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CDC URE > 5A-2 Radar > Flashcards

5A-2 Radar Flashcards

0
Q

Which wavelength is best when you are trying to detect light to moderate rain?

A

3 cm

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1
Q

An electrical current passing through a wire coiled around a metal bar that induces a magnetic field is called

A

Electromagnetism

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2
Q

Which wavelength would be best for you to use when large thunderstorm or hurricanes frequently occur?

A

10.7 cm

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3
Q

The number of cycles per a given unit of time is called

A

Frequency

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4
Q

As electromagnetism waves are emitted from radar and travel through the atmosphere, some of their energy is lost. What is the loss of energy because of the interaction with atmospheric phenomena called?

A

Attenuation

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5
Q

What are the two related factors that attenuation of radar waves depends on?

A

Wavelength of the emitted radio waves and size and composition of the particle encountered by these waves

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6
Q

The amount of time it takes the radar to send one pulse is known as

A

Pulse length

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7
Q

What decides the minimum range of the radar?

A

Pulse length

Max range is listening time

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8
Q

Another term for second-trip echoes is

A

Range folding

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9
Q

How does the radar beam width vary with the wavelength; how does it vary with the diameter of the parabolic reflector of the antenna?

A

Radar beam width and wavelength DIRECTLY proportional

Radar beam width and diameter of reflector INVERSELY proportional

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10
Q

Sample volume is equal to

A

One-half the pulse length and beam diameter

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11
Q

What kind of resolution is it called when the radar can distinguish between two targets at the same range but different directions from the radar?

A

Bearing resolution

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12
Q

The ability of the radar to differentiate between two closely spaced targets at the same range and bearing but at different elevations depends on

A

Beam width

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13
Q

Range resolution depends on

A

Pulse length

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14
Q

Side lobes can cause certain side effects. Which is a side effect?

A

Ground clutter

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15
Q

Superrefraction is when the curvature of the radar beam is

A

Greater than the earth’s curvature

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16
Q

Another effect of superrefraction is the displayed height values are

A

Overestimated

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17
Q

Straightening of the radar beam upward best defines

A

Subrefraction

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18
Q

What does subrefraction do?

A

Reduces the maximum range of detection of low-level targets

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19
Q

Computation of the equivalent reflectivity factor (Ze) depends on

A

Average returned power, range to target, and a set of known factors called the “radar constant”

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20
Q

While performing a radar METWATCH, the operator notices a storm that had increased from 40 tom43 dBZs at one elevation slice. The operator must assume the intensity of this storm has

A

Doubled

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21
Q

The factor that allows a Doppler radar to remember the frequency of transmitted energy for later comparison to returning energy is

A

Coherency

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22
Q

The WSR-88D has only one antenna, it only measures the component of wind that is

A

Parallel to the radar beam

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23
Q

Which action is an effective means of decreasing velocity aliasing?

A

Increase the pulse repetition frequency

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24
Q

The Doppler dilemma is a trade off between

A

Range and velocity

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25
Q

What kind of pulse repetition frequencies (PRF) are required for high velocity measurements and long ranges?

A

High PRFs are required for high velocity measurements, and low PRFs are required for long ranges

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26
Q

What’s the Doppler spectrum?

A

The distribution of power received by the radar at each frequency within a sample volume

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27
Q

The spectral slope of the Doppler spectrum of a large thunderstorm with hail appear

A

Broad and flat

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28
Q

The spectrum width product is useful for the early detection of thunderstorm development because

A

The detection of high spectrum widths may be indicative of currents present in a convective atmosphere

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29
Q

Widespread low spectrum width values with isolated areas of higher values is most likely indicative of

A

Embedded storms

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30
Q

The beam width of the WSR-88D is approximately

A

1.0 degree

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31
Q

Which sub component of the radar data acquisition (RDA) takes raw analog data from the receiver and process it into a digital base data?

A

Signal processor

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32
Q

Solid (ground clutter) return has very low spectrum width values ranging from

A

0.1 to 0.5 m/sec

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33
Q

Data thresholding occurs at the

A

Radar data acquisition (RDA)

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34
Q

How many elevation slices does both volume coverage pattern (VCP) 31 and VCP 32 (clear air mode) complete in ten minutes?

