High Latitudinal Regions Research Articles

Unforced Surface Air Temperature Variability and Its Contrasting Relationship with the Anomalous TOA Energy Flux at Local and Global Spatial Scales*

Abstract Unforced global mean surface air temperature () is stable in the long term primarily because warm anomalies are associated with enhanced outgoing longwave radiation () to space and thus a negative net radiative energy flux (, positive downward) at the top of the atmosphere (TOA). However, it is shown here that, with the exception of high latitudinal and specific continental regions, warm unforced surface air temperature anomalies at the local spatial scale [T(θ, ϕ), where (θ, ϕ) = (latitude, longitude)] tend to be associated with anomalously positive N(θ, ϕ). It is revealed that this occurs mainly because warm T(θ, ϕ) anomalies are accompanied by anomalously low surface albedo near sea ice margins and over high altitudes, low cloud albedo over much of the middle and low latitudes, and a large water vapor greenhouse effect over the deep Indo-Pacific. It is shown here that the negative versus relationship arises because warm anomalies are associated with large divergence of atmospheric energy transport over the tropical Pacific [where the N(θ, ϕ) versus T(θ, ϕ) relationship tends to be positive] and convergence of atmospheric energy transport at high latitudes [where the N(θ, ϕ) versus T(θ, ϕ) relationship tends to be negative]. Additionally, the characteristic surface temperature pattern contains anomalously cool regions where a positive local N(θ, ϕ) versus T(θ, ϕ) relationship helps induce negative . Finally, large-scale atmospheric circulation changes play a critical role in the production of the negative versus relationship as they drive cloud reduction and atmospheric drying over large portions of the tropics and subtropics, which allows for greatly enhanced .

Dispersal, niche, and isolation processes jointly explain species turnover patterns of nonvolant small mammals in a large mountainous region of China.

Understanding the mechanisms that govern the spatial patterns of species turnover (beta diversity) has been one of the fundamental issues in biogeography. Species turnover is generally recognized as strong in mountainous regions, but the way in which different processes (dispersal, niche, and isolation) have shaped the spatial turnover patterns in mountainous regions remains largely unexplored. Here, we explore the directional and elevational patterns of species turnover for nonvolant small mammals in the Hengduan Mountains of southwest China and distinguish the relative roles of geographic distance, environmental distance, and geographic isolation on the patterns. The spatial turnover was assessed using the halving distance (km), which was the geographic distance that halved the similarity (Jaccard similarity) from its initial value. The halving distance was calculated for the linear, logarithmic, and exponential regression models between Jaccard similarity and geographic distance. We found that the east-west turnover is generally faster than the south-north turnover for high-latitudinal regions in the Hengduan Mountains and that this pattern corresponds to the geographic structure of the major mountain ranges and rivers that mainly extend in a south-north direction. There is an increasing trend of turnover toward the higher-elevation zones. Most of the variation in the Jaccard similarity could be explained by the pure effect of geographic distance and the joint effects of geographic distance, environmental distance, and average elevation difference. Our study indicates that dispersal, niche, and isolation processes are all important determinants of the spatial turnover patterns of nonvolant small mammals in the Hengduan Mountains. The spatial configuration of the landscape and geographic isolation can strongly influence the rate of species turnover in mountainous regions at multiple spatial scales.

Temperature and zooplankton size structure: climate control and basin‐scale comparison in the North Pacific

The global distribution of zooplankton community structure is known to follow latitudinal temperature gradients: larger species in cooler, higher latitudinal regions. However, interspecific relationships between temperature and size in zooplankton communities have not been fully examined in terms of temporal variation. To re-examine the relationship on a temporal scale and the effects of climate control thereon, we investigated the variation in copepod size structure in the eastern and western subarctic North Pacific in 2000–2011. This report presents the first basin-scale comparison of zooplankton community changes in the North Pacific based on a fully standardized data set obtained from the Continuous Plankton Recorder (CPR) survey. We found an increase in copepod community size (CCS) after 2006–2007 in the both regions because of the increased dominance of large cold-water species. Sea surface temperature varied in an east–west dipole manner, showing the typical Pacific Decadal Oscillation pattern: cooling in the east and warming in the west after 2006–2007. The observed positive correlation between CCS and sea surface temperature in the western North Pacific was inconsistent with the conventional interspecific temperature–size relationship. We explained this discrepancy by the geographical shift of the upper boundary of the thermal niche, the 9°C isotherm, of large cold-water species. In the eastern North Pacific, the boundary stretched northeast, to cover a large part of the sampling area after 2006–2007. In contrast, in the western North Pacific, the isotherm location hardly changed and the sampling area remained within its thermal niche throughout the study period, despite the warming that occurred. Our study suggests that while a climate-induced basin-scale cool–warm cycle can alter copepod community size and might subsequently impact the functions of the marine ecosystem in the North Pacific, the interspecific temperature–size relationship is not invariant and that understanding region-specific processes linking climate and ecosystem is indispensable.

Early seed plants from Western Gondwana: Paleobiogeographical and ecological implications based on Tournaisian (Lower Carboniferous) records from Argentina

The oldest seed occurrences in Western Gondwana have been recognized in a new stratigraphic section located in Western Argentina (Precordillera Basin). Palynological evidence indicates an Early Mississippian (probably Tournaisian) age for this new succession. The two identified early seeds generas, Pseudosporogonites cf. hallei and Warsteinia sancheziae n. sp. were up to now considered as restricted to the Devonian of Laurussia. This finding suggests a dispersal of earliest spermatophytes between Laurussia and Gondwana during Devonian/Tournaisian times, thus accounting for the Rheic Ocean as a surmountable biogeographic barrier for continental biotas. Alternatively, contrasting biogeographic hypotheses dealing with early spermatophytes rising in paleotropics and then displacing herbaceous communities of non-spermatophytes typical from cool high latitudinal regions, are explored for explaining the recognized paleobiogeographical pattern. The new information supports a weak impact of the Devonian/Carboniferous biotic crisis on earliest seed plant diversity. Based on preliminary evidences of niches differentiation and ecological dynamics probably affected by wildfires, Tournaisian Gondwanan plant communities from high latitudes are interpreted as being more complex than previously thought, and more similar to those reported from Laurussia. In addition, their discovery in a sedimentary environment associated to glacigenic deposits, show that this new record might be linked to the coeval glacial age widely recorded elsewhere in Gondwana.

Coevolution of brachiopod Boreal Realm and Pangea

The Boreal Realm originated in the early Carboniferous; the realm became more firmly established during the late Carboniferous and early Permian, and peaked in the middle Permian before decaying in the late Permian. In the early Carboniferous, the geographic distribution of the Boreal Realm was latitudinally narrow, and many brachiopod genera of the realm were also common in the Tethys Realm. The Boreal Realm faunas were, however, also characterized by many geographically and temporally restricted genera. The Boreal Realm was well developed in the late Carboniferous, as represented by the continued expansion of the geographical ranges and numbers of occurrences of many Permian characteristic Boreal Realm genera. In the early Permian, the geographic distribution of the Boreal Realm expanded further, as did the distribution of characteristic Boreal Realm genera. In the middle Permian, the geographic distributions of the Boreal Realm had expanded to their greatest extent, and the characteristic Boreal Realm genera were most abundant and diverse. In the late Permian, the cool-water characteristic genera, which flourished during the Carboniferous to middle Permian, disappeared in these areas, and resulted in the decay of Boreal Realm.The development of the Boreal Realm was closely related to events leading to the formation of Pangea, in which a variety of plates (Laurussian, Siberian, etc.) were continuously drifting northwards; some plates/blocks entered middle- and high-latitudinal regions and were located in cool climatic environments. During the evolution of Pangea, the Siberian, Kazakhstan, and Eastern European plates were continuously located in the center of the Boreal Realm; the Barents Ocean developed to the west and the Paleo-Asian Ocean developed to the east of these plates. This configuration of oceans and continents differentiated the eastern Central Asia Region and the western Barents Region. In the Paleo-Asian Ocean tectonic domain, the northern branch of the Paleo-Asian Ocean was surrounded by the Siberian plate, the Kazakhstan plate, and the Jiamusi–Mongolia Block, and named the Mongolia–Okhotsk Ocean. The Mongolia–Okhotsk brachiopod fauna developed on the southern margin of the Mongolia–Okhotsk Ocean (i.e., the northeastern margins of the Siberian and Kazakhstan plates, and the northern margin of the Jiamusi–Mongolia Block), thus forming the Mongolia–Okhotsk Province. During the middle Permian, the Xar Moron Ocean was enclosed by the Jiamusi–Mongolia Block and the Kazakhstan, Tarim, and South China plates. On the southern margin of the Xar Moron Ocean (i.e., the southern margin of the Jiamusi–Mongolia Block), the Zhesi brachiopod fauna developed, and the Inner Mongolia Province was formed. During the Carboniferous–Permian, the Kolyma-Chukchi block, Siberian plate, and North American plate comprised the Barents Ocean tectonic domain. The Verkhoyansk brachiopod fauna developed on the northern margin of the Barents Ocean (i.e., on Verkhoyansk and the southwestern margin of the Siberian plate), thus forming the Verkhoyansk–Taymyr Province. Starting in the late Carboniferous, a cool-water brachiopod fauna developed on the southern margin of the Barents Ocean (i.e., the northern margin of the North American plate and the northern margin of the Eastern European plate), thus forming the Yukon–Pechora Province, the geographical range of which extended continuously with time.

The tornado over Khanty-Mansiysk: An exception or a symptom?

Analyzed are large- and mesoscale atmospheric processes which preceded and accompanied the tornado formation on June 12, 2012 near Khanty-Mansiysk city (61° N) in West Siberia. After the record-breaking hot weather observed in the region during the first half of June 2012, the tornado formation was favored by the passage of the cold front (cold advection at low altitudes), by the wind rotation with height in the lower atmospheric layer of 1.5 km (by more than 180°), and by very high air humidity in the surface layer with the cloud base of about 200 m. Estimated are the possible trends in the nature of the atmospheric circulation over West Siberia at the global warming observed in the 21st century which may contribute to a more regular tornado formation in high-latitudinal regions due to the physiographic peculiarities of the region.

Investigation of temporal characteristics of terrestrial water storage changes and its comparison to terrestrial mass changes

AbstractThis study investigates the dominant component of terrestrial water storage (TWS) and its contribution ratio at both seasonal and interannual time‐scales on a global‐scale, using a land‐surface hydrological model, and estimates the climatological mean mass changes. The largest annual range of the four components of TWS, namely soil moisture, snowpack, river channel water storage, and shallow groundwater storage, and the range ratio of the largest annual range among the four components to that of TWS at both seasonal and interannual time‐scales on a global‐scale are investigated using the land‐surface hydrological model. Although soil moisture covers most areas as the largest annual range at the monthly time‐scale, the three other components show unique geographical distributions. At the interannual time‐scale, geographical distribution is basically similar to that of the monthly time‐scale except for the replacement of snowpack to soil moisture in high latitudinal regions. These results provide qualitative information about which component is important for a certain region. In addition, mass changes, namely mineral dust and sediment transports as natural phenomena, crude oil, coal, and natural gas, iron, and bauxite mining as anthropogenic phenomena, are estimated. Comparison of the mass changes with the TWS variability show that it takes a long time for the mass changes to become equivalent to the interannual variability of TWS in magnitude in most regions or fields. Detectability of the mass changes by a satellite gravity mission is examined and the mass decreases due to mineral dust and sediment transports and mining are detectable in regions with large signals within 20 years under ideal conditions. These results provide basic but new information about hydrological features of TWS and mass changes. Copyright © 2012 John Wiley & Sons, Ltd.

