Image Interpretation for Weather Analysis Part I 29 October 2009 Dr. Steve Decker

Two Kinds Polar Orbiting Polar Orbiting –Polar-orbiting Operational Environmental Satellite (POES) NOAA-17 (2002), NOAA-18 (2005), NOAA-19 (2009) NOAA-17 (2002), NOAA-18 (2005), NOAA-19 (2009) MetOp-A (2006) MetOp-A (2006) Two in operation at one time Two in operation at one time –2:00 and 7:30 Geostationary Geostationary –Geostationary Operational Environmental Satellite (GOES) –How does a geostationary orbit work?

Meet the GOES Satellites GOES-8, 1994 GOES-8, 1994 –Was GOES-East, now decommissioned GOES-9, 1995 GOES-9, 1995 –Was GOES-West, then operated by Japan, now decommissioned GOES-10, 1997, 60°W GOES-10, 1997, 60°W –Was GOES-West, now providing coverage for South America GOES-11, 2000, 135°W GOES-11, 2000, 135°W –Current GOES-West GOES-12, 2001, 75°W GOES-12, 2001, 75°W –Current GOES-East GOES-13, 2006 GOES-13, 2006 GOES-14, 2009 GOES-14, 2009

Meet the GOES Satellites GOES-8, 1994 GOES-8, 1994 –Was GOES-East, now decommissioned GOES-9, 1995, 160°E GOES-9, 1995, 160°E –Was GOES-West, now operated by Japan GOES-10, 1997, 60°W GOES-10, 1997, 60°W –Was GOES-West, now providing coverage for South America GOES-11, 2000, 135°W GOES-11, 2000, 135°W –Current GOES-West GOES-12, 2001, 75°W GOES-12, 2001, 75°W –Current GOES-East GOES-13, 2006 GOES-13, 2006 GOES-14, 2009 GOES-14, 2009

Meet the GOES Satellites GOES-8, 1994 GOES-8, 1994 –Was GOES-East, now decommissioned GOES-9, 1995, 160°E GOES-9, 1995, 160°E –Was GOES-West, now operated by Japan GOES-10, 1997, 60°W GOES-10, 1997, 60°W –Was GOES-West, now providing coverage for South America GOES-11, 2000, 135°W GOES-11, 2000, 135°W –Current GOES-West GOES-12, 2001, 75°W GOES-12, 2001, 75°W –Current GOES-East GOES-13, 2006 GOES-13, 2006 GOES-14, 2009 GOES-14, 2009

Improvement Example Registration GOES-12 vs. GOES-13 Registration GOES-12 vs. GOES-13 Registration GOES-12 vs. GOES-13 Registration GOES-12 vs. GOES-13

GOES Image Frequency Standard Operations Standard Operations –Every 30 minutes for CONUS –Every three hours for full disk (takes 26 minutes) Rapid Scan Operations Rapid Scan Operations –Every 5 to 15 minutes for CONUS Super Rapid Scan Operations Super Rapid Scan Operations –Every minute for small region –Example: Hurricane Frances Hurricane FrancesHurricane Frances

Common Channels Visible Visible –0.65 μm (red) Infrared (IR) Infrared (IR) –10.7 μm Water Vapor Water Vapor –6.7 μm Shortwave IR Shortwave IR –3.9 μm

Visible Channel Measures amount of sunlight reflected Measures amount of sunlight reflected –Approximates Earths albedo Clouds Clouds –Thick: High albedo White –Thin: Moderate albedo Light or medium gray Ocean: Low albedo Black Ocean: Low albedo Black Land: Variable albedo Shades of gray Land: Variable albedo Shades of gray

Sun Angle Effects Brightness varies by time of day Brightness varies by time of day Terminator: sunrise/sunset line Terminator: sunrise/sunset line Cloud shadows Cloud shadows –Bumpy cloud top lumpy depiction –Flat cloud top smooth depiction Sunglint Sunglint –Brighter smoother sea

Sun Angle Effects Brightness varies by time of day Brightness varies by time of day Terminator: sunrise/sunset line Terminator: sunrise/sunset line Cloud shadows Cloud shadows –Bumpy cloud top lumpy depiction –Flat cloud top smooth depiction Sunglint Sunglint –Brighter smoother sea

Infrared Channel Amount of radiation received by satellite with λ=10.7 μm Amount of radiation received by satellite with λ=10.7 μm Combination of surface and cloud-top temperatures Combination of surface and cloud-top temperatures For monochrome images, colder temperatures are brighter For monochrome images, colder temperatures are brighter –Why? Snow vs low clouds vs land Snow vs low clouds vs land

IR Enhancement

Geographic Features Background for the weather features Background for the weather features Coasts Coasts –Vis: Sudden change from dark (ocean) to light (land) –IR: At night, land is often colder (brighter) than water. Vice versa during daytime. Lakes Lakes –Vis: Shows ice-cover (bright)

Geographic Features Background for the weather features Background for the weather features Coasts Coasts –Vis: Sudden change from dark (ocean) to light (land) –IR: At night, land is often colder (brighter) than water. Vice versa during daytime. Lakes Lakes –Vis: Shows ice-cover (bright)

Geographic Features Background for the weather features Background for the weather features Coasts Coasts –Vis: Sudden change from dark (ocean) to light (land) –IR: At night, land is often colder (brighter) than water. Vice versa during daytime. Lakes Lakes –Vis: Shows ice-cover (bright)

Another Example

Geographic Features Land type Land type –Wooded Darker on Vis –Sandy; little vegetation Brighter on Vis Heat islands Heat islands –Dark spots in IR at night Snow Snow –Vis: Distinguishable from clouds in animations –Vis: Brighter in treeless areas

Geographic Features Land type Land type –Wooded Darker on Vis –Sandy; little vegetation Brighter on Vis Heat islands Heat islands –Dark spots in IR at night Snow Snow –Vis: Distinguishable from clouds in animations –Vis: Brighter in treeless areas

Geographic Features Land type Land type –Wooded Darker on Vis –Sandy; little vegetation Brighter on Vis Heat islands Heat islands –Dark spots in IR at night Snow Snow –Vis: Distinguishable from clouds in animations –Vis: Brighter in treeless areas

Cloud Patterns Cloud shield Cloud shield –Broad pattern with similar width in any direction Cloud band Cloud band –Continuous formation with a distinct long axis Cloud line Cloud line –Narrow cloud band (less than 60 n mi wide) Cloud street Cloud street –Narrow cloud band with distinct elements –Often come closely packed in parallel Cloud element Cloud element –Smallest resolvable cloud in imagery Comma cloud Comma cloud –Spiraling cloud with at least one band, often shaped like a comma

Cloud Streets

Animation for Comma Cloud Comma.fli Comma.fli

Cloud Identification Compare visible and infrared images Compare visible and infrared images Brightness Brightness –Height and thickness Texture Texture –Visible only; shadows Pattern Pattern Edge definition Edge definition Size Size Shape Shape

Identifying Stratiform Clouds Stratus Stratus –Smooth, flat tops; low altitude –IR: Difficult to see –Vis: Often quite bright Altostratus Altostratus Fog Fog –Difficult to distinguish from stratus using Vis and IR –Motionless; evaporates from outside in –Valley fog

Identifying Stratiform Clouds Stratus Stratus –Smooth, flat tops; low altitude –IR: Difficult to see –Vis: Often quite bright Altostratus Altostratus Fog Fog –Difficult to distinguish from stratus using Vis and IR –Motionless; evaporates from outside in –Valley fog

Identifying Cumuliform Clouds Cumulus Cumulus –Vis: Medium bright; lumpy –IR: Dark to medium gray; hard to see individual elements

Identifying Cumuliform Clouds Cumulus Cumulus –Vis: Medium bright; lumpy –IR: Dark to medium gray; hard to see individual elements Stratocumulus Stratocumulus –Vis: Bright; often cellular –IR: Dark; can be hard to detect

Identifying Cumuliform Clouds Cumulus Cumulus –Vis: Medium bright; lumpy –IR: Dark to medium gray; hard to see individual elements Stratocumulus Stratocumulus –Vis: Bright; often cellular –IR: Dark; can be hard to detect Cumulonimbus Cumulonimbus –Very bright in both Vis and IR

Identifying Cirriform Clouds Cirrus Cirrus –Vis: Dark/medium gray; wispy; thin –IR: Light gray; not as fibrous

Identifying Cirriform Clouds Cirrus Cirrus –Vis: Dark/medium gray; wispy; thin –IR: Light gray; not as fibrous Cirrostratus Cirrostratus –Vis: Smooth; light gray; thicker –IR: Light gray to white

Identifying Cirriform Clouds Cirrus Cirrus –Vis: Dark/medium gray; wispy; thin –IR: Light gray; not as fibrous Cirrostratus Cirrostratus –Vis: Smooth; light gray; thicker –IR: Light gray to white Cirrocumulus Cirrocumulus

Identifying Cirriform Clouds Cirrus Cirrus –Vis: Dark/medium gray; wispy; thin –IR: Light gray; not as fibrous Cirrostratus Cirrostratus –Vis: Smooth; light gray; thicker –IR: Light gray to white Cirrocumulus Cirrocumulus Anvil Cirrus Anvil Cirrus