2. Work Program
The HALO Circle instrumentation will consist of the same suite of instruments envisaged for the CoMet 2.0 campaign. The HALO cabin layout (floor plan variant 12) for CoMet 2.0 has already been prepared during the CoMet certification and consists of a suite of the most advanced remote sensing and in-situ instruments for greenhouse gases plus ancillary data already deployed within the first CoMet 2018 campaign. An important replacement will be MAMAP2D which is an improved 2-dimensional imaging spectrometer system currently in development for CoMet 2.0. The core payload will be complemented by a quantum cascade laser spectrometer to measure ethane (C 2 H 6 ), a tracer for emissions from oil and gas emissions. Possible synergetic additions could include instruments for in-situ GHG and isotope monitoring, or instruments able to address the OH sink of methane. The CoMet payload still provides some available rack space.
The data collected will be used within regional inverse models and regionally nested global chemistry climate models in combination with wetland models. In addition to the CH 4 data products from MERLIN, the CH 4 and CO 2 data products from ongoing missions expected for this timeframe (Sentinel-5, OCO-2/-3, GOSAT-2/-3, Microcarb … ) will be validated with HALO Circle data.
The timing of the HALO Circle campaign has to be compatible with the MERLIN launch and its subsequent commissioning phase. Given he current launch date of MERLIN, which is foreseen for 2024, and the requirement that this mission has to be performed in northern hemispheric summer, a campaign period in late summer 2025 at the earliest, or 2026 is envisaged.
The campaign shall comprise a period of ~6 weeks with a total of ~120-140 flight hours. This should be adequate to circle the Arctic at least twice (preferably three times) to investigate interhemispheric differences, intrahemispheric variations, and also provide an adequate number of in-situ profiles and surveys over areas of particular interest such as oil and gas fields, profiles extending as close to the ground as possible, and dedicated flight patterns for MERLIN validation.
Flight patterns will consist of large-scale flights loosely following the course of the Arctic Circle at 66°N. Doing so, we can achieve measurements in all important boreal wetlands (Western Siberia, Mackenzie Delta, Hudson Bay Lowlands, etc.) and also in the vicinity of important gas and oil fields (e.g. Tyumen, Alaskan North Slope, Athabascan oil sands, etc.). The detailed flight routing and decision on the stop-over bases will be based on a feasibility study.
It is obvious that flying into Russia is a huge endeavour, both politically and logistically, and requires a tight cooperation with Russian entities. As an example, the V.E. Zuev Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences in Tomsk will support the mission. Furthermore, international co-operation with Canadian, American (e.g. NASA), Scandinavian, British, Japanese, and – as part of the MERLIN validation efforts – French partners (e.g. CNES) will be established or reinvigorated.