caa a22 4500 605474249 CHVBK 20210128100346.0 cr unu---uuuuu 210128e20150101xx s 000 0 eng 10.1007/s00382-014-2190-9 doi (NATIONALLICENCE)springer-10.1007/s00382-014-2190-9 Assessing the forecast skill of Arctic sea ice extent in the GloSea4 seasonal prediction system [Elektronische Daten] [K. Peterson, A. Arribas, H. Hewitt, A. Keen, D. Lea, A. McLaren] An assessment of the ability of the Met Office seasonal prediction system, GloSea4, to accurately forecast Arctic sea ice concentration and extent over seasonal time scales is presented. GloSea4 was upgraded in November 2010 to include the initialization of the observed sea ice concentration from satellite measurements. GloSea4 is one of only a few operational seasonal prediction systems to include both the initialization of observed sea ice followed by its prognostic determination in a coupled dynamical model of sea ice. For the forecast of the September monthly mean ice extent the best skill in GloSea4, as judged from the historical forecast period of 1996-2009, is when the system is initialized in late March and early April near to the sea ice maxima with correlation skills in the range of 0.6. In contrast, correlation skills using May initialization dates are much lower due to thinning of the sea ice at the start of the melt season which allows ice to melt too rapidly. This is likely to be due both to a systematic bias in the ice-ocean forced model as well as biases in the ice analysis system. Detailing the forecast correlation skill throughout the whole year shows that for our system, the correlation skill for ice extent at five to six months lead time is highest leading up to the September minimum (from March/April start dates) and leading up to the March maximum (from October/November start dates). Conversely, little skill is found for the shoulder seasons of November and May at any lead time. Her Majesty the Queen in Right of United Kingdom, 2014 Arctic sea ice nationallicence Seasonal forecasting nationallicence Ocean and sea ice analysis nationallicence Data assimilation nationallicence Ice concentration nationallicence Peterson K. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut Arribas A. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut Hewitt H. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut Keen A. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut Lea D. Met Office, FitzRoy Road, EX1 3PB, Exeter, UK aut McLaren A. Met Office, FitzRoy Road, EX1 3PB, Exeter, UK aut Climate Dynamics Springer Berlin Heidelberg 44/1-2(2015-01-01), 147-162 0930-7575 44:1-2<147 2015 44 382 https://doi.org/10.1007/s00382-014-2190-9 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-014-2190-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Peterson K. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut NATIONALLICENCE 700 1- Arribas A. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut NATIONALLICENCE 700 1- Hewitt H. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut NATIONALLICENCE 700 1- Keen A. Met Office Hadley Centre, FitzRoy Road, EX1 3PB, Exeter, UK aut NATIONALLICENCE 700 1- Lea D. Met Office, FitzRoy Road, EX1 3PB, Exeter, UK aut NATIONALLICENCE 700 1- McLaren A. Met Office, FitzRoy Road, EX1 3PB, Exeter, UK aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 44/1-2(2015-01-01), 147-162 0930-7575 44:1-2<147 2015 44 382