4 Methodology

Methodological approach used to examine the characteristics of maritime regular lines of cargo and passengers’ disruptions from and to Las Palmas province islands, due to bad weather conditions, consisted of the following steps. Initially, a database of disruption events, including interruptions, cancellations, delays, or diversions, of the above cited regular maritime lines has been developed by using information provided by Fred Olsen Express shipping company and that extracted from the JABLE database. Events were organized in chronological order and by shipping lines.

The following step consisted in organizing datasets of wind (wind speed and direction) and wave parameters (significant wave height, peak period, significant wave steepness, and wave direction) by point along each route. Each parameter time series was first examined as a whole to establish the general behavior of winds and waves along each route and along its different sections. Subsequently, the evolution of each parameter at each point along a specific route during the detected disruption events was examined in detail.

In particular, seasonality of the disruption of inter-insular maritime traffic was assessed converting the 365 days per year to angles between 0 and 360 degrees, which are then represented in polar coordinates. It interesting to note that days of the year can also be represented on the line. However, this approach generates artificial discontinuities at the edges that are eliminated by using a graphical representation in polar coordinates, due to the cyclic nature of the variable.

Concerning the directionality of wind and waves, the bivariate empirical distribution \(θ_{m} - H_{m0}, θ_{m} - T_{p}\), as well as wind speed and direction have been obtained for the whole dataset and represented in polar coordinates, that is, as wave and wind roses, since this kind of display allows to appreciate better the distributions between linear and directional parameters.

Regarding the socioeconomic assessment, first a general review of the socioeconomic situation and the tourism sector was made. To obtain the economic value of the disruption of maritime lines, a final consumption expenditure approach was made, which is the consumption made of final products made by the private and public sector. In addition, this final consumption is very high in most countries, in Spain is around 78.1% of its GDP (World Bank, 2021). This expenditure approach of GDP is defined as, private final consumption expenditure + government final consumption expenditure + gross capital formation + exports – imports. In Spain, private final consumption expenditure only is around 56% of its GDP (Eurostat, 2021; World Bank, 2021). Thus, it seems an appropriate approach being also that the economy of the islands is tourism-based.

To this end, 2017 - 2019 data before the collapse due to the pandemic, published by the ports considered in this study, were analyzed to search for structures such as trends and seasonality. To obtain the economic value due to the disruption, first it was attained the market share of Fred Olsen Express, being the only shipping company sharing its disruptions information. Then, the number of passengers during several years was compared to the total of regular passengers according the State Ports and the Canarian Ports. Next, the average for the 3 years provided by Fred Olsen Express (2017 – 2019) was obtained. In this way, it was achieved that Fred Olsen Express controls 32% of the regular passenger market around the islands.

Second, with Fred Olsen Express data, the average number of passengers by route and month was estimated. Next, using the estimated percentage of market share, the total average of passengers was estimated for every month, trip and route. Thirdly, using the ISTAC data of tourism, data on the percentage of tourists by the most representative nationalities by month on each island were matched with available data, however their estimation about the average spending of tourists and the number of tourists had a small sample per month, making them weak. The daily tourist’s expenditure estimated by ISTAC was divided by 16, assuming they have 8 hours of sleep, that is, time without consuming. Finally, it was assumed that 67% of the regular passengers travel for tourism on each route, this percentage was achieved by adding regular passengers of each port by island and dividing them for the monthly average number of tourists by island and averaging them. Despite the low samples and limited information around it, the approach provides an appropriate characterization, achieving an economic value due to the disruption of maritime lines by islands and months.