april 29, 2000, day 120 july 18, 2000, day 200october 16, 2000, day 290 results – seasonal surface...
DESCRIPTION
Satellite Aerosol Optical Thickness Climatology SeaWiFS Satellite, Summer Percentile 99 Percentile90 Percentile 60 PercentileTRANSCRIPT
April 29, 2000, Day 120 July 18, 2000, Day 200 October 16, 2000, Day 290
Results – Seasonal surface reflectance, Eastern US
SeaWiFS Satellite Platform and Sensors
• Satellite maps the world daily in 24 polar swaths
• The 8 sensors are in the transmission windows in the visible & near IR
• Designed for ocean color but also suitable for land color detection, particularly of vegetation
Swath
2300 KM
24/day
Polar Orbit: ~ 1000 km, 100 min.
Equator Crossing: Local NoonChlorophyll Absorption
Designed for Vegetation Detection
Satellite Aerosol Optical Thickness ClimatologySeaWiFS Satellite, Summer 2000 - 2003
20 Percentile
99 Percentile90 Percentile
60 Percentile
Satellite AOT – Time Fraction (0-100%)SeaWiFS Satellite, Summer 2000 - 2003
Dec, Jan Feb
Sep, Oct, NovJun, Jul, Aug
Mar, Apr, May
SeaWiFS AOT – Summer 60 Percentile1 km Resolution
Technical Challenge: Characterization
• PM characterization requires many different instruments and analysis tools.
• Each sensor/network covers only a limited fraction of the 8-D PM data space.
• Most of the 8D PM pattern is extrapolated from sparse measured data.• Some devices (e.g. single particle electron microscopy) measure only a
small subset of the PM; the challenge is extrapolation to larger space-time domains.
• Others, like satellites, integrate over height, size, composition, shape, and mixture dimensions; these data need de-convolution of the integral measures.
Summary
• Satellite data have aided the science of Particulate Matter since the 1970s
• Satellite data have supported PM air quality management since the 1990s.
• Past satellite data helped the qualitative description of PM spatial pattern
• Quantitative satellite data use and fusion with surface data is still in infancy
• Satellite data applications will require collaboration across disciplines
April 29, 2000, Day 120 July 18, 2000, Day 200 October 16, 2000, Day 290
Results – Seasonal surface reflectance, Western US
Results – Eight month animation
Apparent Surface Reflectance, R• The surface reflectance R0 is obscured by aerosol scattering and absorption before it reaches the sensor
• Aerosol acts as a filter of surface reflectance and as a reflector solar radiation
Aerosol as Reflector: Ra = (e-– 1) P
R = (R0 + (e-– 1) P) e-
Aerosol as Filter: Ta = e-
Surface reflectance R0
• The apparent reflectance , R, detected by the sensor is: R = (R0 + Ra) Ta
• Under cloud-free conditions, the sensor receives the reflected radiation from surface and aerosols• Both surface and aerosol signal varies independently in time and space
• Challenge: Separate the total received radiation into surface and aerosol components