![]() ![]() Today, GOSAT (Greenhouse Gases Observing Satellite) of JAXA has the ability to measure CH 4 from space. Therefore, it is necessary to apply spaceborne measurement techniques in order to obtain global coverage at high precision. Source regions of key importance to the global CH 4 cycle such as the Arctic permafrost, Boreal forests and Tropical wetlands are difficult to access hence, they are underrepresented or not sampled at all. Ground-based in-situ observations are insufficient because the existing measurement network is too coarse. 1) 2) 3) 4) 5)Ī major problem in the understanding of CH 4 source- and sink-processes is the lack of precise global measurements of atmospheric CH 4. Alongside carbon dioxide, methane is one of those gases for which the Kyoto Protocol stipulates that cuts must be achieved. ![]() Natural sources include swamps and marshlands as well as thawing permafrost. ![]() Methane emissions are caused by human activities as well as natural sources – for example, from rice paddies, animal husbandry, biomass decomposition, landfill sites or energy generation. Methane is after carbon dioxide the strongest anthropogenic greenhouse gas. Since pre-industrial times, the amount of methane in the atmosphere has more than doubled, whereas the growth in carbon dioxide levels during the same period has been 'only' thirty per cent. Now, at a time when there is much discussion about mankind being directly responsible for the rise in the emission of greenhouse gases, methane emission levels already far outstrip carbon dioxide. Methane (CH 4) and carbon dioxide (CO 2) both cause global warming, although the impact of methane is 25 times more powerful than the one of carbon dioxide on a timescale of 100 years. The primary objective is to obtain spatial and temporal gradients of atmospheric methane (CH 4) columns with high precision and unprecedented accuracy on a global scale. ![]() MERLIN is a Franco-German collaborative minisatellite climate mission. Spacecraft Launch Sensor Complement Ground Segment References MERLIN (Methane Remote Sensing Lidar Mission) Minisatellite Payload data will be downlinked in X-band at 180 to 310 Mbit/s. Telemetry, Tracking and Command (TT&C) data will be transmitted in S-band at uplink rates of 16, 32 and 64 kbit/s and a downlink rate of 625 kbit/s. With a total spacecraft mass of 430 kg, MERLIN will carry 28 kg of hydrazine fuel to support a design life of approximately three years. To enable low altitude flight, a bi-compliant chemical propulsion system has been developed for green propellant and hydrazine fuels, to be used by its four 1N thrusters. The 260 kg minisatellite platform has an increased solar array capacity and power distribution, an improved ACOS (Attitude and Orbital Control Systems), an increase of the payload data storage, and compatibility with low flight altitudes. Space and Hardware Componentsĭeveloped by CNES, the MERLIN platform is an enhancement of a minisatellite from the Myriade platform series referred to as Myriade Evolutions. The satellite is designed to be compatible with a Local Time Ascending Node (LTAN) of 06 hours. MERLIN is set to undergo a near-polar sun-synchronous orbit of altitude 500 km, orbital period of 90 minutes and a repeat cycle of approximately 28 days. Featuring a 10 m accuracy of measurement for scattering surface elevation, MERLIN will also target a Relative Random Error (RRE) of less than 8 ppb and a Relative systematic error of less than 1 ppb. IPDA LIDAR onboard MERLIN will aim to provide global coverage, resolving total columns with a 50 km horizontal resolution. Specific scientific performance requirements include the ability to resolve large wetland fluxes, inter-hemisphere gradients, seasonal and annual methane gas budgets on a continental and country-scale and Kyoto protocol-like monitoring. IPDA LIDAR is set to have unprecedented accuracy and precision of spatial and temporal gradients of atmospheric methane gas columns to thus contribute to research into the causes of climate change. IPDA LIDAR will use the laser light of a wavelength at the centre of the methane absorption line scattered back from the Earth’s surface, in comparison with a reference beam, to determine the column content of methane gas in the atmosphere. MERLIN will carry a single instrument onboard, an Integrated Path Differential-Absorption Lidar (IPDA LIDAR). ![]()
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