Zonal Index Research Articles

Spectral Properties of Analyzed and Forecast Global 500 mb fields

Abstract Global ECMWF data for winter and summer seasons are used to study the spectral structure of 500 mb analyzed height variance and forecast error variance, as well as the effect of spectral truncation in the height and temperature variance calculations. The high wavenumber region of the variance of the analyses is nearly homogeneous and isotropic and follows the −5 power law both in the zonal, two-dimensional and meridional wavenumber indexes. The high wavenumber region is dominated by transient waves. The low wavenumber region is dominated by the stationary part, being anisotropic and seasonally variable. The transition between the two regions is at wavenumbers 7–8. The temperature variance follows a −4 power law in the high wavenumber region. The ECMWF forecast error variance is dominated by the nonsystematic error, the maximum of which shifts from medium to long zonal waves during the forecast. The nonsystematic error variance spectrum is quite similar to the transient variance in the analyses.

Local zonal index and circulation change in the European area, 1873–1972

Local zonal index and circulation change in the European area, 1873–1972

Über abgeschnittene Modelle der barotropen Vorticity-Gleichung in sphärischer Geometrie

A particular truncated spectral model of the barotropic vorticity equation is considered in spherical geometry. Two wave disturbances are taken into account together with an arbitrary zonal flow. It is shown that there exists some evidence that truncation at reasonably high values of both meridional and zonal indexes does not introduce significant errors in the estimate of time evolution.

Characteristics of northern hemisphere blocking as determined from a long time series of observational data

30 years of observational 500 mb geopotential height data have been used to assess the characteristics of northern hemisphere blocking situations. A zonal index suitable for identification of blockings is defined and translated into a computer program. Characteristics of blocking situations have been computed and are presented as statistics. As expected, there are 2 preferred regions for blocking, the Atlantic region and the Pacific region. The results show that the number of days with blocked flow has a maximum over the eastern part of the Atlantic region, while the maximum is found over the western part of the Pacific region. The annual variation shows that there is an extended maximum from February through April in the Atlantic region, while there is a pronounced maximum in January in the Pacific region. The occurrence of simultaneous blocking in the 2 regions has also been investigated. The results show that there is no preference for a connection. Investigation of individual blocking situations reveals that the shortest ones are also formed in preferred geographical locations, and are not just random configurations in the changing pattern of waves in the Westerlies. There is a tendency for blocking episodes to seem to be concentrated in certain geographical locations, the longer the duration of the episode. The results also show that long-lasting episodes are notably more frequent in the Atlantic region than in the Pacific. DOI: 10.1111/j.1600-0870.1983.tb00210.x

Zonal index and circulation change in the north Atlantic area, 1873–1972

AbstractMonthly and annual values are calculated of a zonal index based on surface pressure at 35°N and 55°N between 60°W and 10°W. The period under study, 1873‐1972, is divided into three sub‐periods which approximate with three epochs proposed by Lamb (1972). A comparison of our indices with Lamb's results is followed by a discussion of our monthly index, and the rarity of easterly flow in the 100‐year period is noted. The results are subjected to a trend and a power spectrum analysis and the latter indicates a number of periodicities some of which are not easily explicable.

On some aspects of interaction between middle latitude westerlies and monsoon circulation

Day to day zonal index between 30-50 deg. N has been computed and discussed in relation to the break monsoon conditions. Relation between the mean zonal index and general distribution of the precipitation in the central parts of the country, has been investigated. Distortion in the 500 mb flow pattern across Tibet due to the interaction between westerly trough and monsoon Circulation has also been discussed.

