307 Flashcards
2 means of using precision grid lines to provide accurate reference on a satellite image
- Lines depicting geographical and geopolitical boundaries
- lines of lat and long
- -usually to within 4km of actual position
- -POES is less accurate because of fast relative motion.
examples of of geography affects satellite imagery
- Sloping terrain-orographic lift
- land/water interface - sea breazes, air mass modification
- Valley effects- valley fog, inversions, snow on ground
5 characteristics of cloud pattern recognition on SAT imagery
- Size
- Shape
- Shadow
- Texture
- Tone
Ways to ‘proof’, or integrate data
- surface reports
- -pilot reports
- RADAR
- Upper air soundings
- surface and upper air analysis
Shadow length determination
-VIS or NIR only
-Solar elevation
-Height separation between layers
Small sepration will cast narrow shadows
large separation will cast pronounces shadows
2 factors of texture on VIS
- Shape of cloud structure
- Degree of lighting
3 factors of tone (brightness)
- Height of sun
- Sensor reviewing anglr
- Albedo of surface
Factors that affect the tone of grey on any SAT image
- Cloud composition
- Thickness of cloud
- Resolution of sensor
- Enhancement of curve
High cloud on SAT
- Size - mesoscale to synoptic, dependent on extent of physical processes
- shape - defined by generating physical processes
- –often elongated streaks
- –ill defined, whispy, fibrous
- shadow, may cast moderate shadow on lower layers
- Texture/tone - VIS fibrous, whispy, thin white.
- IR minimal texture
- grey to white. dependent on thickness
AC/AS on SAT
Size-larger than mesoscale, dependent on physical processes
- Shape - edges well defined
- mountains may induce gravity wave patterns - Shadow- may cast shadow on lower deck
- texture and tones - VIS, AS smooth, no texture, grey to white. -AC minimal texture
- IR little texture, grey to white ~temp
Low Level Cloud on SAT, ST FG
-Size- generally a local phenomena
-Shape- defined by terrain,sharp edges associated with topo features
-Shadow -Cast NO shadow
-Texture and Tone - smooth, little or no texture,VIS may show whisps over water, IR will not distinguish different surfaces of like temp, inversions appear dark
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Low Level Cloud on SAT, SC
-Size- mesoscale or larger
-Shape - Defined by physical process, terrain and topo can influence shape, edges not sharp
-Shadow- little to none
-Texture and tone - VIS - fairly smooth, lumpiness depends on stability, roughness and underlying surfaces and boundary conditions, white to grey.
IR - usually smooth, minimal texture, grey.
Low Level Cloud on SAT, CU, TCU
-Size - individual clouds are mesoscale or less
Shape - circular shapes that can be organized into lines or streaks, sharp edges. influenced by processes and terrain.
-Shadow -May cast shadow on lower decks, depending on vertical extent
-Texture and tone- VIS - very lumpy globular, bright white
- IR - moderate texture
Low Level Cloud on SAT, CB
-Size individual clouds are mesoscale
-Shape -circular, sharp except anvil top,blown downstream if upper winds are significant, edges are sharp
-Shadow - May cast strong shadow on lower decks
-Texture and tone -VIS -very lumpy, globular, bright white.
IR - Strong texture, bright white
Areas of stability on SAT
- Smooth texture
- uniform, extensive coverage
- uniform temps
- ST,SC,AS,AC,CI,CS
Areas of instability on SAT
- Brighter responses
- Globular, anvils
- Strong contours (enhanced IR)
- CU TCU,CB, ACC
Pattern recognition
-Comma looking returns are occluding systems
Techniques to recognize the centre of a low on SAT
- Pattern recognition
- Dynamic support deduction,-usually found under the strongest positive vorticity advection
- ground truthing with surface obs
- Warm front will be on the southern part of the CS or continuous middle cloud
Techniques to recognize the jetstream Axis
- CI baroclinic leafs from to the south of an anticyclonic jet.
- Maximum wind axis coincides with the dry air intrusion
- In the absence of high cloud, separates various low clouds
- combo of any or all of above
Areas of turbulence on SAT
-Strong surface wind - SC, CU. BL
-Convection -CU,TCU,CB ACC
-Stationary waves- rotor clouds, acsl, band clouds,
-Windshear - Transverse cloud banding, CI leafsm commas.
Deformation zones - band and comma cloud
Appearance of deformation zone is controlled by
- relative atmospheric flow
- strength of convergence
- the available moisture
On VIS 3 factors that lower reflectivity
-Sun angle falls below 45 degrees
-aging snow cover will have lower albedo
rain o snow will have a lower albedo
Black Stratus
-Strong inversion will show stratus as darker than the underlying ground
Sun Glint
-GOES - s of 23.5 N only
POES- ~on relative position of satellite and sun, may appear as a band
-Smooth surface - concentrated and very white
-rough surface - large, diffuse, not as white