Observed trends in surface freezing/thawing index over the period 1987–2005 in Mongolia

Abstract The annual ground surface freezing and thawing indices can be useful to assess the temporal changes of ground thermal regime in permafrost and seasonally frozen ground regions. The previous analyses of in-situ observation results show that the annual freezing/thawing index could be reliably obtained from monthly observation data. We thus employ monthly ground surface temperature to calculate the annual surface freezing/thawing index in Mongolia. In this study we used Mann–Kendal test and Sen-slope estimate to perform the temporal and spatial trend analysis of annual surface freezing/thawing index at a set of 20 meteorological stations in Mongolia. The study indicates that the annual surface freezing index displays a general increasing trend at 70% of stations although the trend is not statistically significant, which corresponds to a slight winter cooling over the period 1987–2005 in Mongolia. However, the annual surface thawing index shows a statistically significant increase in Mongolia during the past 19 years. The surface thawing index has increased by 29 °C-days/yr in Mongolia, which is far greater than that in the high-latitudinal regions of Northern Hemisphere during recent decades. The intensive increase of annual surface thawing index is predicted to be responsible for the increase in active layer thickness, as well as the changes of permafrost distribution in this country.

The Tidal Coulomb Failure Stresses on Various Kinds of Seismic Fault

AbstractThe tidal Coulomb failure stresses (TCFS) on various kinds of seismic faults are calculated and their latitudinal variation characters are studied. We compute tidal Coulomb failure stresses at shock‐occurring times on 20395 earthquake faults and analyze the latitudinal distribution of various kinds of real seismic faults that are slip‐encouraged by TCFS. The results show that the features of tidal failure stress are closely correlated with fault type, fault strike and fault location. The TCFS variation properties are different on various kinds of fault during the same period. And there are obvious differences in amplitudes and signs of TCFS on same kind fault in different latitudinal regions. For normal faults, the tidal slip‐encouraged effects are outstanding in low and middle latitudinal regions; for thrust faults, the tidal slip‐encouraged effects are obvious in middle and high latitudinal region; for strike‐slip fault, the tidal slip‐encouraged effects are reducing with latitude increasing.

The Interconnectivity Of Weather System And Ozone Concentration Over West Africa

The relationship between some meteorological parameters and ozone distributions as revealed by satellite EPTOM over four West African stations namely, Lagos (Nigeria), Dakar (Senegal) Lamto (Ivory Coast) and Ekona (Cameroon) was studied for the period 1997 to 2002. The mean ozone concentration over these stations for the period were 270.8±0.3DU at Lagos, 264.9±0.3DU at Dakar, 269.8±0.3DU and 269.0±03DU at Lamto and Ekona respectively. The average monthly maximum ozone concentration of 288.6DU and 285.1DU respectively were observed for Lagos and Dakar, between July and August, which coincided with the period of tropical summer rain-fall over the West African region. This coincidence could be attributed to reduction in the effect of the extra-tropical suction pump (ETSP) action responsible for the transportation of ozone concentration from the tropical stratosphere into the mid and high latitudinal region. This re-duction may be due to decrease in the atmospheric heat engine expected to drive the ETSP, as the tropical surface temperature and evaporation are at their minimum during the raining sea-son. The surface temperature and evaporation at Lagos-Nigeria both had significant negative correlation values of -0.73 and -0.68 with the ozone concentration respectively.Keywords: West Africa, ozone variation, rainfall, temperature, evaporation

Middle Permian western Tethyan fusulinids from southern Baoshan Block, western Yunnan, China

New fusulinid collections from the Baoshan Block in southwest China necessitate paleobiogeographic reevaluation of the Mid-Permian fusulinids in this region. From Xiaoxinzhai Section in the southern Baoshan Block, 32 fusulinid species of nine genera are described and illustrated. Among them,Eopolydiexodina parvais a new species, and elements of Neoschwagerinidae and Verbeekinidae are confirmed. The studied fusulinids are ascendingly grouped into three biozones: theSchwagerina yunnanensisRange Zone,EopolydiexodinaAbundance Zone, andSumatrina annaeRange Zone. The lower two could be assigned in age to the Murgabian and the uppermost one to the Midian. Midian fusulinids are for the first time reported from the Baoshan Block. In terms of fusulinid paleobiogeography, these three assemblages should belong to the western Tethyan Province A because of the presence ofEopolydiexodinaand characteristic Tethyan genera, e.g.,Verbeekina, Sumatrina, and Pseudodoliolina.Moreover, these assemblages may occupy a comparatively high latitudinal region within Tethyan Realm, judging from the overall low diversity.

Atmospheric DDTs over the North Pacific Ocean and the adjacent Arctic region: Spatial distribution, congener patterns and source implication

During the 2003 Chinese Arctic Research Expedition (CHINARE 2003) from Bohai Sea to the high Arctic (37°N–80°N), air samples were collected and analyzed for DDTs. ∑DDTs (sum of six congeners) ranged from 0.52 to 265 pg m −3 with an average of 13.1 pg m −3. Higher DDT concentrations were observed in Bohai Sea and near eastern Russia. The congener patterns were obviously different between the Far East Asia and the higher latitudinal regions that p,p'-DDT and o,p'-DDT were dominated in the former; while o,p'-DDT and o,p'-DDE were dominated in the latter. The source contributions of technical DDT and dicofol type DDT were estimated. Results showed that technical DDT was the dominant source (>94%) which was fresher in the Far East Asia compared to the North Pacific Ocean and the Arctic. For dicofol type DDT, the estimated contribution was minor. The “new” o,p'-DDT observed should have relatively more contribution from dicofol type DDT in the North Pacific Ocean and the Arctic.

Occurrence and source characteristics of the high-latitude components of Jovian broadband kilometric radiation

Ulysses had a “distant encounter” with Jupiter when it was within 0.8 AU of the planet during February, 2004. The passage of the spacecraft was from north to south, and observations of the Jovian radio waves were carried out for a few months from high to low latitudes (+80° to +10°) of Jupiter. The statistical study performed during this “distant encounter” event provided the occurrence characteristics of the Jovian broadband kilometric radiation (bKOM), including the high-latitude component as follows: (1) the emission intensity of bKOM was found to have a sinusoidal dependence with respect to the central meridian longitude (CML), showing a broad peak at ∼180°, (2) bKOM was preferably observed in the magnetic latitudinal range from ∼+30° to +90°, and the emission intensities at the high latitudes were found to be two times larger than that at the equatorial region, and (3) the emission intensity was controlled possibly by the sub solar longitude (SSL) of Jupiter. The intensity had a sharp peak around SSL ∼210°. A 3D ray tracing approach was applied to the bKOM in order to examine the source distribution. It was suggested that: (1) the R-X mode waves generated through the Cyclotron Maser Instability process would be unable to reproduce the intense high-latitude component of the bKOM, (2) the L-O mode, which was assumed to be generated at frequencies near the local plasma frequency, was considered to be the dominant mode for past and present observations at mid- and high-latitudinal regions, and (3) the high-latitude component of bKOM was found to have a source altitude of 0.9–1.5 Rj (Rj: Jovian radii), and to be distributed along magnetic field lines having L>10.

Polybrominated Diphenyl Ethers in Airborne Particulates Collected during a Research Expedition from the Bohai Sea to the Arctic

In July to September 2003, particulates in the oceanic atmosphere from the Bohai Sea to the high Arctic (37 degrees N to 80 degrees N) were collected aboard a research expedition icebreaker, Xuelong (Snow Dragon), under the 2003 Chinese Arctic Research Expedition Program (CHINARE 2003). These samples were analyzed to elucidate the atmospheric distributions of polybrominated diphenyl ethers (PBDEs) in the North Pacific Ocean and adjacent Arctic region. The levels of 11 PBDE congeners (BDE-28, -47, -66, -100, -99, -85, -154, -153, -138, -183, and -209; the sum was defined as sigma11PBDE) in the oceanic atmosphere of Far East Asia (34-48 degrees N/122-148 degrees E) ranged from 2.25 to 198.9 pg/m3 with a mean of 58.3 pg/m3. BDE-47, -99, -100, and -209 were the dominant congeners in all the samples, suggesting that the widely used commercial penta- and deca-BDE products were the original sources. The PBDE levels exhibited a decreasing trend from the mid- to high-latitudinal regions of the North Pacific Ocean, probably resulting from dilution, deposition, and decomposition of PBDEs during long-range transport of air masses. On the other hand, no apparent geographical pattern of PBDE distribution was observed within the Arctic, attributable to unstable air circulation and strong air mixing. Correlations among the PBDE congeners suggested that air masses collected from the North Pacific Ocean were relatively fresh, whereas those from the Arctic were aged as a result of photodecompoisiton. The higher average level (17.3 pg/m3) of PBDE congeners in the Arctic than those in the adjacent North Pacific Ocean (12.8 pg/m3) or other remote areas reported in the literature was attributed to the impact of the North American continent and temperature effects, which was consistent with the hypotheses of global fractionation.

Three-dimensional MHD simulation for the solar wind structure observed by Ulysses

Ulysses has been the first spacecraft to explore the high latitudinal regions of the heliosphere till now. During its first rapid pole-to-pole transit from September 1994 to June 1995, Ulysses observed a fast speed flow with magnitude reaching 700–800 km/s at high latitudinal region except ±20° area near the ecliptic plane where the velocity is 300–400 km/s. The observations also showed a sudden jump of the velocity across the two regions. In this note, based on the characteristic and representative observations of the solar magnetic field and K-coronal polarized brightness, the large-scale solar wind structure mentioned above is reproduced by using a three-dimensional MHD model. The numerical results are basically consistent with those of Ulysses observations. Our results also show that the distributions of magnetic field and plasma number density on the solar source surface play an important role in governing this structure. Furthermore, the three-dimensional MHD model used here has a robust ability to simulate this kind of large-scale wind structure.

Dependence of the energy budget at mesopause heights on variable circulation patterns

The global energy budget of the mesopause region strongly depends on the variable circulation patterns, controlling in particular the heat transport. A better understanding of this dependence is desirable. Regarding the complexity of the problem and the difficulties in obtaining suitable measured data on a global scale numerical models appear to be a convenient and necessary tool to approach the problem. In this paper energy budget studies are presented employing a mechanistic 3-d circulation model of the middle atmosphere (0–150 km). Special attention is drawn to two terms of the mesopause heat budget: the adiabatic heating by vertical motions and diabatic heating by eddy heat fluxes. The model calculations show heating and cooling rates of more than 100 Kelvin per day which can even occur at high latitudinal regions due to the wave — mean flow interaction of stationary and planetary waves. A high variability of the eddy heat fluxes in space and time is found according to temporal and spatial changes of tidal, gravity and planetary wave activity. The major component of mechanical dissipation is contributed by gravity wave drag, which plays an essential role in controling the strength and variability of the circulation patterns at mesopause heights.

Phylogenetic Differentiation of the Cultivated Rice Plant. : V. Variation of minimum germination temperature and temperature constant among rice varieties.

1. From germination tests at six temperature levels ranging from 30 to 11.7'C, minimum germination temperature and temperature response in germination rate wer.e measured in various varieties of Eastern Asia. The mininium temperature was shown by the lowest temperature at which the germination capacity within 20 days reached 50%. The temperature response was expressed in terms of BELEHRADEK'S temperature constant, since the days of germination and temperature showed, if both were in logarithms, a rectilinear regression line. 2. Varieties of the Continental group were generally higher in minimum germination temperature than those of t.he Inslrlar group, while within the same group, varieties frcm high latitudinal regions were lower than those from low latitudinal regions. The lowest was 11'C for some Japanese varieties, and the highest was 17'C for some varieties of Indochina. Varieties of the Insular group were generally low in germination rate, and those with relatively high germination rates tended to be low in regard to minimum germination temperature.