A

Five

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35
Q

How many hours does the JAZ drive have the capability to hold?

A

450 hours

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36
Q

Control of the radar product generator (RPG) is accomplished from a computer terminal known as the

A

Master system control function (MSCF)

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37
Q

Who owns the MSCF at a majority of the CONUS locations?

A

National Weather Service (NWS)

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38
Q

How is data transferred from the radar product generator (RPG) to an Open Principal User Processor (OPUP)?

A

By the wideband communications link

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39
Q

What is the maximum number of workstations a large OPUP can consist of?

A

10

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40
Q

Which system supports direct connections to up to seven WSR-88Ds?

A

Medium OPUP

41
Q

The OPUP uses which operating system and user interaction is done through the common desktop environment (CDE) Graphic User Interface (GUI) by

A

Unix; keyboard and mouse

42
Q

The OPUP product display window can display up to how many windows per screen?

A

12

43
Q

Which value is considered non-precipitable and are often just cloud droplets?

A

+18 dBZ

44
Q

Where would you look for a hook echo signature?

A

In the right rear quadrant of the trailing half of the parent echo

45
Q

Embedded thunderstorms are detected by the WSR-88D quite well because

A

It’s 10 cm wavelength can see through the stratiform precipitation because less attenuation occurs

46
Q

Outflow boundaries may be seen on the WSR-88D even when no clouds are present because

A

Of the gradient in the refractive index

47
Q

Which product is used to detect and locate motions in and around potentially severe weather producing storms?

A

Base mean radial velocity

48
Q

When the Doppler zero line has a noticeable S-shaped pattern, winds are considered

A

Veering with height

49
Q

When the radar detects pure cyclonic rotation, the Doppler zero line is oriented

A

Parallel to the viewing direction

50
Q

The spectrum width product is most effective when

A

Used with other products

51
Q

The spectrum width product is useful for the early detection of thunderstorm development because

A

The detection of high spectrum widths may be indicative of currents present in a convective atmosphere

52
Q

Data collected for generation of the composite reflectivity product is derived from

A

All elevation slices

53
Q

Which statement is NOT a use of the composite reflectivity (CR) product?

A

It can be used to show 3-D structure of the reflectivity pattern
USES:
First step in identifying sig weather features
Quick check on overall reflectivity pattern
Provides instant snapshot of most imp reflectivity patterns

54
Q

The melting level is displayed on the composite reflectivity product as

A

Multiple rings of enhanced reflectivity around the RDA

55
Q

Which procedure is a primary use for the layered composite reflectivity maximum (LRM) product?

A

Quickly identifying stronger storms and areas with a greater potential for convection

56
Q

Which condition indicates an intense updraft and strong likelihood for severe weather on the layered composite reflectivity product?

A

Strong reflectivity values (>50 dBZ) in the high altitude layer

57
Q

What is the minimum depth layer for the layered composite reflectivity pattern?

A

1000 ft

58
Q

What is the major difference between composite reflectivity and user selectable composite reflectivity?

A

Composite reflectivity is produced by using the entire volume scan

59
Q

Which is a true statement concerning ground clutter?

A

Ground clutter principally affects lower elevations, and has low radial velocity and spectrum width

60
Q

Identify the three processing regions of the layered composite reflectivity maximum (LRM) anomalous propagation removed (APR) algorithm.

A

Omit all, accept if, and reject if

61
Q

As the strength of the updraft in a storm increases, the vertically integrated liquid (VIL) values of that storm

A

Increase

62
Q

Vertically integrated liquid (VIL) algorithm display VIL values for storms based on

A

Reflectivity data converted to liquid water content values

63
Q

A strongly tilted storm may cause what mind of vertically integrated liquid (VIL) values to be displayed?

A

Lower

64
Q

The echo tops (ET) product is based on data from what other product?

A

Base reflectivity

65
Q

The echo tops (ET) product computes echo top height by using

A

2.2 x 2.2 nm grid boxes

66
Q

What is the function of the tilt test in the hybrid scan reflectivity (HSR) algorithm?

