Saturday, September 24, 2011

Recalibrating in space for greater modeling accuracy

Science Daily: A new paper published in Philosophical Transactions of the Royal Society A, explains weaknesses in our understanding of climate change and how we can fix them. These issues mean predictions vary wildly about how quickly temperatures will rise, resulting in serious implications for long term political and economic planning, experts say. The paper's lead author is Dr Nigel Fox of The National Physical Laboratory, The UK's National Measurement Institution.

Earth's climate is undoubtedly changing, but how fast and what the implications will be are unclear. Our most reliable models rely on data acquired through a range of complex measurements. ...Dr Nigel Fox, head of Earth Observation and Climate at NPL, says: "Nowhere are we measuring with uncertainties anywhere close to what we need to understand climate change and allow us to constrain and test the models. Our current best measurement capabilities would require >30 yrs before we have any possibility of identifying which model matches observations and is most likely to be correct in its forecast of consequential potentially devastating impacts. The uncertainties needed to reduce this are more challenging than anything else we have to deal with in any other industrial application, by close to an order of magnitude. It is the duty of the science community to reduce this unacceptably large uncertainty by finding and delivering the necessary information, with the highest possible confidence, in the shortest possible time."

The solution put forward by the paper is the TRUTHS (Traceable Radiometry Underpinning Terrestrial- and Helio- Studies) mission, a concept conceived and designed at NPL. This which would see a satellite launched into orbit with the ability to not only make very high accuracy measurements itself (a factor ten improvement) but also to calibrate and upgrade the performance of other Earth Observation (EO) satellites in space. In essence it becomes "NPL in Space."

...However, not only will it provide its own comprehensive and climate critical data sets but can also facilitate an upgrade in performance of much of the world's Earth observing systems as a whole, both satellite and ground data sets. By performing reference calibrations of other in-flight sensors through near simultaneous observations of the same target, it can transfer its calibration accuracy to them. Similarly its ability to make high accuracy corrections of atmospheric transmittance allow it to calibrate ground networks measuring changes at the surface e.g. flux towers and forests and other reference targets currently used by satellites such as snowfields of Antarctica, deserts, oceans and the Moon. In this way it can even back correct the calibration of sensors in-flight today....

The TIMED satellite, from NASA, used here as a generic satellite illustration

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