Detect microbursts, gustfronts, wind shifts, pecipitaion TDWR : Follow aircraft on the ground at some airports ARDE :

  9. ELECTRO-MAGNETIC WAVES Radio & radar electro-magnetic radiation f : 1 Hz=1 cycle / second c: m/s : m

  10. Elektromagnetic spectrum Skolnik, 1980.

  11. Radar bands and corresponding frequency bands, (Rinehart, 2001). Radar Bands Frequency Wavelength HF 3-30 MHz 100-10 m VHF 30-300 MHz 10-1 m UHF 300-1000 MHz 1-0.3 m L 1-2 GHz 30-15 cm S 2-4 GHz 15-8 cm C 4-8 GHz 8-4 cm X 8-12 GHz 4-2.5 cm Ku 12-18 GHz 2.5-1.7 cm K 18-27 GHz 1.7-1.2 cm Ka 27-40 GHz 1.2-0.75 cm mm or W 40-300 GHz 7.5-1 mm

  12. cu (always) n1 (unitless parameter) Actually, it has two components ; k Absorption of coefficient of the medium REFRACTIVE INDEX c : the speed of light in a vacuum u: the speed of light in a medium n: refractive index For air; m=1.003

  13. REFRACTIVITY [N] Atm. Press. (mb, hPa) Temp. (°K) Vap. Press. (mb, hPa) Num. of free electron / m3 Freq. of the radar (Hz.) Under normal atmospheric contions; Ground N Z N

  14. RADAR EQUATION FOR POINT TARGET radar storms Rainrate and ... radar Puls of energy into space by antenna Power A spherically expanding shell of energy r : the range from the radar Power density : S

  15. target The power intercepted bye the target The amount of energy detected by radar will be: Ae : The effective area of the receiving antenna

  16. THE BACK-SCATTERING CROSS-SECTIONAL AREA OF THE TARGET New! Final Form “Large” : SPHERICAL TARGETS A sphere is LARGE RAYLEIGH region A sphere is SMALL “Small” :

  17. In the Rayleigh region : : related to the complex index of refraction of the material (Battan, 1973) RAYLEIGH REGION Meteorological targets small MET. RADAR USE SOME STANDART POINT TARGETS : Spheres, birds, aircraft, buildings, water towers and radio towers.... In conclusion; Point targets are imp. source of echo for many radars. By making careful measurements of the return from point targets, much canbe learned about the targets. Well-chosen point targets also make it possible to monitor the health and quantitative reliability of a particular radar system.

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