ISSN:1350-4827    

DOI:10.1002/met.5060020101

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractConvective and mesoscale processes can be diagnosed in some detail by careful scrutiny of high‐resolution satellite imagery. An example is presented in which lines of convergence within warm, moist, low‐level air created a series of very straight rope‐like clouds whose smooth texture, as seen by polar orbiting satellite imagery, indicated that they were capped by a stable lid. The moist air deepened with time until the lid was penetrated and deep convection was observed to break out. The rope‐like clouds occurred near the leading edge of a so‐called dry intrusion and they are believed to have been associated with the kind of multiple cold frontal structure often encountered in suc

ISSN:1350-4827    

DOI:10.1002/met.5060020102

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractMeasurements of air temperature and wind speed and direction during the months of February, March and April 1988, at Aegion, Greece (38°14.25′ N, 22°7.5′ E) are analysed to detect topographic influences on the climate of this region. The analysis shows that this climate is controlled by nighttime weak cold katabatic winds from the south–south‐west sector, which is bounded by mountains, and stronger warmer daytime winds from the east–north–west sector, which is bounded by the Gulf of Corinth. The presence of weak katabatic winds is also supported by nighttime measurements of the air temperature along the Corinth–Patras road, which show significant temperature depressions at the openings of the several ravines that are found

ISSN:1350-4827    

DOI:10.1002/met.5060020103

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA review of several methods for assessing the economic and social benefits of meteorological services provided in Australia is undertaken. Meteorological services discussed are the basic public weather service and several user‐pay specialised services produced by the Australian Bureau of Meteorology for firms in various sectors of the economy. The usefulness and limitations of the contingent valuation technique often used to estimate the economic value of public goods and services (such as the basic public weather service) are reviewed. Methods for valuing the economic benefits of user‐pay services discussed include the direct economic benefits derived from the use of meteorological services for producers and consumers based on the producer and consumer surplus concepts, simulation modelling incorporating economic optimisation based on the cost–loss ratio technique and cost function analysis to establish the effect of the quality of weather information on the operating costs of a business firm. The social or non‐economic benefits of meteorological services are also discussed, including the difficulty of placing monetary values on these b

ISSN:1350-4827    

DOI:10.1002/met.5060020104

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo methods for fog forecasting in Cuba are compared: use of the classical Fisher discriminant function, and the LVQ algorithm developed by the Laboratory of Computer and Information Sciences, Helsinki University of Technology. The relative number of correct forecasts is over 70% for both, which can be considered a good performance. When the learning sample is large enough and nearly equi‐probabalistic, the LVQ algorithm provides a greater number of correct forecasts than those obtained via the Fisher discriminant function. However, the results attained via the LVQ algorithm are not steady when the learning sample is far from being equi‐probabalistic, because the number of fog cases is much reduced. Until larger samples are available for some regions, it will be necessary to use both methods for fog forecasting in C

ISSN:1350-4827    

DOI:10.1002/met.5060020105

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper deals with the influence of the annual temperature distribution on anchovy fishing in Trabzon and its surroundings (which have been taken to be representative of the coastal region of the south‐east Black Sea). Data used in this study come from two periods: 1960 to 1990 and 1987 to 1992. It is shown that the variation in temperature distribution has no effect on anchovy fishing. Also, it is demonstrated that commercial fishing takes place when the temperature is lower than the annual mea

ISSN:1350-4827    

DOI:10.1002/met.5060020106

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractDecember 1993 turned out to be very wet on the European continent. Around 20 December the Meuse basin in Belgium and France was hit by an unusual amount of precipitation, which gave rise to extensive flooding of the Meuse in the Dutch province of Limburg. For a 33‐day period starting on 6 December 1993 the precipitation forecasts for the Belgian Ardennes were evaluated using the observations of 20 Belgian climate stations. Besides short‐term forecasts made with regional models like the HIRLAM, level 2.0, the UKMO‐model and the RACMO/HIRHAM, precipitation prognoses extracted from ECWMF‐forecasts were examined. On average all model predictions were too low, varying from 10% for the 36‐ to 60‐hour (day‐2) ECMWF‐forecast to over 50% for the 6‐ to 30‐hour UKMO‐forecast. On the other hand, the UKMO‐forecast correlated best with the observations (0.85). The rainfall on 20 December, the wettest day, was underestimated by all model predictions, with the exception of the day‐2 ECMWF‐forecast. With the RACMO/HIRHAM a three‐day rerun was made starting from the 1200 UTC ECMWF‐analysis on 18 December 1993. The resulting precipitation on 20 December compared very well with the data. A similarly prepared HIRLAM‐run, however, performed worse

ISSN:1350-4827    

DOI:10.1002/met.5060020107

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractNatural disasters are caused by natural events, which can be grouped as (i) extreme unstable events; (ii) large ‘variability’ events associated with extremes of the inherent variability and chaotic behaviour of geophysical systems; and (iii) global change events. These primary events are usually followed by equally harmful secondary events, such as mud slides or tsunamis following volcanic eruptions. Whether these events lead to disasters depends to a large extent on the preparedness and resistance of the afflicted community – i.e. its vulnerability. Forecasts for these different categories of event are of two types: ‘risk’ forecasts based on data of previous events, and real‐time forecasts. For group (i) events, these forecasts only begin following some initial detection, whereas for groups (ii) and (iii), forecasts are made before any indication of the event. Many (but not all) types of secondary event may also be forecast with increasing accuracy using local geophysical data and computational models of relevant processes. In this paper the organisation of forecasts and warnings is described, as is how it involves geophysical and disaster or emergency centres at the national, regional and international level. Satisfactory arrangements for issuing, receiving and acting on forecasts and warnings between countries (including the use of broadcasting media) require carefully negotiated procedures at the intergovernmental level. It is pointed out that international procedures developed for meteorology need to be extended to include other types of geophysical event and disaster. The final section of this paper reviews the need for defining targets for improvement in forecasting during the current International Decade for Natural Disaster Reduction (IDNDR), and that this should be preceded by establishing the accuracy of current methods, i.e. the baseline. Clarification of our objectives and targets may well lead to greater financial support from governments and o

ISSN:1350-4827    

DOI:10.1002/met.5060020108

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper reports on a storm event which, due to its extreme nature, produced severe attenuation and local anomalous propagation of the weather radar beam. The effect of this phenomenon on the perceived precipitation is reported, together with the synoptic situation.

ISSN:1350-4827    

DOI:10.1002/met.5060020109

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSutcliffe development theory and the similar omega equation provide an objective framework for the understanding of synoptic‐scale development in the extra‐tropics. Both are widely applied by forecasters in the UK Met. Office, with the omega equation also being used by forecasters working in other meteorological services. Using results from experiments with a quasi‐geostrophic numerical model, this paper examines the pitfalls associated with each, and suggests ways in which these can be avoided. The partitioning between so‐called steering and development terms in the Sutcliffe equation is shown to be misleading, and an alternative form is suggested which is more accurate and circumvents significant cancellation problems associated with the existing form. It is shown that oversimplifiction of the omega equation can lead to it being applied in unsuitable ways. In particular, it is argued that the conversion from omega forcing to vertical velocity is best made at the mid‐tropospheric level, say at 500 hPa, and that therefore diagnostics such asQ‐vectors or their divergence are better applied at this level than, say, at 700 hPa. The so‐called Sutcliffe, or Trenberth, form of the omega equation is recommended as being suitable for subjectiv

ISSN:1350-4827    

DOI:10.1002/met.5060020110

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY