摘要:

AbstractThe surface energy balance of intertidal sediments is complex. Heat is exchanged across sediment‐atmosphere and sediment‐water interfaces at differing states of the tide. This takes place within the context of seasonal changes in the temperature of the atmospheric boundary layer, and sea and river water. Subsurface heat flux in an intertidal mudflat near Grangemouth in the Forth Estuary, Scotland, was determined over a full seasonal range of ambient conditions during 1981. Measurements of temperature and weather variables were made from a 4.3m high instrument tower. Thermal properties of the muddy sediment were determined under laboratory conditions. Heat flux in and out of a 0.1 m deep surface layer of mud was calculated. Time of high water exerts a strong control over net heat flux in a 24 hour period. This is due to variation in heat exchange across the sediment‐water interface during tidal inundation, and across the sediment‐atmosphere interface at low water. The relationship between time of high water and net heat flux during inundation follows a broadly similar form at all seasons. Season, however, determines the magnitude of heat ex

ISSN:0196-1748    

DOI:10.1002/joc.3370050502

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe optimization of agricultural productivity by means of numerical weather models requires a detailed analysis of historical daily weather data in order to determine which areas best meet the climatic requirements of a particular crop. The determination of the profiles of climatic factors, in order to identify climatologically similar and closely correlated zones, provides an adequate method of transferring locally tested numerical crop‐weather models from one area to others with the same agroclimatic conditions.This study was made on a small but meteorologically, orographically and agriculturally varied area. It is based on daily measurements of precipitation and of minimum and maximum temperatures, taken by 42 weather recording stations over the period 1961‐1977. The climatic profiles are made by analysing the spatial and temporal variability of meteorological parameters in order to select the similarity functions to be used in models of hierarchical cluster

ISSN:0196-1748    

DOI:10.1002/joc.3370050503

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of topography on two measures of temperature, the daily minimum and the diurnal range, were investigated using the conventional network of climatological stations in the U.K. The effects of large bodies of water and buildings were minimized by restricting the analysis to data obtained from 145 inland rural sites.Topographic influences were considered to be mainly due to the effects of ‘local’ and ‘large‐scale’ shelter. Local shelter is associated with ‘height above the valley’ and is represented by the drop in altitude within 3 km, whereas large‐scale shelter is associated with nocturnal drainage of cold air, and is represented by the average height of the terrain above the valley over a radius of 10 km. The height above the valley is the most important variable and its maximum effect on diurnal range occurs in the early autumn, when the difference in soil moisture deficit between valleys and summits reaches its maximum. Large‐scale shelter is more important in winter than in summer, and for diurnal range, for rare rather than common events. This represents the increasing importance of nocturnal air drainage with the length of the night and suitable radiating conditions. For minimum temperatures in winter, however, the maximum impact of large‐scale shelter occurs for events with a return‐period around 2 years, and which are loosely associated with cold spells lasting a day or so. More extreme temperatures are usually attained at the end of cold spells lasting several days, when continued radiational cooling over level ground can produce temperatures as low as those attained thro

ISSN:0196-1748    

DOI:10.1002/joc.3370050504

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractSalient features of the long‐term variation of surface air temperature for India as a whole and for different regions of the country have been presented. Temperature data at 73 fairly widespread stations, for the period 1901‐1982. have been used in the study. Seasonal and annual temperature anomaly series have been obtained for the different regions. Such series have also been obtained for latitude‐ and longitude‐wise classifications. The long‐term variation in the temperature has been evaluated by linear trend.The results indicate a slight but definite warming trend in the mean annual Indian temperatures. This warming is found to be mainly contributed by the post‐monsoon and winter seasons. West coast, interior peninsula, north central and north‐east regions of the country have shown pronounced warming in the mean annual temperatures. The post‐1940 cooling reported for the Northern Hemisphere is not conspicuous in the mean annual Indian temper

ISSN:0196-1748    

DOI:10.1002/joc.3370050505

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractA principal component analysis (PCA) of Florida thunderstorm patterns (1948‐1982) revealed three statistically significant spatial modes of variation from summer‐to‐summer. The most important was in the region of sea breeze convergence, which has been previously hypothesized to be the main initiator of summer thunderstorms over peninsular Florida.A companion analysis of 500 mb height data over the south‐eastern U.S. uncovered only one significant pattern of variation from the mean, when tested against uncorrelated data. We hypothesized, prior to testing, that dynamic considerations would make it negatively correlated with the most important thunderstorm pattern. A subsequent regression analysis allows that hypothesis to continue to be entertained. A canonical analysis verifies this finding.The results suggest that the sea‐breeze‐related thunderstorm patterns are influenced over seasonal and longer time scales by the first 500 mb component. There has been a significant secular change both in the most important thunderstorm pattern and its related 500 mb pattern over the period of

ISSN:0196-1748    

DOI:10.1002/joc.3370050506

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractUsing thunderstorm and rainfall information from five Nigerian stations for a five year period, the separate contributions of line squalls, thunderstorms and ordinary monsoons to the total rainfall and their variations with latitude are investigated. Total and thunderstorm rainfall decreases with increasing latitude but monsoon precipitation decreases exponentially while line squall rainfall is at a maximum around 9°N. Rainfall from thunderstorms shows a single annual peak in July/August at stations north of about 8°N whereas line squall precipitation exhibits a double maximum for all stations south of 12°N. It is also shown that, in the mean, line squalls are the most important rain producing systems, giving 47‐6 per cent of the mean total annual precipitation compared with 39 per cent and 13‐4 per cent from thunderstorms and ordinary monsoon rain, respec

ISSN:0196-1748    

DOI:10.1002/joc.3370050507

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractClimate plays a major role in determining variations in Australian crop production. The El Niño‐Southern Oscillation (ENSO) phenomenon is an important mode of climatic variation affecting the Australian region. Interannual fluctuations of Australian crop production and ENSO might thus be expected to be quite closely related. Analysis of the limited data available at present suggests that fluctuations in some Australian crops are in fact associated with ENSO and may be predictable, well in advance of harvest, from observed sea‐surface temperatures around northern Austr

ISSN:0196-1748    

DOI:10.1002/joc.3370050508

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractA multivariate statistical model for forecasting anomalies of surface pressure over Europe and the North Atlantic Ocean at medium to long range used routinely in the Synoptic Climatology Branch of the Meteorological Office is described. The model discriminates between broad classes of circulation type using a multivariate predictor space (including areal sea surface temperature anomalies). The forecasts may take categorical or probabilistic form, and the likelihood of the occurrence of categories of circulation index, temperature and rainfall over the U.K. can be produced using Bayesian methods. Emphasis is laid on the difficulties of applying classical statistical analysis to atmospheric fields, as this important aspect of long range forecasting by empirical methods tends to be neglected in the literature.

ISSN:0196-1748    

DOI:10.1002/joc.3370050509

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370050510

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370050511

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY