palaeoflood records for the red river manitoba canada derived from anatomical tree ring signatures palaeoe ood records for the red river in southern manitoba canada were derived from anatomical tree ring signatures in quercus macrocarpa michx collected at 16 living tree sites several historical buildings and archaeological sites and subfossil logs buried in river alluvium prolonged inundation of trees during spring and early summer induces the development of anatomical anomalies e ood rings that provide a proxy record of extreme e oods flood signature records for the lower red river basin lrb extend from ad 1999 to 1648 and suggest that the red river e ood of 1826 was the largest during the last 352 years the tree ring record identie es e ve of the largest seven e oods in the lrb during the last 200 years and documents extreme e oods in 1747 1762 1826 1852 1950 1979 and 1997 the upper red river basin tree ring e ood record extends from ad 1997 to 1448 and contains e ood rings for 1510 1538 1658 1682 1726 1727 1741 1747 and 1762 factors ine uencing the formation of e ood rings and hence efe cacy of e ood ring records include e ood timing age and availability of trees and variations in response along the stem evidence from the lrb indicates intervals of increased e ood frequency during the mid 1700s the mid 1800s and the second half of the twentieth century and intervals without extreme e ooding in 1648 1746 1763 1825 and 1862 1949 the tree ring evidence supports the premise that high red river e ows are non stationary and that past climatic and landscape changes may have ine uenced local e ood risks

annual climate variability in the holocene interpreting the message of ancient trees abstract over vast areas of the world s landmasses where climate beats out a strong seasonal rhythm tree growth keeps unerring time in their rings trees record many climate melodies played in different places and different eras recent years have seen a consolidation and expansion of tree ring sample collections across the traditional research areas of north america and europe and the start of major developments in many new areas of eurasia south america and australasia from such collections are produced networks of precisely dated chronologies records of various aspects of tree growth registered continuously year by year across many centuries their sensitivities to different climate parameters are now translated into ever more detailed histories of temperature and moisture variability across expanding dimensions of time and space with their extensive coverage high temporal resolution and rigid dating control dendroclimatic reconstructions contribute significantly to our knowledge of late holocene climates most importantly on timescales ranging from 1 to 100 years in special areas of the world where trees live for thousands of years or where subfossil remnants of long dead specimens are preserved work building chronologies covering many millennia continues apace very recently trees have provided important new information about major modes of general circulation dynamics linked to the el nino southern oscillation and the north atlantic oscillation and about the effect of large volcanic eruptions as for assessing the significance of 20th century global warming the evidence from dendroclimatology in general supports the notion that the last 100 years have been unusually warm at least within a context of the last two millennia however this evidence should not be considered equivocal the activities of humans may well be impacting on the natural growth of trees in different ways making the task of isolating a clear climate message subtly difficult

amplitude phase and period variations of the quasi 2 day wave in the mesosphere and lower thermosphere over london canada 43 n 81 w during 1993 and 1994 because there is as yet no conclusive evidence pointing to the source of the quasi 2 day wave further observations are required in order to resolve questions about the generating mechanism as well as to better understand the role of the wave in the middle atmosphere in this paper we investigate the period amplitude phase and vertical wavelength for the quasi 2 day wave in the mesosphere and lower thermosphere using the university of western ontario 2 mhz radar near london canada and in addition we look at possible coupling with atmospheric tides the results of the present study bring out certain new aspects of the quasi 2 day wave at midlatitude in the northern hemisphere that have not been previously reported in particular we show that the period of the quasi 2 day wave determined from our study is smaller 46 47 hours than the 51 to 52 h period generally suggested by other northern hemisphere results and our periods also showed variability as a function of time we also draw attention to the annual variability and especially highlight the occurrence of the wave in nonsummer months for example a brief occurrence in april is not uncommon our study also contributes additional midlatitude geographical data that should aid in developing a better picture of the quasi 2 day wave

stable isotopic and geochemical characteristics of groundwater in kherlen river basin a semi arid region in eastern mongolia summary inorganic solute ion concentrations and stable isotopes of oxygen and hydrogen in groundwater river water and precipitation were investigated to gain insight into the groundwater recharge process in the kherlen river basin a semi arid region in eastern mongolia the solute constituents in the river water main stream were of ca hco3 type spatially invariant and low in concentration groundwater in the upstream region was also characterized by a ca hco3 type though all ion concentrations were higher than in the river water on the other hand the chemical composition of the groundwater in the midstream region southern and eastern was spatially variable and the na mg2 cl and hco 3 concentrations were considerably higher than in the river water and upstream groundwater the stable isotopic compositions showed an evaporation effect on the groundwater and river water as well as an altitude effect in the precipitation and river water preferential recharge by relatively large rainfall events is thought to have caused the depleted isotopic ratio in the groundwater in the dry regions the stable isotope chemical and hydrological data suggest that the main stream water of the kherlen river is recharged by precipitation that falls in a headwater region at an altitude of more than 1650 m and that the interaction between the groundwater and river water is not dominant in the midstream and downstream regions of the river basin

the 8 hour tide in the arctic mesosphere and lower thermosphere an all sky vhf meteor radar at esrange 68 n 21 e near kiruna in northern sweden has been used to investigate the 8 hour tide in the arctic mesosphere and lower thermosphere we present a climatology of the 8 hour tide over the period october 1999 to april 2001 the tide appears to be a persistent feature of the arctic atmosphere although a large day to day variability of the tidal amplitude is observed at times the 8 hour tide reaches amplitudes over 30 m s 1 the amplitude of the tide increases with height across the observed height range of 80 100 km monthly mean tidal amplitudes range from 2 m s 1 to values as large as 10 m s 1 a clear seasonal behavior is apparent with maximum amplitudes observed in the autumn vertical wavelengths are shortest in winter and spring 25 35 km and longest in summer and autumn 50 90 km at least on some occasions the vertical wave number relationships between the 8 12 and 24 hour tides suggest that the 8 hour tide is being generated by nonlinear interaction between the 12 and 24 hour tides

climatology of the migrating terdiurnal tide tw3 in saber timed temperatures 1 the present paper is focused on the global spatial altitude and latitude structure and seasonal and interannual temporal variability of the migrating terdiurnal tide tw3 seen in 8 years 2002 2009 of observations of the kinetic temperature measured by the saber instrument on the timed satellite the tides migrating and nonmigrating and the planetary waves zonally traveling and stationary are simultaneously extracted from the satellite data it is found that the saber tw3 tide is dominated by different hough modes below and above 80 to 90 km height in the mesosphere it reflects mainly the evanescent feature of the first symmetric mode and in the lower thermosphere propagating modes with shorter vertical wavelengths dominate its structure the seasonal behavior of the terdiurnal tide at low latitudes is dominated by an annual variation with local summer amplification while that at midlatitudes is a combination of semiannual variation with maxima in equinoxes and an annual variability with winter enhancement the hough modes of the solar heating from waccm heating to a large extent determine the predominantly antisymmetric features of the saber tw3 tide during the solstice but are not able to explain well the predominant symmetric features in the equinoxes the tw3 tide reveals some interannual variability with a period of quasi 2 years which indicates an enhancement during the eastward phase of the stratospheric qbo

observation of a large amplitude wave and inversion layer leading to convective instability in the mesopause region over fort collins co 41 n 105 w 1 sodium resonance lidar observations on the night of nov 3 1997 ut recorded a temperature inversion with 80 k amplitude moving downward from 90 to 83 km with the maximum temperatures exceeding 280 k these are the highest temperatures and largest inversion layer observed in 10 years over fort collins colorado the inversion can be decomposed into a 50 k peak to peak amplitude oscillation with an apparent 8 hr period and 25 km vertical wavelength plus a residual 30 k inversion layer the temperature gradient above this maximum is near adiabatic from 88 100 km for 4 hours with multiple super adiabatic layers several km in depth streamlines derived from the sodium mixing ratio and the potential temperature both indicate a 10 km upward movement in the adiabatic region presumably a large amplitude upward propagating wave saturated when it reached the inversion layer just below the mesopause and broke leading to convective instabilities with large vertical and temporal scales

a decade long climatology of terdiurnal tides using timed saber observations 1 in this paper we globally characterize the solar terdiurnal tide in the 80 110 km region of earth s atmosphere through analysis of 10 years of temperature measurements made by the sounding of the atmosphere using broadband emission radiometry instrument on the thermosphere ionosphere mesosphere energetics and dynamics spacecraft the sun synchronous migrating component tw3 which is longitude independent and achieves maximum amplitudes of order of 5 k 10 k at 90 km 110 km not too different than the 7 15 k amplitudes that are typical of the migrating diurnal and semidiurnal tides in this region significant longitude variability 20 25 in terdiurnal temperature amplitudes also exists which is decomposed into zonal wave number components the largest of these te1 tw4 and tw5 reveal distinct seasonal latitudinal and height versus latitude patterns and interannual consistency in addition it is demonstrated that these particular components vary in ways that suggest that they originate from nonlinear interactions between diurnal and semidiurnal tides specifically between de3 and sw2 for te1 between dw2 and sw2 for tw4 and between dw1 and sw4 for tw5 we also demonstrate that the terdiurnal tides derived here are not influenced to any significant degree by aliasing due to the presence of other waves

terdiurnal migrating tide signature in ionospheric total electron content we report the latitudinal seasonal and solar cycle variations of terdiurnal migrating tide i e terdiurnal westward wave number 3 tw3 signature in ionospheric total electron content tec our investigations are based on the jpl global ionospheric maps gims during 1999 2011 the absolute amplitude of tw3 exhibits maximum values in the magnetic equatorial region which reaches about 8 tecu under high solar activity and 1 5 tecu under low solar activity the relative amplitude of zonal mean tec in equatorial region however shows persistent patterns from 1999 to 2011 with little solar activity dependence the relative amplitude of tw3 has a peak of similar to 10 in the magnetic equatorial region and a second one of similar to 7 at magnetic middle latitudes 30 degrees 50 degrees at high latitudes in local winter seasons the maximum relative amplitude occurs which varies between 8 and 15 with slightly larger amplitudes in the northern hemisphere the global structure of tw3 signature in tec should shed some light on the coupling between the ionosphere thermosphere and the lower atmosphere

