2012 AGU Chapman Conference on Remote Sensing of the ...

Shahroudi, NargesMicrowave Emissivities of Land Surfaces: Detectionof Snow over Different Surface TypesShahroudi, Narges 1 ; Rossow, William 11. CCNY, New York, NY, USAThe sensitivity of passive microwave satelliteobservations to different land surface types and thepresence/absence of snow are evaluated for the years 2000,2001, and 2002 for the whole globe. Surface microwaveemissivities are derived from SSM/I observations byremoving the contributions of the cloud and atmosphereand separating the surface temperature variations using datafrom the International Satellite Cloud Climatology Project(ISCCP). Vegetation and snow flags are compiled from alarge number of published sources. The spatial and temporalvariability of microwave emissivities over land surfaces withand without snow between 19 and 85 GHz have beenstudied: the presence of snow and the variations of land typeand temperature (as well as precipitation) all affect the signalthat is received by satellite. In this analysis the variations dueto snow presence are isolated from these other factors,revealing much clearer contrasts in the range of theemissivities between snow and snow-free surfaces. Passivemicrowave emissivities at higher frequencies are moresensitive to the presence of shallow layers of snow whereasthe lower frequencies only respond to deeper layers of snow.Combining these two provides a more general technique toidentify the global distribution of snowcover on a daily basis.Such a method was developed and compared with theavailable NOAA weekly snow cover maps. Agreement wasfound in 90% of locations and times. The behavior of thedisagreements was investigated further. Some of theexplanation occurs because the NOAA product, based largelyon visible satellite radiance analysis, misses some snow inforested areas. More interestingly, much of the disagreementcould be explained by differences in the evolution of snowemissivities associated with freeze-melt-re-freeze cycles andadditional snowfall. This source of disagreement results inpart because of the low time resolution of the NOAAproduct. The results were compared with the snow depthproduct from Canadian Meteorological Centre (CMC) andthe snow cover from the Moderate Resolution ImagingSpectroradiometer (MODIS) sensor on NASA’s EarthObserving System (EOS) Aqua and Terra satellites and theywere correlated with our results in about 80% of the timesand locations. Also to confirm our conclusions aboutdetection sensitivity we are investigating the predictions of amicrowave emission model of layered snowpack where weadjust the inputs to attain the observed emissivities.Shields, Gerarda M.Developing a Prioritization Plan to Assess theImpact of Climate Change Predictions on theHydraulic Vulnerability of Coastal BridgesShields, Gerarda M. 11. CMCE, NYC College of Technology, Brooklyn, NY, USAWith the reality of climate change now widely acceptedthe world over by recognized scientific organizations andgovernments, bridge owners are beginning to consider howclimate change may affect the safety of their bridges. In astudy of bridge failure causes in the United States, over 60%were due to hydraulic factors. Changes in sea-level rise,precipitation, and storm frequency may have importantimplications in the hydraulic design, analysis, inspection,operation and maintenance of bridge structures. Climatechange predictions for the northeastern United States areparticularly alarming as many coastal cities would beaffected. For example, regional climate models for the NewYork City coastal region predict sea level to rise as much as12 – 55 inches (30 – 140 cm), possible precipitation increasesof 5 to 10% and an increase in the frequency of storm eventssuch as the 100-year storm by the year 2080. Theincorporation of climate change predictions with respect tobridge hydraulics and scour will be discussed using the NewYork City coastal region as a case study.Shige, ShoichiImprovement of rainfall retrieval for passivemicrowave radiometer over the mountain areasShige, Shoichi 1 ; Taniguchi, Aina 11. Graduate School of Science, Kyoto University, Kyoto,JapanHigh-resolution precipitation products have beenprovided using combined data from passive microwaveradiometers (MWRs) in low Earth orbit and infrared133