INTERACTION BETWEEN ATMOSPHERE AND OCEAN AND TELECONNECTION IN THE ATLANTIC DURING THE COLD SEASON

In this paper,the WA teleconnection pattern of SST in the Atlantic during the cold season is confirmed.The resultsshow the WA pattern of atmosphere is linked to the SST pattern and relative higher frequencies account for most of theWA signal.The linked pair of atmosphere and ocean patterns might be mutually supportive and exhibit“quasi-annualcycle”.The possible explanation for the polarity reversal of WA pattern is also discussed.     

The 55- to 60-ka Te Whaiau Formation: a catastrophic,avalanche-induced,cohesive debris-flow deposit from Proto-Tongariro Volcano,New Zealand

Te Whaiau Formation is a massive volcaniclastic deposit interbedded within gravelly and sandy volcanogenic sediments of the northwestern Tongariro ring plain. The ca. 0.5-km³ deposit comprises a clay-rich, matrix-supported diamicton with lithological and physical properties that are typical of a cohesive debris-flow deposit. Clays identified in the matrix are derived from hydrothermally altered andesite lava and pyroclastic rocks. The distribution pattern of the deposit, and the nature of the clay matrix, point to a source area that was located in the vicinity of Mt. Tongariro's current summit (1967 m). Most of the proximal zone is buried under late Pleistocene lavas forming the northwestern flank of the massif. In contrast, the medial and distal zones are well exposed to the northwest in the Whanganui River catchment. Lithofacies exposed in these latter zones contain isolated volcaniclastic megaclasts and well-preserved, jointed blocks of andesite. Small hummocks, up to 5 m high, are present only in the distal margins of the deposit. Based on these observations, possible source areas and analogy with similar deposits elsewhere, we infer that Te Whaiau Formation was initiated as a fluid-saturated debris avalanche that transformed downstream into a single, cohesive debris flow. It is interpreted that the mass flow was initially confined to the northwestern flank of Tongariro before spreading laterally onto the lowlands to the northwest. The resulting heterolithological diamicton filled stream channels in the western sector of the Tongariro ring plain. At 15 km from source, the debris flow encountered an elevated terrain, which acted as a barrier to further spreading to the north. The stratigraphy of the cover beds and K/Ar data on an underlying lava indicate that Te Whaiau Formation was emplaced between 55 and 60 ka, a cool period characterized by intense volcaniclastic sedimentation around the Tongariro massif. Jigsaw-fit fractured volcanic bombs suggest that an explosive eruption through hydrothermally altered rock and pyroclastic deposits probably triggered the mass flow. The characteristics of the deposit indicate that a large portion of the proto-Tongariro edifice collapsed en masse to form the initial avalanche. Hence, we infer that the current morphology of Tongariro volcano is derived not only from glacial erosion, but also from gravitational failure. Prehistoric eruptions and current geothermal activity on the upper northern and western slopes of the Tongariro massif suggest that avalanche-induced debris flows must be considered a potential future volcanic hazard for the region.     

Pan evaporation and wind run decline in the Cape Floristic Region of South Africa (1974�C2005): implications for vegetation responses to climate change

In many regions of the world, increasing temperatures in recent decades are paradoxically associated with declining pan evaporation, but evidence is sparse for this trend from the southern hemisphere in general and sub-Saharan Africa in particular. In this study, we examined changes in pan evaporation and four other meteorological variables (rainfall, wind run, temperature and vapour pressure deficit) at 20 climate stations in the predominantly winter-rainfall Cape Floristic Region (CFR) of South Africa over the period 1974?C2005. Our results show that pan evaporation has declined significantly at 16 climate stations at an average rate of 9.1 mm a^???2 while wind run has declined significantly at all climate stations by more than 25% over the study period. Annual rainfall has not changed significantly at any of the climate stations while maximum temperature has increased significantly at all but one climate station at an average rate of 0.03°C a.^???1 over the study period. The trends in vapour pressure deficit are mixed and no clear regional pattern is evident. Our results raise important questions about the predicted catastrophic impact that the projected changes in twenty-first century climates will have on the rich flora of the region. If evaporative demand has declined over the last 30 years in the Cape Floristic Region then it is possible that more water has become available for plant growth, infiltration and runoff despite the widespread increase in temperature. However, decreased pan evaporation and wind run combined with increased temperatures could potentially reduce transpiration and exacerbate heat stress of plants on increasingly frequent hot and windless days during the summer drought. Contrary to other predictions for the area, it is also likely that the changing conditions will decrease the frequency and/or intensity of fires which are an important component of the ecology of the fire-adapted CFR. Consideration of other factors besides changes in temperature and rainfall are essential in debates on the impact of climate change on the vegetation of this region.     

Characteristics of faults and shear zones in deep mines

The characteristics of fault and shear zones to depths of 2.5 km are well documented in deep mines in North America. The characteristics may be summarized as follows. (a) Fault zones usually are irregular, branched, anastomosed, and curved rather than simple and planar. (b) Faults are generally composed of one or more clay or clay-like gouge zones in a matrix of sheared and foliated rock bordered by highly fractured rock. (c) The widths of fault zones appear to be greater when faults have greater displacement, probably as a result of a long history of repeated minor movements. Fault zones with kilometers of displacement tend to be 100 m or more wide, whereas those with only a few hundred meters of displacement commonly are only 1 m or less wide. (d) Some zones represent shear distributed across hundreds of meters without local concentration in a narrow gouge zone. (e) Many fault zones are wet even above the water table, and water moves along them at various rates, but some also serve as subsurface dams, ponding ground water as much as several hundred meters higher on one side than on the other. No striking differences in the characteristics of faults over the vertical range of 2.5 km are documented.     

Abrupt climate change revisited

Taken together, evidence from east Greenland's mountain moraines and results from atmospheric models appear to provide the answer to a question which has long dogged abrupt climate change research: namely, how were impacts of the Younger Dryas (YD), Dansgaard–Oeschger (D–O) and Heinrich (H) events transmitted so quickly and efficiently throughout the northern hemisphere and tropics? The answer appears to lie in extensive winter sea ice formation which created Siberian-like conditions in the regions surrounding the northern Atlantic. Not only would this account for the ultra cold conditions in the north, but, as suggested by models, it would have pushed the tropical rain belt southward and weakened the monsoons. The requisite abrupt changes in the extent of sea ice cover are of course best explained by the turning on and turning off of the Atlantic's conveyor circulation.     

Sourcing and identifying andesitic tephras using major oxide titanomagnetite and hornblende chemistry,Egmont volcano and Tongariro Volcanic Centre,New Zealand

 Canonical discriminant function analysis was employed to discriminate between electron microprobe-determined titanomagnetite and hornblende analyses from Egmont volcano and Tongariro Volcanic Centre. Data sets of 436 titanomagnetite and 206 hornblende analyses from the two sources were used for the study. Titanomagnetite chemistry provided the best discrimination between these two sources with classification efficiencies of 99% for sample averages and 95% for individual analyses. The difference between sources for hornblende chemistry was less marked, but classification efficiencies of 100% for sample averages and 87% for individual analyses were achieved. Using the same methods a preliminary discrimination of individual Egmont volcano-sourced tephras was attempted. Titanomagnetite chemistry enabled the discrimination of several individual tephras or at least pairs of tephra units, but hornblende chemistry provided little discrimination. This technique provides an improvement on previous methods for chemically distinguishing distal tephra from the two sources as well as potentially identifying individual tephras from a particular source. A major advantage over previous discrimination techniques is that individual analyses can be classified with a known probability of group membership (with groups such as volcano source or an individual tephra unit). Tephras in a depositional environment where mixing is common such as within soil, loess and marine sequences, can be sourced or identified more easily with classification of individual grains. Received: 19 July 1995 / Accepted: 13 February 1996     

The secular behavior of X-ray and radio emission from supernova remnants

General models for the secular behavior of the radio and X-ray emission from supernova remnants are examined and compared with the observations. Hot plasma and synchrotron models for the X-ray emission are considered. Among other things, it is concluded that (1) the total kinetic energy released in most supernova outbursts is probably less than about 10⁵¹ ergs; (2) continuous injection probably occurs for at least 10 yr in every case and about 1000 yr in most supernova remnants, in which case the supernova remnants 3C392, W28, Pup A and IC443 should produce 1–10 keV X-ray fluxes 10^–10 ergs/cm² sec; and (3) the X-ray sources in the Crab Nebula, Cas A and Tycho can be explained in terms of a model wherein continuous injection occurs for 300 yr for the Crab Nebula, much less than 250 yr for Cas A and much longer than 400 yr for Tycho. Finally, it is shown that if Tycho and Cas A contain an X-ray star such as NP0532, it is quite possible that the X-ray emission from those sources is predominantly due to the X-ray star.Supported by the Air Force Office of Scientific Research under Contract No. F44620-67-C-0065.     