a survey of groundwater levels and hydrogeochemistry in irrigated fields in the karamay agricultural development area northwest china implications for soil and groundwater salinity resulting from surface water transfer for irrigation analysis of the water budget along with hydrochemistry and stable isotopes in shallow groundwater were carried out in the karamay agricultural development area kada in order to assess the impact of transfer of irrigation water from the irtysh river in particular in relation to the mechanisms of salinization and the nature of the water table regime in terms of aquifer dynamics the addition of the irrigation water without any groundwater abstraction has caused a sharp rise in the water table is and the development of serious soil salinity together with an almost complete attenuation of inter seasonal water table oscillations the mean rise in the groundwater table from september 1997 to october 2009 was 6 9 m representing an accumulated total water storage change of close to 150 million cubic meters the analysis of aquifer water budget shows that infiltration of irrigation water occupied over 90 of the total recharge of the groundwater in the kada sources of groundwater recharge and mechanisms of salinization in the kada were also investigated using geochemical and isotopic techniques the groundwater is characterized by cl so 4 na type generally becoming more na and cl dominated with increasing salinity the total dissolved solids tds content of the groundwater ranges from 0 5 g l to over 65 g l with greater tds values in areas of low topographic relief and shallow water tables where the sediments are more permeable e g due to the presence of palaeochannels tds values are generally lower and the seasonal water table fluctuations greater the ratios of k cl ca cl na cl and mg cl decrease with increasing cl concentrations especially in the shallow groundwater from 10 to 15 m depth indicating hydrogeochemical evolution via minor water rock interaction feldspar weathering and significant evaporation the stable isotopic compositions show a characteristic evaporation effect in the shallow groundwater and confirm that direct infiltration of precipitation is generally not a volumetrically important source of recharge to the shallow aquifer preferential recharge of river water after irrigation events and or precipitation from rare heavy rain events is likely responsible for the depleted 2 h and 18 o values in some of the groundwater samples the negative relationship between deuterium excess and 18 o values indicates that even in groundwater with relatively depleted 2 h and 18 o values evaporation has occurred to a significant degree careful management of water quantity and quality and implementation of salinity management strategies are considered necessary in order to reduce the risk of further salt accumulation and damage to farming and local ecosystems

responses of floods to holocene climatic change in the upper mississippi valley abstract dimensions of holocene relict channels and sedimentological characteristics of point bars associated with these relict channels were used to reconstruct a holocene history of long term changes in magnitudes of 1 58 yr floods in upper mississippi valley watersheds of southwestern wisconsin the reconstructed record of floods shows relatively large and persistent nonrandom departures from contemporary long term average flood magnitudes the flood history indicates climatic changes that are broadly similar to climatic changes indicated from fossil pollen in the same region the holocene floods ranged from about 10 15 larger to 20 30 smaller than contemporary floods of the same recurrence frequency large floods were characteristic between about 6000 4500 and 3000 2000 yr b p and during a brief interval after 1200 yr b p small floods were common between about 8000 6500 4500 3000 and 2000 1200 yr b p these fluvial responses were found to be closely associated with a long term episodic mobility and storage of sediments in the wisconsin watersheds during periods of relatively large floods relatively rapid lateral channel migration either reworked or removed extensive tracts of valley bottom alluvium in contrast during periods of relatively small floods relatively slow lateral channel migration is apparent and the channel and floodplain system appear to have been relatively stable

the terdiurnal tide in the mesosphere and lower thermosphere over london canada 43 n 81 w radars have been used successfully for many years to measure atmospheric diurnal and semidiurnal tides but studies of the atmospheric terdiurnal tide have only rarely been reported to date in the literature in this paper we investigate the amplitude phase and vertical wavelength for the terdiurnal tide using the university of western ontario uwo 2 mhz radar near london canada emphasis is placed on short term monthly seasonal and annual variations of the terdiurnal tide the results of the present study bring out certain new aspects of the terdiurnal tide at midlatitudes in the northern hemisphere we show that terdiurnal tides have significant amplitudes in the mesosphere and lower thermosphere indeed the terdiurnal amplitudes are often comparable to the diurnal ones we also draw attention to the annual variability and especially highlight the occurrence of the terdiurnal tide in non winter months for example the occurrence of the terdiurnal tide in spring months is not uncommon thus it seems that the 8 hour component observed over london canada cannot be explained by the terdiurnal tide being due to solar heating alone particular cases of the terdiurnal tide are examined and the observed amplitude and phase profiles of the terdiurnal tide at certain times of the year are discussed in terms of nonlinear interaction between the diurnal and semidiurnal tides we suspect that this effect may also explain the fact that diurnal and semidiurnal tides at our station often seem suppressed relative to other sites thayaparan et al 1995a on the basis of our previous and present observations it is also possible that large terdiurnal amplitudes observed at certain times of the year may be partly explained in terms of tidal gravity wave interactions however this possibility needs to be further investigated in the future

evidence for a traveling two day wave in the middle atmosphere evidence is presented for the existence of a wave number 3 westward traveling 2 day oscillation in the temperature measurements made by the nimbus 5 scr and nimbus 6 pmr instruments the wave has largest amplitude in the mesosphere at low latitudes of the summer hemisphere and has a markedly asymmetrical meridional structure it is suggested that the wave may be a free wave similar to the 5 day wave identified in nimbus 5 scr data by rodgers 1976 the vertical structure shows little phase tilt and a slight indication of an increase in amplitude with height

observational evidence of tidal gravity wave interactions using the uwo 2 mhz radar the degree of interaction between atmospheric gravity waves and tides is an issue which is of great importance in middle atmosphere studies it is especially important with regard to tidal variability which is frequently observed in the mesosphere and lower thermosphere but as yet has not been subject to adequate study in this paper we present some strong observational evidence of such interactions made with the uwo 2 mhz radar near london canada our observations show significant correlation between gravity waves and tides diurnal at certain times of the year and the nature of the correlation is intermittent and varies with time of year it is possible that differences between tidal amplitudes at sites with mesoscale separations may be explained in terms of such phenomena we also propose a simple model which is found to be consistent with the major features of the observed data

modelling river discharge and precipitation from estuarine salinity in the northern chesapeake bay application to holocene palaeoclimate long term chronologies of precipitation can provide a baseline against which twentieth century trends in rainfall can be evaluated in terms of natural variability and anthropogenic influence howev