A

It compares the areal coverage of echoes at the 0.5 and 1.5 elevation slices

67
Q

The storm total precipitation (STP) product provides continuously updated information on precipitation accumulations within how many nautical miles of the radar?

A

124

68
Q

A limitation of the STP product is that it

A

Has trouble with small scale features

69
Q

What information is included in the attribute table that accompanies the user selectable precipitation (USP) product?

A

The total number of hours used to build the product

70
Q

How long is the database for the user selectable precipitation (USP) product?

A

30 hours

71
Q

What is the maximum number of hours that the user selectable precipitation product can be generated for?

A

24 hours

72
Q

When is the only time snow products are useful?

A

During dry snowfall events

73
Q

What are the typical strength rank values for a well-defined mesocyclone?

A

Between five and nine

74
Q

The mesocyclone detection (MD) product can be graphically displayed, what symbol is displayed for a circulation having a strength rank less than 5?

A

A thin yellow open circle

75
Q

The graphic symbol for a tornadic vortex signature (TVS) is a

A

Red-filled, inverted, isosceles triangle

76
Q

The graphic symbol for an elevated tornadic vortex signature (TVS) is a

A

Red, open, inverted, isosceles triangle

77
Q

The maximum shear associated with a tornadic vortex signature (TVS) must be at least

A

36 m/s (=~ 72 knots) anywhere in the circulation

78
Q

Which statement is NOT a limitation of the tornadic vortex signature (TVS) product?

A

It only identifies TVSs associated with mesocyclones

79
Q

The total number of vertical wind profiles that can be displayed on a single velocity azimuth display winds profile (VWP) is up to

A

11

80
Q

The velocity azimuth display (VAD) wind profile (VWP) displays

A

The true wind speed and direction

81
Q

The color-coded root mean square (RMS) of displayed velocity azimuth display (VAD) winds is related to the

A

Reliability of the winds

82
Q

Data thresholds for the vertical winds profile (VWP) can be changed

A

By the master system control function (MSCF)

83
Q

The velocity azimuth display (VAD) winds profile (VWP) can detect features such as

A

Wind shifts and jet streams

84
Q

The SRM/SRR depends on what algorithm?

A

Storm tracking

85
Q

The velocity cross-section product is limited to a range within

A

124nm

86
Q

Resolution of cross-section products

A

Remain constant

87
Q

Which algorithm is the output of the storm cell segments algorithm directly sent to?

A

Storm cell centroids

88
Q

The Storm Cell Identification and Tracking (SCIT) algorithm can track how many individual storm cells?

A

100

89
Q

How does the storm cell tracking algorithm handle a storm cell centroid when it can’t correlate with a storm cell centroid from a previous volume scan?

A

It labels the storm as “NEW” and doesn’t forecast a track

90
Q

What determines the length of a forecast made by the storm position forecast algorithm?

A

Accuracy of previous volume scan’s forecast

91
Q

The storm track information (STI) product algorithm provides data on

A

Past, present, and future locations of thunderstorms

92
Q

How many minutes does the linear motion feature enable the radar user to manually compute a forecast position?

A

60 minutes

93
Q

What are the three estimates that the hail detection algorithm provides?

A

Probability of hail
Probability of severe hail
Maximum expected hail size

94
Q

The probability of severe hail algorithm will look for hail

A

> 3/4 inch

95
Q

What information needs to be routinely updated to increase the hail detection algorithm’s performance?

A

Mean sea level (MSL) altitudes for 0 deg C and -20 deg C

96
Q

What is the maximum number of volume scans used for history in the cell trends graphic product?

A

10

97
Q

Which dual polarization product is the ratio of the reflected horizontal and vertical power returns and is expected in decibels?

A

Differential reflectivity

98
Q

Which dual polarization product is a dimensionless measure of the similarity between the reflected horizontal and vertical power returns within each radar pulse volume?

A

Correlation coefficient (CC)

99
Q

The outer dashed circle on the melting layer product represents the

A

Point along the radial beyond which the beam is entirely above the melting layer

CDC URE (9 decks)

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