Hendricks
Stefan
Hendricks
Stefan
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ArticleA new structure for the Sea Ice Essential Climate variables of the Global Climate Observing System(American Meteorological Society, 2022-06-01) Lavergne, Thomas ; Kern, Stefan ; Aaboe, Signe ; Derby, Lauren ; Dybkjaer, Gorm ; Garric, Gilles ; Heil, Petra ; Hendricks, Stefan ; Holfort, Jürgen ; Howell, Stephen ; Key, Jeffrey ; Lieser, Jan ; Maksym, Ted ; Maslowski, Wieslaw ; Meier, Walt ; Muñoz-Sabater, Joaquín ; Nicolas, Julien ; Ozsoy, Burcu ; Rabe, Benjamin ; Rack, Wolfgang ; Raphael, Marilyn ; de Rosnay, Patricia ; Smolyanitsky, Vasily ; Tietsche, Steffen ; Ukita, Jinro ; Vichi, Marcello ; Wagner, Penelope M. ; Willmes, Sascha ; Zhao, XiClimate observations inform about the past and present state of the climate system. They underpin climate science, feed into policies for adaptation and mitigation, and increase awareness of the impacts of climate change. The Global Climate Observing System (GCOS), a body of the World Meteorological Organization (WMO), assesses the maturity of the required observing system and gives guidance for its development. The Essential Climate Variables (ECVs) are central to GCOS, and the global community must monitor them with the highest standards in the form of Climate Data Records (CDR). Today, a single ECV—the sea ice ECV—encapsulates all aspects of the sea ice environment. In the early 1990s it was a single variable (sea ice concentration) but is today an umbrella for four variables (adding thickness, edge/extent, and drift). In this contribution, we argue that GCOS should from now on consider a set of seven ECVs (sea ice concentration, thickness, snow depth, surface temperature, surface albedo, age, and drift). These seven ECVs are critical and cost effective to monitor with existing satellite Earth observation capability. We advise against placing these new variables under the umbrella of the single sea ice ECV. To start a set of distinct ECVs is indeed critical to avoid adding to the suboptimal situation we experience today and to reconcile the sea ice variables with the practice in other ECV domains.
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ArticleCryoSat-2 estimates of Arctic sea ice thickness and volume(John Wiley & Sons, 2013-02-28) Laxon, Seymour W. ; Giles, Katharine A. ; Ridout, Andy L. ; Wingham, Duncan J. ; Willatt, Rosemary ; Cullen, Robert ; Kwok, Ron ; Schweiger, Axel ; Zhang, Jinlun ; Haas, Christian ; Hendricks, Stefan ; Krishfield, Richard A. ; Kurtz, Nathan ; Farrell, Sinéad L. ; Davidson, MalcolmSatellite records show a decline in ice extent over more than three decades, with a record minimum in September 2012. Results from the Pan-Arctic Ice-Ocean Modelling and Assimilation system (PIOMAS) suggest that the decline in extent has been accompanied by a decline in volume, but this has not been confirmed by data. Using new data from the European Space Agency CryoSat-2 (CS-2) mission, validated with in situ data, we generate estimates of ice volume for the winters of 2010/11 and 2011/12. We compare these data with current estimates from PIOMAS and earlier (2003–8) estimates from the National Aeronautics and Space Administration ICESat mission. Between the ICESat and CryoSat-2 periods, the autumn volume declined by 4291 km3 and the winter volume by 1479 km3. This exceeds the decline in ice volume in the central Arctic from the PIOMAS model of 2644 km3 in the autumn, but is less than the 2091 km3 in winter, between the two time periods.