Lessons from Response to Superstorm Sandy using COSMO-SkyMed Radar Satellites to Produce Damage Proxy Maps of New York City

In response to Superstorm Sandy's devastation on the East Coast of the United States, we produced a damage proxy map of New York City, the place with the highest casualty, using X-band radar data from the constellation of COSMO-SkyMed satellites and implemented visual inspection on each pixel of the damage proxy map for accuracy. The radar data processing was done with ROI_PAC and the damage proxy map algorithm, both of which were developed at the Jet Propulsion Laboratory and California Institute of Technology. The product contains red (damage) and transparent (no damage) pixels for simplicity. For validation, we overlaid the damage proxy map on a Google Earth or ArcGIS Online base map and imported NOAA's aerial photographs that were provided by the US Geological Survey's Hazards Data Distribution System archive. We then compared the damage proxy map, pre-Sandy high-resolution optical images, and the post-Sandy NOAA's high-resolution optical images, and marked each red pixel of the damage proxy map either as correct detection or false alarm. The damage proxy map algorithm produced about 0.8 percent of red pixels mostly along the coastline, representing changes on the ground (Figure 1). The validation marked each red pixel as correct detection if it appears to be caused by Hurricane Sandy, and as false positive if it seems to be anthropogenic change or change in natural terrain (Figure 2). With no dedicated system or personnel prepared for this major disaster, we were able to download the data on Day 9, produce the damage proxy map on Day 11, and complete validation task of it on Day 15. This involved manual data discovery, manual data request (via Emails), manual data downloading (via ftp file transfer), and manual coordination of work (via teleconference and Emails). The results demonstrate the great potentials of a future automated response system that the Advanced Rapid Imaging and Analysis (ARIA) projects at JPL/Caltech are building. With the operational system and a proper coordination between agencies, the total latency from sensor (i.e. data acquisition) to user (after product validation) can potentially be reduced from 15 days to a couple of days.

Figure 1. Damage proxy map derived from radar data from radar satellites COSMO-SkyMed.

Figure 2. A map of confirmed damage.