NOAA's Use of GNOME for Japan Tsunami Debris Modeling

NOAA's Office of Response and Restoration's Emergency Response Division (OR&R/ERD) is providing routine modeling products to estimate the distribution of the debris in the North Pacific Ocean from the March 11, 2011 Japanese tsunami. The modeling work is being done to help NOAA's Marine Debris Program coordinate the response to the incoming debris which began showing up on U.S. coastal waters during the fall and winter of 2011. The challenge for the modeling team was to come up with an approach that could handle the large uncertainty associated with the effort and still provide useful results.

In support of this effort three types of modeling products are being produced. The first is a monthly hindcast(updated monthly) that shows the latest estimated distribution of the debris. The second is a 9 month outlook product that takes into account forecast seasonal changes in winds and currents. The third product is a short term forecast of particular large items of debris that have been identified off the West Coast; the goal is to determine if the object will make landfall in the next 48 - 72 hours. The transport model being used is OR&R's General NOAA Operational Modeling Environment (GNOME). Wind and current data and forecasts for the GNOME runs come from various publicly available sources.

The modeling results to date indicate that objects floating high in the water have come ashore beginning in the winter/spring of 2012 along the West Coast from the Northeast Gulf of Alaska to the Oregon shoreline. Then, with the transition from spring to summer, the modeling results indicate that the bulk of the debris along the West Coast moved south and offshore.

The tools and data used for the modeling provided useful results for both short term forecast and longer term outlook. However, the lack of field data to calibrate the modeling has resulted in large uncertainties. It has been impossible to predict what will come ashore, how much will come ashore, or when and where it will come ashore come with significant certainty.