HR: 08:30h
AN: OS31A-03    [Abstracts]
TI: Assessment of the Ice Extent Climatic Parameters for the Arctic Region and Regional Seas Based on Historic Ice Charts and the Last Decades Passive Microwave Climatic Records
AU: * Smolyanitsky, V
EM: vms@aari.ru
AF: Arctic and Antarctic Research Institute (AARI), 38 Bering str., St.Petersburg, 199397, Russian Federation
AB: Current report presents results of the assessment of the Arctic ice cover climatic parameters in terms of statistical analysis of sea ice total concentration probability distribution functions' (PDF) centre, scale and type and ice extent temporal variability. Close to centennial historical 5-10 days ice charts collection for 1933-present and ice extent data for 1900-present from the WMO "Global Digital Sea Ice Data Bank" (GDSIDB) are used as the basis material to assess the special features of the PDF's as well as robust parameters of regional ice extent variability. Commonly-used last decades passive microwave Nasateam and Bootstrap algorithm daily ice concentration patterns and extent distributed by the NSIDC are used to complement and compare results of the previous analysis either for areas with insufficient information from ice charts or underline the effect of shorter time series. Using results of analysis of the various basic and quantile statistics representing the sea ice total concentration PDFs' center, scale and type it is shown what within the area of Arctic Basin and regional seas and in seasonal cycle non-Gaussian i, j and U PDF's types are well pronounced. Subsequent PDFs' classification is proposed on the basis of Pirson curves. The same analysis based on passive microwave data shows that these data source though containing absolute errors complement classification of PDFs type for such areas as the high Arctic due to higher relative resolution of concentration up to 1% in comparison to 5% from ice charts. Verification (confirmatory) discriminate analysis (DA) of the discriminate variables (DV) chosen from both basic and quantile statistics is used to specify the shares and spatial position of the revealed i, j, U and Gaussian-form PDF types. Analysis of the DA results carried out in the space of canonical discriminate functions shows the presence of mixtures of distributions and allows to draw a conclusion, that the class of PDF revealing specific system of thermodynamic processes in the ice cover is the initial and the system of DV defined through the quantile and basic statistics is not optimum. Analysis of the form of the variability of the ice extent in the Arctic Seas based on historical ice collection shows the high probability of existence of quasi-periodical oscillations of different period. Wavelet analysis reveals the cycles of about 10, 20 and 50-60 years in the long-term changes of the ice extent during the XX century occurring against the background linear trends different in space and time. Maximum decrease of ice extent evaluated in linear term was noted during the first part of XX century for Eurasian sub-region including Greenland, Barents and Kara Seas, whereas for the second part of the century magnitude of linear trend estimated for the same region is several times less. Level of significance for the linear trend for sub- region including Laptev, Eastern-Siberian and Chukcha Seas is close to zero, the same is observed for the Beaufort Sea. The same analysis based on the passive microwave data shows that though ice extent values may slightly differ in absolute values they follow the previous ones based on ice charts, however, shorter longevity of the data source can not reveal periods prior to 1978 visible on that from the historical ice collection.
DE: 0750 Sea ice (4540)
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly