Radar Principles

Question 1

Types of Radar Deployments

Answer 1

Airborne, Space, Mobile, NEXRAD

Question 2

K-band

Answer 2

Wavelength 0.75-1.2cm, 1.7-2.5cm and frequencies of 27-40 GHz and 12-18 GHz (Police/radar guns)

Question 3

X-band

Answer 3

Wavelength 2.4-4 cm and frequency 8-12 GHz (aircraft weather avoidance radars, DOW)

Question 4

C-band

Answer 4

Wavelength 4-8 cm and frequency 4-8 GHz (former NWS local warning radars; TV stations)

Question 5

S-band

Answer 5

Wavelength 8–15 cm frequency 2-4 GHz (NWS NEXRAD, WSR-88D Doppler weather surveillance radar requires antenna dish 25-30 ft diameter; ATC ASR radars)

Question 6

L-band

Answer 6

Wavelength 15-30 cm and frequency 1-2 GHz (air traffic control ARSR radars; clear air turbulence studies)

Question 7

Microwave oven E-M radiation is ~2450 MHz frequency and the wavelength is about 12cm (~4.7in) which is very similar to _______

Answer 7

Weather radar surveillance operations

Question 8

E-M Microwave radiation emitted by ________ and ________ is __________

Answer 8

Weather radars, home microwave ovens, Non ionizing radiation

Question 9

rearrange DNA and other cellular structures

Answer 9

Ionizing radiation

Question 10

Does not rearrange DNA and other cellular structures

Answer 10

Non-ionizing radiation

Question 11

The _______ (shorter) the ______ the _____ (smaller) the precip-size particle that can be detected

Answer 11

Longer, wavelength, larger

Question 12

The ______(shorter) the _______, the ____(more) likely that precip attenuation of the radar signal will occur

Answer 12

Longer, wavelength, less,

Question 13

The _______(shorter) the ________ the _______(smaller) the diameter of the radar antenna/dish is required; this has major implications for onboard aircraft ______________

Answer 13

Longer, wavelength, larger, rather-avoidance radars

Question 14

The NOAA National Weather Service WSR-88D Doppler radar is a ___________ (s-band) weather detection radar that is excellent at sampling most precip particles without encountering any __________ due to precip attenuation

Answer 14

10-cm wavelength, significant signal loss

Question 15

A large amount of horizontally polarized EM energy is transmitted but only a ______ of energy is reflected back to the radar receiver,

Answer 15

Fraction

Question 16

Range-Height Information (RHI) assume ________

Answer 16

Standard refractivity index

Question 17

Power returned to the radar by a target is ______ related to the ___________ Z, and _______ related to the ______ R.

Answer 17

Directly, reflectivity factor, inversely, range

Question 18

Only a _____ increase in drop diameter can result in a ______ increase in reflectivity Z

Answer 18

Small, large

Question 19

Large drops return ______ power….. but can contribute ______ to total water mass

Answer 19

Most, less

Question 20

One 1/4 inch diameter drop returns as much energy as ________ of 1/8 inch diameter

Answer 20

64 drops

Question 21

However, one 1/4 inch diameter drop has a volume of only 0.065in^3, where as 64 1/8inch diameter drops yield a volume of 0.52 in^3 or __________ total water mass

Answer 21

8 times as much

Question 22

The one 3mm diameter rain drop returns _______ and produces a larger reflectivity than the 64 1mm drops do….. yet the one 3mm diameter rain drop contains ______ total water mass than the 64 1mm rain drops

Answer 22

More power, much less

Question 23

Since we don’t know the _____ distribution of ______ particles we can use the ________ (sintead of reflectivity), which is a function of the power returned and the range/distance from the radar

Answer 23

Actual, precipitation, equivalent reflectivity

Question 24

A Doppler weather measures a single component of motion, but only ______ or _____ from the radar

Answer 24

Toward, away

Question 25

Typical rain drop is a ‘flat’ oblate spheroid with a ______ horizontal _____ that returns more energy in the horizontal plane

Answer 25

Wider, axis

Question 26

Dual-polarized radar provides better z-r relationship and rainfall estimates by determining _________

Answer 26

Precipitation type

Question 27

Values of Zdr well ______ indicate the hydrometeors in the volume are ________ (rain) meaning their horizontal axis is longer than their vertical axis

Answer 27

Above zero, horizontally oriented

Question 28

Values of Zdr well ______ indicate the hydrometeors in the volume are ________ (large hail) meaning their vertical axis is longer than their horizontal axis

Answer 28

Below zero, vertically oriented

Question 29

Values of Zdr ______ indicate hydrometeors in the volume have nearly ________ (snow, giant hail) in the mean

Answer 29

Near zero, spherical shape

Question 30

Zar values for meteorological echos typically range between _____ dB and _____ dB

Answer 30

-2, 6

Question 31

Power returned to the radar is ________ to the power transmitted and the target reflectivity

Answer 31

Directly related

Question 32

Power returned to the radar is _______ to the target range

Answer 32

Indirectly relates

Question 33

Radar ______ increases with increasing ________

Answer 33

Beam height, range

Question 34

WSR-88D Doppler weather radar 4-bin-average (4BA) Doppler velocity data _______ as reconnaissance aircraft flight-level wind speed data

Answer 34

Is as accurate

Question 35

Zero greater than or equal to 2 is

Answer 35

Rain

Question 36

Zdr less than or equal to 0 is

Answer 36

Hail/graupel