Port Calls

There is growing research on the use of Automatic Identification System (AIS) data as alternative source for port and seaborne trade statistics. In recent years, the UK and US statistical agencies started publishing AIS-derived maritime statistics as part of their real-time faster economic indicators for UK [1] and Covid-19 related transport statistics for US [2]. For pacific island economies where official data is not readily available, AIS data shows great potential to fill the gaps on
seaborne trade activities [3]

Data and Methods#

Our main data sources are the UN Global Platform (UNGP) for AIS and Ship Registry [4], and global port boundaries requested from the author of “Tracking trade from space: an application to pacific island countries“[3]. We used the helper functions from ais python package [5] with some refinements to generate a port calls dataset.

Port Calls Methodology

The figure above presents a general overview of the methodology to capture port calls. The term “port buffer” refers to a large area encompassing the port, with a square boundary of 22 km from the port. AIS data within the port buffer are extracted and then aggregated into routes. A route comprises consecutive AIS messages transmitted by a vessel during a port visit. It summarizes essential information such as the vessel’s port arrival and departure time at the port, as well as the changes in its draught. From here, the vessels are verified in the Ship Registry data to identify routes undertaken by individual ships. The Ship Registry data provides additional information about the ship’s characteristics that are not available in AIS but are necessary for trade estimation purposes. Following this, the next port calls for each route are generated to update the departure draught information and determine if the vessel is embarking on an international voyage. The port calls data consists of routes from vessels that meet two criteria: cargo-carrying (excluding for passenger ships) according to the Ship Register and engaged in international voyages according to their next port calls.

Contents

Port Calls#

Data and Methods#

Port Calls#