The Network of European World Meteorological Deutscher Meteorological Services Organization Wetterdienst European Climate Support World Climate Data Department Climate Network and Monitoring Programme Monitoring Annual Bulletin on the Climate in WMO Region VI - Europe and Middle East - 2009 ISSN: 1438 – 7522 Internet version: http://www.dwd.de/rcc-cm Editor: Deutscher Wetterdienst P.O. Box 10 04 65, D – 63004 Offenbach am Main, Germany Phone: +49 69 8062 2936 Fax: +49 69 8062 3759 Responsible: Peter Bissolli E-mail: [email protected] Technical assistance: Volker Zins E-mail: [email protected] Acknowledgements: Special thanks go to our colleagues G. Engel, K. Friedrich, G. Müller-Wester- meier, H. Nitsche, W. Thomas, B. Tinz and A. Walter for their valuable com- ments and corrections. This text is an extended version of the publication: A. Obregón et al., 2010: Europe, in “State of the climate in 2009”, Bull. Amer. Meteor. Soc., 91 (6), S160-S170. Annual Bulletin on the Climate in WMO Region VI - Europe and Middle East - 2009 The Bulletin is a summary of contributions from the following National Meteorological and Hydrological Services and was co-ordinated by the Deutscher Wetterdienst, Germany Armenia Austria Azerbaijan Belarus Belgium Bosnia and Herzegovina Bulgaria Croatia Cyprus Czech Republic Denmark Estonia Finland France Georgia Germany Greece Hungary Iceland Ireland Israel Italy Jordan Kazakhstan Latvia Lithuania Luxembourg The Former Yugoslav Republic of Macedonia Malta Moldova Monaco Montenegro Netherlands Norway Poland Portugal Romania Russia Serbia Slovakia Slovenia Spain Sweden Switzerland Turkey Ukraine United Kingdom List of Contents Foreword 5 Outstanding Events and Anomalies 6 Annual Survey 7 Seasonal Survey 33 Seasonal Maps 40 Monthly and Annual Tables 46 Monthly Surveys January 53 February 59 March 64 April 68 May 74 June 78 July 82 August 87 September 90 October 93 November 98 December 102 SPECIAL CONTRIBUTIONS: ECSN Activities Report 2009 109 The Ozone Layer over Central Europe in 2009 113 Annual Bulletin on the Climate in WMO Region VI - 2009 5 Foreword The year 2009 completed the warmest decade on record since the beginning of widespread instrumental measurements around 1850 - in Europe and around the world. Against this backdrop and in the light of global warming, 2009 was just another warm year. However, 2009 was characterised by some particularities which do not occur every year. It was no surprise that most of the warming took place in the Arctic during winter months – this is what had happened in previous years too. But what was outstanding in that year was the month of April: extremely warm and dry in large parts of Central Europe, in some places even topping April 2007, which had also been very warm over a large area. Interestingly, there were also some very cold months in 2009, especially October (in northern Europe) and even more December. The Arctic Oscillation, which is an important circulation pattern for the northern hemisphere in general and seems to be one of the key factors in the European climate, shows an extremely low value for December 2009, by far the lowest in any December since at least 1950 according to NOAA data. In terms of precipitation, 2009 was a normal year only when looking at the annual average. April was not only warm but also extremely dry. On the other hand, some heavy precipitation events occurred, though confined to very limited areas and of high impact. Among these were the exceptionally heavy rainfall events in Istanbul in September, in the north-west of England in November and in southern Spain in December. These few examples show that climate in Europe is far from being boring although it is generally less extreme than in other parts of the world. Climate monitoring, and especially climate monitoring in Europe, remains an important task to be accomplished to find out whether climate trends continue and which factors of climate variability and its extremes can modulate, mask or even change current trends. Climate monitoring is one link in a chain of climate activities from gathering of data, its evaluation and interpretation as well as the identification of interrelations through to climate modelling, long-range weather and climate predictions. It is for sure that climate predictions will be more convincing if today's climate variability already reveals indications for the future. A very important action for climate assessment within our RA VI Region is the development of a Regional Climate Centre network. The approval of the RCC implementation plan in 2009 by RA VI was an important step in this direction. The RA VI Region consists of quite a large number of Member countries with a very diverse climate. In general, the RCC activities have a cross-border view (climate does not stop at national borders), but at the same time they also take account of the