terdiurnal tidelike variability in sporadic e layers 1 time series analysis was performed on a large database of ionosonde recordings taken over 12 years for the 6 month period from the beginning of may to the end of october when sporadic e layer occurrence is frequent the results show that in addition to the well known 24 and 12 hour tidal variations there is also a weaker but regular 8 hour periodicity in midlatitude sporadic e layers es statistically this terdiurnal periodicity is significant and occurs in both the sporadic e layer critical frequency foes and the layer virtual height h es becoming strongest around summer solstice and later in october after a minimum in september at times a weak 6 hour periodicity can also be present in es but its effects are much less significant than those of the 8 hour oscillation the 8 hour periodicity in es is attributed to the terdiurnal tide presumably acting through its vertical wind shear forcing of the metallic ions in the lower thermosphere the relation to the terdiurnal tide was inferred from simultaneous ionosonde recordings from three widely spaced stations in the same midlatitude zone showing the 8 hour oscillation to be present simultaneously in all ionosonde stations and have phases which are consistent with a westward propagating terdiurnal wave of zonal wave number 3 the present study establishes the regular occurrence of a terdiurnal tidelike oscillation in es which needs to be incorporated into the physics and modeling of sporadic e layer formation and dynamics

meteor radar observations of short term tidal variabilities in the low latitude mesosphere lower thermosphere evidence for nonlinear wave wave interactions 1 short term tidal variabilities in the mesosphere lower thermosphere mlt region using the meteor radar observations over trivandrum 8 5 n 77 e during march 2006 to february 2007 are discussed spectral analysis of daily averaged zonal and meridional winds revealed the presence of planetary waves with periods ranging from 2 to 30 days in the height region of 82 98 km the hourly zonal and meridional wind measurements are then used to estimate day to day diurnal tide amplitudes in the mlt region for the first time over this latitude spectral analysis of zonal and meridional diurnal tide amplitudes revealed tidal modulations at periods ranging from 2 to 30 days further during a strong episode of tidal modulation which is identified from the wavelet spectra a group of subsidiary spectral components around the diurnal tide is observed the presence of subsidiary spectral components around the diurnal tide has provided evidence for nonlinear interaction between tides and planetary waves to substantiate this result bispectral analysis is carried out which showed the nonlinear tide planetary wave interactions by revealing the presence of secondary waves exactly at the anticipated periods as the present observational site is very near to dip equator it is envisaged that the present results will have important implications in interpreting day to day variabilities in the equatorial ionosphere

flow reconstructions in the upper missouri river basin using riparian tree rings river flow reconstructions are typically developed using tree rings from montane conifers that cannot reflect flow regulation or hydrologic inputs from the lower portions of a watershed incorporating lowland riparian trees may improve the accuracy of flow reconstructions when these trees are physically linked to the alluvial water table we used riparian plains cottonwoods populus deltoides ssp monilifera to reconstruct discharge for three neighboring rivers in the upper missouri river basin the yellowstone n 389 tree cores powder n 408 and little missouri rivers n 643 we used the regional curve standardization approach to reconstruct log transformed discharge over the four months in early summer that most highly correlated to tree ring growth the reconstructions explained at least 57 of the variance in historical discharge and extended back to 1742 1729 and 1643 these are the first flow reconstructions for the lower yellowstone and powder rivers and they are the furthest downstream among rocky mountain rivers in the missouri river basin although mostly free flowing the yellowstone and powder rivers experienced a shift from early to late summer flows within the last century this shift is concurrent with increasing irrigation and reservoir storage and it corresponds to decreased cottonwood growth low frequency flow patterns revealed wet conditions from 1870 1980 a period that includes the majority of the historical record the 1816 1823 and 1861 1865 droughts were more severe than any recorded revealing that drought risks are underestimated when using the instrumental record alone this article is protected by copyright all rights reserved

observations of the quasi 2 day wave from the high resolution doppler imager on uars a strong westward traveling oscillation with a period of 2 days and zonal wave number 3 is observed in the mesospheric and lower thermospheric winds from the high resolution doppler imager on the upper atmosphere research satellite the important events happen in january july and september october of which the occurrence in january is the strongest with an amplitude over 60ms 1 detailed analyses for the periods of january 1992 and january 1993 reveal a cause and effect relationship in the wave developing process at 95km the global structures of the wave amplitude and phase are also presented

evaluation of evaporation rate from forested soil surface using stable isotopic composition of soil water in a headwater basin the stable isotopic composition of rain water and soil water was analysed and the soil surface evaporation rate was evaluated using the isotope value of soil water taken from a forested headwater basin in central japan rainfall throughfall soil water groundwater and discharge water were sampled at intervals of one month to determine the isotopic compositions of deuterium d and oxygen 18 18 o therein in addition tensiometric observation of soil water was performed continuously the stable isotopic ratio of soil water was homogenized between the soil surface and a depth of 100 cm by means of active soil water movement above 100 cm in depth the mean 18 o in deep soil water below a depth of 100 cm was 0 24 higher than the volume weighted mean 18 o in throughfall consequently the mean evaporation rate from the soil surface was calculated as 5 of the evapotranspiration rate using the difference between the 18 o in throughfall and in deep soil water based on the rayleigh equation under equilibrium condition

observations of the 2 day wave in nmc stratospheric analyses abstract observational characteristics of the 2 day wave a westward propagating zonal wave 3 oscillation in the summer subtropical upper stratosphere and mesosphere are studied based on five years of national meteorological center nmc operational stratospheric analyses these data show episodic occurrence of the 2 day wave in the upper stratosphere in january centered near 20 s and july august centered near 20 n these episodes are strongly correlated with observed reversals of the zonal mean potential vorticity gradient near the core of the summer easterly jet consistent with previous suggestions that the 2 day wave is generated by an in situ instability of this jet on the other hand the horizontal and vertical structure of the waves is very similar to that calculated by salby for a global normal mode rossby wave the combination of normal mode structure and instability signature suggests that the 2 day wave is a near resonant mode forced by dynamical instability

modeling and analysis of the structure and generation of the terdiurnal tide the terdiurnal or 8 h tide has been seen in a number of midlatitude radar measurements and has recently been mapped globally at 95 km a series of calculations and model simulations are used to examine the processes responsible for generating this tide and for its strong hemispheric asymmetry the model tidal structure deviates significantly from the structure of a single hough mode in contrast to the diurnal tide the dominant cause of the hemispheric asymmetry is the sensitivity of the propagation to the background state particularly the static stability several conceptual views of the tide are explored to give a heuristic view of this asymmetry this analysis predicts that particular modes are prohibited from propagating in large regions of the summer mesosphere the tide occurs naturally in a three dimensional nonlinear model extending from the tropopause to the lower thermosphere the model tide shows a number of features in common with observations including amplitude maxima in midlatitudes a wintertime peak and zonal winds larger than meridional winds the tidal amplitude in the model is weaker than observed at 95 km several interactive model integrations are performed to determine the forcing mechanism for the tide these calculations indicate that the direct solar forcing of the terdiurnal tide is the dominant mechanism occurring in the model at middle and high latitudes nonlinear interactions contribute to the low latitude tide

a tree ring based record of annual mass balance changes for the ts tuyuksuyskiy glacier and its linkages to climate change in the tianshan mountains abstract fluctuations in glacier mass and volume are indicative of changes in the climate system they also strongly affect regional climate and hydrology in this paper we explore possible relationships between the radial growth of schrenk spruce picea schrenkiana fisch et mey and the mass balance of the tsentralniy tuyuksuyskiy ts tuyuksuyskiy glacier which is located on the northern slopes of the tianshan mountains in arid central asia we attempt to reconstruct the historical mass balance variability of the ts tuyuksuyskiy glacier using tree ring widths and stable carbon isotope chronologies the reconstruction is able to explain 62 1 of the variance in the annual glacier mass balance record over the 1965 2014 calibration period we also analyzed centennial mass balance variability and its linkages to climate change the ts tuyuksuyskiy glacier has a negative annual mass balance in most years and since 1968 has undergone the most rapid and longest melting process in the past 166 years the mass balance change of the glacier is controlled by the combination of temperature and precipitation conditions this study could be useful for more detailed glaciological hydrological and climatological assessments in this portion of the tianshan mountains

multi millennial streamflow dynamics in two forested watersheds on vancouver island canada abstract holocene streamflow was reconstructed for two rivers on vancouver island british columbia canada in 500 yr intervals the san juan river watershed is located on the wetter western side of the island whereas the koksilah river watershed is positioned on the drier eastern side both watersheds are forested to reconstruct streamflow temporal changes in precipitation estimated using a pollen based transfer function and evapotranspiration were established for each watershed and integrated into a water balance model calibrated using modern data while seasonal streamflow variability was maintained throughout the holocene with greater flow in the winter relative to the summer the amount of discharge has changed markedly through time lowest simulated flow occurred in the earliest holocene with low flow conditions beginning earlier in the year and extending later into the fall such conditions may have inhibited salmon from using many of the smaller rivers in the region streamflow steadily increased throughout the early holocene so that by ca 6500 cal yr before present near modern flow regimes were established as climate changes in the future the san juan and koksilah watersheds are expected to remain as pluvial hydroclimatic regimes though with an extended season of low flow similar to conditions during the early holocene

stable isotopic and geochemical identification of groundwater evolution and recharge sources in the arid shule river basin of northwestern china stable isotopic dvsmow and 18ovsmow and geochemical signatures were employed to constrain the geochemical evolution and sources of groundwater recharge in the arid shule river basin northwestern china where extensive groundwater extraction occurs for agricultural and domestic supply springs in the mountain front of the qilian mountains the yumen tashi groundwater ytg and the guazhou groundwater gzg were ca hco3 ca mg hco3 so4 and na mg so4 cl type waters respectively total dissolved solids tds and major ion mg2 na ca2 k so42 cl and no3 concentrations of groundwater gradually increase from the mountain front to the lower reaches of the guazhou basin geochemical evolution in groundwater was possibly due to a combination of mineral dissolution mixing processes and evapotranspiration along groundwater flow paths the isotopic and geochemical variations in melt water springs river water ytg and gzg together with the end member mixing analysis emma indicate that the springs in the mountain front mainly originate from precipitation the infiltration of melt water and river in the upper reaches the lateral groundwater from the mountain front and river water in the middle reaches are probably effective recharge sources for the ytg while contribution of precipitation to ytg is extremely limited the gzg is mainly recharged by lateral groundwater flow from the yumen tashi basin and irrigation return flow the general characteristics of groundwater in the shule river basin have been initially identified and the results should facilitate integrated management of groundwater and surface water resources in the study area copyright 2015 john wiley sons ltd

terdiurnal surface pressure oscillations over the continental united states abstract the small terdiurnal pressure oscillation s3 p is determined over the conterminous united states by analyzing long time series of hourly barometer data from 180 stations spectral analysis of these time series reveals that the terdiurnal band is dominated by three or four spectral peaks separated in frequency by 1 cpy the central peak at 3 cpd is invariably smaller than the two immediate side peaks indicative of extraordinarily strong seasonal variations in the tide the largest terdiurnal tide occurs over the south central united states in winter where amplitudes exceed 300 bar summertime amplitudes are roughly one half as large summer and winter tides are almost completely out of phase with rapid 180 shifts occurring in the equinox seasons when amplitudes are very small

seasonal variations of the terdiurnal tide in the mesosphere and lower thermosphere a model study observations of the terdiurnal 8 hour tidal wind oscillations in the mesosphere and lower thermosphere mlt reveal strong seasonal and latitudinal variations the tidal amplitudes reach a maximum of about 15 20 m s 1 at midlatitudes in winter the vertical phase progression corresponds to very long vertical wavelengths during summer the amplitudes are typically weaker and the phases are less regular first simulations of the terdiurnal tide with the spectral mesosphere lower thermosphere model are presented the model explicitly accounts for the solar thermal excitation in the middle and upper atmosphere and reproduces the salient features of the terdiurnal wind oscillations well the preferential solar excitation of antisymmetric terdiurnal modes capable of propagating into the mlt combined with an asymmetric atmospheric response appears to be primarily responsible for the observed seasonal variations nonlinear interactions of the diurnal and semidiurnal tides are demonstrated to make a noticeable in situ contribution to the excitation of the terdiurnal tide at 95 100 km especially during equinox

the quasi two day wave observed in the equatorial middle atmosphere an oscillation with a period near 2 days is found in radar wind measurements made in the upper mesosphere and lower thermosphere at christmas island 2 n 157 w in the central pacific the oscillation is particularly strong in the meridional wind component and seems to be present almost continuously ir the 80 100 km height region although some intermittency is evident wave amplitudes are especially large about one month after the solstices in july august and in january february at times coincident with large 2 day wave events in the summer mesosphere at extratropical latitudes power spectral and complex demodulation techniques are used to study the amplitude and frequency variations of the oscillation as a function of height and time downward phase propagation is found consistent with upward energy propagation and with a vertical wavelength of about 70 km an unusual feature is a shift in wave period from near 50 hours in july august to 48 hours in january february when the largest amplitudes up to 45 m s 1 are observed a 16 hour oscillation is also found at times when the 2 day wave amplitudes are largest the observations are consistent with the 2 day wave being a manifestation of the 3 0 rossby gravity normal mode another weaker oscillation is also found in the meridional wind field at a period near 44 hours this oscillation may be due to the 2 0 normal mode

using stable hydrogen and oxygen isotopes to reveal monsoonal and related hydrological effects on meteoric water in the western pacific monsoon region a case study of the ilan region northeastern taiwan abstract this study analyzes the isotopic compositions 2h and 18o of meteoric waters including precipitation and stream water to reveal what major hydrological processes affect the hydrological regime of the ilan region northeastern taiwan the isotopic results indicate monsoonal flows as the fundamental factors affecting studied precipitation and stream water summer precipitation sourced from southerly air mass exhibits lower and deuterium excess de values than winter precipitation sourced from northerly air masses the 18o and de values are respectively 7 7 and 8 for summer precipitation and 3 3 and 24 for winter precipitation furthermore semi quantitative estimations using de evidence indicate that summertime southerly air masses generally contribute more to stream water than wintertime northerly air mass flows approximately 54 vs 46 however the contribution fractions are controlled by the orientation of catchments to the windward side of respective monsoonal flows northern catchments located on the windward side of southerly air masses receive about 60 of their water from precipitation condensed from the southerly air masses and 40 from the northerly air masses by comparison southern catchments located on the windward side of northerly air masses receive about 59 of their water from northerly air masses and 41 from southerly air masses additionally catchment effect induced from value is notable in stream basins with high elevations but this is not related to catchment sizes besides this altitude effect which is determined in terms of 18o values was derived using data from four precipitation stations of northern taiwan it ranges from 2 5 to 3 0 per 100 m depending on the season moreover based on the de evidence secondary evaporation effects are apparent with moisture recycling influencing inland summer precipitation and raindrop evaporation influencing inland winter precipitation

hydrobiogeochemistry of forest ecosystems in japan major themes and research issues hydrobiogeochemical information on forested watersheds in the japanese archipelago is reviewed to qualitatively summarize the major factors affecting the hydrology and biogeochemistry of this region major features that distinguish japanese forest watersheds from those of north central europe and the northeast united states generally include higher temperature greater precipitation and steeper topography there have been three major themes in hydrobiogeochemistry research on japanese forest ecosystems 1 investigations of nutrient cycles with particular emphasis on the establishment and maintenance of forest ecosystems 2 evaluations of streamwater chemistry as an output from the forest ecosystem and 3 hydrological studies using biogeochemical tracers high precipitation inputs during the growing season affect the seasonality of the streamwater no3 concentration resulting in different temporal patterns than those generally found in north central europe and the northeast united states the high alkalinity and ph of japanese surface waters is due to the rapid weathering of relatively young soils that are generated by steep hillslopes warm temperatures and elevated soil moisture enhance high rates of mineral weathering hydrological studies using biogeochemical tracers have shown that the steep topography contributes to the highly heterogeneous movement of water within japanese catchments copyright 2001 john wiley sons ltd

terdiurnal tide in the extended canadian middle atmospheric model cmam 1 we use the extended canadian middle atmosphere model cmam a general circulation model gcm to investigate the nature of the terdiurnal tide temperature and horizontal winds from a model run are analyzed to delineate the character of this tide for zonal wave numbers s 5 to 5 descriptions of the annual mean amplitudes seasonal variations and total tide superposed from the migrating and 10 nonmigrating components are provided the amplitudes and vertical wavelengths of the various components and the total terdiurnal tide are found to depend strongly on season latitude and altitude the migrating terdiurnal component maximizes at mid and high latitudes with significant amplitudes annual mean amplitude in wind temperature 10 m s k in the upper mesosphere and lower thermosphere mlt region between 80 and 100 km maximum amplitudes occur in winter in both hemispheres whereas above 100 km maximum amplitudes occur during solstices for the zonal wind field the nonmigrating terdiurnal components te5 te3 te4 tw4 and tw5 tend to peak at 50 n s with amplitudes between 2 and 8 m s the other nonmigrating components maximize in the polar regions with amplitudes of 2 10 m s possible generation mechanisms solar heating and nonlinear interactions for the migrating terdiurnal tide in the mlt region are also examined correlation analysis indicates that nonlinear interactions between the migrating diurnal and semidiurnal tides are unlikely to be the source of the migrating terdiurnal tide

seasonal variations of mlt tides revealed by a meteor radar chain based on hough mode decomposition seasonal variations of different tides in the mesosphere and lower thermosphere are investigated from wind observations of a meteor radar chain on the basis of hough mode decomposition first the observed winds are decomposed into different diurnal semidiurnal and terdiurnal tidal components different seasonal patterns are revealed for each component pronounced semiannual oscillation sao is presented in the diurnal component while latitude dependent seasonal variation is found in the semidiurnal and terdiurnal components at the low midlatitude stations the semiannual annual oscillation is relatively stronger then hough mode decomposition is utilized to extract the dominant tidal modes of each decomposed component it is found that each component is dominated by one of its symmetric tidal modes with strong seasonal dependency apparent sao is observed in the dominant 1 1 mode 2 4 mode is strong in the autumn and winter months after the september equinox based on the extracted results we further map the three dimensional distribution latitude altitude season of each tidal component the mapped results are finally compared with the corresponding values observed by the thermosphere ionosphere mesosphere energetics and dynamics doppler interferometer tidi and modeled from the global scale wave model gswm each mapped tidal component agrees well with corresponding tidi observation in the seasonal variation meanwhile coincidences are found in the seasonal dependency of the diurnal component between the mapped values and the modeled results from gswm while difference between them exists in that of the semidiurnal one

coordinated observations of 8 and 6 hr tides in the mesosphere and lower thermosphere by three meteor radars near 60 s latitude

water movement in desert soil traced by hydrogen and oxygen isotopes chloride and chlorine 36 southern arizona abstract understanding soil water movement is important for water resource management and for analyzing pollutant transport in the vadose zone seasonal variations in shallow soil profiles may have profound effects on deep soil water and solutes we have investigated seasonal soil water movement in the top meter of undisturbed desert soil in the southern arizona using 2 h 18 o cl and bomb 36 c1 six soil profiles were sampled from a young terrace holocene during 1991 to 1992 on a seasonal basis one soil profile was sampled from an older terrace latest pleistocene in october 1992 and one from a yet older fan surface late pleistocene in march 1992 the results indicate that repeated seasonal cyclic movement of soil water in the top 60 80 cm active zone tends to produce a consistent stable isotope composition for the soil water below the active zone in different seasons the deep 18 o on the oldest surface is about 6 heavier than on the younger surfaces probably resulting from greater evaporative loss due to the larger proportion of fines in the older soil this deep isotopic composition is closely related to the composition of the local average annual precipitation an annual average evaporation rate of 35 mm year 1 was estimated using a steady state diffusion model whereas the actual regional evapotranspiration rate is 175 250 mm year 1 this suggests that about 80 of the soil water is lost through transpiration and first stage evaporation before quasi steady state is reached the long term average infiltration rate below the active zone is about 4 mm year 1 for the younger terrace based on both chloride mass balance and bomb 36 cl and 0 02 mm year 1 for the older terrace and the fan surface based on chloride mass balance the correlation between the deep 18 o the reduction of downward flux and the surface age suggests that increasing soil development has resulted in a significant decrease of soil water infiltration and hence an increase in evaporation and surface runoff

the quasi two day wave event of january 1984 and its impact on the mean mesospheric circulation abstract studies of the quasi two day wave show that it is a summertime phenomenon in the summer of 1983 84 at adelaide 35 s 138 e the main phase of the wave appeared as a pulse in mid january which lasted about seven cycles 14 days coincident with the onset of the pulse a temporary but substantial change occured in the prevailing circulation throughout a deep layer of the upper mesosphere a perturbation of more than 10 m s 1 occurred in the northward flow whereas the change in the zonal flow about 30 m s 1 westward actually caused a reversal of the prevailing eastward simulation above 84 km it is suggested that these changes in the prevailing circulation were a response to the wave pulse a simple calculation is performed to estimate the anticipated response to the observed wave event under plausible assumptions about the magnitude of mean and eddy dissipation processes predicted circulation changes agree reasonably well with those observed it is concluded that such events have a substan

a 963 year reconstruction of summer jja stream flow in the white river arkansas usa from tree rings an average of three baldcypress taxodium distichum ring width chronologies was used to recon struct total summer jja mean daily flow of the white river at clarendon arkansas for years 1023 1985 a quadratic transformation of the tree ring data accounted for 68 r 2 adjusted for degrees of freedom lost when regressed against total summer flow 1931 1985 the distribution of the quadratic reconstruction matched the gauged distribution much better than a simple linear model which only accounted for 62 of the variance the model was validated by comparing regression estimates against independent data years with summer flow below the 25th percentile occur nonrandomly i e they tend to cluster in both the reconstructed and gauged data hydrologic regimes have apparently varied considerably in the past on annual to century time scales with extended dry and wet periods that exceeded anything in the modern record the frequency of both wet and dry extremes has varied considerably over the last millennium the eleventh through thirteenth cen turies were not analysed due to reduced replication but the well replicated fourteenth and twentieth centuries both have large numbers of extremes the twentieth century appears to have more extreme low flows than the previous centuries and also to have a large number of high flows the practical consequences for society of variation in extremes and persistence of low flows may be considerable climatic change or anthropogenic changes to the watershed e g widespread upland clearing for agriculture and logging of bottomland forests may be responsible for the change in hydrologic regime during the twentieth century

