See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/312536222 Short presentation of SKIM Presentation · January 2017 CITATIONS READS 0 320 1 author: Fabrice Ardhuin University of California, San Diego 324 PUBLICATIONS 7,700 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Cyclone Global Navigation Satellite System View project ESA Climate Change Initiative: Sea State View project All content following this page was uploaded by Fabrice Ardhuin on 20 January 2017. The user has requested enhancement of the downloaded file.
Picture by S. Lamarche The ocean Surface KInematics Multiscale monitoring mission (SKIM) A proposal for ESA Earth Explorer 9 : Why and how ? 1.5 km The SKIM Team – https://www.facebook.com/SKIM4EE9 http://tinyurl.com/SKIMonRG http://www.umr-lops.fr/Projets/Projets-actifs/SKIM
1. What is SKIM ? SKIM combines - an « altimeter on steroids » looking straight down (at nadir) (very high PRF Ka-band radar, 200 MHz bandwidth, SAR unfocused) → very low noise measurements of sea level, wave height, ice freeboard … (the best altimeter ever flown) - a novel wave + current spectrometer This is a real aperture radar with 5 to 7 rotating beams (5 in 2016 design) at 6 and 12° incidence → measurement of full wave spectrum unambiguous in direction, down to 20 m wavelength, 5° resolution + wind vector → companion to Sentinel 1 : wave bias correction on total ocean surface currents (single component, error goal < 20 cm/s @ dx= 20 km ) → SKIM alone : total ocean surface vector currents (error goal < 30 cm/s on each component over a 6 km footprint) Example of surface Line-of-sight current map, achievable with S1 + SKIM 2 (Chapron et al. JGR 2005)
2. How does SKIM work ? - rotating plate carrying horns - pattern of footprints illuminated over 30 ms. - not a full picture but many footprints : each is 6 km in diameter - 1D wave spectrum + radial current on each footprint. - Higher res than 6 km possible with SAR unfocused 3
3. What is SKIM good at ? a. Ocean circulation SKIM correction on S1 SAR will give total surface current on each pass at high resolution SAR only : Altimeters : many passes averaged Only geostrophic current High resolution resolution ~ 100 km Rouault et al. (JGR 2010). 4
3. What is SKIM good at ? b. Ocean circulation There is no geostrophy at the equator : no currents from altimeters … not a problem for SKIM and SKIM + S1 Envisat (below) → eastward current with a 3 month average S1+SKIM and SKIM → global map every 15 days From Collard et al. (SEASAR 2008) 5
3. What is SKIM good at ? b. waves : coastal, wave+current interaction Measuring much shorter waves than CFOSAT : fraction of resolved wave energy Measuring shorter waves → measuring Stokes drift fraction of resolved energy or Stokes drift 6
3. What is SKIM good at ? b. waves : wave-ice interactions Arctic ice is thinning and shrinking : the Arctic may soon be a giant Marginal Ice Zone in which waves play a big role → urgent to make reliable wave spectra & ice measurements at the ice edge → S1 can be used in the ice (> 10 km from the edge) → SKIM for the open water + leads + near the edge (range bunching on 6° beam) 1-day coverage complementarity with Sentinel 1 (only beam 1 and 6 are shown) 7
3. What is SKIM good at ? b. waves : extremes Measuring detailed directional spectrum → extreme water levels at shoreline A narrow directional spectrum gives larger run-up (Guza and Feddersen JGR 2012) 8
3. What is SKIM good at ? b. waves : extremes Measuring detailed directional spectrum → freak waves estimation Wave spectrum probability of crest height example Freak wave (Fedele et al., Scientific Reports 2016) 9
3. What is SKIM good at ? b. solid Earth : microseism sources SKIM wil measure the full wave spectrum … we still have to verify that we can separate waves in opposite directions. If that works we will directly measure the sources of microseism → considerable improvement in Earth tomography and real time monitoring (Obrebski et al. GRL 2012) 1
4. What you can do for SKIM - have other ideas of something SKIM can do ? - want to use SKIM data one day ? → advocate to your national ESA representatives → join the team of PIs or supporters → spread the word about SKIM ! SKIM needs you … without you it will never happen 1
4. What you can do for SKIM More details and updates : 1.5 km The SKIM Team https://www.facebook.com/SKIM4EE9 http://tinyurl.com/SKIMonRG http://www.umr-lops.fr/Projets/Projets-actifs/SKIM 1 View publication stats View publication stats
Recommend
More recommend
