D4.2 Improving the prediction of HNS concentration in the atmosphere

Responding to maritime accidents can be extremely challenging when involving HNS that behave as evaporators. Due to their potential to form toxic or combustible clouds, evidence-based decisions are needed to protect the crew, responders, the coastal population and the environment. However, when an emergency is declared, key information is not always available for all the needs of responders. A case in point is the lack of knowledge and data to assess the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities when allowing a shipping casualty to dock at a place of refuge.

The MANIFESTS project aims to address these uncertainties and improve response and training capacities through the development of an operational decision-support system (DSS) for volatile HNS spills. Besides management and communication, the project includes four other work packages: WP2 on collecting new data on evaporators, WP3 on table top exercises and field training, WP4 on improving modelling tools and WP5 on the development of the DSS. Key expected outcomes include:

· Operational guidance;

· Desktop and field exercises;

· In situ training;

· Experimental data on gas cloud fate;

· A brand-new fire and explosion modelling module;

· Improved HNS database with new experimental data on evaporation/dissolution kinetics.

This report presents the developments realized in the framework of the task 4.2. This task gave the opportunity to the MANIFESTS consortium to improve one or several features of their models allowing to better simulate the HNS concentration in the atmosphere. Only RBINS seizes this opportunity and has implemented in OSERIT some improvements in order to better simulate the HNS concentration at the sea surface, evaporation processes and finally has implemented a new atmosphere transport and dispersion model.

OSERIT (Oil Spill Evaluation and Response Integrated Tool) is a model which describes the drift of a pollutant at sea using Lagrangian particle. It can be used in case of an accident with release of oil or chemical, to obtain an estimation of the pollution trajectory as well as some basic information about its behavior and fate at sea.

In the framework of the MANIFESTS project, a new atmospheric dispersion module fully coupled to OSERIT has been developed and several marine processes have been improved. In this report, the improved processes are described and their actual implementation in OSERIT is explained.