effect of concentration of dispersed organic matter on optical maturity parameters interlaboratory results of the organic matter concentration working group of the iccp abstract the main objective of this work was to study the effect of the kerogen isolation procedures on maturity parameters of organic matter using optical microscopes this work represents the results of the organic matter concentration working group omcwg of the international committee for coal and organic petrology iccp during the years 2008 and 2009 four samples have been analysed covering a range of maturity low and moderate and terrestrial and marine geological settings the analyses comprise random vitrinite reflectance measured on both kerogen concentrate and whole rock mounts and fluorescence spectra taken on alginite eighteen participants from twelve laboratories from all over the world performed the analyses samples of continental settings contained enough vitrinite for participants to record around 50 measurements whereas fewer readings were taken on samples from marine setting the scatter of results was also larger in the samples of marine origin similar vitrinite reflectance values were in general recorded in the whole rock and in the kerogen concentrate the small deviations of the trend cannot be attributed to the acid treatment involved in kerogen isolation but to reasons related to components identification or to the difficulty to achieve a good polish of samples with high mineral matter content in samples difficult to polish vitrinite reflectance was measured on whole rock tended to be lower the presence or absence of rock fabric affected the selection of the vitrinite population for measurement and this also had an influence in the average value reported and in the scatter of the results slightly lower standard deviations were reported for the analyses run on kerogen concentrates considering the spectral fluorescence results it was observed that the max presents a shift to higher wavelengths in the kerogen concentrate sample in comparison to the whole rock sample thus revealing an influence of preparation methods acid treatment on fluorescence properties

radiative dynamical consequences of dry tongues in the tropical troposphere abstract dry layers are frequently observed in atmospheric soundings from the climatologically humid western pacific warm pool region some 2400 soundings from the toga coare field program were objectively examined for humidity drops layers in which relative humidity decreases rapidly with height indicative of the bases of dry layers these occur throughout the lower and middle troposphere with frequency peaks near 550 the 0 c level 800 and 950 mb a composite constructed from these sounding data indicates the following almost all dry layers are too dry and not warm enough to be interpreted as conservative vertical displacements rather they apparently consist of filaments or tongues of low moist static energy air advected into the column often from the subtropics dry tongues are anomalously virtually warm near their bases with a slight cool layer below that is they sit atop sharp stable layers or inversions the authors hypothesize that radiation is responsible for the thermal structure o

a comparison of vitrinite reflectance measurements made on whole rock and dispersed organic matter concentrate mounts abstract a comparison of mean random vitrinite reflectance r v r values calculated from measurements on polished whole rock and on concentrates of dispersed organic matter dom mounts of the same samples generally show little difference compared to measurements on dom mounts r v r measurements by the same microscopist on corresponding whole rock samples are up to a few tenths of a percent lower over the range of 0 6 3 2 r v r and have a slightly higher standard deviation whole rock mounts have an advantage over dom mounts in the identification of first cycle vitrinite and differentiation of solid bitumen from vitrinite

observations of tropical precipitating clouds ranging from shallow to deep convective systems 1 regional and temporal variability in a broad spectrum of tropical precipitation systems is investigated in conjunction with the large scale environment the analysis utilizes four storm categories shallow cumulus congestus deep stratiform and deep convective determined from tropical rainfall measuring mission trmm measurements deep stratiform and deep convective systems are found to be clearly correlated with large scale circulation deduced from a reanalysis data set and are modulated by a distinct seasonal cycle over land the shallow category is practically the only component of tropical oceanic rainfall for cold sea surfaces while it gives way to deeper systems as sst exceeds 28 29 c the cloud horizontal scale of organized rainfall systems tends to be increasingly extensive relative to the raining portion as the system becomes larger the present results are discussed in light of existing relevant studies

standardization of reflectance measurements in dispersed organic matter results of an exercise to improve interlaboratory agreement vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation however until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale efforts to correct this deficiency resulted in publication of astm d7708 standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks i n 2012e2013 an interlaboratory exercise was conducted to establish precision limits for the d7708 measurement

the vertical structure of toga coare convection part i radar echo distributions radar data collected by the 5 cm mit radar which was deployed aboard the r v vickers during the intensive observing period of the tropical ocean global atmosphere coupled ocean atmosphere response experiment are partitioned into convective and stratiform cartesian grid columns the vertical structure of convective echo is examined through the use of two variables echo top height and the height of the 30 dbz reflectivity contour the first of these variables has traditionally been used to describe the vertical structure characteristics of convection and the second has recently been linked to internal microphysical properties and lightning histograms of the relative frequency of convective only echo top heights and 30 dbz contour heights were constructed for the three cruises of the vickers with each cruise experiencing different phases of the intraseasonal oscillation iso cruise 1 which was dominated by the convectively inactive phase of the iso was characterized by the highest frequency of shallow convection based on echo top heights whereas cruise 2 which was dominated by a particularly well defined passage of the convective phase of the iso exhibited the tallest echo top heights cruise 3 convection was influenced by moderate westerly surface winds characteristic of postwesterly wind burst conditions and convection was of intermediate height when viewed as a function of internal vertical structure i e 30 db z contour height the frequency distributions vary less from cruise to cruise with cruises 1 and 2 having nearly identical distributions of convective 30 dbz contour heights furthermore when the contribution to convective rainfall is examined as a function of 30 dbz contour height it is seen that relatively more rain fell from vertically intense convection i e convection with tall 30 dbz contours during cruises 1 and 3 than during cruise 2 instantaneous correlations between rainfall rate and radar echo height were highly scattered about a mean value of about 0 55 whereas rainfall rate and 30 dbz contour height correlations peaked at about 0 8 and exhibited much less scatter

vertical diabatic heating structure of the mjo intercomparison between recent reanalyses and trmm estimates abstractcapitalizing on recently released reanalysis datasets and diabatic heating estimates based on tropical rainfall measuring mission trmm the authors have conducted a composite analysis of vertical anomalous heating structures associated with the madden julian oscillation mjo because diabatic heating lies at the heart of prevailing mjo theories the intention of this effort is to provide new insights into the fundamental physics of the mjo however some discrepancies in the composite vertical mjo heating profiles are noted among the datasets particularly between three reanalyses and three trmm estimates a westward tilting with altitude in the vertical heating structure of the mjo is clearly evident during its eastward propagation based on three reanalysis datasets which is particularly pronounced when the mjo migrates from the equatorial eastern indian ocean eeio to the western pacific wp in contrast this vertical tilt in heating structure is not readily seen in the three trmm product

the central pacific near equatorial convergence zone the central pacific near equatorial convergence zone cz lies north of the equator throughout the year on an average it moves between 4 n in spring and 8 n in autumn probably in response to annual variation in the strengths of the northeast and southeast trade winds for 6 weeks in the period november 1977 to january 1978 a noaa p 3 research aircraft flew between hawaii and tahiti southward along 150 w and northward along 158 w at a frequency of one round trip per week during this time the cz lay near its climatological latitude late season north pacific and early season south pacific tropical cyclones caused the cz to be more variable than usual especially along 158 w the aircraft flew at an altitude of 250 m between 11 n and 0 5 s and the data from these segments of the flights have made possible an examination of the cz in unprecedented detail high resolution satellite images high and low cloud movement vectors soundings from several island stations and soundings made by the aircraft while it descended to and ascended from the low level segments were all used to determine the large and small scale influences on the cz at the time of each traverse from the aircraft data time series of selected variables and time latitude sections showing variables averaged over 1 4 latitude were plotted the types of cz s encountered had several common features and yet were remarkably diverse ten s averages revealed that the cz was almost always clearly delineated by abrupt changes in temperature and humidity in many cases convergence and rainfall were greatest at these boundaries while divergence was large somewhere between narrow zones with low moist static energy were frequently encountered within the cz indicating that a midtropospheric dry layer and compensating sinking existed within the cz a region which had been commonly thought to be merely a funnel for moist surface air to be moved to the upper troposphere where the energy of condensation is exported to higher latitudes measurements from the gust probe showed that turbulent fluxes of sensible and latent heat were not necessarily greatest in the cz implying that the associated sea surface temperature maximum did not regulate the position or intensity of the convergence zone there are indications that the upper troposphere played an important role soundings showed that the trade wind inversion extended to the latitude of the cz without significant change in height along the trade wind trajectory the inversion may even extend across the cz and thus inhibit deep convection at least in the central pacific it appears that the cz may make only a small contribution to the hadley cell and have little effect on mid latitude circulations

influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter comparative exercise using data from the qualifying system for reflectance analysis working group of iccp the development of a qualifying system for reflectance analysis has been the scope of a working group within the international committee for coal and organic petrology iccp since 1999 when j koch presented a system to qualify vitrinite particles according to their size proximity to bright components and homogeneity of the surface after some years of work aimed at improving the classification system using photomicrographs it was decided to run a round robin exercise on microscopy samples the classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites this paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed results indicated that the reflectance of particles classified as excellent good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed the differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants overall satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed this was so for samples having abundant and easy to identify vitrinites higher plant derived organic matter as well as for samples with scarce and difficult to identify particles samples with dominant marine derived organic matter the highest discrepancies were found for the organic rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult special instructions should be provided for the analysis of this sort of samples the certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation the same statistical approach as that followed in the iccp vitrinite reflectance accreditation program for single seam coals has been used for data evaluation the results indicated low to medium dispersion for 17 out of 22 participants this combined with data from other sets of comparative analyses over a long period is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter

geologic constraints on rain fed qocha reservoir agricultural infrastructure northern lake titicaca basin peru this paper reports new data on qocha ponds from the rio pucaraeazangaro interfluvial zone northern lake titicaca basin peru qocha are a little known form of andean agriculture that developed around 800e500 b c and remain in use today prior estimates suggested that in the study area there were more than 25 000 qocha while most andean sunken beds are excavated to reach groundwater qocha are rainfed ponds how these rain fed ponds functioned has been an open question but one that is answered in part by research presented in this paper we suggest that a thick impermeable stratum of clay that was possibly deposited by paleolake minchin created a perched water table that makes rain fed qocha reservoir agriculture possible field geology shows that within the study area this stratum only exists under terrace e based on this model we hypothesized that persistently used qocha should only be found on terrace e to test this hypothesis we used remotely sensed data to inventory qocha and to determine their distribution by each terrace present we identified 11 737 qocha by area 93 77 and by count 94 33 of the qocha are located on terrace e these results strongly supported our hypothesis this case study illustrates that the long term viability of this form of agriculture is made possible by a physical context that is beyond human control

trmm radar observations of shallow precipitation over the tropical oceans abstract observations from the precipitation radar aboard the tropical rainfall measuring mission satellite provide the first opportunity to map vertical structure properties of rain over the entire tropics and subtropics storm height histograms reveal a distinct bimodal distribution over the oceans with the lowest mode near 2 km and the upper mode at 5 km the low mode is the dominant feature over regions previously associated with precipitating marine stratocumulus stratus and trade wind cumulus in those regions a lognormal distribution fits the observed storm height distributions quite well and a strong correlation exists between conditional mean rainfall rate and storm height in addition the low mode appears within the major tropical convergence zones associated with significant precipitation and in those regions a mixed lognormal distribution is used to separate the storm height distribution into two parts shallow and deep in this exploratory analysis the correlation between rainfall intensi

organic geochemistry and petrology of subsurface paleocene eocene wilcox and claiborne group coal beds zavala county maverick basin texas usa abstract coal samples from a coalbed methane exploration well in northern zavala county maverick basin texas were characterized through an integrated analytical program the well was drilled in february 2006 and shut in after coal core desorption indicated negligible gas content cuttings samples from two levels in the eocene claiborne group were evaluated by way of petrographic techniques and rock eval pyrolysis core samples from the paleocene eocene indio formation wilcox group were characterized via proximate ultimate analysis in addition to petrography and pyrolysis two indio formation coal samples were selected for detailed evaluation via gas chromatography and fourier transform infrared ftir and 13c cpmas nmr spectroscopy samples are subbituminous rank as determined from multiple thermal maturity parameters elevated rank relative to similar age coal beds elsewhere in the gulf coast basin in the study area is interpreted to be a result of stratigraphic and or structural thickening related to laramide compression and construction of the sierra madre oriental to the southwest vitrinite reflectance data along with extant data suggest the presence of an erosional unconformity or change in regional heat flow between the cretaceous and tertiary sections and erosion of up to 5 km over the cretaceous the presence of liptinite rich coals in the claiborne at the well site may indicate moderately persistent or recurring coal forming paleoenvironments interpreted as perennially submerged peat in shallow ephemeral lakes with herbaceous and or flotant vegetation however significant continuity of individual eocene coal beds in the subsurface is not suggested indio formation coal samples contain abundant telovitrinite interpreted to be preserved from arborescent above ground woody vegetation that developed during the middle portion of mire development in forested swamps other petrographic criteria suggest enhanced biological chemical and physical degradation at the beginning and end of indio mire development fluorescence spectra of sporinite and resinite are consistent and distinctly different from each other attributed to the presence of a greater proportion of complex asphaltene and polar molecules in resinite gas chromatography of resinite rich coal shows sesquiterpenoid and diterpenoid peaks in the c14 17 range which are not present in resinite poor coal quantities of extracts suggest bitumen concentration below the threshold for effective source rocks 30 50 mg hydrocarbon g total organic carbon hc g toc saturate aromatic and pristane phytane pr ph ratios are different from values for nearby tertiary reservoired crude oil suggesting that the indio coals are too immature to source liquid hydrocarbons in the area however moderately high hi values 200 400 mg hc g rock may suggest some potential for naphthenic paraffinic oil generation where buried more deeply down stratigraphic structural dip extractable phenols and c20 alkanes are suggested as possible intermediates for acetate fermentation in microbial methanogenesis which may however be limited by poor nutrient supply related to low rainfall and meteoric recharge rate or high local sulfate concentration

thermal maturity assessment study of the late pliensbachian early toarcian organic rich sediments in southern france grands causses quercy and pyrenean basins abstract thermal maturity of late pliensbachian early toarcian organic rich sediments in the grands causses sueges section quercy caylus section and pyrenean pont de suert section basins was determined through multiple parameters including spore coloration index sci hydroid random reflectance hrr and spectral fluorescence of tasmanites algae max the main objective of this study is to test the effectiveness and make comparisons of organic matter thermal maturity in these three sections by different techniques and particularly hydroid reflectance for the sueges section sci presented a value of 3 5 4 0 hrr ranges between 0 36 and 0 47 which corresponds to 0 45 0 52 vreq and shows a good correlation with sci values spectral fluorescence analysis presents a max of 560 nm for most samples the fluorescence spectral maximum seems to be redshifted in comparison to other thermal maturity parameters the caylus section exhibited sci of 3 5 4 0 hrr ranges between 0 32 and 0 50 corresponding to 0 42 0 54 vreq spectral fluorescence analysis points out a max of 560 nm displaying a good correlation with sci when req values determined through sci are compared with equivalent vitrinite reflectance values determined through max a redshift of the fluorescence spectrum maximum is detected for the pont de suert section sci ranges between 8 0 8 5 and 8 5 9 0 hrr varies between 0 85 and 1 18 which corresponds to 0 76 0 98 vreq even though there are lower values than those obtained by sci vreq is reliable and acceptable to determine the thermal evolution stage furthermore hrr values also present a good correlation with sci these data indicate that the majority of the samples from the sueges and caylus sections are in the immature to early mature evolution stages and pont de suert section samples are in late mature to early overmature evolution stages for liquid hydrocarbons generation supporting a very similar thermal evolution for the grands causses and quercy basins and an entirely different thermal history for the pyrenean basin this is in accordance with the similar tectonic and sedimentary context of the quercy and grands causses basins the pont de suert section located near the collision front of the pyrenees mountains records a more complex sedimentary and tectonic history in addition this study presents the first reflectance data for jurassic hydroids which show a good correlation with other rank parameters

testing reproducibility of vitrinite and solid bitumen reflectance measurements in north american unconventional source rock reservoir petroleum systems abstract an interlaboratory study ils was conducted to test reproducibility of vitrinite and solid bitumen reflectance measurements in six mudrock samples from united states unconventional source rock reservoir petroleum systems samples selected from the marcellus haynesville eagle ford barnett bakken and woodford are representative of resource plays currently under exploitation in north america all samples are from marine depositional environments are thermally mature tmax 445 c and have moderate to high organic matter content 2 9 11 6 wt toc their organic matter is dominated by solid bitumen which contains intraparticle nano porosity visual evaluation of organic nano porosity pore sizes 1 0 produced lowest r values generally 0 5 absolute reflectance similar to a prior ils for similar samples other traditional approaches to outlier removal outside mean 1 5 interquartile range and outside f10 to f90 percentile range also produced similar r values standard deviation values

the structure of the atmospheric boundary layer in the central equatorial pacific during january and february of fgge abstract the structure of the atmospheric boundary layer for a region between hawaii and the equator is studied using dropwindsonde data 900 soundings collected in january and february 1979 as part of the first garp global experiment these data were used to establish the longitudinal and latitudinal variations in the thermodynamic and wind structure of the boundary layer and describe differences in the structure for convectively active and inactive conditions low level inversions at a pressure of approximately 850 mb were found to be an important feature of the structure of the boundary layer for undisturbed conditions although the frequency of low level inversions decreased equatorward from hawaii the average height of the inversions observed in these regions did not vary significantly in the north south direction for convectively undisturbed conditions low level inversions are on the average of sufficient strength to suppress deep convection however it is shown they could easily be modified

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

a mechanism for giant raindrop formation in warm shallow convective clouds abstract giant raindrops 4 8 mm diameter have been observed recently within warm convective rainbands with depths 2 km off the coast of the big island of hawaii the presence of giant raindrops in these clouds was initially surprising since model and laboratory results support the view that collisional breakup should rapidly destroy such drops in natural clouds a mechanism proposed by beard et al and others to explain the giant raindrops is that exceptionally large aerosol particles act as nuclei for very large cloud droplets near cloud base such rare large cloud drops then grow rapidly into giant raindrops by accretion of smaller cloud droplets in the updraft we show here that an additional set of circumstances is required to explain the existence of giant raindrops in hawaiian rainband clouds one which prolongs their growth and separates them from smaller raindrops we present data from the 1985 joint hawaiian warm rain project that suggest that giant raindrops result when selected small raindro

dynamical adjustment of the trade wind inversion layer abstract in schematic north south cross sections the trade inversion layer is often depicted as sloping upward as air flows toward the intertropical convergence zone this conceptual view is consistent with purely thermodynamic boundary layer models which predict a deeper boundary layer with increasing sea surface temperature and decreasing large scale subsidence the slopes implied by such thermodynamic models and incorporated into schematic diagrams are approximately 2000 m 1000 km in contrast observational studies of the inversion structure over the atlantic and pacific oceans reveal a less dramatic slope on the order of 300 m 1000 km to address this inconsistency the authors adopt a somewhat different view of the trade inversion layer in particular rather than regarding it as a purely thermodynamic structure it is regarded as a dynamical structure by formulating a generalization of the rossby adjustment problem the authors investigate the dynamical adjustments of a trade wind inversion laye

numerical simulations and a conceptual model of the stratocumulus to trade cumulus transition abstract a two dimensional eddy resolving model is used to study the transition from the stratocumulus topped boundary layer to the trade cumulus boundary layer the 10 day simulations use an idealized lagrangian trajectory representative of summertime climatological conditions in the subtropical northeastern pacific the sea surface temperature is increased steadily at 1 5 k day 1 reflecting the southwestward advection of the subtropical marine boundary layer by the trade winds while the free tropospheric temperature remains unchanged results from simulations with both a fixed diurnally averaged shortwave radiative forcing and a diurnally varying shortwave forcing are presented a two stage model for the boundary layer evolution consistent with these simulations is proposed in the first stage decoupling is induced by increased latent heat fluxes in the deepening boundary layer after decoupling cloud cover remains high but the cloudiness regime changes from a single stratocumulus layer to sporadic

on the dynamics of hawaiian cloud bands island forcing abstract this study focuses on basic island scale forcing mechanisms for the formation and evolution of a band cloud typically present upwind of the island of hawaii by means of numerical experiments and verification of our results against observations and laboratory experiments reported in the literature we show that the band cloud is a complex three dimensional phenomenon which is inseparable from the airflow around the island in particular we demonstrate that the event needs to be analyzed in terms of the basic fluid dynamics of strongly stratified flow past a three dimensional obstacle the band cloud is found to arise primarily from the dynamic interaction of the trade winds with the island the upwind surface flow forms a separation line with an associated stagnation point a low level convergence zone forms along this line resulting in an updraft line if the updrafts are strong enough a band cloud forms formation and characteristics of such a system are mostly controlled by the environmenta

evolution of precipitation and convective echo top heights observed by trmm radar over the indian ocean during dynamo radar data from the tropical rainfall measuring mission show the evolution of echo tops of convective elements over the indian ocean and maritime continent during the dynamics of the madden julian oscillation dynamo field campaign of 2011 2012 echo top heights exhibited a bimodal distribution wherein cumulonimbi of moderate height constituted a congestus mode while vertically extensive cumulonimbus made up a deep mode an intraseasonal time scale dominated variability in these modes from october to january over much of the indian ocean over the maritime continent there was no clear intraseasonal signal in convective echo top heights where the intraseasonal oscillation was detected radar echoes evolved from being dominated by the congestus mode to being characterized by more deep mode convection on time scales of less than 1 week the areal coverage of congestus echoes began to increase 2 8 days prior to the rise in area of deep echoes these satellite derived results confirm that the time scale for convective deepening seen at individual dynamo observational sites is consistent with that of convection on the large scale over the indian ocean intraseasonal variability of zonal wind temperature and humidity as depicted by reanalysis is also consistent with that derived from rawinsonde observations during dynamo thus the gradual buildup of convection as depicted by recent versions of the discharge recharge hypothesis does not accurately describe evolutions of convection prior to mjo events observed during dynamo although cloud moistening processes may still be relevant on time scales of 1 week or less

tropical inversions near the 0 c level abstract soundings taken from the tropical western pacific warm pool region during toga coare reveal the common occurrence of temperature and moisture perturbations near the 0 c level the perturbations frequently are characterized by shallow layers of increased stability or occasionally temperature inversions and reversals or inflections in the vertical profile of specific humidity similar temperature and moisture inversions have been observed elsewhere in the tropics and midlatitudes but have not received much attention isothermal layers are known to exist just below the melting level in stratiform rain regions however not all stable layers observed over the warm pool are confined to precipitation systems the perturbation in the specific humidity profile accounts for the often observed double peak structure in the apparent moisture sink q2 in tie tropics stratification of the data based on relative humidity criteria indicates that the stable layers near the 0 c level generally fall into two main

a ramm study of thermal maturity of dispersed organic matter in marine source rocks abstract the raman maturity method ramm is a non graphical technique for thermal maturity determination based on the multi linear regression analysis of parameters derived from carbon raman spectra of humic macerals it is calibrated against vitrinite reflectance with a suite of australian mostly permian coals in a previous communication an equation to cover the range 0 4 1 2 equivalent vitrinite reflectance was derived in this report we extend the range with a second equation for the range 1 0 2 5 and validate its use by testing a series of australian permian and german carboniferous coals the special features of the technique are that it is equally applicable to vitrinite and inertinite it corrects internally for the suppression of vitrinite reflectance effect grains as small as 5 m are suitable and it does not require well depth information to be available the technique has been applied to two wells cape range 2 and dampier 1 from the rift margin of the north west shelf of australia both wells intersect large thicknesses of fine grained marine jurassic and cretaceous sediments including the major source rock formation of the carnarvon basin there are no terrestrial sediments for control there is good agreement between ramm and vr results for vr 1 2 for cape range 2 however within the oil window in both wells ramm results indicate the vitrinites in many of the samples have reflectance suppression to such a degree that the vr results would be misleading or useless for maturity modeling it is likely that this problem which is well documented for marine influenced coals to some degree affects organic matter in marine source rocks worldwide

ramm raman maturity method study of samples used in an interlaboratory exercise on a standard test method for determination of vitrinite reflectance on dispersed organic matter in rocks abstract ramm raman maturity method is a thermal maturity tool for humic macerals in coals or as dispersed organic matter dom expressed in equivalent vitrinite reflectance eqvr the eqvr values are based on a recently established calibration according to multi linear regressions of selected parameters from raman spectra of vitrinite and inertinite in a suite of australian coals with vitrinite reflectance vr in the range 0 4 2 5 the study contributes to the application of raman spectroscopy for thermal maturity determinations as applicable to the petroleum exploration industry and researched by many groups worldwide a suite of samples to apply the technique was made available from an interlaboratory round robin exercise on application of astm d7708 a method for determination of vr of dom in sedimentary rocks this exercise involved the distribution of two sets of six unknown rock samples to all participating laboratories collated vr results from some samples of the first set having high maturities and low organic matter om contents showed a disturbingly high degree of scatter although general agreement exists between ramm determinations and the average of mean random vr values determined at the various laboratories some important differences emerged for some samples in the range eqvr 1 2 1 8 on ramm diagrams which involve plots of eqvrs derived from the two regression equations defining the method the pattern of distribution of vitrinite and inertinite changes with thermal maturity for normal coals and with om composition in subhydrous versus perhydrous coals most of the round robin samples contained solid bitumens having reflectances close to those of the associated vitrinite measurements taken from solid bitumen were avoided as much as possible but because the ramm study was done in air medium some contamination of the humic maceral data was inevitable many of the solid bitumens and other potentially complicating components such as tasmanites related alginite can be identified on the ramm diagram and eliminated from ramm results for lower maturity samples eqvr 1 8 the humic dom of marine samples having eqvr 1 0 has spectral properties that differ from those of humic macerals of the same maturity in terrestrially deposited rocks this could possibly explain any discrepancies between ramm eqvr and vr data for the marine rocks the presence of contaminating solid bitumen with reflectance similar to that of vitrinite is the main complicating factor for thermal maturity evaluation using either vr or ramm analyses of gas shales and tight oil reservoir rocks to enable the best results from ramm studies of these types of rocks a preliminary study of the solid bitumen component should be carried out to determine its field on the ramm diagram with the object of eliminating contaminating solid bitumen data from eqvr calculations

the microphysical structure and evolution of hawaiian rainband clouds part i radar observations of rainbands containing high reflectivity cores abstract radar reflectivity factors exceeding 60 dbz are documented within shallow 0 c summertime tropical rainbands offshore of the island of hawaii dual doppler radar measurements from the hawaiian rainband project are used to document the formation evolution and kinematic structure of the high reflectivity cores the authors show that extremely high radar reflectivities 50 60 dbz can develop from echo free regions 20 dbz within approximately 15 min and are preceded by 5 9 m s 1 peak updrafts high reflectivities 50 dbz typically first formed in the middle or upper part of the clouds over the next 10 15 min the mature high reflectivity cores extended vertically through the cloud depth and then collapsed to the surface as the updrafts weakened a near upright orientation of most updrafts producing these high reflectivity cores is conceptually consistent with the idea that large raindrops grow in the highest liquid water content while falling through the updraft core strong

the echo size distribution of precipitating shallow cumuli abstract s band radar surveillance scans of precipitating shallow convection are analyzed the scans are complied from 52 days of near continuous measurements in the winter trades of the north atlantic during the rain in cumulus over the ocean rico field campaign after being analyzed and filtered to exclude spurious returns the scans are segmented to identify contiguous returns or echoes the echo size and reflectivity statistics are then analyzed a new normalization method is developed to account for biases associated with the nonuniformity in the native radar grid the echo area distribution robustly exhibits power law scaling up until sizes of about 10 km2 with a scaling exponent of about 1 1 at larger sizes the scaling behavior breaks down and varies more markedly across subsamples of the data conditional sampling suggests that the scaling behavior of the larger echoes does however approach that of the smaller echoes as echo coverage increases which supports the idea of a limiting distrib