specific features characterising the climate in Europe and the Middle East. The Annual Bulletin on the Climate in RA VI – now on its 16th issue presenting the overview assessment for 2009 – is one part of RCC climate monitoring activities in our Region. Its preparation would not have been so fruitful without the valuable contributions from nearly all Member countries and almost impossible without a reliable co-ordinator. The Deutscher Wetterdienst (DWD) has once again volunteered to take over this task. My sincere thanks go to the editorial team of DWD, especially to Peter Bissolli for compiling and writing the texts, Volker Zins for his technical support and, of course, to all the national contributors and internal reviewers. I wish everyone a pleasant reading. Ivan Cacic President of WMO Regional Association VI 6 Annual Bulletin on the Climate in WMO Region VI - 2009 Outstanding Events and Anomalies in 2009 Temperature - Extremely warm April in central Europe - Widespread cooling in December over northern Europe Precipitation - Unusual snowfall in February in the United Kingdom - Extremely dry April in eastern and eastern central Europe - Heavy rain with flooding in June in eastern central Europe - Heaviest rain in Istanbul for 80 years on 9 September - Exceptionally heavy rainfall and flooding in Cumbria, north-west England on 19-20 November - Extremely heavy rainfall in southern Spain in late December Storm - Heavy storm (Klaus) in south-western France and northern Spain on 23-24 January Annual Bulletin on the Climate in WMO Region VI - 2009 7 Annual Survey 1. Atmospheric circulation The year 2009 was characterised by strong fluctuations in the atmospheric circulation patterns in the Region throughout the year, notably a transition from a La Niña to an El Niño phase, high fluctuations of the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) with extremely low values for both indices at the end of the year, but also by several high pressure phases over Europe. 1.1. El Niño / La Niña Moderate La Niña conditions in winter 2008/09 came to an end in March, as documented by the Southern Oscillation Index (Fig. 0.1). A typical feature of La Niña conditions is a dislocation of the frontal zone to northern latitudes and a stronger Azores high. This was to be seen on the seasonal scale for winter 2008/09. The consequence was a flow of mild and humid air to the Arctic whereas much of western and central Europe was cold and dry. An El Niño event started in June 2009 with first signatures in the tropical Pacific. In October 2009, the Southern Oscillation switched to a moderate El Niño phase. Here, the typical pattern is a southerly frontal zone due to a stronger subtropical jet and a weaker Azores high. This pattern occurred especially in October and December 2009 with northern Europe being cold and mainly dry whereas the Mediterranean was mainly wet. Fig. 0.1: Standardised Southern Oscillation Index for 2009, as expressed by the difference of stan- dardised sea level pressure anomalies in Tahiti and Darwin (Australia) Source: NOAA, www.cpc.ncep.noaa.gov/data/indices/soi 1.2. Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) On the monthly scale, AO and NAO were characterized by strong fluctuations during the year (Fig. 0.2). Positive AO and NAO phases, implying a stronger zonal flow component over the northern hemisphere (AO) and particularly over the North Atlantic (NAO), occurred in January, late spring (April/May), late summer / early autumn (August/September) and in November. In all these months, northern Europe was mainly warmer than normal because cold Arctic air was confined to the northern polar region. 8 Annual Bulletin on the Climate in WMO Region VI - 2009 In contrast, negative AO and NAO phases (weaker-than-normal zonal or a meridional flow) took place in February, early summer (June/July), October and December. The end of the year was characterized by an extremely negative phase of the Arctic Oscillation (AO) with high pressure dominating the higher latitudes of the Northern Hemisphere and affecting the weather in Europe. The AO Index in December 2009 was -3.4, the lowest value observed for any December in 60 years. The NAO, too, was extraordinary in December and in June. During all these negative AO/NAO phases, parts or even the whole of northern Europe and some parts of the middle and southern latitudes were colder than normal. Fig. 0.2: Standardised Arctic Oscillation (AO) Index and North Atlantic Oscillation (NAO) Index for 2009, as expressed by the difference of standardised sea level pressure anomalies between southern and northern latitudes over the whole northern hemisphere (AO) and the North Atlantic (NAO) Source: NOAA (AO), www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml and Climate Research Unit, University of East Anglia, United Kingdom (NAO), www.cru.uea.ac.uk/cru/data/nao/ 1.3.