Timeseries of integrated emission sensitivity over specific regions. The
quantity, given in s/m, represent the potential influence of eventual
emissions so that, when multiplied by the emissivity flux over a region
of a species (given in units of kg m-2 s-1), it will give an estimate of
the relative contribution of each region to the concentration (in kg m-3
) observed by the ship measurements.

The integrated emission sensitivity is also reported for the encounter
of sea ice cover. In that case, the emission sensitivity is directly
proportional to the fraction (from 0% to 100%) of sea ice cover over the
geographical grid encountered by the air masses. The sea ice cover is
given, at daily frequency, by the AMSR satellite data (Spreen, G., L.
Kaleschke, and G.Heygster (2008), Sea ice remote sensing using AMSR-E 89
GHz channels J. Geophys. Res.,vol. 113, C02S03,
doi:10.1029/2005JC003384.)

The timeseries can be considered proportional to the relative
contribution of each region when considering a transport lasting 1, 7,
10 or 30 days. When using the 100m file, the values are considering only
the influence from a 100m layer above the surface. The 3000m is taking
into account the whole layer from the surface up to 3000 m.

The main division in region is illustrated in Figure_mask.png. The
"Land" region is the sum of NorthAmerica, NorthAsia and Europe. The
"Ocean" region includes everything that is not "Land". To obtain the
free ocean contribution, the "Ice" contribution should be subtracted.
The ice cover in the figure is only illustrative of the yearly average
of ice cover at 30%, 50% and 99% concentration.