A relationship between equatorial lower stratospheric QBO and El Niño

Cycle-to-cycle evolution of zonal wind QBO is studied making use of meteorological balloon and M-100 rocket data at Trivandrum (8.5°N, 77°E) for a period of about 19 yr from 1971 to 1990. The height of occurrence of zonal wind QBO maxima is found to vary systematically from one cycle to the next. The successive QBO maxima (easterly or westerly) occur progressively at greater heights and, after reaching a particular height, the next maximum (easterly or westerly) occurs at a lower height. Thereafter, the upward progression of the successive maxima starts again. It is found that the upward progression of the QBO maxima is closely associated with the occurrence of an El Niño event. A simple physical mechanism is suggested for this relationship between the QBO and El Niño. It is hypothesized that if the vertical wavelength of the Kelvin and mixed Rossby-gravity (MRG) waves are smaller during an El Nino event, the observed upward progression of the QBO maxima can be explained.     

Youth aspirations and employment in provincial Indonesia: a view from the lower middle classes

ABSTRACT

Demographically and geographically, lower middle class youth occupy an ambiguous position in Indonesian society, embodying elements of both privilege and marginality. Drawing on interviews and 16 months of ethnographic fieldwork conducted between 2008 and 2013, this article considers how an emerging provincial middle class seeks to make good on the promises of an expanding higher education system and proliferation of globalised youth cultures. I examine the capacity and limits of higher education in facilitating young people’s aspirations for youth lifestyles, jobs and the future in a regional labour market with high levels of youth underemployment and informality. Young people’s aspirations for employment and middle class standards of living are mitigated by their responsibilities towards their families and difficulties to establish the social connections needed to access jobs and opportunities. Faced with limited upward mobility, class as an aspirational category rather than everyday reality underpins young people’s claims about the good life.     

Dynamics of the Antarctic and Arctic mesosphere and lower thermosphere regions—II. The semidiurnal tide

The semidiurnal tidal dynamics of the Antarctic and Arctic mesopause regions (95 ± 15 km) are investigated through comparative analyses of monthly mean tidal wind fields determined from radar measurements at the Scott Base (78°S), Molodezhnaya (68°S), and Mawson (67°S) stations in the Antarctic, and the near-conjugate stations of Heiss I. (81°N) and Poker Flat (65°) in the Arctic region. The main feature common to all stations is the fall equinoctial maximum in amplitude (10–20 m s⁻¹), which is also reproduced by the most recent numerical tidal model. However, the wintertime amplitude growth with height and the shorter vertical wavelengths characterizing the model are features not reflected in the data. There is also a spring equinoctial maximum in the Antarctic data which the model does not reproduce.Examination of interannual variability reveals characteristics similar to those noted in Part I for the mean zonal wind; namely, some degree of year-to-year variability superimposed on apparent long-term decreases of order 0.3–0.5 m s⁻¹ yr⁻¹ (depending on month) in the Southern Hemisphere semidiurnal tidal amplitudes. Numerical simulations presented herein indicate that changes of this magnitude cannot even be induced (via mode coupling) by a change in the mean zonal wind field of order 30%, and are more plausibly explained by a secular change in the tidal forcing by ozone insolation absorption. However, contrary to Part I, the annual mean tidal amplitude is not characterized by any significant secular trend, remaining within the 10.0 ± 2.5 m s⁻¹ range throughout the 1970–1986 period. Analyses of other data sets are required to ascertain confidence in the apparent trend reported here.     

Dynamics of the Antarctic and Arctic mesosphere and lower thermosphere regions—I. The prevailing wind

The dynamics of the Antarctic and Arctic mesopause regions (ca. 95 ±15 km) are investigated through comparative analyses of winds measured by radars at the Scott Base (78°S), Molodezhnaya (68°S), and Mawson (67°S) stations in the Antarctic, and the near-conjugate stations of Heiss I. (81°N) and Poker Flat (65°N) in the Arctic region. The data were analyzed specifically to delineate hemispheric differences in mean monthly prevailing wind climatologies, and show the circulation systems in the Arctic and Antarctic mesosphere and lower thermospheres to exhibit significant asymmetries. These asymmetries may be attributable to hemispheric differences in dynamical forcing due to one or more of the following: insolation absorption by ozone, other mesospheric heat sources such as exothermic chemical reactions, tropospheric forcing of vertically or obliquely propagating gravity waves which engage in mesospheric mean-flow interactions, and dissipation of planetary waves which find ducting channels through the middle atmosphere.Interannual variability is also examined in the Molodezhnaya and Heiss I. data, which cover the periods 1967–1986 and 1968–1985, respectively. Accompanying significant year-to-year variability, eastward winds at 95 km over the Antarctic (Molodezhnaya station) exhibit a trend of decreasing amplitude from 1968 to 1977 that is not reflected in the Arctic data (Heiss I.); for instance, the annual mean wind decreases in a monotonie sense from 20–25 to 5 m s⁻¹ during this period. It cannot be unambiguously established whether this trend represents a decrease in intensity accompanying secular changes in thermal forcing, or a latitudinal contraction or shifting of the mesospheric jet system. The annual mean winds at Molodezhnaya remain at the 4–8 m s⁻¹ level from 1977 to 1986.In addition, existing empirical models are evaluated against the data, and are shown to be deficient in reproducing some salient characteristics of the high-latitude circulation systems. This latter result especially questions the common practice of deriving winds based on the geostrophic approximation in this altitude/latitude regime.     

Dynamic regime of the mesopause—lower thermosphere at mid-latitudes of the northern hemisphere by radio meteor observations

The coherent pulse Meteor Automatic Radar System (MARS) based at Kharkov (49°30′N, 36°51′E) was used to measure zonal winds in the altitude range 80–105 km in the period from November 1986 to December 1990. It was found that, for the greater part of the year, the zonal prevailing wind component was in the eastward direction. The change from eastward to westward direction begins in the lower thermosphere in February–March, propagating downwards to the mesosphere, and it remains there until June–July. The structure of semidiurnal tides has general regularities at different sites. Annual variations in the monthly mean values of semidiurnal vertical wavelengths are practically the same, both in the northern and southern hemispheres. Wavelengths are more than 100 km in summer months, whereas they are less than 60 km in winter months.Studies of internal gravity wave (IGW) parameters in the height range of 80–105 km have shown that the internal gravity wave amplitude does not exceed 30 m/s, the vertical wavelength is in the range of 10–30 km, the horizontal wavelengths are 100–800 km and the horizontal phase velocities are in the range 20–160 m/s. The propagation and breaking of upward and downward IGW at heights of 80–100 km have been recorded.     

On the role of the 9.6 μm O3 band in the energetics of the mesosphere and lower thermosphere

Radiative cooling and heating in the 9.6 μm O₃ band has been calculated for the 50–105 km region. The NLTE effects due to the excitation of the ozone ν₃ vibrations by atmospheric and solar radiation and by the release of chemical energy into vibrations upon recombination of O + O₂ into O₃ have been taken into account. It is shown that the LTE approximation is good for altitudes below 70 km where fundamental transitions comprise the main contribution to the cooling rate. Above 70 km, the contribution of the hot transitions to radiative cooling may exceed the contribution of the fundamental ones. In the presence of chemical excitation, part of the chemical energy radiates in the hot transitions, resulting in an additional cooling rate of about 0.5 K/day at 90 km. A method of parameterizing radiative heating which is based on the separation of the effects of fundamental and hot transitions in the 9.6 μm O₃ band is proposed.     

Vertical structure of AGW associated ionospheric fluctuations in the E- and lower F-region observed with EISCAT—a case study

The vertical structure of AGW (atmospheric gravity wave) associated fluctuations of ionospheric plasma parameters for the 100–240 km altitude range in the daytime of 7 September 1988 has been investigated by making use of the data provided by the Tromsø measurements in the EISCAT CP1 observation mode.The wave power profile vs height has been studied by integrating the power spectral density in each altitude. The essential feature of the power variation can be explained in terms of the energy conservation of AGWs propagating in a dissipative thermosphere. Intrinsic propagation parameters of the dominant AGW have been successfully estimated with a method based on the retrieval of the Doppler effect due to the horizontal prevailing wind. From the fluctuation structure analysis in a time-altitude frame, a downcoming AGW has been clearly identified. This downcoming wave might have been reflected from a wind shear at the altitude around 200 km, which is inferred from the meridional prevailing wind profile.     

The southernmost records of Anhingidae and a new basal species of Anatidae (Aves) from the lower–middle Miocene of Patagonia,Argentina

New bird fossils from the Santa Cruz Formation (lower–middle Miocene), Santa Cruz Province, Patagonia, Argentina, are described. They represent an indeterminate species of the extinct anhingid Macranhinga and a new genus and species of basal Anatidae Ankonetta larriestrai. The record of the giant darter Macranhinga constitutes the southernmost record for the family, and expands the known stratigraphic range of the genus, previously restricted to the upper Miocene. Based on an analysis of the fossil anhingid record from South America, we hypothesize that giant darters disappeared from South America in the early Pliocene due to climatic deterioration, regression of marine and freshwater environments, the arrival of placental carnivorous mammals, and also probably by competition with phalacrocoracid cormorants. The new anatid Ankonetta is based on an incomplete but informative tarsometatarsus, with superficial similarities to extant Dendrocygna. A brief overview of several fossil ducks from the Patagonian Cenozoic concludes that most pre-Pliocene examples belong to non-anatine taxa, indicating that plesiomorphic ducks were the dominant anseriforms in those times, a pattern also evident on other continents.     

The mineralogy and petrography of Low Lands Ware 1 (Roman lower Rhine–Meuse–Scheldt basin; the Netherlands,Belgium, Germany)

Over the last 80 years Belgian, Dutch and German archaeologists working in the lower Rhine–Meuse–Scheldt basin have encountered a Roman pottery group that occurs in large quantities at most Roman sites in the region. Several researchers have separately tried to define this pottery, resulting in different names. Petrographic and geochemical analyses of 100 samples have now shown that the production of this ware predominantly made use of one source of raw material, divisible into three sub-groups on the basis of technological choices. The probable source lies in the early-Pleistocene Tegelen-formation, a clay rich in muscovite mica and garnet, which outcrops in the tertiary Scheldt escarpment (Nl) and the campine microcuesta (B). On the basis of geographical characteristics, Roman finds and the presence of a large Medieval pottery industry, production in the Bergen-op-Zoom area is suggested. In view of these new findings the name ‘Low Lands Ware 1’ is introduced to refer to this pottery group.     

Some regularities of the lower thermosphre wind regime in summer and autumn from meteor radar measurements in obninsk (55°N, 38°E)

Meteor wind measurements made at Obninsk during MAC/SINE and MAC/EPSILON, and in the summer and autumn of other years since 1973, are reported. The zonal wind, which is presumed to be in the 93–95 km height region, is generally westerly, and the meridional wind is mainly northerly. Quasi-two-day oscillations are studied, as are semidiurnal tides. There is some evidence for a 22-yr periodicity in the amplitude of the semidiurnal tide     

1987–1989 total ozone and ozone sounding observations in Northern Scandinavia and Antarctica,and the climatology of the lower stratosphere during 1965–1988 in Northern Finland

The total ozone observations of Tromsö (Northern Norway), Sodankylä (Northern Finland) and Murmansk (Northwestern Soviet Union) for 1987–1989 have been studied. Comparisons of the total ozone with stratospheric temperatures observed at Sodankylä have been made. These values have also been compared with the long-term mean total ozone at Tromsö and the long-term means of stratospheric temperatures at Sodankylä. No severe ozone depletions were observed. The exceptionally high total ozone values at these stations in February 1989 were connected to abnormally high stratospheric temperatures. The comparison of total ozone observed at roughly the same southern latitudes revealed great differences in the springtime.The 1989 ozone sounding observations of Sodankylä, Bear Island and Ny Ålesund (Spitzbergen) did not reveal any indications of pronounced ozone depletion. A comparative study of ozone, temperature and relative humidity indicated that the springtime variability of ozone in the lower stratosphere was clearly connected to meteorological variability. The lower tropospheric ozone had two distinct maxima, one in spring with large-scale photochemical causes and the other in summer connected with the emissions of hydrocarbons and oxides of nitrogen in Europe.Temperature observations made at Sodankylä over 24 yr revealed the existence of a potential for polar stratospheric cloud formation in the lower stratosphere in winter and early spring. A trend analysis of 50 hPa temperature revealed a negative trend of −0.16 K/yr in January and a positive trend of 0.15 K/yr in April; the annually-averaged trend was only −0.02 K/yr for this 24-yr period. When the January–February mean temperatures are separated according to the phase of the QBO in the tropical stratosphere, correlations between temperatures and sunspot numbers are found.     

About two seal-impressed jars from Tell Abraq (Emirate of Umm al-Quwain). New evidence for intercultural networks in the lower Arabian Gulf in the late 2nd – beginning of the 1st millennium BC

Ongoing excavations at Tell Abraq (Emirate of Umm al-Quwain, U.A.E.) are revealing new aspects of this multiperiod site, which was occupied from c. 2500 BC to 300 AD. Together with substantial architecture dated to the 2nd and 1st millennia BC, relevant assemblages of archaeological materials are being collected and dated to different phases of the site’s life. Among this material, exceptional is the discovery of two jars bearing the impression of two different cylinder seals, which will be presented here. Seal impressions on any media are extremely rare in the whole of south-eastern Arabia and strongly indicate a foreign provenance for the jars. Their iconographic study, the fabric and morphological parallels for the jars, and probable chronology will be discussed, as this can highlight transmarine connections during the late 2nd-first half of the 1st millennium BC, as well as provide new data to address chronological issues in south-eastern Iran itself.