1. Thresholds of Detection for Falling Snow from Satellite-Borne Active and Passive Sensors IGARSS 2011 Vancouver, Canada Gail Skofronick Jackson Benjamin Johnson Joe Munchak NASA Goddard Space Flight Center, Greenbelt, Maryland [email_address]

3. Percentages from Surface , Snow , & Water Vapor Lake Effect 2-3km tops (0.5 to 1.0 IWP) Synoptic 5-7km tops (0.5 to 1.0 IWP) Blizzard ~10km tops (0.5 to 1.0 IWP) Blizzard ~10km tops (9 to 10 IWP) “ Surface and Atmospheric Contributions to Microwave Brightness Temperatures for Falling Snow Events,” by Gail Skofronick-Jackson and Benjamin Johnson, JGR-Atmos, published Jan 2011. (a) (b) (a) (b) Macro and microphysical cloud characteristics affect TB signal These use dendrite snowflakes

5. (1) Surface Emissivity Part 1 Urban crop land deciduous evergreen/mixed water Surface Temperature Vegetation Type Snow Depth WRF Simulations Courtesy of W.-K. Tao & team Lake Effect Case Synoptic Snow Case IWP (Jan 20 0400UTC) IWP (Jan 22 0600UTC)

6. Radar Calculations W-Band (-26dBZ) Ka-Band (12dBZ) Ku-Band (18dBZ) Thresholds of Detection for Falling Snow from Satellite-borne Active and Passive Sensors by G. Skofronick-Jackson, et al., IEEE TGRS, submit 9/11 These use 3-bullet rosette snowflakes

7. Reflectivities Depend on Particle Shape W-Band Ka-Band Ku-Band

8. Reflectivities Depend on Particle Shape W-Band Ka-Band Ku-Band Ka

9. Z-Thresholds Depend on Particle Shape Average IWC Detected at Surface Assumed minimum instrument Z: Ku: 18 dBZ Ka: 12 dBZ W: -15 dBZ ±One std dev of variability over 11 shapes is plotted Snowflake Shape (#) Ku-Band Ka-Band W-Band Long Hex Col. (0) 0.037 0.020 0.0020 Short Hex Col. (1) 0.037 0.020 0.0019 Block Hexag. Col. (2) 0.039 0.020 0.0020 Thick Hex Plate (3) 0.035 0.019 0.0019 Thin Hex Plate (4) 0.033 0.018 0.0022 3-Bullet Rosette (5) 0.062 0.038 0.0018 4-Bullet Rosette (6) 0.065 0.052 0.0026 5-Bullet Rosette (7) 0.062 0.047 0.0022 Six Bullet Rosette (8) 0.063 0.101 0.0023 Sector Snowflake (9) 0.077 0.049 0.0018 Dendrite Snow (10) 0.079 0.145 0.0032

10. Radiometer Threshold Procedure Y-Axis: TBhydr – TBclearair (with perfect surface, etc knowledge) X-Axis: IWP (max of 6 kg/m 2 ) 3-Bullet Rosette Shape: Red Line = Land surfaces, Blue line = Water Surfaces These use 3-bullet rosette snowflakes 10V 183 ± 3V 166V 89V 37V 183 ± 7V

11. Radiometer Thresholds Depend on Shape 89V 166V 166V 166H 183 ± 3V 183 ± 7V 166V 22 Jan

12. Radiometer Thresholds Depend on Snow Vertical Structure and Surface Type Channel (GHz) Total Threshold Cutoff (rounded up) (in K) From 0.05 error in emissivity From 10 o C error in surface T From 10% change in Tprofile From 10% change in RHprof 10 25 14 10 0 0 19 25 14 10 0 0 23 25 14 10 0 0 37 25 13 10 0 0 89 25 13 9 0 0 166 20 11 8 1 1 183±3 5 1 2 1 1 183±7 15 5 6 0 1

13. Radiometer Thresholds Depend on Snow Vertical Structure and Surface Type Channel (GHz) Total Threshold Cutoff Average Detected IWP Lake Effect over Land Detected IWP Lake Effect over Lakes V-pol Detected IWP Lake Effect over Lakes H-pol Detected IWP Synoptic over Land Detected IWP Synoptic over Lakes V-pol Detected IWP Synoptic over Lakes H-pol 10 25 19 25 23 25 3.2 na na 37 25 1.2 2.0 1.1 89 25 0.4 0.5 1.5 0.5 0.6 0.8 166 20 0.2 0.2 0.2 0.3 0.3 0.3 183±3 5 1.8 na 1.1 1.1 na 183±7 15 0.4 0.4 na 0.6 0.6 na

15. RGB Composite AMSU-B Emissivity Map Three Color Emissivity Map by Joe Munchak 89 GHz (red), 150 GHz (green), 183 GHz (blue) Darker colors indicate lower emissivities (more reflective) Missing data (black).

18. Questions? Questions? IEEE Geoscience and Remote Sensing Society Administrative Committee (AdCom) Member Voting is open All GRSS members can vote for new AdCom members Please vote this week at the GRSS booth or online by Sept. 16, 2011