Satellite And Radar Imagery Flashcards
With respect to NZ IFR operations, using given examples of satellite imagery, identify the processes causing each significant area or mass of cloud.
- Warm and cold fronts
- Jet-streams
- Stable cloud in anticyclones
- Unstable cloud in cyclones
- Orographic lifting caused by hills/mountains
With respect to NZ IFR operations, using given examples of satellite imagery, identify the likely cloud types and weather associated with each significant area of cloud.
- Unstable areas will have showers
- Stable areas will have clear skies or stratiform drizzle
- Fronts and tropical cyclones will have associated weather, including icing and turbulence
With respect to NZIFR operations, interpret radar imagery in terms of likely cloud types associated with the precipitation echo.
- Dark blue and above, most likely showers from Cb or large cumuliform like TCu
- Yellow is more stable and most likely drizzle in St
- Very fine drizzle is not picked up by radar
- Easiest to pick up wet hail out of all precipitation types as most reflective to weather radar
Describe how infra-red and visible satellite imagery can be used together to provide information on the areal extent of cloud.
- Areal means seeing how far the cloud spreads horizontally
- Visible imagery very accurately at determining areal extent during the day
- At night visible imagery less accurate at determining areal extent during
- Infra-red does not identify clouds close to the surface as cloud temperature is similar to the land/ocean
Describe how infra-red and visible satellite imagery can be used together to provide information on the height of the cloud top.
- Low cloud will show on visible imagery but not infra-red
- High level cloud will show as low temperatures on infra-red
- Hard to identify high level cloud on visible imagery as low level clouds blend with high level clouds
Describe how infra-red and visible satellite imagery can be used together to provide information on the types of cloud.
- Cloud cloud tops detected with the infra-red are high level clouds or Cb/TCu clouds
- Visible imagery, cirrus clouds show as wispy flow in long trail west to east with jet-streams or ahead of a warm front
- Cu clouds are isolated puffs and stratiform are smooth white over large areas
Describe how infra-red and visible satellite imagery can be used together to provide information on the movement of cloud.
- Time lapse of images shows which direction cloud is moving
- Most detailed on visible imagery during the day
For international operations interpret and assess the impact of given examples of satellite imagery.
- CBS will need to be diverted around if possible
- Jet-streams can be identified of cloud is present
- Extra fuel will need to be loaded if it is likely you will have to divert around a large storm
Describe how, within the coverage of the radar(s), radar imagery can be used to provide information on the areal extent of precipitation.
- Will show areas of rain and hail
- May not show areas of drizzle or snow as they don’t reflect easily
- Is calibrated to show precipitation therefore clouds have been filtered out
Describe how, within the coverage of the radar(s), radar imagery can be used to provide information on the areal extent of precipitation.
- Mountain ranges will also block radar imagery
- The further the Doppler pulse has to travel before returning, the weaker it will be
- Means two areas of equal precipitation will appear weaker with greater distance
Describe how, within the coverage of the radar(s), radar imagery can be used to provide information on the intensity of precipitation.
- dBZ is the logarithmic decibel (dB) value of the energy reflected back at the radar (Z)
Describe how, within the coverage of the radar(s), radar imagery can be used to provide information on movement of precipitation.
- If precipitation is moving closer to the radar station, Doppler waves return at a faster rate increasing the frequency
- If moving away the waves take longer and longer to return, reducing the frequency
- This gets converted into movement
Describe how, within the coverage of the radar(s), radar imagery can be used to provide information on duration of precipitation.
- SHOWERS from cumuliform clouds are short duration (30 minutes)
- CONTINUOUS from stratiform clouds will have no breaks for 60+ minutes
- Can also measure duration of precipitation from satellites sing the same Doppler effect
For international operations interpret and assess the impact of given examples of radar imagery.
- If flying towards highly reflective areas, there is most likely heavy rain, hail, lightning and severe icing if above the freezing level
- On board weather radar cannot detect turbulence
- Can detect wind
Describe the limitations in weather radar coverage in terms of geographical coverage within country boundaries.
- Earth curves under the beam meaning coverage at lower level reduces the further out the beam goes
- Optimal range is 5 - 200km, so multiple radar required over the countries
Describe the limitations in weather radar coverage in terms of minimum radar elevation.
- Minimum elevation of 0.5 degrees above the horizontal
Describe the limitations in weather radar coverage in terms of coverage problems in mountainous regions.
- Any hills or mountains in between precipitation and radar will block accurate returns, Hilly areas will require more radars
- Called radar shadows or beam shielding
Describe the limitations in weather radar coverage in terms of coverage of low-level precipitation close to the radar.
- Will not show low level weather like fog or tornadoes as radars lowest elevation is 0.5 degrees
- Blind spot immediately above the radar means no informations is shown, know as cone of silence
Describe the common weather radar problems in terms of attenuation.
- Heavy precipitations at close range absorbs and scatters radar energy
- Resulting in less energy reaching precipitation further from the radar
- Doesn’t accurately show what is happening further away from the radar
Describe common weather radar problems in terms of ground echoes.
- Stationary objects for example mountains, are filtered out
- Things that move on the ground such as swaying trees and wind farms will show up as a ground echo
- Results in weather radar showing low level precipitation when none exists
Describe the common weather radar problems in terms of sea clutter.
- The sea also has movement associated with waves which cases sea clutter return
- More prevalent when ocean waves are large
Describe common weather radar problems in terms of false echoes at sunrise and sunset.
- Radar uses electromagnetic waves to identify precipitation
- The sun emits electromagnetic waves
- At sunrise and sunset this can cause the radar to receive false returns which are actually coming from the sun
Describe common weather radar problems in terms of bugs on the radar imagery.
- Airborne bugs can create false areas of patchy light rain or drizzle on radar
- Birds and bugs will reflect the electromagnetic waves back to the receiver just as rain drops would
Describe common weather radar problems in terms of interference from radio signals.
- Radios can also operate on the same electromagnetic wavelengths as radar.
- Causes the radio to send false returns to radar
- WIFI will initially scan on installation for other transmissions then if a frequency is in use it won’t use it
- Some WIFI’s don’t do this and send false returns to radar.