Phases of the summer monsoon equatorial trough and oscillations of the equatorial trough

In continuation of earlier studies by Pant (1978), the, oscillations of the equatorial trough and the associated phases of the summer monsoon over the Indian subcontinent were studied. For this purpose, the data relating to MONEX-79 were also considered. A "weak" or "break" monsoon phase is associated with the insitu appearance of the planetary oceanic equatorial trough in the lower troposphere around 10 deg. N. The revival of the monsoon activity is associated with the northward progress of the southern trough and its re-establishment around 20 deg. N. Study of mid-tropospheric temperature, changes over Tibet and Sinkiang have brought out clearly that the setting in of "weak" or "break" 'monsoon condition is concurrent with the occurrence of very low temperatures in the middle troposphere, particularly over Sinkiang. The physical picture that emerges from this study is that under low zonal index conditions advection of cold air behind large amplitude middle latitude troughs results in cooling of the Tibetan Plateau and the neighbourhood in the middle levels. This results in the destruction of the reverse Hadley cell and re-establishment of the direct cell with its upward limb near 10-15 deg. N. This is a physically consistent picture and explains many of the observed characteristics of the weak and active phases of the monsoon described by several authors. The results of the study hold out possibilities of prediction of the phases of the monsoon over periods of a week to ten days based on the temperature changes over the Asian continent to the north of India.

Early to Middle Miocene Planktonic Foraminiferal Datum Levels of the Equatorial and Subtropical Pacific

Early to Middle Miocene Planktonic Foraminiferal Datum Levels of the Equatorial and Subtropical Pacific

Metamorphism, Folding and Plutonism in the Wagga Metamorphic Belt of N.E. Victoria

Structural and metamorphic studies carried out in N.E. Victoria show that the classic low-pressure metamorphism described previously by Vallance (1953, 1967), Joplin (1942, 1944, 1947) and Guy (1968) consisted of a complex interaction of metamorphic events, compressional periods and granite intrusion. Large gaps exist on maps showing the geographical distribution of zonal index minerals due to burial by younger rocks and lack of study (Fig. 1).

India's monsoon rainfall related to mid-latitude zonal index

India's monsoon rainfall related to mid-latitude zonal index

Atmospheric Variations: Vacillations and Index Cycles

Zonal indices, momentum flux, and mean and perturbation kinetic energies of the Southern Hemisphere upper troposphere, derived from the EOLE constant density balloon data set, are found to possess strong 18-23 day variations which are statistically significant to a posteriori levels. Cross-spectra and phase relationships suggest that the variation appears as a barotropic interaction between the middle latitude mean westerlies and ultra large-scale perturbations. Long-period and high-amplitude variations in energy conversion between eddy and mean kinetic energies are found which average out in the long term mean to be very small and positive, consistent with previously measured average hemispheric energetics. Furthermore, the variation is shown to possess an ultra-long wave preference. Examination of two independent data sources, time series of total ozone and stratospheric thickness data from the Selective Chopper Radiometer, suggests that the periodicity is a property of general hemispheric motion rather than just a property of the EOLE data set.

A computer program for the identification of crystalline precipitates by means of selected-area electron diffraction

A computer program for the automatic evaluation of electron-diffraction spot patterns is described. It decides whether an observed zonal plane can belong to a given lattice or not and gives the zonal indices [uvw] of that zone together with the deviations from the calculated d values.

Middle Tertiary Basin Development, San Joaquin Valley, California

An analysis was made of the foraminiferal paleoecology of the middle Tertiary in wells of the San Joaquin Valley, California. This province, which represents the southern half of the Great Valley of California, is bounded on the east by the Sierra Nevada, on the south by the Tehachapi Mountains, on the west by the Coast Ranges, and on the north it joins the Sacramento Valley near Stockton. The marine basin of this study is known as the San Joaquin Basin, and it is located in the southern half of the San Joaquin Valley. Thirteen biofacies are established for the recognition of thirteen paleobathymetric zones between depths of 0 and more than 6000 feet. In the Oligocene and lower Miocene, maximum water depths of the marine basin were abyssal, in excess of 6000 feet; basin filling brought about a decrease to lower bathyal depths during the middle Miocene; rapid sedimentation during the later Miocene resulted in shoaling of the basin to neritic depths in latest Miocene and Pliocene. Most of the better zonal index species are bathyal or lower neritic types; those with the longest stratigraphic ranges appear to be the abyssal and upper neritic assemblages. The primary deep-water connection between the San Joaquin Basin and oceanic waters to the west was consistently at the southwestern corner of the basin across the San Andreas fault. Evidence for this is the continuous dominance of deep-water facies in the southern part of the basin extending westward to the San Andreas fault. Further support is to be seen in the restriction of planktonic foraminiferal facies and radiolarians to the southern areas. Frequencies of planktonic foraminiferans are generally greatest in the southern area near the San Andreas fault, showing decreasing values away from the San Andreas fault around the southern part of the basin in a counterclockwise direction. This pattern indicates that the principal oceanic current entered the basin across the San Andreas fault and moved in a counterclockwise pattern during most of the middle Tertiary. Biofacies to the west of the San Andreas fault do not generally indicate a continuation of deep-water conditions there; right-lateral movements on the San Andreas fault have probably moved the western continuation of these deep-water basin facies far to the north. A comparison of subsidence and sedimentation rates shows about subequal rates at first in the Oligocene, somewhat greater rates of deposition than subsidence during most of the Miocene, and far greater rates of deposition than subsidence in the later Miocene. Throughout the middle Tertiary various tectonic blocks within the San Joaquin Basin apparently moved independently and continuously. More than 5000 cubic miles of rock represent the marine sediment deposited in the San Joaquin Basin during the middle Tertiary stages. Of this amount, more than 4000 cubic miles were deposited in depths of water greater than 300 feet, and most of the oil produced in the basin comes from these strata.

Long‐range prediction of the zonal westerlies and some problems in data analysis

Long‐range weather forecasts, based on cycle analysis, have been attempted without much success. Recent research suggests the possibility of making use of lunar cycles or the quasi‐biennial oscillation (QBO) observed in atmospheric phenomena. Investigation of the sea‐level zonal index for the northern hemisphere, using monthly mean data, shows the existence of the QBO. But in addition to QBO, there is a more pronounced signal that can be interpreted in terms of a general soli‐lunar tidal framework. One reason this signal was not detected previously is due to the reduction in amplitude and the phase distortion produced by summarizing the data by monthly periods centered only at the midpoint of the calendar month. This phenomenon, referred to as the aliasing problem, should be considered in the analysis of all geophysical data (such as tide data) in which periodic components, even of low amplitude, can exist.

Some estimates of the modes of kinematic generation of atmospheric baroclinic intensity

Kinematic generation of baroclinic intensity ℱ was defined in a similar manner to Petterssen's definition of frontogenetic intensity. It was computed at 500 mb over a large area of the northern hemisphere utilizing the daily series synoptic weather maps during a zonal index half-cycle in winter. Spectral analyses of ℱ revealed that the harmonic of wave number 2 around the hemisphere was the most prominent, followed by wave numbers 4 and 1, and confirmed the inferences one draws from similar earlier spectral studies of baroclinicity and available potential energy. During this period perturbation kinetic energy was on the increase, and it was found that wave numbers 4, 5, and 6 were significantly marked with simultaneous increases of kinetic energy and the kinematic generation of baroclinic intensity.

Preliminary stratigraphical results from graptolite studies in the upper Silurian and lower Devonian of Southeastern Australia

Abstract The uppermost graptoloids occurring at Yass are the upper Budnanian (eβ2 = upper Ludlovian ‐ Downtonian) zonal indices Monograptus transgrediens and M. bouceki. Strata below this level, but immediately overlying the Dalmanites Bed, contain M. formosus which indicates the junction between the upper and lower Budnanian (eβ2 — eβ1= upper Ludlovian). The association of Linograptus post‐humus posthumus and M. bohemicus in the beds immediately below the Dalmanites Bed suggests correlation with the uppermost eβ1 (lower upper Ludlovian). In the plant‐graptolite beds in Central Victoria three zones characterised by the following graptolites are distinguished (from above): M. aequabilis subsp. nov., M. thomasi thomasi and M. thomasi subsp. nov. Assignment of these strata to the Praguian (late Siegenian ‐ early Emsian) is favoured.

