Campaign Report TIFAX 2016: Sea ice thickness measurements from Station Nord, Greenland

During the last decade, an increased advection of thick multi-year ice that originates from an area north of Greenland, out of the Arctic through the Fram Strait has been observed. A replacement of this old and thick sea ice by much thinner ice might precondition for rapid sea ice retreat in summer. Aim of the TIFAX campaign is therefore to monitor ice conditions during summer in the main export pathway of the Arctic Ocean. The campaign complements the large scale spring sea ice survey PAMARCMIP and is a continuation of earlier TIFAX campaign in 2010, 2011, 2012 and 2015

TIFAX 2017 Campaign Report: Sea ice thickness measurements with Polar 6 from Station Nord and Alert

Arctic sea ice extent and thickness have undergone dramatic changes in the past decades: Summer sea ice extent has declined at an annual rate of approximately 12.7 % per decade over the satellite record (1978 – present, Meier et al., 2014) and its mean thickness has decreased by 0.58 m +/- 0.07 m per decade over the period 2000 - 2012 (Lindsay et al., 2015). The thinning of sea ice is accompanied by an increase of ice drift velocity (Spreen et al., 2011), deformation (Rampal et al., 2009) and a decrease of net ice growth rates. Climate model simulations indicate that ice extent and thickness will further decline through the 21st century in response to atmospheric greenhouse gas increases (Vravus et al., 2012). However, the mass balance of Arctic sea ice is not only determined by changes in the energy balance of the coupled ice-ocean-atmosphere system but also by the increasing influence of dynamic effects. One aspect of the mass balance of Arctic sea ice are changes of ice volume export rates through Fram Strait and the decline of thick and old multi-year ice North of Ellesmere Island. Thickness surveys carried out North of Greenland and Fram Strait give insight into composition and properties of Arctic sea ice in general and how it changes over time. An extensive data set of ground-based and airborne electromagnetic ice thickness measurements were collected between 2001 and 2016 during several aircraft (PAMARCMIP, TIFAX) and Polarstern campaigns. The first aim of the TIFAX 2017 campaign is to complement earlier measurements made north of Svalbard, Greenland and in Fram Strait. Sea ice thickness information will be used to examine the connection between thickness variability, ice age and source area. Together with satellite based information on sea ice motion, data will be used to number sea ice outflow through Fram Strait in summer. These estimates shall improve the understanding of interannual variability in summer sea ice outflow and complement existing winter volume flux calculations. A second objective is to extent sea ice thickness measurements to the Lincoln Sea where we will study thinning of sea ice due to reduction of old multi-year ice in this area. Like the measurements planned over Fram Strait area, the surveys are a continuation of earlier aircraft campaigns made North of Alert and shall improve understanding of ice mass balance changes in the Arctic. In addition to measurements over sea ice, laser scanner flights over glaciers were made within the framework of MABANG

IceBird 2018 summer Campaign - Sea ice thickness measurements with Polar 6 from Station Nord and Alert

Arctic sea ice extent and thickness have undergone dramatic changes in the past decades: Summer sea ice extent has declined at an annual rate of approximately 12.7 % per decade over the satellite record (1978 – present, [5]) and its mean thickness has decreased by 0.58 m +/- 0.07 m per decade over the period 2000 - 2012 [3]. The thinning of sea ice is accompanied by an increase of ice drift velocity [8], deformation [7] and a decrease of net ice growth rates. Climate model simulations indicate that ice extent and thickness will further decline through the 21st century in response to atmospheric greenhouse gas increases. However, the mass balance of Arctic sea ice is not only determined by changes in the energy balance of the coupled ice-ocean-atmosphere system but also by the increasing influence of dynamic effects. One aspect of the mass balance of Arctic sea ice are changes of ice volume export rates through Fram Strait and the decline of thick and old multi-year ice North of Ellesmere Island. Thickness surveys carried out north of Greenland and Fram Strait give insight into composition and properties of Arctic sea ice in general and how it changes over time. An extensive data set of ground-based and airborne electromagnetic ice thickness measurements were collected between 2001 and 2017 during several aircraft (PAMARCMIP, TIFAX) and Polarstern campaigns. The first aim of the IceBird 2018 summer campaign is to complement earlier measurements made north of Svalbard, Greenland and in Fram Strait. Sea ice thickness information will be used to examine the connection between thickness variability, ice age and source area. Together with satellite based information on sea ice motion, data will be used to quantify sea ice outflow through Fram Strait in summer. These estimates shall improve the understanding of interannual variability in summer sea ice outflow and complement existing winter volume flux calculations. A second objective is to extent sea ice thickness measurements to the Lincoln Sea where we will study thinning of sea ice due to reduction of old multi-year ice in this area. Like the measurements planned over the Fram Strait area, the surveys are a continuation of earlier aircraft campaigns made north of Alert and shall improve understanding of ice mass balance changes in the Arctic

ASIMBO 2018 - Sea ice thickness measurements with Polar 6 from Station Nord and Alert

Aim of the ASIMBO 2018 campaign is to complement earlier ice thickness measurements made by plane or helicoter north of Svalbard, Greenland and in Fram Strait. Sea ice thickness information will be used to examine the connection between thickness variability, ice age and source area. Together with satellite based information on sea ice motion, data will be used to quantify sea ice outflow through Fram Strait in summer. These estimates shall improve the understanding of interannual variability in summer sea ice outflow and complement existing winter volume flux calculations. A second objective is to extent sea ice thickness measurements to the Lincoln Sea where we will study thinning of sea ice due to reduction of old multi-year ice in this area. Like the measurements planned over the Fram Strait area, the surveys are a continuation of earlier aircraft campaigns made north of Alert and shall improve understanding of ice mass balance changes in the Arctic

The First AI4TSP Competition: Learning to Solve Stochastic Routing Problems

This paper reports on the first international competition on AI for the traveling salesman problem (TSP) at the International Joint Conference on Artificial Intelligence 2021 (IJCAI-21). The TSP is one of the classical combinatorial optimization problems, with many variants inspired by real-world applications. This first competition asked the participants to develop algorithms to solve a time-dependent orienteering problem with stochastic weights and time windows (TD-OPSWTW). It focused on two types of learning approaches: surrogate-based optimization and deep reinforcement learning. In this paper, we describe the problem, the setup of the competition, the winning methods, and give an overview of the results. The winning methods described in this work have advanced the state-of-the-art in using AI for stochastic routing problems. Overall, by organizing this competition we have introduced routing problems as an interesting problem setting for AI researchers. The simulator of the problem has been made open-source and can be used by other researchers as a benchmark for new AI methods.Comment: 21 page