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991.
This paper is concerned with the use of Royal Navy ships’ logbooks for the period 1685 to 1750, thereby embracing the oldest members of this documentary series that extends to the present day. The geographic range of the undertaking is confined to the English Channel and its western approaches where the abundance of logbooks for this period allows for the abstraction of a daily series of wind force and direction data. These are verified and processed for inclusion in a database from which indices are derived for air circulation patterns based on the frequency of winds from north, east, south and west quarters, and of gale frequency, based on the contemporary terminology of wind force. The methods by which the data are abstracted and processed are described, as is the nature of the raw data and source material. The results provide a uniquely detailed insight into the changing patterns of air circulation over this critical period that marked the transition from the depths of the Little Ice Age in the late seventeenth century. Attention is also drawn to the changing nature of gale frequency, which revealed a notable decrease over the study period. Associations between changing circulation patterns and temperature regimes are also explored. 相似文献
992.
The Madden?CJulian oscillation (MJO) is the most prominent form of tropical intraseasonal variability. This study investigated the following questions. Do interannual-to-decadal variations in tropical sea surface temperature (SST) lead to substantial changes in MJO activity? Was there a change in the MJO in the 1970s? Can this change be associated to SST anomalies? What was the level of MJO activity in the pre-reanalysis era? These questions were investigated with a stochastic model of the MJO. Reanalysis data (1948?C2008) were used to develop a nine-state first order Markov model capable to simulate the non-stationarity of the MJO. The model is driven by observed SST anomalies and a large ensemble of simulations was performed to infer the activity of the MJO in the instrumental period (1880?C2008). The model is capable to reproduce the activity of the MJO during the reanalysis period. The simulations indicate that the MJO exhibited a regime of near normal activity in 1948?C1972 (3.4?events?year?1) and two regimes of high activity in 1973?C1989 (3.9 events) and 1990?C2008 (4.6 events). Stochastic simulations indicate decadal shifts with near normal levels in 1880?C1895 (3.4 events), low activity in 1896?C1917 (2.6 events) and a return to near normal levels during 1918?C1947 (3.3 events). The results also point out to significant decadal changes in probabilities of very active years (5 or more MJO events): 0.214 (1880?C1895), 0.076 (1896?C1917), 0.197 (1918?C1947) and 0.193 (1948?C1972). After a change in behavior in the 1970s, this probability has increased to 0.329 (1973?C1989) and 0.510 (1990?C2008). The observational and stochastic simulations presented here call attention to the need to further understand the variability of the MJO on a wide range of time scales. 相似文献
993.
D. V. Lisitskii 《Geography and Natural Resources》2016,37(4):296-301
This paper is concerned with some issues related to the changes in the role, properties and characteristics of cartography in connection with the transition of mankind from the industrial age to the information (post-industrial) age. Emphasis is placed on the essence of the process of perception of the environment by humans through data provided to them where the object of perception and the subject perceiving information are located at different points of the space-time continuum. The study identifies eight characteristic features of the information age, the new challenges and requirements, the possibilities of information society, and the related new tasks of cartographic support of the economy. It is shown that the main difference of the information age from the industrial age implies a transition from the commodity-producing economy to the economy of information services. Based on this, it is concluded that there is a need for the provision of various cartographic services, such as the generation of cartographic information as requested as well as supplying it to various users. Seven main statements are formulated, which characterize the peculiarities, properties and methodological foundations of cartography under the new conditions. The definitions of the role and subject of cartography in the information age are suggested. An interpretation is given to the term “neocartography”, and its main characteristics are presented. The notion of a multipurpose cartographic resource is introduced. 相似文献
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Karl W. Butzer 《The Professional geographer》1980,32(3):269-278
Atmospheric carbon dioxide is expected to double by A.D. 2050, raising global temperatures 2 to 3°C. A model for climatic deviations is presented, based upon paleoclimatic experience 5,000 to 8,000 years ago, when midlatitude temperatures were 1.5 to 2.5°C higher. The economic prognosis includes a United States barely able to meet its own agricultural needs and a substantial overall reduction of world food supplies. The revolutionary implications for contemporary sociopolitical alignments suggest an urgent need for long-range planning and more, historically oriented research. 相似文献
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