The influence of organic matter and atmospheric deposition on the particulate trace metal concentration of northwest Atlantic surface seawater

Particulate trace metals (PTM), organic carbon (POC), and organic nitrogen (PON) were measured in a series of surface bucket samples collected between the New England coast of the United States and Bermuda. PTM concentrations were lower or equivalent to the lowest PTM concentrations reported in the literature. Examination of the relative variations in PTM with respect to particulate aluminum and carbon led to the conclusion that organic matter was the probable regulator of PTM abundance in open-ocean surface waters and was important in this respect for continental shelf and slope waters as well.Enrichment factors of trace metals relative to their crustal abundances were found to be similar in the atmosphere sampled in Bermuda and in Sargasso Sea surface water particulate matter. A simplistic vertical flux model was constructed which showed atmospheric input of trace metals to the Sargasso Sea to be of the same approximate magnitude as the rate of removal of PTM from the mixed layer by sinking in association with POC. Essentially all of the particulate Al, Fe, and Mn in the Sargasso Sea mixed layer was attributed to aeolian sources. The fate of other atmospherically derived trace metals in the Sargasso Sea mixed layer was suggested to be a function of their solubility in seawater.     

Long-term trends in benthic habitat quality as determined by Multivariate AMBI and Infaunal Quality Index in relation to natural variability: a case study in Kinsale Harbour, south coast of Ireland

Benthic Ecological Quality Ratios (EQR) are important tools for assessing the ecological status of coastal and transitional water bodies. Here, we use spatial and time-series data from Kinsale Harbour, Ireland to examine the effects of sample processing methodologies on the outputs of two EQRs: Multivariate AMBI (M-AMBI) and Infaunal Quality Index (IQI).Both EQRs were robust to changes in sieve size from 1 mm to 0.5 mm, and to changes in the taxa identified in spatial calibration. Both EQRs classified habitat quality in Kinsale as generally Good or High with no evidence of significant change over the time series (1981-2006). IQI classified the ecological status as higher than M-AMBI.There was a significant relationship between IQI and M-AMBI in spatial calibration, but no significant relationship between them in time series. Further research into the behaviour of EQRs in relation to natural variability over long time-scales is needed to discriminate anthropogenic impacts reliably.     

Nonlinear Force-Free Extrapolation of Emerging Flux with a Global Twist and Serpentine Fine Structures

We study the flux emergence process in NOAA active region 11024, between 29 June and 7 July 2009, by means of multi-wavelength observations and nonlinear force-free extrapolation. The main aim is to extend previous investigations by combining, as much as possible, high spatial resolution observations to test our present understanding of small-scale (undulatory) flux emergence, whilst putting these small-scale events in the context of the global evolution of the active region. The combination of these techniques allows us to follow the whole process, from the first appearance of the bipolar axial field on the east limb, until the buoyancy instability could set in and raise the main body of the twisted flux tube through the photosphere, forming magnetic tongues and signatures of serpentine field, until the simplification of the magnetic structure into a main bipole by the time the active region reaches the west limb. At the crucial time of the main emergence phase high spatial resolution spectropolarimetric measurements of the photospheric field are employed to reconstruct the three-dimensional structure of the nonlinear force-free coronal field, which is then used to test the current understanding of flux emergence processes. In particular, knowledge of the coronal connectivity confirms the identity of the magnetic tongues as seen in their photospheric signatures, and it exemplifies how the twisted flux, which is emerging on small scales in the form of a sea-serpent, is subsequently rearranged by reconnection into the large-scale field of the active region. In this way, the multi-wavelength observations combined with a nonlinear force-free extrapolation provide a coherent picture of the emergence process of small-scale magnetic bipoles, which subsequently reconnect to form a large-scale structure in the corona.