摘要:

AbstractThis study analyses some synoptic situations in which extreme temperatures occur. Cases of temperature‐anomaly spells from ten stations in Argentina are studied. The duration and the maximum deviation in each case are considered. The Lund correlation method or manual classification was used to analyse the synoptic situations. The cold spells in winter during the period 1971/80 occurred in three kinds of synoptic situation. Most of the days have a high‐pressure system to the west and a trough in the centre of the country, which is associated with south‐westerly winds. The coldest days have south‐easterly winds to the north (from the Atlantic), which blow around a high‐pressure system over the southern part of the country. There is a difference between this synoptic situation and the coldest synoptic situation in summer. The coldest conditions in summer take place in south‐westerlies when three or more cold fronts have passed over the area. The warmest spell in summer (January 1972) occurred with a cold front coming from the south, a low‐pressure centre in the middle of the country (between two high‐pressure systems), with a flow from the north over Argentina. In winter the warmest spells occur in similar situations, but there are also warm fronts present over the northern part of the country. Lund's method is appropriate for finding the synoptic situations connected with som

ISSN:1350-4827    

DOI:10.1002/met.5060020401

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractOperational data assimilation systems for numerical weather prediction (NWP) neglect the space‐time drift of radiosonde balloons during their ascent. The validity of this assumption is assessed by reference to the equations of motion and a sensitivity experiment with a mesoscale NWP model. In the experiment, balloon drift is explicitly accounted for in the case of one key ascent which had a significant impact on a short‐period forecast of small‐scale baroclinic development. It is found in this case that, while the impact of balloon drift can indeed be detected, it is small compared with the impact from the observation when assimilated with neglect of balloon

ISSN:1350-4827    

DOI:10.1002/met.5060020402

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo methods have been used to estimate the probable maximum precipitation (PMP) over South West England. The first is based on an analysis of rainfall frequency data; the second uses depth duration data from rare storms. Both methods give results of around 500 mm for the 24‐hour PMP, which for many parts of the region is considerably higher than that given by the Flood Studies Report. By relating PMP to average annual rainfall, new maps of the distribution of PMP over South West England were produced. Values of PMP are highest on low ground, reflecting the effect of convectional processes in these area

ISSN:1350-4827    

DOI:10.1002/met.5060020403

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractRelationships between weather and health have been studied throughout recorded history. This century, air quality has been recognised as an important complicating feature in many urban and industrial locations. In this paper, having defined the difference between climate and weather, we outline some of the relationships which have been defined between both climate and weather conditions, air quality and human health. Links between conditions ranging from mental illness, respiratory and heart disease to flu have been reported. Unfortunately, much of the published work over the years has lacked scientific credibility or has used widely differing analysis tools. However, increased availability of data, and an understanding of the need to follow good scientific practice, are offering the opportunity to place some of the relationships on a more sound foundation. Recent studies identifying susceptible genetic conditions may lead to understanding of previously unexplained linkages. The need for research collaboration between the meteorological, atmospheric chemistry, epidemiology and, most importantly, the medical communities to investigate sometimes complex trigger mechanisms, is highlighted.

ISSN:1350-4827    

DOI:10.1002/met.5060020404

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAn account is given of one Austral summer's experience of forecasting for flying activities and marine operations around the Antarctic Peninsula. Data available included surface and upper‐air observations, analyses and forecasts from the UK Meteorological Office global, 19‐level model and AVHRR satellite imagery. The numerical analyses and forecasts provided good guidance and correctly represented most of the synoptic‐scale features. A number of mesoscale disturbances affected the central Peninsula area and the AVHRR imagery was very valuable in allowing the development and track of these systems to be followed. The major problems were the absence of observations to the west of the Peninsula, the lack of radiosonde ascents from the Peninsula itself and the complexity of local wind systems as a result of the topography. Forecasting frontal activity over the ocean areas was also very difficult because of the unavailability of precipitation forecasts in the GRIB

ISSN:1350-4827    

DOI:10.1002/met.5060020405

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study is aimed at evaluating the impact of non‐conventional winds using data obtained by INSAT satellites over the Indian region. The emphasis is on whether the satellite‐derived wind data improve the depiction of monsoon system, flow patterns, the centre of the system, etc. in the objective analysis of the wind field. For this purpose, monthly climatological normals of the wind field are considered as the initial guess field and then objective analyses of the wind field are performed, first using only conventional winds over the land areas and subsequently including winds constructed from cloud‐motion vectors at 850 and 700 hPa. This experiment was performed for the period of 19–21 September, 1991, when a monsoon depression formed over the Bay of Bengal. Verification of these analyses were made by comparing them with carefully drawn subjective analyses. It is inferred that INSAT winds have a positive impact on the objective analysis, and improvement in the analysis is more marked over the data‐void regions of the Arabian sea and the Bay of Bengal. The results presented in the study reveal that INSAT winds are of potential use in the objective analysis of the wind field, thus giving a better depiction of monsoon depression over the Indi

ISSN:1350-4827    

DOI:10.1002/met.5060020406

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractStatistical methods for predicting the mean monthly precipitation in Cuba have been developed. Two different approaches have been used: multiple linear regression (MLR) and an adaptive scheme using a LVQ algorithm. Three main climatic divisions were defined over the Cuban territory using 180 observation points with a nearly homogeneous geographical distribution. A 50‐year (1941–1990) period was considered. Three types of variable were used as predictors: The Southern Oscillation Index and the Sea Surface Temperature anomaly in the central equatorial Pacific as the ENSO related variables, the Wolf Sunspot Index as a solar activity related variable and variables related to seasonality and persistence. The last of these was found to be the most important in producing high skill. A cross‐validation approach was used to test the prediction quality. This indicated that the LVQ algorithm provided a greater number of correct forecasts but the MLR method showed a slightly higher level of skill. The feasibility of using a LVQ algorithm for predicting mean monthly precipitation is established. However, the high skills found for the MLR method suggest that it should be used as a complementary tool in the decision‐making

ISSN:1350-4827    

DOI:10.1002/met.5060020407

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIt is hard and very often not possible to demonstrate economic benefits to national economies from meteorological and hydrological activities. We propose making a relative estimate of these benefits by evaluating data efficiency. Data efficiency is a function of six parameters, each of equal weight: accuracy, availability, differentiation, timeliness, presentation and up‐date frequency. All these parameters depend on the level of data technology. Improvements in these data parameters result in a bigger volume of data and services sold. On the basis of data efficiency estimation we propose a methodology of how to create an improved strategy for up‐dating the data technology of meteorological and hydrological services. We show that the increase in usefulness of the National Meteorological Service during natural disasters and the rise in revenue from hydrometeorological services are the result of improvements in data efficiency by the new data technology. Alternatively, the increase in data efficiency could be used as good indicator of improvements in the economic benefits of meteorological and hydrological servi

ISSN:1350-4827    

DOI:10.1002/met.5060020408

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe prediction of mesoscale weather phenomena, such as local winds and heavy precipitation, has always been a big challenge because of their direct impact on people's lives. In recent years computer power has increased enough to make it possible to run regional numerical weather forecast models for the prediction of local weather. This paper describes examples of forecasts obtained from a nested mesoscale model currently run operationally at the Danish Meteorological Institute. The potential and problems associated with high‐resolution forecasts are discusse

ISSN:1350-4827    

DOI:10.1002/met.5060020409

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:1350-4827    

DOI:10.1002/met.5060020410

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY