Science.gov

Sample records for eocene equatorial rain

  1. Teleconnections between Ethiopian rains and Equatorial Pacific SST

    NASA Astrophysics Data System (ADS)

    Tefera Diro, G.; Grimes, D. I. F.; Black, E.

    2009-04-01

    Rainfall is the most important climate parameter in Ethiopia as in many part of Africa since the economy is based mainly on rain fed agriculture. Understanding the mechanisms that lead to anomalous rainfall is therefore a great significant for seasonal prediction. Although the statistical link between tropical Pacific (warm/cold) and Ethiopian rainfall (deficit/excess Kiremt (JJAS) and excess/deficit Belg (FMAM)) is well known, the physical mechanism for the observed relationship is not well understood. In this study, the mechanisms for the link between equatorial eastern and central Pacific and Ethiopian rains are studied using observational and modelling studies. In the observational study, two sets of composites were analysed. The first set was composite of large scale atmospheric features based on excess and deficit rains to understand the large scale rainfall controls. The second set was also composite of large scale atmospheric features but based on warm and cold SSTs over equatorial Pacific. The observational study suggests that warm/cold equatorial Pacific SSTAs are linked to excess/deficit summer rainfall via the strength of ITCZ, Tropical Easterly Jet (TEJ), the East African Low Level Jet (EALLJ) and westerly anomalies from Atlantic and north-southward shift of African Easterly Jet (AEJ). In the modelling study, Atmosphere only General Circulation Model (HadAM3) forced with observed (HadISST) and idealised SSTA patterns was used to investigate whether there is a causal link between rainfall and SST and also to understand the mechanism of the link (if the link is causal). The HadISST forced HadAM3 run shows that the model captures the inter-annual variability of rainfall associated with ENSO. The idealised SST experiments confirms that warm equatorial Pacific indeed directly causes deficit rainfall in Kiremt and excess rainfall in Belg seasons. The physical mechanism for these teleconnections is suggested. For Kiremt season; warm SSTA in the tropical

  2. Humidity estimate for the middle Eocene Arctic rain forest

    NASA Astrophysics Data System (ADS)

    Jahren, A. Hope; Silveira Lobo Sternberg, Leonel

    2003-05-01

    The exquisite preservation of fossilized Metasequoia trees that grew near 80°N latitude during the middle Eocene (ca. 45 Ma) in Nunavut, Canada, allowed for δD and δ18O analyses of cellulose, techniques previously restricted to wood <30,000 yr old. From the isotopic results, we determined that the middle Eocene Arctic atmosphere contained ˜2× the water found in the region's atmosphere today. This water vapor contributed to a middle Eocene greenhouse effect that insulated the polar region during dark polar winters.

  3. Middle Eocene Equatorial Pacific Paleoceanography: Insights From Bulk Sediment Geochemistry, ODP Site 1218

    NASA Astrophysics Data System (ADS)

    Tripati, A. K.; Lyle, M.; Backman, J.

    2002-12-01

    The deep equatorial Pacific was dominated by siliceous sedimentation from ~45 Ma to the Eocene-Oligocene boundary. Inspection of Paleogene sediments recovered during Ocean Drilling Program (ODP) Leg 199 and Deep Sea Drilling Program Leg 16 indicate several episodes of carbonate deposition during the Middle Eocene. The well-preserved and expanded sedimentary sequence recovered at ODP Site 1218 presents an opportunity to document the Middle Eocene paleoceanographic history of the equatorial Pacific, and to determine whether the occurrence of Middle Eocene carbonates in Chron C18 is coincident with a sequence of rapid paleoceanographic and climatic changes. Here we present high-resolution bulk sediment oxygen and carbon isotope records, carbonate, opal, and organic carbon accumulation data, and coarse sand fraction data for chalks and radiolarites spanning Chron C18 from ODP Site 1218. Stable isotope and % carbonate records exhibit large-amplitude oscillations corresponding to obliquity and eccentricity frequencies. In addition, a series of stepwise oxygen isotope excursions of 0.5 to 0.8 per mil at roughly 40.5, 40.4, and 40.3 Ma, occur in coincidence with large-scale drops in % carbonate. These data may record rapid CCD fluctuation associated with transient warming and cooling events and/or ephemeral polar ice sheets.

  4. Survival probability of precipitations and rain attenuation in tropical and equatorial regions

    NASA Astrophysics Data System (ADS)

    Mohebbi Nia, Masoud; Din, Jafri; Panagopoulos, Athanasios D.; Lam, Hong Yin

    2015-08-01

    This contribution presents a stochastic model useful for the generation of a long-term tropospheric rain attenuation time series for Earth space or a terrestrial radio link in tropical and equatorial heavy rain regions based on the well-known Cox-Ingersoll-Ross model previously employed in research in the fields of finance and economics. This model assumes typical gamma distribution for rain attenuation in heavy rain climatic regions and utilises the temporal dynamic of precipitation collected in equatorial Johor, Malaysia. Different formations of survival probability are also discussed. Furthermore, the correlation between these probabilities and the Markov process is determined, and information on the variance and autocorrelation function of rain events with respect to the particular characteristics of precipitation in this area is presented. The proposed technique proved to preserve the peculiarities of precipitation for an equatorial region and reproduce fairly good statistics of the rain attenuation correlation function that could help to improve the prediction of dynamic characteristics of rain fade events.

  5. Neotropical eocene coastal floras and [sup 18]O/[sup 16]O-estimated warmer vs. cooler equatorial waters

    SciTech Connect

    Graham, A. )

    1994-03-01

    The history of the earth's sea-surface temperature (SST) in equatorial regions during the Tertiary is unsettled because of uncertainty as to the presence and extent of glaciers during the Paleogene. The [sup 16]O trapped in glaciers and subsequently released back to the ocean basins as meltwater during interglacials affects the [sup 18]O/[sup 16]O ratio of sea water, one of the variables that must be known for oxygen isotope paleotemperature analysis of calcareous fossils. Estimates of SST range from [approximately]18 to 20 C, assuming an ice-free earth, to [approximately]28 C assuming glaciers were present in the Paleogene. Low latitude SST presently averages 28C, so the former estimate gives a value 8 to 10 C cooler than present, while the latter gives a value as warm or slightly warmer than present. The figures are important for interpreting terrestrial vegetational history because the temperature differential between low and high latitudes is a major factor in determining global climates through the control of poleward transfer of heat. The middle( ) to late Eocene Gatuncillo Formation palynoflora of Panama was deposited at the ocean-continental interface at [approximately]9[degrees]N latitude. The individual components and paleocommunities are distinctly tropical and similar to the present vegetation along the Atlantic coast of southern Central America. This is consistent with data emerging from other recently studied tropical coastal biotas and represents a contribution from paleobiology toward eventually resolving the problem of Eocene equatorial marine environments. Collectively, the evidence is beginning to favor a model of Eocene SST near present values. 50 refs., 1 fig., 2 tabs.

  6. Rain ratio variation in the Tropical Ocean: Tests with surface sediments in the eastern equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Mekik, Figen; Loubere, Paul; Richaud, Mathieu

    2007-03-01

    The organic carbon to calcite flux ratio (rain ratio) has a profound effect on the preservation of carbonates in the deep sea and may influence atmospheric pCO 2 over millennia. Unfortunately, the degree to which the rain ratio varies in the more productive regions of the oceans is not well determined with sediment trap data. The rain ratio in the upper ocean appears dominantly linked to diatom productivity, which is not necessarily directly linked to total production and may be regionally variable. However, ballasting and protection of organic carbon by calcareous particles in the deeps may limit ratio variability at the seafloor. Sediment trap data do not exist for the regional determination of rain ratios in key highly productive areas like the eastern equatorial Pacific (EEP). To overcome this, we turn to surface sediment composition and accumulation rates as a representation of modern ratio variation. We present 230Thorium ( 230Th)-normalized carbonate, opal, organic carbon and detrital matter accumulation rates from core top samples in the EEP. We demonstrate a novel approach for estimating modern rain ratios from sedimentary proxies by (1) calculating vertical calcite flux from 230Th-normalized carbonate accumulation rates (CARs) with correction for preservation and (2) calculating organic carbon fluxes with multiple algorithms that depend in varying degrees on ballasting. We find that organic carbon flux estimates from algorithms with and without a ballasting function produce results different from one another. Sediment accumulation rates for opal reflect the likely pattern of diatom production. By contrast, the organic carbon accumulation rate does not correlate well with surface ocean productivity or any of our algorithm-based organic carbon flux estimates. Instead, it correlates with the detrital component of the sediments suggesting an allochthonous input to sedimentary organic carbon accumulation in the EEP, which reduces its value as a productivity

  7. HIV type 1 group M clades infecting subjects from rural villages in equatorial rain forests of Cameroon.

    PubMed

    Zhong, Ping; Burda, Sherri; Urbanski, Mateusz; Kenfack, Henriette; Tongo, Marcel; Heyndrickx, Leo; Nanfack, Aubin; Shang, Judith; Agyingi, Lucy; Zolla-Pazner, Susan; Zekeng, Leopold; Nyambi, Phillipe

    2002-12-15

    Though the HIV-1 subtypes infecting patients living in urban and semi-urban areas in Cameroon have been reported, information on the subtypes infecting patients in rural villages is lacking. To begin to understand the diversity of the HIV-1 group M subtypes infecting persons living in rural villages in the equatorial rain forest regions of Cameroon, 49 plasma samples from 14 rural villages in four provinces of Cameroon were analyzed using heteroduplex mobility analysis (HMA), DNA sequencing, and phylogenetic tree analysis on the basis of env C2V5, gag, or pol regions. Sixty-one percent of the group M infections were clade A or CRF02_AG-like as subtyped by env and gag. Of the remaining group M infections, 12% were either A or CRF02_AG-like or CRF01_AE-like in recombination with other clades; 25% were infections that were entirely non-A or non-CRF02_AG-like; and 2% were CRF11_cpx. The HIV-1 group M clades identified included A, D, F (F2), G, and H. The CRF strains identified were CRF02_AG-like, CRF01_AE-like, and CRF11_cpx. Two new intersubtype recombinant infections, H/G and A/F2, were identified. This study suggests that the HIV-1 diversity in rural villages in the equatorial rain forest of Cameroon is at least as broad as has been observed in major cities of Cameroon and that multiple HIV-1 group M subtypes are infecting persons living in the countryside of Cameroon.

  8. Converging migration routes of Eurasian hobbies Falco subbuteo crossing the African equatorial rain forest.

    PubMed

    Strandberg, Roine; Klaassen, Raymond H G; Hake, Mikael; Olofsson, Patrik; Alerstam, Thomas

    2009-02-22

    Autumn migration of adult Eurasian hobbies Falco subbuteo from Europe to southern Africa was recorded by satellite telemetry and observed routes were compared with randomly simulated routes. Two non-random features of observed routes were revealed: (i) shifts to more westerly longitudes than straight paths to destinations and (ii) strong route convergence towards a restricted area close to the equator (1 degree S, 15 degrees E). The birds migrated south or southwest to approximately 10 degrees N, where they changed to south-easterly courses. The maximal spread between routes at 10 degrees N (2134 km) rapidly decreased to a minimum (67 km) close to the equator. We found a striking relationship between the route convergence and the distribution of continuous rainforest, suggesting that hobbies minimize flight distance across the forest, concentrating in a corridor where habitat may be more suitable for travelling and foraging. With rainforest forming a possible ecological barrier, many migrants may cross the equator either at 15 degrees E, similar to the hobbies, or at 30-40 degrees E, east of the rainforest where large-scale migration is well documented. Much remains to be understood about the role of the rainforest for the evolution and future of the trans-equatorial Palaearctic-African bird migration systems.

  9. Potential Predictability of the Sea-Surface Temperature Forced Equatorial East Africa Short Rains Interannual Variability in the 20th Century

    NASA Astrophysics Data System (ADS)

    Bahaga, T. K.; Gizaw, G.; Kucharski, F.; Diro, G. T.

    2014-12-01

    In this article, the predictability of the 20th century sea-surface temperature (SST) forced East African short rains variability is analyzed using observational data and ensembles of long atmospheric general circulation model (AGCM) simulations. To our knowledge, such an analysis for the whole 20th century using a series of AGCM ensemble simulations is carried out here for the first time. The physical mechanisms that govern the influence of SST on East African short rains in the model are also investigated. It is found that there is substantial skill in reproducing the East African short rains variability, given that the SSTs are known. Consistent with previous recent studies, it is found that the Indian Ocean and in particular the western pole of the Indian Ocean dipole (IOD) play a dominant role for the prediction skill, whereas SSTs outside the Indian Ocean play a minor role. The physical mechanism for the influence of the western Indian Ocean on East African rainfall in the model is consistent with previous findings and consists of a gill-type response to a warm (cold) anomaly that induces a westerly(easterly) low-level flow anomaly over equatorial Africa and leads to moisture flux convergence (divergence) over East Africa. On the other hand, a positive El Nino-Southern Oscillation (ENSO) anomaly leads to a spatially non-coherent reducing effect over parts of East Africa, but the relationship is not strong enough to provide any predictive skill in our model. The East African short rains prediction skill is also analyzed within a model-derived potential predictability framework and it is shown that the actual prediction skill is broadly consistent with the model potential prediction skill. Low-frequency variations of the prediction skill are mostly related to SSTs outside the Indian Ocean region and are likely due to an increased interference of ENSO with the Indian Ocean influence on East African short rains after the mid-1970s climate shift.