THE INDEX CYCLE: A CROSS-SPECTRAL ANALYSIS OF ZONAL INDEX DATA

Abstract In order to examine quantitatively the evidence for an index cycle, 21 years of daily 700-mb. zonal index data for the western longitudes of the Northern Hemisphere were subjected to cross-spectral analyses. The annual variation of the mean and standard deviation of the three zonal indices (polar, temperate, and subtropical) was removed by a standardizing procedure utilizing time-smoothed annual curves. The variance (power) spectra of the individual indices indicated that their correlation structure can be closely approximated by a first-order Markov scheme. No evidence was found for an excess of variance in the range of period (3 to 8 weeks) assigned to the index cycle by subjective means. The cospectra all indicated negative covariability among the indices as would be expected from circulation patterns characteristic of index-cycle-like behavior, but none showed an excess of negative covariability within the period range of interest. Coherence values, indicating the degree of relationship among...

成層圏循環と小笠原高気圧の季節的転移との関係

A zonal index on the 1Omb level is defined to describe the time change of the lowlatitude easterly jet stream in the mid-stratosphere. The index shows a remarkable sudden increase on some day in June. This increase of the zonal index occurs simultaneously in the stratosphere. Further, by examining a relationship between this singular phenomenon and the seasonal transition of the Ogasawara anticyclone in the troposphere, it is found that the increase of the 1Omb zonal index occurs about a month prior to the rapid progress of the northern boundary of the Ogasawara anticyclone to 35°N. Then the perfect summer type circulation pattern prevails over Japan.

ON THE ROLE OF THE SUBTROPICAL JET STREAM OF WINTER IN THE ATMOSPHERIC GENERAL CIRCULATION

Abstract Calculations of budgets of heat, angular momentum and kinetic energy for the tropical latitudes are obtained in a coordinate system following the subtropical jet stream axis at the 200-mb surface. Comparisons of the fluxes of various quantities with those required at certain latitudes show that the vertical mass circulation has a very important role in the tropics and that the daily eddies are important on the poleward side of the jet stream. Large fluxes of various atmospheric properties are computed for 3 different months. The month of January, 1956, shows very large export of kinetic energy and angular momentum from tropics into middle latitudes. Statistics of the middle-latitude zonal and meridional motion are studied. It is shown that the month of January, 1956, was one of very low zonal index, blocking, and very slow eastward wave motion. Possible connection between lower and higher latitude circulations is suggested.

West-Pacific Stratigraphic Correlation

THE development of reliable methods of world-wide stratigraphic correlation involves the gradual replacement of empirical and traditional ‘index fossils’ by zonal index species selected on the basis of carefully analysed factors concerning their evolution and distribution. This approach favours abundant fossils to which statistical methods of population study can be applied, such as Foraminifera; rapidly evolving lineages, such as larger Foraminifera; and widespread forms, relatively independent of facies, such as planktonic organisms. It also necessitates a major effort to clarify stratigraphic terminology and classification which is expected to be significantly advanced soon as a result of the work of the Commission on Stratigraphy of the International Geological Congress. The framework of the conventional stratigraphic subdivisions of geological time, dating back to the time when geological knowledge began to accumulate long ago in Europe, is found to lack precision and to suffer from other deficiencies when attempts are made to accommodate in it the results of precise stratigraphic correlation in previously unknown parts of the world. Patient co-operative work of stratigraphers and palaeontologists in different continents is required in order to overcome the difficulties and misunderstandings resulting from an over-extension of weakly founded terms and concepts. As Gignoux1 has stated, it is essential first to establish local stratigraphic sequences (on a rock stratigraphic and zonal biostratigraphic basis, I might now add) and to generalize them only cautiously.