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WEATHER ANALYSIS AND FORECASTING > WEATHER RADAR FUNDAMENTALS > Flashcards

WEATHER RADAR FUNDAMENTALS Flashcards

1
Q

METEOROLOGICAL OBSERVATIONS

A
  1. Satellite (National to Regional)
  2. RADAR (Regional to Local)
  3. In-Situ Stations (Local to Hyperlocal)
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2
Q

First used during WWII for tracking enemy airplanes and ships. After the war, the technology was adapted, used, and improved by scientists for weather analysis.

A

RADAR

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3
Q

Radars

A

emit pulsed of electromagnetic energy (microwave) Targets scatter energy in all directions. Some are scattered back toward the radar

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4
Q

“_______” back = “_______” = “Radar returns” = “Radar echoes”

A

Reflected

Reflectivity

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5
Q

Radar antenna starts at a low angle, sends out a pulse for a fraction of a second, and then “listens” to receive any returning energy.

A

RADAR SCANNING PATTERN

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6
Q

Types of Radar

A
  1. Horizontal reflectivity
  2. Horizontal Doppler velocity
  3. 2D reflectivity and velocity
  4. Identification of precipitation types
  5. Hail Detection
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7
Q

Types of radar that can provide vertical cross-section view of reflectivity (top) and precipitation type (bottom).

A

Dual polarization

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8
Q

Don’t have a single rotating antenna and don’t have a single rotating antenna.

A

PHASED-ARRAY RADARS

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9
Q

What are the two main scanning modes that modern-day radars have?

A

(i) precipitation scan mode

(ii) clear air scan mode.

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10
Q

What are the main difference of the two modes?

A

The priority of the scan.

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11
Q

Has steeper elevation scan compared to clear air.

A

Precipitation scan mode

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12
Q

What is CONE OF SILENCE?

A

An area in the troposphere that is not scanned by the radar. This is not usually a problem when precipitation is widespread and light-to-moderate, but it can mean that the top portions of thunderstorms within about 20 km (12 miles) will not be observable.

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13
Q

RADAR PRODUCTS

A

Even though majority of radars are designed to scan up to 200 km, the most accurate datasets are from <= 100 km.

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14
Q

It is a 1MW while returning is 1 nW

A

Transmitted pulse

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15
Q

REFLECTIVITY SCALES

A

The radar receiver amplifies the returned scatter and uses its amplitude to calculate the “radar reflectivity factor” (Z).

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16
Q

_______ indicates light precipitation (<= 30 dBZ), while _______ mean heavier precipitation. Above 60 dBZ mean it contains some hail.

A

low dBZ values

higher values

17
Q

BASE REFLECTIVITY

A

The most common type of radar product that indicates precipitation. It is the most common since it is the reflectivity taken from the lowest elevation scan.

18
Q

COMPOSITE REFLECTIVITY

A

Shows the maximum dBZ or precipitation at a certain vertical column. Consequently, it gives a plan view of the most intense portions of a precipitating system regardless of its altitude.

19
Q

Using the concept of Doppler shift, the radar can identify the speed and direction of the wind.

A

BASE VELOCITY

20
Q

What red shift (blue shift) indicates ?

A

the wind is moving away (towards) the radar.

21
Q

What green (red) scale indicates ?

A

the winds moving towards (away) the radar.

22
Q

Radar Limitation

A
  1. Radar miscalibration
  2. Range folding (RF)
  3. Beam Blockage
  4. Resolution
  5. Refraction
  6. Attenuation
23
Q

The time between pulses emitted by a radar must be long enough for any scattered energy from the first pulse to return before the radar has transmitted another pulse; otherwise, the radar will interpret the energy scatter from the original pulse as belonging to the second pulse.

A

Range Folding

24
Q

BEAM BLOCKING

A

It is radar viewing angles physical obstructions.

25
Q

Radar imagery inherently contains areas of varying resolution, which depends on the distance from the radar.

A

Resolution

26
Q

It broaden as they travel away from their source, creating ever larger sample volumes over which the reflectivity and other calculations are performed.

A

Radar pulses

27
Q

Due to the long-range capabilities of radar, its scans are vulnerable to refraction.

A

REFRACTION

28
Q

ATTENUATION

A

Depend on the intensity of precipitation and the wavelength of the radar pulses.

29
Q

Radar Network In the Philippines
As of 2021, there are ____ operational weather radars all over the country. It is expected to grow to _______ in the next 5 years.

A

Twelve (12)

Twenty (20)

30
Q

PAGASA creates a _______ from the individual radar images that they use mainly for weather analysis and weather forecasting.

A

MOSAIC

WEATHER ANALYSIS AND FORECASTING (5 decks)

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