on the occurrence and variability of the terdiurnal tide in the equatorial mesosphere and lower thermosphere and a comparison with the kyushu gcm 1 we studied the occurrence characteristics and variability of the terdiurnal tide 8 hour period in the equatorial mesosphere and lower thermosphere mlt using a meteor radar at koto tabang 0 2 s 100 3 e and mf radars at tirunelveli 8 7 n 77 8 e and pameungpeuk 7 4 s 107 4 e these locations one being located right over the equator and the other two at conjugate points around the equator within 10 form a unique experimental setup to study equatorial mlt dynamics the terdiurnal tide exists as a distinct wave signature at all three locations while the daily amplitudes can be as large as 15 m s 1 the monthly mean amplitudes lie between 1 and 10 m s 1 the amplitude of the terdiurnal tide at pameungpeuk is generally smaller than that observed at tirunelveli and koto tabang the seasonal variation in amplitude shows both annual and semiannual oscillations of 1 m s 1 at all three locations the present observations combined with previous reports indicate that the timing of the primary maximum of the terdiurnal tide amplitude shifts from autumn to late spring and early summer as one moves from high latitudes to the equator all with respect to the northern hemisphere the amplitudes and seasonal variation in the present observations show good comparison with that simulated by the general circulation model gcm developed by kyushu university japan this study supports the occurrence of nonlinear interaction between diurnal and semidiurnal tides and shows that gravity waves play an important role in the generation of the terdiurnal tide

tides in the mesopause region over fort collins colorado 41 n 105 w based on lidar temperature observations covering full diurnal cycles 1 eighteen sets of 24 hour continuous lidar temperature observation well distributed throughout the year have been analyzed to reveal the mean amplitude and phase of oscillations with 24 12 8 and 6 hour periods for four seasons the amplitude and phase of both 24 and 12 hour components are compared to the prediction of the most recent global scale wave model gswm 00 the variability of diurnal and semidiurnal oscillations is examined by comparing the amplitude and phases of each observed day in autumn winter and spring even with the limited data sets reported here surprisingly good general agreement between the observed and model tidal phases can be established implicating the prevalence of migrating diurnal and semidiurnal tides compared to the diurnal and semidiurnal phases which typically show clear downward phase progression the 8 and 6 hour components exhibit small amplitude and show unorganized phase propagation as a function of altitude the advantage of having coverage over complete diurnal cycle and entire mesopause altitudes as demonstrated here would hopefully stimulate future tidal studies with lidar temperature and zonal and meridional wind observations

a multicentury reconstruction of may precipitation for the mid atlantic region usingjuniperus virginianatree rings abstractthis paper presents a multicentury reconstruction of may precipitation 1200 1997 for the mid atlantic region of the united states the reconstruction is based on the first principal component pc1 of two millennial length juniperus virginiana l eastern red cedar tree ring chronologies collected from rocky limestone sites in the ridge and valley province of west virginia a split calibration linear regression model accounted for 27 of the adjusted variance in the instrumental record and was stable through time the model was verified by the reduction of error re 0 21 and coefficient of efficiency ce 0 20 statistics multidecadal changes in precipitation were common throughout the reconstruction and wetter than median conditions and drier than median conditions occurred during the medieval climate anomaly 1200 1300 and the little ice age 1550 1650 respectively the full reconstruction contained evidence of interannual and decadal variability however the twentieth century reco

tree ring based streamfiow reconstruction for ashley creek northeastern utah implications for palaeohydrology of the southern uinta mountains two ring width chronologies from douglas fir pseudotsuga menzeisii and one from pinyon pine pinus edulis were used to reconstruct mean annual discharge of ashley creek in the uinta mountains utah for the years ad 1637 1970 a backward elimination multiple linear regression model identified six statistically significant variables including annual lags ranging from 1t o 2 years the final model explains 71 of variability r 2 adjusted for degrees of freedom lost when regressed against the annual discharges recorded for 1915 72 statistical analysis of the model reconstruction using the reduction of error statistic the durbin watson statistic and the hypergeometric distri bution all indicate fidelity of the model for reconstructing discharge the lilliefors test indicates that years of extreme discharge greater than the 90th percentile or less than the 10th percentile are non randomly distributed between 1637 and 1970 persistent years of above median discharge as well as non random clustering of years above the 90th percentile occurred from 1692 1704 and 1898 1945 analysis of the modern gauge data set shows that mean annual discharge on ashley creek explains between 81 and 91 of the variations of mean annual discharge on the other main stream in the southern uinta mountains indicating that reconstructed mean annual discharge on ashley creek is representative of palaeohydrologic conditions across the south flank of the range these data suggest that the southern uinta mountains experienced persistent below median discharge for 1741 1897 through the peak of the little ice age as identified in numerous surrounding mountain ranges in the central rockies this interpretation agrees with lichenometric evidence for extremely limited little ice age glacial activity in the uintas indicating that the range experienced unusually warm dry conditions at this time

structure of the terdiurnal tide at 95 km satellite wind observations from the high resolution doppler interferometer hrdi instrument on the upper atmosphere research satellite uars are used to describe the latitudinal structure and seasonal variation of the terdiurnal 8 hour atmospheric tide at 95 km the amplitude of the annual average tide is 5 m s meridional and 15 m s zonal within the range observed 60 s to 60 n the maximum amplitudes are found during fall and winter at midlatitudes only weak temporal correlations with the diurnal and semidiurnal tides are seen on the monthly time scales resolved