摘要:

AbstractEarlier work has demonstrated that the results of a correlation‐based (Kirchhofer) synoptic classification are dependent on the way that the internal parameters and data are used. In this study, varying classifications are compared to the climate at one location. The results show that associations between temperature and the synoptic patterns are usually physically interpretable and somewhat stable, whereas precipitation‐synoptic type relationships are more difficult to explain and highly variable. We conclude that varying classifications do not produce equivalent synoptic climatologies. Furthermore, we know of no apparent objective or subjective means for determining a ‘best’ classification. Based on these findings, we discourage the use of correlation‐based techniques in all but the most controlled s

ISSN:0196-1748    

DOI:10.1002/joc.3370080302

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe search for teleconnections usually involves the calculation of sample cross correlation functions for pairs of atmospheric/oceanic time series. Properties of the theoretical cross correlation function are derived by means of analytical techniques, and properties of the sample cross correlation function are obtained by means of simulations. In particular, the effect of autocorrelation of the individual time series is to ‘smear out’ any contemporaneous cross correlation that might be present, producing nonzero cross correlations at nonzero lags. To combat this problem, the advantages of ‘prewhitening’ before computing cross correlations are demonstrated. Moreover, the operation of smoothing individual time series has the effect of inflating the values of the cross correlation coefficients at nonzero lags. Finally, the behaviour of running cross correlation coefficients is somewhat counterintuitive, making this technique potentially very misleading for detecting changes in relationships over time. For illustrative purposes, these calculations are also performed for Darwin and Tahiti time series of monthly sea level p

ISSN:0196-1748    

DOI:10.1002/joc.3370080303

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractEvidence for a narrow band‐limited signal with period near 18.6‐years is found in 126 out of 136 yearly total precipitation records, and in 1531 out of 1668 monthly records in the northeastern United States. From 1840 to near the end of the 19th century, rainfall minima in the wavetrain are highly correlated with tidal maxima of the 18.6‐year luni‐solar tide, the twelfth largest tidal constituent in Newton's theory; the wavetrain then switched phase by 180° and for most of the 20th century rainfall maxima are correlated with tidal maxima at 1917.5, 1936.1, 1954.7, and 1973.3. This bistable phenomenon of atmospheric science was discovered by Currie (1983) in a study of tree‐rings from the Patagonian Andes, and O'Brien and Currie (1988) have suggested a dynamical explanation in terms of mathematical physics. In terms of yearly rainfall, the mean percentage amplitude modulation of the wave was near ±6% until 1940 after which it began to increase rapidly, reaching ±10% in the 1960s and 1970s. These results provide a rational explanation for the severe water shortage crisis that occurred at tidal minimum 1964.0 (Namias, 1966; 1967), and reoccurred 19 years later. In addition, a smaller band‐limited term with period 10 to 11‐years is found in a little more than hal

ISSN:0196-1748    

DOI:10.1002/joc.3370080304

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractUtilising daily mean rainfall from dense rain gauge networks, the dates of onset of the southwest monsoon over south and north Kerala have been derived on the basis of objective criteria for the years 1901 to 1980. These dates have been compared with the onset dates as per records of the India Meteorological Department. Statistics of the onset dates are presented. The mean onset date for south Kerala is found to be 30 May and for north Kerala 1 June with a standard deviation of about 9 days in both cases. The sharp increase in rainfall that heralds the onset of the monsoon is highlighted by superposed epoch analysis. The prevailing notion that rainfall from pre‐monsoon thunderstorms progressively increases and merges with the monsoon rainfall is shown to be not vali

ISSN:0196-1748    

DOI:10.1002/joc.3370080305

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractAnnual, seasonal and storm rainfall characteristics are analysed for the Njemps Flats, a semi‐arid area near Lake Baringo in the Kenya Rift Valley. Storm rainfall is analysed in terms of intensity, timing, duration and total storm depth. Storms characteristically occur in the early evening, with one storm of around 2 h making up the daily rainfall totals. High intensity rainfall seldom persists longer than 30 min. The maximum 30 min intensity recorded was 80 mm/h, the maximum 60 min intensity was 75 mm/h. An analysis of annual and monthly recurrence intervals of storm depth indicate that for a 1 in 10 year recurrence interval, June, July and April suffer the heaviest falls, whereas for a 1 in 2 year recurrence interval the months with the heaviest storms become August, July and April. The significance of this to erosion potential and runoff harvesting are discusse

ISSN:0196-1748    

DOI:10.1002/joc.3370080306

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractGiles and Kings (1987) suggest the use of windchill as an alternative indication of coldness for use in the UK Department of Health and Social Security's exceptionally cold weather payments scheme. It is argued here that the use of windchill confers no obvious benefit and would result in added problems.

ISSN:0196-1748    

DOI:10.1002/joc.3370080307

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370080308

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370080309

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370080310

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370080311

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY