3d gravity inversion of basement relief a depth dependent density approach we present a 3d gravity inversion technique based on the marquardt algorithm to analyze gravity anomalies attributable to basement interfaces above which the density contrast varies continuously with depth the salient feature of this inversion is that the initial depth of the basement is not a required input the proposed inversion simultaneously estimates the depth of the basement interface and the regional gravity background applicability and efficacy of the inversion is demonstrated with a synthetic model of a density interface we analyze the synthetic gravity anomalies 1 solely because of the structure 2 in the presence of a regional gravity background and 3 in the presence of both random noise and regional gravity background the inverted structure remains more or less the same regardless of whether the regional background is simulated with a second degree polynomial or a bilinear equation the depth of the structure and estimated regional background deviate only modestly from the assumed ones in the presence of random noise and regional background the analyses of two sets of real field data one over the chintalpudi subbasin india and another over the pannonian basin eastern austria yield geologically plausible models with the estimated depths that compare well with drilling data

climatology of tropical intraseasonal convective anomalies 1979 2002 tropical intraseasonal convective anomalies tica have a central role in subseasonal changes in the coupled ocean atmosphere system but the climatology of tica events has not been properly documented this study exploits 24 years of outgoing longwave radiation olr data and a tracking algorithm to develop a climatology of eastward propagating tica events three distinct types of tica occurrences are documented according to their propagation characteristics the first type ind is characterized by events that propagate in the indian ocean without significant influence in the western pacific ocean the second and third types are associated with occurrences of the madden julian oscillation during boreal winters mjo and summers iso the frequency of occurrence of tica events is highest in april june and october december and lowest in july september an analysis of the spatial and temporal characteristics reveals that mjo events tend to have the longest life cycle greatest intensity and largest variability inside the contiguous region of olr anomaly given the data record of 24 years the analysis of interannual occurrences of tica events does not show statistically significant

geothermal potential of egypt abstract one hundred and sixty samples of groundwater from nearly all parts of egypt have been collected and chemically analyzed in order to assess the country s geothermal potential the samples considered to be thermal include 20 wells t 35 c 4 springs t 30 c and 1 spring not included in the present inventory the remaining samples together with data from the literature establish background chemistry the hottest springs are located along the east shore of the gulf of suez uyun musa 48 c and ain hammam faraoun 70 c additional warm springs are located along both shores of the gulf of suez and this region is the most promising for geothermal development the eastern desert of egypt particularly the coastal area adjacent to the red sea has above normal heat flow 72 0 mw m 2 and therefore some geothermal potential although only one thermal well umm kharga 35 8 c could be located in the major oases of the western desert kharga dakhla farafra and bahariya the regional temperature gradient is low c km but many of the wells tap deep artesian aquifers and produce large volumes of water in the 35 43 c range such wells constitute a low temperature geothermal resource none of our samples in northern egypt can be considered thermal including several reported hot springs application of the silica nakca and nakcamg geothermometers does not indicate the presence of a high temperature geothermal resource at any area we visited

melting runoff and the formation of frozen lakes in a mixed snow and blue ice field in dronning maud land antarctica large scale melting phenomena such as meltwater drainage channels and meltwater accumulation basins of frozen lakes were surveyed on the land ice mass in jutulgryta dronning maud land antarctica during the norwegian antarctic research expedition in 1989 90 nare 1989 90 the largest frozen lake that was observed was close to 1 km in width these melting features were also detected in a landsat thematic mapper image recorded on 12 february 1990 then during nare 1993 94 a 5year glaciological programme was started in this area in spite of negative air temperatures and the presence of a frozen ice surface sub surface melting and runoff were found within the uppermost metre in blue ice fields the sub surface melting is a consequence of solar radiative penetration and absorption within the ice i e the solid state greenhouse effect temperatures in blue ice were about 6 c higher than for snow internal melt and meltwater transport were observed throughout the 1 month of measurements the conditions for active melting in jutulgryta are probably marginal a slight increase of air temperatures can result in more classical surface melting whereas a cooling may disable sub surface melting studies of how the extent and characteristics of the melting features change with time can be particularly valuable as indicators of climate change this ongoing programme clearly identifies the importance of analyzing how these melting features originate of mapping their present areal distribution of determining how sensitive they are to climate change and of studying changes in the past and possible changes in the future

circulation anomalies associated with tropical convection during northern winter abstract lagged cross correlations between outgoing longwave radiation olr and national meteorological center global analyses are utilized to isolate the preferred upper level and surface circulation anomalies associated with tropical convection during northern winter three intraseasonal time scales are studied 30 70 14 30 and 6 14 days in the 30 70 day band the upper level circulation signals are zonally elongated with zonal wavenumbers 0 2 dominant higher frequency signals are dominated by zonal wavenumbers 5 and 6 in the 14 30 day band convection over the eastern hemisphere is associated with upper level anticyclones in the subtropics and appears to be linked in some cases to midlatitude wave trains the strongest signals are for convection over africa australia and the eastern indian ocean only weak signals are seen for convection over indonesia in these regions of upper level easterlies olr anomalies peak prior to the maximum anomalies in wind suggesting forcing of the circulation b

exploration and assessment of the geothermal resources in the hammam faraun hot spring sinai peninsula egypt abstract the tectonic position of egypt in the northeastern corner of the african continent suggests that it may possess significant geothermal resources especially along its eastern margin the most promising areas for geothermal development in the northwest red sea gulf of suez rift system are located where the eastern shore of the gulf of suez is characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures magnetotelluric and gravity reconnaissance surveys were carried out over the geothermal region of hammam faraun to determine the subsurface electric resistivity and the densities that are related to rock units these surveys were conducted along profiles one dimensional 1d and two dimensional 2d inversion model techniques were applied on the mt data integrating the 2d inversion of gravity data the objectives of these surveys were to determine and parameterize the subsurface source of the hammam faraun hot spring and to determine the origin of this spring based on this data a conceptual model and numerical simulation were made of the geothermal area of hammam faraun the numerical simulation succeeded in determining the characteristics of the heat sources beneath the hammam faraun hot spring and showed that the hot spring originates from a high heat flow and deep ground water circulation in the subsurface reservoir that are controlled by faults these studies were followed by an assessment of the geothermal potential for electric generation from the hammam faraun hot spring the value of the estimated potential is 28 34 mw as the reservoir is assumed to be only 500 m thick this value would be enough for the desalination of water for both human and agricultural consumption

seasonal variations of tropical intraseasonal oscillations a 20 25 day oscillation in the western pacific abstract spectral analysis within a movable time window is used to investigate the frequency and intensity of tropical oscillations with intraseasonal time scales surface and rawinsonde time series from several locations in the western pacific and indian oceans are used evidence is provided that the madden julian oscillation mjo in the indian ocean region shows a seasonal variation in its preferred period from 50 days during northern hemisphere winter to about 35 days during summer though this evidence is weak and stretches the limits of our ability to define a precise period for the oscillation in the western tropical pacific during the september december season a pronounced spectral peak with a central frequency between 20 and 25 days is observed this spectral peak appears to reveal an oscillation that is distinct from the mjo but may also result from coupling between the large scale motion and latent heat release on much smaller scales a relationship between the oscillation and the occurrence

aspects of palyno organic facies analysis comprehensive evaluation of the source rocks and age of some subsurface lower cretaceous core materials in the north western desert egypt abstract the palyno organic facies aspects of the subsurface lower cretaceous core samples are extensively investigated in three wells in the northern part of the western desert of egypt these wells are burg el arab 1 and mamura 1 mersa matruh 1 bax 1 max 1 and mmx 1 respectively the study is based on the palynofacies and organic geochemical analyses the palynofacies examination includes a statistical analysis of the different classes of organic particles by cluster analysis and principal component analysis pca this analysis leads to identify 4 palynofacies types a b c1 and c2 which are dominated by various levels of terrestrial floral materials the paleoenvironmental settings that are attributed to these palynofacies types are the distal suboxic oxic proximal oxic transitional oxic and highly distal oxic the principal component analysis pca differentiates between these palynofacies types mathematically by the biplot of components 1 and 2 the component 1 corresponds to distance from the terrestrial floral sources the identification of quantity type quality and thermal maturity of organic matter is discussed depending on the palynofacies and organic geochemical analyses the thermal maturity is assessed digitally by measuring the rgb color channels in the spore images and their corresponding thermal alteration index tai incorporated with values of tmax these measures are integrated in burial history models with geothermal gradient and depositional history the study reveals that most of the core samples represent generally fair to good enriched sources of gas prone type iii kerogen and less mixed gas oil type ii iii kerogen additionally some occasional high levels of organic conversions are recorded the burial history models indicate that oil expulsion window initiated in the cretaceous the examinations indicate mature oil sources in the alam el bueib formation in mmx 1 well the organic geochemical parameters are correlated versus the component 1 and sum of all components of pca the correlation coefficients r2 pointed to good correlation between the oxygen index oi toc and s2 and lower correlation with hydrogen index hi

below surface ice melt on the coastal antarctic ice sheet in the jutulgryta area of dronning maud land antarctica subsurface melting of the ice sheet has been observed the melting takes place during the summer months in blue ice areas under conditions of below freezing air and surface temperatures adjacent snow covered regions having the same meteorological and climatic conditions experience little or no subsurface melting to help explain and understand the observed melt rate differences in the blue ice and snow covered areas a physically based numerical model of the coupled atmosphere radiation snow and blue ice system has been developed the model comprises a heat transfer equation which includes a spectrally dependent solar radiation source term the penetration of radiation into the snow and blue ice depends on the solar radiation spectrum the surface albedo and the snow and blue ice grain sizes and densities in addition the model uses a complete surface energy balance to define the surface boundary conditions it is run over the full annual cycle simulating temperature profiles and melting and freezing quantities throughout the summer and winter seasons the model is driven and validated using field observations collected during the norwegian antarctic research expedition nare 1996 97 the simulations suggest that the observed differences between subsurface snow and blue ice melting can be explained largely by radiative and heat transfer interactions resulting from differences in albedo grain size and density between the two mediums

quasi periodic oscillations in a symmetric general circulation model abstract long lime integrations with a symmetric version of the clas climate model with hydrology have shown that the hadley circulation has well defined strong and weak episodes this oscillation of the hadley circulation seems to occur in two dominant range of periodicities one with periods between 10 and 15 days and another with periods between 20 and 40 days this quasi periodic behavior of the hadley circulation is seen only when the moist convective heating is determined by dynamics if the latent beating in the atmosphere is prescribed and kept artificially fixed this oscillation of the hadley circulation disappears thus this oscillation of the hadley circulation appears as a result of interactions between moist convective and dynamical processes a wave phenomenon is seen in the lower atmosphere that propagates toward the position of maximum radiative beating this wave perturbation has a length scale of about 15 20 degrees latitude in the north south direction this phenomenon has large ampli

development of convection along the spcz within a madden julian oscillation a subtropical rossby wave propagation mechanism is proposed to account for the poleward and eastward progression of intraseasonal convective anomalies along the south pacific convergence zone spcz that is observed in a significant proportion of madden julian oscillations mjos large scale convection associated with an mjo is assumed to be already established over the indonesian region the latent heating associated with this convection forces an equatorial rossby wave response with an upper tropospheric anticyclone centred over or slightly to the west of the convection large potential vorticity pv gradients associated with the subtropical jet and the tropopause lie just poleward of the anticyclone and large magnitude pv air is advected equatorwards on the eastern side of the anticyclone this high pv air or upper tropospheric trough is far enough off the equator that it has associated strong horizontal temperature gradients and it induces deep ascent on its eastern side at a latitude of about 15 30 if this deep ascent is over a region susceptible to deep convection such as the spcz then convection may be forced or triggered hence convection develops along the spcz as a forced response to convection over indonesia the response mechanism is essentially one of subtropical rossby wave propagation this hypothesis is based on a case study of a particularly strong mjo in early 1988 and is tested by idealized modelling studies the mechanism may also be relevant to the existence of the mean spcz as a forced response to mean indonesian convection

studies of snow surface characteristics by landsat tm in dronning maud land antarctica large scale melting phenomena like meltwater drainage channels and meltwater accumulation basins or frozen lakes have been surveyed on the land ice mass in dronning maud land antarctica these melting features were also detected in a landsat thematic mapper tm image recorded on 12 february 1990 image processing techniques such as principal component pc analysis band ratioing and histogram equalizing are carried out to emphasize the melting phenomena interestingly a histogram equalized single tm band 5 image appears to be a good discriminator leaving the melting phenomena as bright areas in the tm scene the largest frozen lake is close to 1km wide while some of the drainage channels stretch more than 5 km there is also a comparison of satellite derived and in situ reflectance and temperature the atmospheric corrected satellite data underestimate surface snow albedo by about 16 while tm measurements of surface temperature are 2 to 6 c lower than that measured on the ground

seasonality of the structure and propagation characteristics of the mjo the seasonality of the madden julian oscillation mjo is documented in observational data and a nonlinear shallow water model is used to help interpret some of the contrasts in mjo structure between the boreal winter season november march ndjfm and the asian summer monsoon period june september jjas at upper tropospheric levels the flanking rossby waves remain centered around 28 degrees n s year round but they tend to be stronger in the winter hemisphere where the climatological mean jet stream is stronger rendering the subtropical circulation more sensitive to forcing by a near equatorial heat source amplitudes of the mjo related deep convection and lower tropospheric zonal wind are stronger in the summer hemisphere where the column integrated water vapor is larger during ndjfm the equatorial asymmetry is subtle as in the annual mean moisture convergence into swallowtail shaped regions of enhanced deep convection is an integral part of the equatorial rossby wave signature and the eastward propagation is due to moistening of the air to the east of the enhanced convection by poleward moisture advection during the asian summer monsoon in jjas the convection assumes the form of northward propagating west northwest east southeast oriented rainbands embedded within cyclonic shear lines these features are maintained by frictional convergence of moisture and their northward propagation is mainly due to the presence of features in the climatological mean fields that is the west east moisture gradient over india and the arabian sea and the southwesterly low level monsoon flow over the northwest pacific

correlation of aerogravity and bht data to develop a geothermal gradient map of the northern western desert of egypt using an artificial neural network the northern part of the western desert of egypt represents the second most promising area of hydrocarbon potential after the gulf of suez province an artificial neural network ann approach was used to develop a new predictive model for calculation of the geothermal gradients in this region based on gravity and corrected bottom hole temperature bht data the best training data set was obtained with an ann architecture composed of seven neurons in the hidden layer which made it possible to predict the geothermal gradient with satisfactory efficiency the bht records of 116 deep oil wells 2 000 4 500 m were used to evaluate the geothermal resources in the northern western desert corrections were applied to the bht data to obtain the true formation equilibrium temperatures which can provide useful constraints on the subsurface thermal regime on the basis of these corrected data the thermal gradient was computed for the linear sections of the temperature versus depth data at each well the calculated geothermal gradient using temperature log data was generally 30 c km with a few local high geothermal gradients in the northwestern parts of the study area explained by potential local geothermal fields the bouguer gravity values from the study area ranged from 60 mgal in the southern parts to 120 mgal in the northern areas and exhibited ne sw and e w trends associated with geological structures although the northern western desert of egypt has low regional temperature gradients 30 c km several potential local geothermal fields were found 40 c km the heat flow at each well was also computed by combining sets of temperature gradients and thermal conductivity data aerogravity data were used to delineate the subsurface structures and tectonic framework of the region the result of this study is a new geothermal gradient map of the northern western desert developed from gravity and bht log data

blue ice areas in antarctica derived from noaa avhrr satellite data we have mapped antarctic blue ice areas using the u s national oceanic and atmospheric administration noaa advanced very high resolution radiometer avhrr antarctica cloud free image mosaic established by the united states geological survey the mosaic consists of 38 scenes acquired from 1980 to 1994 our results show that approximately 60 000 km2 of blue ice exist for each of the two main types of blue ice melt induced and wind induced normally the former type is located on slopes in coastal areas where climate conditions i e persistent winds and temperature together with favourable surface orientation sustain conditions for surface and near surface melt the latter blue ice category occurs near mountains or on outlet glaciers often at higher elevations where persistent winds erode snow away year round and combined with sublimation creates areas of net ablation furthermore we have identified an additional area of 121 000 km2 as having potential for blue ice however in these areas features such as mixed pixels glazed snow surfaces crevasses and or shadows make interpretation more uncertain in conclusion a conservative estimate of antarctic blue ice area coverage by this method is found to be 120 000 km2 0 8 of the antarctic continent with a potential maximum of 241 000 km2 1 6 of the antarctic continent

measuring snow and glacier ice properties from satellite satellite remote sensing is a convenient tool for studying snow and glacier ice allowing us to conduct research over large and otherwise inaccessible areas this paper reviews various methods for measuring snow and glacier ice properties with satellite remote sensing these methods have been improving with the use of new satellite sensors like the synthetic aperture radar sar during the last decade leading to the development of new and powerful methods such as sar interferometry for glacier velocity digital elevation model generation of ice sheets or snow cover mapping some methods still try to overcome the limitations of present sensors but future satellites will have much increased capability for example the ability to measure the whole optical spectrum or sar sensors with multiple polarization or frequencies among the methods presented are the satellite derived determination of surface albedo snow extent snow volume snow grain size surface temperature glacier facies glacier velocities glacier extent and ice sheet topography in this review emphasis is put on the principles and theory of each satellite remote sensing method an extensive list of references with an emphasis on studies from the 1990s allows the reader to delve into specific topics

estimation of formation temperature from borehole measurements summary a new numerical method is described for modelling the thermal disturbance around a borehole and a comparison is made with the commonly used line source model the numerical model generally gives an estimate of the equilibrium formation temperature which is up to about 20 per cent higher than the horner plot method the relaxation of the borehole temperature is sensitive to the contrast between the thermal properties of the drilling fluid and of the surrounding rock as well as to the disturbance time the importance of vertical temperature gradients and fluid motion both free convection in the borehole and flow in the formation is also examined it is found that vertical temperature gradients are unlikely to be important provided temperatures are measured more than 10 borehole radii above the bottom convective heat transfer can be important under some drilling conditions

rock properties and seismic attenuation neural network analysis using laboratory data the influence of rock parameters on seismic attenuation has been analyzed using artificial neural networks and regression models the predictive capabilities of the neural networks and multiple linear regresssion were compared the neural network outperforms the multiple linear regression in predicting attenuation values given a set of input of rock parameters the neural network can make complex decision mappings and this capability is exploited to examine the influence of various rock parameters on the overall seismic attenuation the results indicate that the most influential rock parameter on the overall attenuation is the clay content closely followed by porosity though grain size contribution is of lower importance than clay content and porosity its value of 16 percent is sufficiently significant to be considered in the modeling and interpretation of attenuation data

simulation of the madden julian oscillation in a coupled general circulation model part ii the role of the basic state abstract in part i of this study it was shown that air sea coupling had a positive impact on some aspects of the simulation of the madden julian oscillation mjo by a gcm however errors in the basic state climate of that gcm appeared to be preventing the mjo related convection from propagating into the west pacific in this paper the actual impact of these errors will be addressed an integration of a flux adjusted version of the coupled model has been performed which has reduced basic state errors in the west pacific in this version of the coupled gcm the mjo does propagate into the west pacific the simulation of the mjo by a coupled model with the same atmospheric component but a different ocean gcm is also analyzed this coupled gcm has similar systematic errors in low level zonal wind and precipitation to the model studied in part i but with warmer ssts results from this experiment together with the other available evidence suggest that it is the errors in the low level zonal wind component

real time multivariate indices for the boreal summer intraseasonal oscillation over the asian summer monsoon region the boreal summer intraseasonal oscillation bsiso of the asian summer monsoon asm is one of the most prominent sources of short term climate variability in the global monsoon system compared with the related madden julian oscillation mjo it is more complex in nature with prominent northward propagation and variability extending much further from the equator in order to facilitate detection monitoring and prediction of the bsiso we suggest two real time indices bsiso1 and bsiso2 based on multivariate empirical orthogonal function mv eof analysis of daily anomalies of outgoing longwave radiation olr and zonal wind at 850 hpa u850 in the region 10 s 40 n 40 160 e for the extended boreal summer may october season over the 30 year period 1981 2010 bsiso1 is defined by the first two principal components pcs of the mv eof analysis which together represent the canonical northward propagating variability that often occurs in conjunction with the eastward mjo with quasi oscillating periods of 30 60 days bsiso2 is defined by the third and fourth pcs which together mainly capture the northward northwestward propagating variability with periods of 10 30 days during primarily the pre monsoon and monsoon onset season the bsiso1 circulation cells are more rossby wave like with a northwest to southeast slope whereas the circulation associated with bsiso2 is more elongated and front like with a southwest to northeast slope bsiso2 is shown to modulate the timing of the onset of indian and south china sea monsoons together the two bsiso indices are capable of describing a large fraction of the total intraseasonal variability in the asm region and better represent the northward and northwestward propagation than the real time multivariate mjo rmm index of wheeler and hendon

seasonality in the madden julian oscillation abstract this study using observational data and global reanalysis products synthesizes existing knowledge on the seasonality in the madden julian oscillation mjo and discusses its possible dependence on the mean background state the seasonality in the mjo is documented in terms of its components in low level zonal wind and precipitation a single peak season boreal winter exists near the equator in the indian and western pacific oceans for the broad tropical region however the seasonality in the mjo is featured by a latitudinal migration across the equator between two peak seasons the primary peak season is in boreal winter december march during which mjo signals are mainly confined to the indian and western pacific ocean and reach their maxima in the south pacific convergence zone the secondary peak season is boreal summer june september during which the strongest mjo occurs north of the equator from the bay of bengal to the south china sea and another separated region of strong mjo

antarctic surface and subsurface snow and ice melt fluxes abstract this paper presents modeled surface and subsurface melt fluxes across near coastal antarctica simulations were performed using a physical based energy balance model developed in conjunction with detailed field measurements in a mixed snow and blue ice area of dronning maud land antarctica the model was combined with a satellite derived map of antarctic snow and blue ice areas 10 yr 1991 2000 of antarctic meteorological station data and a high resolution meteorological distribution model to provide daily simulated melt values on a 1 km grid covering antarctica model simulations showed that 11 8 and 21 6 of the antarctic continent experienced surface and subsurface melt respectively in addition the simulations produced 10 yr averaged subsurface meltwater production fluxes of 316 5 and 57 4 km3 yr 1 for snow covered and blue ice areas respectively the corresponding figures for surface melt were 46 0 and 2 0 km3 yr 1 respectively thus demonstrating the dominant role of subsurface ov

mjo initiation in the real time multivariate mjo index abstractmadden julian oscillation mjo initiation in the real time multivariate mjo rmm index is explored through an analysis of observed case studies and composite events specific examples illustrate that both the dates of mjo initiation and the existence of the mjo itself can vary substantially among several well known mjo indices depending on whether the focus is on convection or circulation composites of primary mjo initiation events in which the rmm index rapidly increases in amplitude from a non mjo state to an mjo state are presented and are supplemented by two case studies from the 1985 86 winter season results illustrate that for primary mjo initiation events in the indian ocean rmm phase 1 slowly eastward propagating 850 hpa 200 hpa easterly westerly anomalies over the indian ocean precede the amplification of the rmm index by at least 10 days while suppressed convection over the western pacific ocean precedes the amplification by 5 days these local eastern hemispheric prede

the south atlantic convergence zone intensity form persistence and relationships with intraseasonal to interannual activity and extreme rainfall abstract the characteristics of intensity geographical location and persistence of the south atlantic convergence zone sacz during the austral summer are investigated intensity and spatial features of the sacz are identified by performing a factor analysis of structural properties of outgoing longwave radiation olr data the first two leading factors explain 65 of the total variance of structural properties and characterize the sacz according to intensity and location oceanic versus continental an index is constructed based on the magnitude of the factor scores to identify intense weak and oceanic continental sacz the intense sacz category is associated with negative olr anomalies over a large area of tropical south america extending from the western amazon to the atlantic ocean the weak sacz category is observed with positive olr anomalies over tropical south america and negative olr anomalies over southeastern south america oceanic and continental aspects of the sacz are related to a

geothermal resources in egypt integrated with gis based analysis abstract the energy of egypt is generally derived from petroleum products however advancements in the development of the generation capacity using sustainable and renewable resources for example solar wind and geothermal resources and investment in nuclear power plants are planned the geology and structure setting of egypt affirms that reasonable geothermal resources are available particularly along the gulf of suez the red sea the western desert and parts of the nile valley the main objective of this research is to develop a geothermal favourability map of egypt which may be considered as a screening tool for the assessment of optimal areas for geothermal development digital data layers and maps were employed in a gis model to select the most promising areas for geothermal potentiality the arcgis model includes six thematic layers distance to faults bouguer anomaly distance to seismic activity curie depth heat flow and temperatures at different depths the validation of the generated geothermal favourability map was performed by a comparison with thermal water wells and hot springs generally the most encouraging zones for geothermal probability in egypt are located near the shorelines of the gulf of suez and the red sea

subsurface structural features of the basement complex and geothermal resources using aeromagnetic data in the bahariya oasis western desert egypt egypt gives priority to western desert in land reclamation and sustainable development projects the bahariya oasis a northernmost oasis of egypt is closer to the capital compared to other remote oases and represents the most interesting potential candidates for the sustainable development many researches provide insight into the hydrogeology and structural geology of the bahariya oasis however very few attempts have been done to investigate its geothermal potentiality the aim of present study is to reflect the geothermal resources of the bahariya oasis encountered with the predominant structures utilizing aeromagnetic and borehole data the main subsurface structures and the depth to basement map were retrieved from the 2d modelling of the aeromagnetic data the results of the 2d models were verified by well stratigraphic data spectral analysis of the aeromagnetic data was applied to estimate the curie point depth cpd and to produce geothermal gradient and heat flow maps for the bahariya oasis the results of the study indicated that the depth to the basement rocks in the area ranges from 0 6 to 4 0 km the cpd is 15 km in the central parts and increases to 24 km eastward the geothermal gradient varies from 20 to 35 c km with an average 30 c km however the heat flow changes from 60 to 100 m w m2 with an average of 90 m w m2 these results in addition to basement structures imply a high temperature gradient and heat flow correlating with shallow curie depths the results are in agreement with previous work in the same region

circulation response to fast and slow mjo episodes abstractfast and slow madden julian oscillation mjo episodes have been identified from 850 and 200 hpa zonal wind and outgoing longwave radiation olr for 32 winters 16 october 17 march 1980 81 2011 12 for 26 fast cases the olr took no more than 10 days to propagate from phase 3 convection over the indian ocean to phase 6 convection over the western pacific for 8 slow cases the propagation took at least 20 days fast episode composite anomalies of 500 hpa height z500 show a developing rossby wave in the mid pacific with downstream propagation through mjo phases 2 4 changes in the frequency of occurrence of the nao weather regime are modest this rossby wave is forced by anomalous cooling over the maritime continent during phases 2 and 3 seen in phase independent wave activity flux the upper level anticyclonic response to phase 3 heating is a secondary source of wave activity the z500 slow episode composite response to mjo phases 1 and 2 is an enhanced aleutian low followed by a north a

intraseasonal periodicities in indian rainfall abstract spectral analysis of a 70 year 1901 70 record of daily precipitation from 3700 stations in the country of india is carried out to search for periodicities on subseasonal time scales during the summer monsoon two statistically significant spectral peaks are found a 40 50 day spectral peak corresponding to the madden julian oscillation is found over most of the portion of india south of 23 n the phase of the oscillation is such that the precipitation maximum appears first over the relatively dry southeastern portion of the peninsula ten to 12 days later the precipitation peaks simultaneously all along the coast west of the western ghats and along a line running across india between 20 and 25 n the precipitation maximum then spreads slowly northward and loses significance cross spectral analysis shows strong coherence between the precipitation patterns and wind oscillations the zonal wind oscillations at 850 and 200 mb am about 180 degrees out of phase equatorward of about 20 n but in pha

uranium isotopic study of artesian and pluvial contributions to the nubian aquifer western desert egypt the groundwater systems of the nubian aquifer beneath six major oases baris kharga dakhla farafra bahariya and siwa in the western desert of egypt have been studied to establish their sources and mixing volumes using uranium isotopes one hundred six groundwater samples from different depths of the nubian aquifer have been analyzed for uranium content and 234u 238u activity ratio ar the aquifer under the western desert is known to have more than one source of water at bahariya and farafra oases the nubian artesian water migrating from the south has been augmented by local recharge during pluvial times at siwa oasis in the northwestern desert a shallower aquifer component migrating from the north or west is also present at dakhla kharga and baris oases in the southwestern desert the main source is the nubian artesian water migrating from southeast uweinat upland and northwest sudan these water masses have distinctive uranium isotopic signatures the nubian aquifer water is characterized by very low u concentrations 1 5 the shallow northwest aquifer water also has a high ar but a much higher u concentration the locally recharged pluvial waters have high u concentrations 0 1 ppb but low ars near unity a diagnostic derivative parameter is excess 234u content the deep nubian aquifer water is characterized by a relatively low excess 234u 0 02 ppb equivalent while the shallow siwa water has a very high excess 234u ar 1 u conc the bahariya and farafara waters are also high in this component probably because of pluvial water percolation through phosphate rich strata at all oases u isotopic mixing diagrams show that the deep aquifer sources predominate however the pluvial contributions are significant ranging from about 5 at remote baris oasis to about 26 at the more northerly farafra oasis the observed lowering of potentiometric surfaces in the western desert is caused not only by pumping at a rate greater than inflow from the aquifer systems but also by the withdrawal of pluvial water which in modern times is not being replaced at all

stabilization of bottom hole temperature with finite circulation time and fluid flow summary as an alternative to finite element or finite difference modelling analytical solutions are derived by the method of laplace transformation and numerical results obtained for several models of the bottom hole temperature stabilization included in the models are the finite circulation time the thermal property contrast between the borehole mud and the surrounding formation and the presence of radial or lateral fluid flow in the formation all of which are found to have significant effects on the dissipation of the thermal disturbance induced by drilling the mud circulation is considered to have the effect of either maintaining the borehole mud at a constant temperature or supplying a constant amount of heat per unit length per unit time to the borehole for small circulation times the former reduces to the zero circulation model in which the mud circulation creates an instantaneous temperature anomaly at the hole bottom for small borehole radii the latter reduces to the line source model and the traditional horner plot for typical drilling operations in which the bottom hole temperatures are measured several hours to several tens of hours after the hole is shut in the new models generally predict higher equilibrium formation temperatures than does the horner plot however predictions from the various models converge if the bhts are taken after the hole has been shut in for a period which is greater than about five times the circulation period

a naive zero dimensional sea ice model a single observation of the microwave brightness temperature over sea ice cannot determine the composition of the ice surface in terms of the three constituents open water first year ice and multiyear ice the ambiguity can be removed by interpreting the time series of brightness temperatures at a fixed location in the context of a model of how the composition evolves in time a model is discussed which includes the effects of ice growth melting deformation and aging the aging process accounts for the change of first year ice into multiyear ice at the beginning of the cold season the model reproduces the annual cycle of brightness temperature a procedure based on kalman filtering is presented for estimating the fractional areas of the three surface types the procedure combines the model of ice evolution with the time series of brightness temperatures the estimation errors are in the range 2 12 these methods can be used with existing passive microwave data to construct a climatology of sea ice based on the three type classification it is also possible to use the observations to improve model parameters such as the rate of melting and the rate of creation of open water by mechanical processes

application of an artificial neural network model to a na k geothermometer abstract a new geothermometer model is proposed by applying data obtained from a known na k geothermometer to an artificial neural network in this model na and k values were implemented as input signals and geothermometers as the output signal multi layer perceptrons and back propagation were used as training algorithms for the artificial neural network reservoir temperatures of some geothermal fields in turkey determined by this method are in accord with those determined from other methods

barrier effect of the indo pacific maritime continent on the mjo perspectives from tracking mjo precipitation abstractexplanations for the barrier effect of the indo pacific maritime continent mc on the mjo should satisfy two criteria first they should include specific features of the mc namely its intricate land sea distributions and elevated terrains second they should include mechanisms for both the barrier effect and its overcoming by some mjo events guided by these two criteria a precipitation tracking method is applied to identify mjo events that propagate across the mc mjo c and those that are blocked by the mc mjo b about a half of mjo events that form over the indian ocean propagate through the mc most of them 75 become weakened over the mc the barrier effect cannot be explained in terms of the strength horizontal scale or spatial distribution of mjo convection when it approaches the mc from the west a distinction between mjo b and mjo c is their precipitation over the sea versus land in the mc region mjo c events rain much more over the sea than over land whereas rainfall over

a combined wave number frequency and time extended eof approach for tracking the progress of modes of large scale organized tropical convection an algorithm combining filtering in the wave number frequency domain with time extended empirical orthogonal function eeof analysis is developed and applied to diagnose and track signals associated with modes of organized moist deep convection in the tropics the wave number frequency spectrum of outgoing long wave radiation olr is broken down into five broad filter bands in order to concentrate signals associated with the madden julian oscillation convectively coupled equatorial rossby kelvin and mixed rossby gravity waves easterly waves and low frequency variations such as the el nino southern oscillation enso the eeof patterns are obtained from analysis of the filtered data and principal component pc time series are generated by projection of temporally smoothed but otherwise unfiltered data onto the eeof patterns filtered data are reconstructed by taking the product of the eeof patterns and the corresponding pcs these reconstructed data compare well with unfiltered olr anomalies and with olr anomalies filtered in the wave number frequency domain for the same modes the method is easily applied in real time since results are not influenced by the proximity to the end of the dataset copyright 2009 royal meteorological society

spectral signature of alpine snow cover from the landsat thematic mapper mapping of snow and estimation of snow characteristics from satellite remote sensing data require that we distinguish snow from other surface cover and from clouds and compensate for the effects of the atmosphere and rugged terrain the spectral signature of the snowpack is calculated from a radiative transfer model accounting for scattering and absorption by the ice grains water inclusions and particulates in interpreting the spectral reflectance measured from the thematic mapper or from any other satellite we need to account for topographic effects without requiring that satellite data be precisely registered to digital elevation data because the poor quality of most digital elevation data introduces considerable noise into calculations of slope and azimuth for a range of snow types atmospheric profiles and topographic illumination conditions i estimate typical spectral signatures for the landsat thematic mapper tm images of the southern sierra nevada are analyzed to distinguish several classes of snow from other surface covers snow can be reliably distinguished from other surfaces and from clouds at all sun angles encountered in the mid latitudes in tm band 1 or 2 snow is brighter than other natural surfaces and in band 5 clouds are usually much more reflective than snow therefore the intersection of the following criteria maps the snow cover planetary reflectance rp in tm band 1 is greater than about 0 16 rp tm5 is less than about 0 2 the normalized band 2 5 difference rp tm2 rp tm5 rp tm2 rp tm5 is greater than about 0 4 large surface grain sizes can be distinguished from areas where the grain size is finer at the snow surface using tm bands 2 4 and 5 because of saturation in tm band 1 estimation of the degree of contamination by absorbing aerosols is not feasible rp tm2 rp tm5 rp tm2 rp tm5 is

the 30 50 day variation of convective activity over the western pacific ocean with emphasis on the northwestern region abstract coherent 30 50 day oscillations between regions north and south of 20 n were observed using the latitude time y t diagram of a convective index ic along 140 e over the entire 1979 summer may september the oscillation in the northern region exhibits a relatively regular north south movement of deep convective clouds while the oscillation in the southern region shows enhancement or suppression fluctuations of broad and intensive deep convective clouds with a period of 30 50 days the southward northward movement of the midlatitude oscillation coincides with the suppression enhancement of the tropical deep convective clouds the midlatitude deep convective clouds are usually maintained by the divergent circulation and are associated with fronts the empirical orthogonal function eof analysis of velocity potential at 200 mb shows that the north south 30 50 day oscillation of deep convective clouds over the northwestern pacific is a response of the regional weather system to the eastwar

tracking of tropical intraseasonal convective anomalies 1 seasonality of the tropical intraseasonal oscillations a tracking algorithm based upon a multiple object tracking method is developed to identify track and classify tropical intraseasonal oscillations tiso on the basis of their direction of propagation daily national oceanic and atmospheric administration outgoing longwave radiation anomalies from 1979 2017 are lanczos band pass filtered for the intraseasonal time scale 20 100 days and spatially averaged with nine neighboring points to get spatially smoothed anomalies over large spatial scales 105 km2 tiso events are tracked by using a two stage kalman filter predictor corrector method two dominant components of the tiso eastward propagating and northward propagating are classified and it is found that tiso remains active throughout the year eastward propagating tiso events occur from november to april with a phase speed of 4 m s and northward propagating tiso events occur from may to october with a phase speed of 2 5 m s in both the indian and pacific ocean basins composites of the mean background states wind sea surface temperature sst and moisture reveal that the co occurrence of warm sst and mean westerly zonal wind plays an important role in the direction of propagation and the geographical location of tiso events in mean state sensitivity experiments with sp cam4 we have found that the seasonality of tiso in terms of the geographical location of occurrences and direction of propagation is primarily associated with the annual march of the maximum sst and low level zonal wind which tends to follow the sst

the boreal summer intraseasonal oscillation relationship between northward and eastward movement of convection the summertime intraseasonal oscillation iso is an important component of the south asian monsoon lagged regressions of intraseasonally filtered 25 80 days outgoing longwave radiation olr reveal that centers of convection move both northward and eastward from the central equatorial indian ocean subsequent to the initiation of an iso eastward movement of convection is also seen at indian subcontinent latitudes 10 8 208n based on the regression results the summertime iso convection signal appears as a band tilting northwestward with latitude and stretching from the equator to about 208n viewed along any meridian convection appears to propagate northward while equatorial convection propagates to the east to examine the robustness of the connection between eastward and northward movement individual isos are categorized and composited relative to the strength of the large scale eastward component of convection in the central equatorial indian ocean it is found that the majority of isos that exhibit northward movement onto the indian subcontinent 42 out of 54 isos or 78 also exhibit eastward movement into the western pacific ocean it is also found that when convection in the central indian ocean is not followed within 10 20 days by convection in the western pacific ocean 12 out of 54 isos or 22 the independent northward movement of convection in the indian ocean region is somewhat stunted the link between the eastward and northward movement of convection is consistent with an interpretation of the summertime iso in terms of propagating equatorial modes the northward moving portion of convection is forced by surface frictional convergence into the low pressure center of the rossby cell that is excited by equatorial iso convection a similar convergence pattern is seen for the northern winter iso but it does not generate poleward movement due to relatively cool ssts underlying the surface convergence

stabilization of bottom hole temperature in the presence of formation fluid flows reliable estimates of bottom hole temperature bht in oil wells are of considerable interest in reservoir engineering problems as well as in geothermal research because bht measurements are usually made soon after drilling true formation temperature can be obtained only by correcting for the effects of drilling disturbances the magnitude of drilling disturbance depends upon duration of drilling time elapsed after stoppage of drilling well characteristics thermal properties of drilling fluid and the nature of heat exchange between the well and the formation

dynamics of breaks in the indian summer monsoon abstract in this paper the authors present results of diagnostic analysis of observations and complementary experiments with a simple numerical model that enable them to synthesize the morphology and dynamics of breaks in the indian summer monsoon ism almost one week ahead of the onset of a break spell over india a monotonically decreasing trend in convective activity is found to occur over the bay of bengal in response to a steady eastward spreading of dry convectively stable anomalies from the equatorial indian ocean a major intensification of the convectively stable anomalies over the bay of bengal is seen about 2 3 days prior to commencement of a monsoon break both observations and modeling experiments reveal that rapid northwest propagating rossby waves are triggered in response to such a large strengthening of the convectively stable anomalies it is shown that an abrupt movement of anomalous rossby waves from the bay of bengal into northwest and central india marks the initiation of a break

the generation of global rotational flow by steady idealized tropical divergence abstract tropical convective heating is balanced on the large scale by the adiabatic cooling of ascent the horizontal divergence of the wind above this heating may be viewed as driving the upper tropospheric rotational wind field a vorticity equation model is used to diagnose this relationship it is shown that because of the advection of vorticity by the divergent component of the flow the rossby wave source can be very different from the simple fd source often used in particular an equatorial region of divergence situated in easterly winds can lead to a rossby wave source in the subtropical westerlies where it is extremely effective this part of the source can be relatively insensitive to the longitudinal position of the equatorial divergence a divergence field which is asymmetric about the equator can lead to a quite symmetric rossby wave source for a steady frictionless flow the rossby wave source averaged over regions within closed streamfunction or absolute vorticity contours is under cert

mechanisms of monsoon low frequency variability surface hydrological effects abstract observations indicate that monsoon systems are characterized by orderly large scale and low frequency variations with a time scale of two weeks and sometimes longer regions of ascending motion are observed to form to the north of the equator and propagate slowly northward across southeast asia the propagation appears to be associated with the active break sequence of the summer monsoon which acts as a modulator on the activity of the synoptic scale disturbances a zonally symmetric non linear two layer model containing an interactive ocean and a continent poleward of 18 n is used to investigate the mechanisms which produce the observed low frequency variability only when a full hydrology cycle is considered does the model product variations which resemble the observed structures mechanisms are traced to include the interaction of the components of the total heating function the sensible heat input in the boundary layer although considerably smaller than the other heating components de

propagating and standing components of the intraseasonal oscillation in tropical convection abstract two questions related to the intraseasonal variability of tropical convection and circulation remain controversial 1 to what degree is the convective component of the madden julian oscillation mjo a standing oscillation 2 is the eastward propagating circulation anomaly of the mjo coherent with a standing oscillation in convection in an attempt to settle these issues the authors undertake a series of statistical analyses of gridded outgoing longwave radiation and winds to quantify the magnitudes of the propagating and standing components of convection and their coherence with the propagating component of the circulation they demonstrate that no dominant standing oscillation in convection can be identified instead intraseasonal variability of convection is dominated by an eastward propagating mode which the authors interpret as the convective signal of the mjo this propagating component accounts for almost all of the convective variance that is coherent with the eastward propagating di

the south to north progression of rainfall anomalies across india during the summer monsoon season the low frequency spatio temporal intraseasonal evolution of monsoon rainfall over india is studied by considering the pentad rainfall averages taken over 2 5 wide and 5 0 long blocks lying across the central longitudinal and latitudinal transacts the time latitude cross sections show south to north progressions of rainfall anomalies with a recurrence period of about 40 days the progressions show considerable inter annual and intra seasonal variation in frequency amplitude and rate of progression the extended empirical orthogonal function analysis shows that the first two most important functions correspond to this northward progression of rain anomalies recurring after an interval of about 40 days the rate of progression of anomalies is about 0 5 lat day the time longitude cross sections show the movement of rainfall anomalies towards both directions east and the west with slight preference towards the east the importance of these signals in rainfall forecasting is foreseen

reflectances of glaciers as calculated using landsat 5 thematic mapper data landsat 5 thematic mapper tm data have been used in previous work in order to locate zones of similar spectral reflectance on glaciers in austria and alaska and to relate these zones to the glacier facies which are indicative of glacier mass balance in this paper landsat 5 digital numbers dns have been used to compute the at satellite planetary reflectances p on spectrally similar zones on the meares and schwanda glaciers in alaska and the grossglockner glacier group in austria the patterns of tm derived reflectances in the ablation areas of the grossglockner glacier group and the meares glacier compare favorably with published reflectance curves measured on the surface of glacier ice though the surface reflectance of snow covered ice is higher than the landsat derived reflectance for the glaciers studied the accuracy of the at satellite planetary reflectances is shown to be affected by topographic and atmospheric effects and by the anisotropic nature of snow reflectance use of reflectance values for analysis of snow and ice facilitates scene to scene comparisons of glaciers

intraseasonal behavior of clouds temperature and motion in the tropics abstract the spectral character of tropical convection is investigated in an 11 yr record of outgoing longwave radiation from the advanced very high resolution radiometer to identify interaction with the tropical circulation along the equator in the eastern hemisphere the space time spectrum of convection possesses a broad peak at wave numbers 1 3 and eastward periods of 35 95 days significantly broader than the dynamical signal of the madden julian oscillation mjo this quasi discrete convective signal is associated with a large scale anomaly that propagates across and modulates time mean or climatological convection over the equatorial indian ocean and western pacific outside that region the convective signal is small even though under amplified conditions coherence can be found east of the date line and in the subtropics having a zonal scale of approximately wavenumber 2 anomalous convection propagates eastward at some 5 m s 1 and suppresses as well as reinforces climatological convection

regional geothermal exploration in egypt although egypt is not characterized by abundant cenozoic igneous activity its location in the northeastern corner of the african plate suggests that it may possess geothermal resources especially along its eastern margin regional geothermal exploration has been carried out in egypt using the thermal gradient heat flow technique and groundwater temperature chemistry technique in the thermal gradient heat flow study existing oil well bottom hole temperature data as well as subsurface temperature measurements in existing boreholes were utilized before special thermal gradient holes were drilled groundwater temperature and chemistry data were used to extend the geographic range of the direct subsurface thermal measurements on a very modest budget a regional thermal high has been discovered along the eastern margin of egypt and a local thermal anomaly has been discovered in this zone published geological information suggests that the sandstones of the nubian formation may be a suitable reservoir for geothermal fluids the new data indicate that temperatures of 150 sup 0 c or higher may be found in this reservoir in the gulf of suez and red sea coastal zone where it lies at a depth of 4 km and deeper

a model for the boreal summer intraseasonal oscillation abstract the tropical intraseasonal oscillation iso exhibits pronounced seasonality the boreal summer iso is more complex than its winter counterpart due to the coexistence of equatorial eastward off equatorial westward and northward propagating low frequency modes and their interactions based on observational evidence and results obtained from numerical experiments a mechanism is proposed for the boreal summer iso in which the northern hemisphere summer monsoon nhsm circulation and moist static energy distribution play essential roles with a climatological july mean basic state the life cycle of model low frequency waves consists of four processes an equatorial eastward propagation of a coupled kelvin rossby wave packet an emanation of moist rossby waves in the western pacific a westward propagation and amplification of the rossby waves in south asian monsoon regions and a reinitiation of the equatorial disturbances over the central indian ocean the life cycle spans about one month and p

origin of low frequency intraseasonal oscillations in the tropical atmosphere iii monsoon dynamics abstract this is the third in a series of papers to study the origin of intraseasonal oscillations in this paper we address the issue of the interaction of the monsoon large scale circulation and intraseasonal oscillations we show that as a result of the interaction of the large scale monsoon flow with the near equatorial intraseasonal oscillation unstable baroclinic disturbances are generated over the monsoon region these disturbances have spatial scales of approximately 3000 4000 km and periods of 5 6 days with the vertical wave axis tilting eastward with height the rapid development of these cyclonic disturbances along 15 20 n and the concomitant weakening of the equatorial disturbances are accompanied by the rapid northward shift of the rising branch of the local hadley circulation they may also be identified with the observed sudden jump of the mei yu rainband over east asia and the inverse relationship between the monsoon itcz and the equatorial itcz over india and east asia from a linear s