Hardy_ESM266_FINALv2

Hardy_ESM266_FINALv2 - The Effects Of Snow Cover on Surface...

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Unformatted text preview: The Effects Of Snow Cover on Surface Albedo Darren Hardy ESM 266 (Dozier) Spring 2005 Global Warming Earth Observing System measurement objectives Global warming Long-term climate change Socio-economic implications Climate system response to human forcing Land cover and socioeconomic interactions You are here Research questions (Asrar & Dozier, 1994) (IPCC, 2001) Surface Albedo Surface albedo Reflectivity at the Earth's surface Lack good global data on albedo over land ASTER: AST13 CERES: ES-9 MISR: MIS04, MIS05 MODIS: MOD09, MOD43 King et al. (1997, p. 160) Albedo data products Snow Cover Critical component of global energy budget High albedo = Low absorption Snow reflects radiation back to space Global mean snow albedo contributes to warming of the atmosphere Mean snow cover , Mean surface albedo snowflakebentley.com (King et al., 1997, p. 196) (Stroeve et al., 2005, p. 46) Question How does observed snow cover correlate with observed surface albedo? Theory: linear correlation Data Products: MOD09A1 (surface reflectance, 8-day) MOD10A1 (snow cover, daily) MOD10A2 (snow cover, 8-day) MOD09A1 MODIS/Terra Surface Reflectance 8-Day L3 Global 500m SIN Grid 7 Bands (centered: 648, 858, 470, 555, 1240, 1640, 2130 nm) From MODIS Level 1B RGB = (Band 1, Band 4, Band 3) April 7, 2001 Zeniths, azimuth Quality control MOD10A1 MODIS/Terra Snow Cover Daily L3 Global 500m SIN Grid V004 algorithm (Snowmap) Normalized Difference Snow Index (NDSI) (TM Band 2 - TM Band 5) (TM Band 2 + TM Band 5) NDSI = Grayscale = (Snow Cover) April 7, 2001 MOD10A2 MODIS/Terra Snow Cover 8-Day L3 Global 500m SIN Grid same as A1 Snowmap Composite of 8 days Grayscale = (8-day Snow Cover) April 7, 2001 MOD09A1 Surface Albedo RGB = (Band 1, Band 4, Band 3) April 7, 2001 RGB = (Band 5, Band 6, Band 7) April 7, 2001 MOD10A2 Snow Cover Grayscale = (8-day Snow Cover) April 7, 2001 Grayscale = (Maximum Snow Extent) April 7, 2001 Analysis Preparation Research MODIS data products Search for MOD09A1, MOD10A1/2 Study Area is California EOS Data Gateway Land Processes DAAC National Snow and Ice Data Center DAAC Download granules (2001089, 2001097) Define Region of Interest for California Analysis Overview Projection Snow Cover 0 1 3 4 11 25 37 39 50 100 200 Missing No decision Scan angle limit exceeded Erroneous data Night Snow-free land Lake or inland water Open water (ocean) Cloud obscured Snow-covered lake ice Snow Mercator (WGS84) Georeferenced Link geographic Correlate albedo with snow cover MOD09A1 (8-day) surface albedo Bands 1 7 MOD10A2 (8-day) snow cover (max ext) Step 1 Compute total surface albedo float (b ) i =1 i 7 Step 2 Filter 8-day Snow Cover b1 = 200 Step 3 Compare Albedo & Snow Cover 1 2 (b1 > 0) ( float (b1 ) - float (b2 )) Results White is 100% correlation; Black is no snow April 7, 2001 Results Lake Tahoe White is 100% correlation; Black is no snow April 7, 2001 Histogram of Results 0.35% snow cover vs. surface albedo differences 0.30% 0.25% Frequency 0.20% 0.15% 0.10% 0.05% 0.00% large difference small difference Temporal Comparison Total Surface Albedo April 7, 2001 April 7, 2000 Temporal Comparison Snow Cover April 7, 2001 April 7, 2000 Temporal Comparison Results April 7, 2001 April 7, 2000 Temporal Comparison Results April 7, 2001 0.35% 0.30% 0.25% Frequency 0.20% 0.15% 0.10% 0.05% 0.00% April 7, 2000 Frequency 0.80% 0.70% 0.60% 0.50% 0.40% 0.30% 0.20% 0.10% 0.00% Greenland EarthAsArt.gsfc.nasa.gov ...
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