[1] Airborne in situ measurements of NO, NO 2 , NO y , CO, CO 2 , O 3 , J(NO 2 ), and CN were performed in European thunderstorms during the field experiment EULINOX in July 1998. The measurements in the upper troposphere show enhanced NO x (= NO + NO 2 ) concentrations within thunderstorms and their outflow at horizontal scales from 300 m to several 100 km. The maximum NO mixing ratio measured inside a thundercloud close to lightning (the aircraft was also hit by a small lightning strike) was 25 ppbv. A regional NO x enhancement of 0.5 ppbv over central Europe could be traced back to a thunderstorm event starting $24 hours earlier over Spain. The fractions of NO x in thunderclouds which are produced by lightning and convectively transported from the polluted boundary layer are determined by using CO 2 and CO as tracers for boundary layer air. The analyses show that on average about 70% of the NO x increase measured in the anvil region was found to result from production by lightning and about 30% from NO x in the boundary layer. Thunderstorms are also strong sources of small particles. The peak CN concentrations measured within thunderstorm outflows (>30,000 particles STP cm À3 ) were distinctly higher than in the polluted boundary layer. The amount of NO x produced per thunderstorm and NO produced per lightning flash was estimated. The results imply that the annual mean NO x budget in the upper troposphere over Europe is dominated by aircraft emissions (0.1 TgN yr À1 ) in comparison to lightning production ($0.03 TgN yr À1 ). On the global scale, NO x produced by lightning (mean 3 TgN yr À1 ) prevails over aircraft-produced NO x (0.6 TgN yr À1 ).

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Following the Early Eocene climatic optimum (EECO, ~55–50 Ma), climate deteriorated and gradually changed the earth from a greenhouse into an icehouse, with major cooling events at the Eocene-Oligocene boundary (∼34 Ma) and the Middle Miocene (∼15 Ma). It is believed that the opening of the Drake Passage had a marked impact on the cooling at the Eocene-Oligocene boundary. Based on an Early Eocene simulation, we study the sensitivity of climate and ocean circulation to tectonic events such as the closing of the West Siberian Seaway, the deepening of the Arctic-Atlantic Seaway, the opening of the Drake Passage, and the constriction of the Tethys and Central American seaways. The opening of the Drake Passage, together with the closing of the West Siberian Seaway and the deepening of the Arctic-Atlantic Seaway, weakened the Southern Ocean Deep Water (SODW) dominated ocean circulation and led to a weak cooling at high latitudes, thus contributing to the observed Early Cenozoic cooling. However, the later constriction of the Tethys and Central American Seaways is shown to give a strong cooling at southern high latitudes. This cooling was related to the transition of ocean circulation from a SODW-dominated mode to the modern-like ocean circulation dominated by North Atlantic Deep Water (NADW)