Lecture4_091511

Lecture4_091511 - RADAR IMAGERY & FRONTS MSC 243...

Info iconThis preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon
RADAR IMAGERY & FRONTS MSC 243 Lecture #4 09/15/2011
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Radar Imagery: (i) Reflectivity (rain) & (ii) Doppler Winds “Remote Sensing” instrument (like satellites) Ground based (in our course) “RAdio Detection And Ranging” Sends an electromagnetic pulse When the pulse hits an object, the energy is scattered. Some of this energy is scattered back towards the radar Can determine location and size of object With Doppler Effect, can determine motion.
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Radar Images Main use of radar: measurement of precipitation intensity and distribution. The larger the target, the stronger the signal. The more targets to scatter the pulse, the stronger the signal. Radar measures power of signal (“echoes”) which is converted to REFLECTIVITY.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Radar Reflectivity Larger raindrops => higher reflectivity More raindrops => higher reflectivity Reflectivity (labeled Z) is empirically related to rainfall rate R via the “ Z-R relationship ”: Z=300 R 1.4 This relationship is not always accurate, since R depends on (i) raindrop size, (ii) raindrop distribution, (iii) fall velocity, (iv) type of precip. Need a special Z-R relationship for tropical
Background image of page 6
SHORT RANGE (143 miles) LONG RANGE (286 miles) 1-HR TOTAL STORM TOTAL NWS RADAR (Ophelia 2005)
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Base reflectivity Composite reflectivity CAUTION: Take care when interpreting radar images!
Background image of page 8
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Ground Clutter (seen in “ clear sky mode”) Echoes from surface targets appear in almost all radar reflectivity images. In the immediate area of the radar, "ground clutter" generally appears within a radius of 20 nm. This appears as a roughly circular region with echoes that show little spatial continuity. It results from radio energy reflected back to the radar from outside the central radar beam, from the earth's surface or buildings, or bugs!
Background image of page 10
Light Rain Heavy Rain Radar in “ precipitation mode
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Squall Line
Background image of page 12
Radar Derived Precipitation KMLC 201453Z AUTO 17018G26KT 7SM RA OVC032 18/18 A2998 RMK
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 14
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 39

Lecture4_091511 - RADAR IMAGERY & FRONTS MSC 243...

This preview shows document pages 1 - 14. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online