Novaya Zemlya effect and sunsets

Systematics of the Novaya Zemlya (NZ) effect are discussed in the context of sunsets. We distinguish full mirages, exhibiting oscillatory light paths and their onsets, the subcritical mirages. Ray-tracing examples and sequences of solar images are shown. We discuss two historical observations by Fridtjof Nansen and by Vivian Fuchs, and we report a recent South Pole observation of the NZ effect for the Moon. (C) 2003 Optical Society of America

Klimaatprojecties voor Europa: modelvergelijkingen en een analyse van de voorspelbaarheid

Abstract niet beschikbaarThe predictability of the European climate is investigated on three aspects. First, for 3 GCM models (i.e. ECHAM4-OPYC3, Hadcm3, CCCma) is determined how an enhanced greenhousegas-concentration influences the temperature, precipitation and pressure. This influence is determined for different spatial scales, i.e. global, regional (Europe) and local (De Bilt). The changes are expressed in a quality number, which compares the greenhouse signal with the capability of the models to describe the mean and the variability of the current climate. The second aspect considered is the way the probability density function (PDF) of the temperature changes due to an enhanced greenhousegas-concentration. The KNMI-model ECBilt shows for the end of this century not only a shifted, but also a narrower PDF. Specifically investigated is the effect on cold winter temperatures. For an event occurring once in 10 years, the shift is 1.2 WC, whereas the narrower PDF causes an extra 1.5 WC, being 2.7 WC in total. The third aspect is the surge level at the Dutch coast. Not only the effect of the greenhouse climate is investigated, but also is determined if the observed record can be used for estimating the surge level belonging to the (socially relevant) return period of 10.000 year. The research shows that the available records of 100 year deficit considerably. For the greenhouse climate, ECBilt indicates the excitation of so-called 'super-storms': storms of a extreme rareness, with an other intensity-frequency relation than the extreme storms we know from the current climate. For return periods longer than several centuries, the statistics of the extremes for wind and surge in the ECBilt greenhouse experiment are determined by these super-storms.SG-NO

Gerrit de Veer's true and perfect description of the Novaya Zemlya effect, 24-27 January 1597

The first recordings of the Novaya Zemlya (NZ) effect were made during Willem Barents' third Arctic expedition. Ray-tracing analyses of the three key observations, on 24-27 January 1597, show that all the reported details can be explained by adopting one common and realistic type of temperature inversion. In particular, the Moon-Jupiter conjunction could have been visible over the central mountain ridge of the island. We show that the NZ effect distorts the relative positions of Jupiter and the Moon in such a way that the looked-for fingerprint of the conjunction occurred almost 2 h after the true conjunction. The quoted direction for the apparent Moon-Jupiter conjunction is then found to be accurate to within 1degrees. This delay of the apparent conjunction largely explains the error of 29degrees in their longitude determination. The truthfulness of these observations, debated for four centuries, now appears to be beyond doubt. (C) 2003 Optical Society of America.</p

Strategieen voor een geintegreerd water management voor de Rijn en Maas

Abstract niet beschikbaarWater management of the Rhine and Meuse is surrounded by major uncertainties. The central question is then: given the uncertainties, what is the best water management strategy? This raises the need for integrated scenarios that consider possible futures in a coherent and consistent way. In the present NRP project a scenario study was carried out in which physical modelling has been combined with socio-cultural theory. Existing climate, land use and socio-economic scenarios, as well as water management strategies have been structured using the Perspectives method. This resulted in integrated scenarios for water management, each representing a different view on the future, together with the according water management style. These were put in a scenario matrix with combinations of world views and management styles, both where these match and mis-match. Using a suite of existing modelling tools the implications of each scenario for the water systems were evaluated. Finally, a comparison of different water management styles under different possible futures was made, showing the risk, cost and benefits of different strategies.SG-NO