Search Suggestions and Model Assumptions

Our model allows us to estimate the pathways of tracers between a probable source and a known destination Here are the detailed assumptions we used to run the IPRC Ocean Drift Model and the resulting suggestions for searching for further MH370 debris and for its crash site. For our modelling work we chose the most probable crash location based on satellite communication with the airplane and the plane's possible range.

Probable crash location and trajectory to Paluma Sandbank

March 7, 2016

Figure 1. Drift field of the tracer between the likely source, equi-distributed along the 7th arc on March 8, 2014, and arrival on Paluma Sandbank, Benguerra Island in Mozambique. The tracer was run with 0.8% windage in the IPRC Ocean Drift Model.

Probable crash location and trajectory to Reunion

( August, 2015).

Figure 2. Drift field of the tracer with 0.8% windage between the estimated source, equi-distributed between 37S and 34S along the 7th arc on March 8, 2014, and the arrival on Reunion Island on July 28, 2015. The tracer was run with 0.8% windage in the IPRC Ocean Drift Model.

Determining the best windage estimate for debris found on Reunion and Paluma Sandbank

The velocity of debris floating on the ocean surface is a function of surface water velocity and debris velocity relative to water due to the effects of waves and wind, or "windage." In other words, windage is the fraction of the local wind velocity added to the ocean current velocity to effectively simulate the drift of the debris in question. Ideally, windage is computed by tracking the object for several weeks together with measurements of the concurrent values of wind and current. Some experts can estimate windage values by using photographs and movies of how the debris floats in the ocean and by comparison with previous d ebris flows.

Unfortunately, no assessment of the windage of the flaperon found on Reunion, nor of the fragment found on Paluma have been made available. We had estimated the windage for debris arriving on Reunion in the end of July 2015 by comparing (weighing) fluxes of a model tracer, released along the 7th arc, with windages 0, 1, 2, 3, 4, and 5%. Our best estimate of the windage turned out to be 0.8%, which resulted in the trajectory field to Reunion shown in the figure above.

Since 0.8% windage was the most likely for the flaperon, we also used this parameter as the most likely for the fragment found over half a year later on Paluma in Figure 1.

Suggestions for searching for MH370 debris on-shore

Finding further pieces of debris from Flight MH370 will improve modeling and therefore better guide the search for the plane's crash site. Simulations based on our model show that tracers with all windages first drifted northward from the source in Figures 1 and 2 and then westward. High-windage tracers moved significantly faster than low-windage tracers. The flaperon found on Reunion was probably on its westward path toward the northeastern coastline of Madagascar.

Figure 3. Density of 0.8% windage tracer on March 2, 2016, simulated with the IPRC Ocean Drift Model.

Figure 4. Density of 0.8% windage tracer on July 28, 2015, simulated with the IPRC Ocean Drift Model.

Searching for MH370 debris on shore is difficult. However, it is incomparably easier and has much better chance of success than searching in the vast Indian ocean, where debris will have been scattered over millions of square miles with hundreds of miles between individual items. Affter two years since the crash, only low-windage items will probably still remain in the water.

Debris accumulates on shorelines in a relatively narrow band. Our model shows debris is very likely to arrive on the eastern coastlines of Madagascar.

Coastlines that are fairly frequently visited will be known to be either clean or have much ordinary marine debris accumulate. Given this knowledge, periodic surveys of only a fraction of the shoreline will produce a timeline of debris arrivals. Such monitoring and surveys should be organized by experts, who have had experience from previous disasters in distinguishing specific debris from the usual marine debris, or done by local groups motivated and trained by the experts.

After five years of experience with the debris from the 2011 tsunami in Japan, such experts are available (and willing to help) in Hawaii, on the US/Canada westcoast, and in Japan if necessary travel funding is made available. Our simulations estimate that the peak of the debris from MH370 is expected to arrive on Madagascar from October to December 2015. Once on shore, debris may degrade quickly, broken by surf or picked up by unaware beach visitors.

Given the likelihood of debris washing up on Madagascar shores, teams to monitor and search for MH370 debris on the east-facing coasts of Madagascar could improve chances of finding further pieces of the airplane. This in turn would improve modeling and finding the plane's crash site at a tiny fraction of the funds and resources required for ocean surface or subsurface search.

Currently the main model used to advise the search for MH370 debris is the CSIRO model. The cloud of particles in this model during July-August 2015 are significantly farther south than in the IPRC Ocean Drift Model, and they barely reach Reunion and are slowly drifting toward southern Madagascar. This means the search should be along the whole eastern coastline of Madagascar. The added benefit of using both models (and others) to guide the search is that the strenghts of the models can be combined, something that is important for coordinating this and future searches.

One remaining puzzle is the lack of reports from the West Australia, where all models predict some onshore flux in Jun-Nov 2014. A more thorough search of this shoreline may bring additional evidence.