Mean annual first arrival dates (FAD) of 45 migratory bird species recorded in Moravia (Czech Republic, c. 49º N) in 109 spring seasons between 1881 and 2007 were correlated with the preceding winter (December to March) North Atlantic Oscillation (NAO) index. The arrival of birds occurred significantly earlier following high NAO winter index values (those result in spring warmer than normal in central Europe) in all short-distance migratory species with a European or North African winter range, whereas the arrival timing did not correlate significantly with the seasonal NAO index in long-distance migrants having sub-Saharan winter range. When the values of Pearson coefficient between NAO and FAD were correlated with the migration distance of all 45 bird species, the correlation was remarkable and significant (p<0.001): r = 0.848 for the distance to central locations of winter range, and r = 0.822 for the northern limits of the wintering area. The migration distance was thus responsible for 68–72 % of variation in the regression of birds’ arrival on NAO winter index in central Europe. The data are robust (this is the longest avian phenological record analyzed for correlation with NAO in Europe), and indicate different mechanisms that govern timing between short-distance and long-distance migrants in their departure from wintering areas.
Long-term spring phenological instants of 57 migratory bird species, i.e. arrival in summer visitors and departure in winter visitors, were recorded in South Moravia (Czech Republic) from 1952 through 2001 and evaluated for annual correspondence with the North Atlantic Oscillation (NAO) weather system. The migration instants occurred significantly earlier following positive winter/spring NAO index values (causing periods warmer than normal in Europe) in a number of short-distance migrants with a European winter range (e.g., Alauda arvensis, Columba palumbus, Corvus frugilegus, Motacilla alba, Phoenicurus ochruros, Phylloscopus collybita, Serinus serinus, Sturnus vulgaris, Vanellus vanellus), whereas they did not correlate with NAO in most long-distance migrants having a sub-Saharan winter range (e.g., Acrocephalus spp., Anthus trivialis, Apus apus, Cuculus canorus, Delichon urbica, Ficedula albicollis, Hippolais icterina, Hirundo rustica, Jynx torquilla, Lanius collurio, Locustella spp., Muscicapa striata, Oriolus oriolus, Phylloscopus sibilatrix, Riparia riparia, Streptopelia turtur, Sylvia spp.). The winter/spring (especially February and March) NAO conditions thus affect the migration timing of short-distance migrants that winter in western or southern Europe, and could explain their earlier than normal arrival that had been observed in Europe since the 1980s.
The aim of the paper is to analyse a possible teleconnection of AO (Artic Oscillation), SO (Southern Oscillation), PDO (Pacific Decade Oscillation), NAO (North Atlantic Oscillation) and QBO (Quasi Biennial Oscillation) phenomena with long-term streamflow fluctuation in Hron River basin (Central Slovakia). The spectral analysis shows that for the series of AO, NAO, SO, and PDO indexes we can identify the ca 2.4-; 3.6-; 7.8-; 14-; 21-;30- and 36-yr cycles. The coincident cycles were found in the monthly discharge time series from the Hron basin (period 1931-2000) using combined periodogram method. As these periods were found in almost all discharge series analysed within very different geographical zones, it can be considered as the general regularity on the earth. The regularity is related to general oceanic and atmospheric circulation, part of which are also the SO, AO, PDO and NAO phenomena. and Cieľom predloženej štúdie je analýza možných telekonekcií Arktickej oscilácie (AO), Južnej oscilácie (SO), Tichomorskej dekádnej oscilácie (PDO), Severoatlantickej oscilácie (NAO) a Kvázi dvojročnej oscilácie (QBO) s viacročnými cyklami priemerných ročných prietokov v povodí rieky Hron (stredné Slovensko). Spektrálnou analýzou časových radov AO, NAO, SO, a PDO indexov boli nájdené nasledujúce viacročné cykly kolísania indexov: ca 2,4; 3,6; 7,8; 14; 21; 30 a 36 rokov. Metódou kombinovaného periodogramu boli nájdené zhodné cykly kolísania viacročných suchých a mokrých období i v mesačných prietokových radoch z povodia Hrona (1930-2000). Keďže tieto periódy boli nájdené vo všetkých prietokových radoch z rôznych geografických zón, môžu byť považované za všeobecný jav na Zemi. Toto pravidelné opakovanie mokrých a suchých období súvisí so všeobecnou cirkuláciou oceánov a atmosféry, súčasťou ktorých sú i SO, AO, PDO, NAO a QBO javy.
The main purpose of the research was to determine the conditions affecting ice phenomena, including the three-phase cycle of ice: expansion, retention and decay of the ice cover on selected rivers of the Baltic coastal zone in the Northern Poland (Przymorze region). The analysis has been elaborated for the years 1951–2010 against the backdrop of currently occurring climatic changes, with particular emphasis on the development and phase variability of the NAO. The article presents the impact of the variability in atmospheric circulation which has manifested in an increase in air temperature, over the last 20 years, on thermal conditions during winter periods in the South Baltic Coastal Strip. The increase in air temperature has contributed to an increase in the temperature of river waters, thus leading to a shortening of the duration of ice phenomena on rivers in the Przymorze region. The article also brings to light an increased occurrence of winter seasons classified as cool, and a disruption in the occurrence of periods classified as normal over the last 30 observed years. The research has demonstrated a significant dependence between the seasonal change in air temperature and the variability of thermal conditions of water, which has a direct impact on the variability of the icing cycle of rivers in the Przymorze region. The authors also show that the variability in forms of ice phenomena for individual river sections is determined by the local factors, i.e. anthropogenic activity, impact of urbanized areas or inflow of pollutants.