In this study,we present an approach to estimate the extent of large-scale coastal floods caused by Hurricane Sandy using passive optical and microwave remote sensing data.The approach estimates the water fraction fro...In this study,we present an approach to estimate the extent of large-scale coastal floods caused by Hurricane Sandy using passive optical and microwave remote sensing data.The approach estimates the water fraction from coarse-resolution VIIRS and ATMS data through mixed-pixel linear decomposition.Based on the water fraction difference,using the physical characteristics of water inundation in a basin,the flood map derived from the coarse-resolution VIIRS and ATMS measurements was extrapolated to a higher spatial resolution of 30 m using topographic information.It is found that flood map derived from VIIRS shows less inundated area than the Federal Emergency Management Agency(FEMA)flood map and the ground observations.The bias was mainly caused by the time difference in observations.This is because VIIRS can only detect flood under clear conditions,while we can only find some clear-sky data around the New York area on 4 November 2012,when most flooding water already receded.Meanwhile,microwave measurements can penetrate through clouds and sense surface water bodies under clear-or-cloudy conditions.We therefore developed a new method to derive flood maps from passive microwave ATMS observations.To evaluate the flood mapping method,the corresponding ground observations and the FEMA storm surge flooding(SSF)products are used.The results show there was good agreement between our ATMS and the FEMA SSF flood areas,with a correlation of 0.95.Furthermore,we compared our results to geotagged Flickr contributions reporting flooding,and found that 95%of these Flickr reports were distributed within the ATMS-derived flood area,supporting the argument that such crowd-generated content can be valuable for remote sensing operations.Overall,the methodology presented in this paper was able to produce high-quality and high-resolution flood maps over largescale coastal areas.展开更多
The worldwide slum population currently stands at over one billion,with substantial growth expected in the coming decades.Traditionally,slums have been mapped using information derived mainly from either physical indi...The worldwide slum population currently stands at over one billion,with substantial growth expected in the coming decades.Traditionally,slums have been mapped using information derived mainly from either physical indicators using remote sensing data,or socio-economic indicators using census data.Each data source on its own provides only a partial view of slums,an issue further compounded by data poverty in less-developed countries.To overcome such issues,this paper explores the fusion of traditional with emerging open data sources and data mining tools to identify additional indicators that can be used to detect and map the presence of slums,map their footprint,and map their evolution.Towards this goal,we develop an indicator database for slums using open sources of physical and socio-economic data that can be used to characterize slum settlements.Using this database,we then leverage data mining techniques to identify the most suitable combination of these indicators for mapping slums.Using three cities in Kenya as test cases,results show that the fusion of these data can improve the mapping accuracy of slums.These results suggest that the proposed approach can provide a viable solution to the emerging challenge of monitoring the growth of slums.展开更多
基金supported by the NOAA JPSS Program Office[grant number#NA12NES4400008]NASA Disaster Program[grant number#NNX12AQ74G].
文摘In this study,we present an approach to estimate the extent of large-scale coastal floods caused by Hurricane Sandy using passive optical and microwave remote sensing data.The approach estimates the water fraction from coarse-resolution VIIRS and ATMS data through mixed-pixel linear decomposition.Based on the water fraction difference,using the physical characteristics of water inundation in a basin,the flood map derived from the coarse-resolution VIIRS and ATMS measurements was extrapolated to a higher spatial resolution of 30 m using topographic information.It is found that flood map derived from VIIRS shows less inundated area than the Federal Emergency Management Agency(FEMA)flood map and the ground observations.The bias was mainly caused by the time difference in observations.This is because VIIRS can only detect flood under clear conditions,while we can only find some clear-sky data around the New York area on 4 November 2012,when most flooding water already receded.Meanwhile,microwave measurements can penetrate through clouds and sense surface water bodies under clear-or-cloudy conditions.We therefore developed a new method to derive flood maps from passive microwave ATMS observations.To evaluate the flood mapping method,the corresponding ground observations and the FEMA storm surge flooding(SSF)products are used.The results show there was good agreement between our ATMS and the FEMA SSF flood areas,with a correlation of 0.95.Furthermore,we compared our results to geotagged Flickr contributions reporting flooding,and found that 95%of these Flickr reports were distributed within the ATMS-derived flood area,supporting the argument that such crowd-generated content can be valuable for remote sensing operations.Overall,the methodology presented in this paper was able to produce high-quality and high-resolution flood maps over largescale coastal areas.
文摘The worldwide slum population currently stands at over one billion,with substantial growth expected in the coming decades.Traditionally,slums have been mapped using information derived mainly from either physical indicators using remote sensing data,or socio-economic indicators using census data.Each data source on its own provides only a partial view of slums,an issue further compounded by data poverty in less-developed countries.To overcome such issues,this paper explores the fusion of traditional with emerging open data sources and data mining tools to identify additional indicators that can be used to detect and map the presence of slums,map their footprint,and map their evolution.Towards this goal,we develop an indicator database for slums using open sources of physical and socio-economic data that can be used to characterize slum settlements.Using this database,we then leverage data mining techniques to identify the most suitable combination of these indicators for mapping slums.Using three cities in Kenya as test cases,results show that the fusion of these data can improve the mapping accuracy of slums.These results suggest that the proposed approach can provide a viable solution to the emerging challenge of monitoring the growth of slums.