  10. 226Ra-in marine barite: relationship with carbonate dissolution and sediment focusing in the equatorial pacific

    NASA Astrophysics Data System (ADS)

    van Beek, P.; Reyss, J.-L.; DeMaster, D.; Paterne, M.

    2004-02-01

    Sedimentation rates were determined from the 226Ra ( T 1/2=1602 a) decay in barite in seven cores collected from the western, central and eastern equatorial Pacific. Timing of the last carbonate dissolution increase was investigated with this new chronometer. However, an unconformity in the 226Ra-in-barite profiles was observed at some sites, which could be related to this carbonate dissolution event. We discuss different mechanisms that may have generated these unconformities, including (1) bioturbation, (2) possible bias in the estimate of the correction for supported 226Ra activities, (3) changes in the 226Ra/Ba ratio within surface waters and (4) processes that may have affected the 226Ra/Ba ratio recorded in barite, either within the water column or at the sediment-water interface. Among the processes invoked, an increase in the sediment focusing during the Holocene constitutes the mechanism that can most likely explain the observed unconformities. An increase in the sediment redistribution by bottom currents would enhance the lateral transport of old resuspended barite crystals (with a low 226Ra/Ba ratio). The 226Ra/Ba ratio of barite that accumulates in the sediments, therefore, may have decreased, leading to the unconventional 226Ra-profile shape observed in several cores. A change in the chemistry of the bottom waters that transport the resuspended sediment may have also affected the sediment carbonate contents.

  11. Eocene precipitation: a global monsoon?

    NASA Astrophysics Data System (ADS)

    Greenwood, D. R.; Huber, M.

    2011-12-01

    The Eocene was the warmest part of the Cenozoic, with warm climates extending across all continents including Antarctica, and extending into the Arctic. Substantive paleobotanical evidence (leaf floras and palynofloras) has demonstrated the existence of broadleaf and coniferous polar forests - a circumpolar rain forest - at both poles. North and South America, Australia, and China in the Eocene were well-forested and humid continents, in contrast to today where 2/3 of these continental areas are arid or semi-arid and lack forests. Each of these regions reflect past climate states - mesothermal moist climates with low thermal seasonality at high latitudes - that have no analog in the modern world. Recent modelling and paleontological proxy data, however, is revealing a high degree of seasonality to precipitation for these continental areas, indicating a monsoon-type precipitation regime may have characterized Eocene 'greenhouse climates'. Paleobotanical proxies offer 2 methods for estimated paleo-precipitation; leaf physiognomy (including both CLAMP and leaf area analysis), and quantitative analysis of nearest living relatives ('NLRs') of macrofloras. Presented here are 1) an updated leaf area analysis calibration with smaller errors of the estimate than previously provided, and 2) analyses of fossil floras from North America, Canada, the Arctic, and Australia. Analysis of the Canadian floras indicate moist climates (MAP >100cm/a) in the early and middle Eocene at middle and high paleolatitudes. Precipitation for western North America at mid-latitudes is also estimated as high, but a seasonally dry interior and south-east is indicated. For Australia, precipitation in the south-east is estimated >120 cm/a, but the macrofloras indicate a drier interior (MAP ~60 cm/a) and seasonal drought, contradicting estimates of ~120 cm/a based on NLR analysis of pollen floras. Recently published data show that north-eastern China in the Eocene had a monsoonal-type seasonality for

  12. Equatorial Guinea.

    PubMed

    1989-03-01

    Equatorial Guinea is situated on the Gulf of Guinea along the west African coast between Cameroon and Gabon. The people are predominantly of Bantu origin. The country's ties with Spain are significant; in 1959, it became the Spanish Equatorial region ruled by Spain's commissioner general. Recent political developments in Equatorial Guinea include the formation of the Democratic Party for Equatorial Guinea in July of 1987 and the formation of a 60-member unicameral Chamber of Representatives of the People in 1983. Concerning the population, 83% of the people are Catholic and the official language is Spanish. Poverty and serious health, education and sanitary problems exist. There is no adequate hospital and few trained physicians, no dentists, and no opticians. Malaria is endemic and immunization for yellow fever is required for entrance into the country. The water is not potable and many visitors to the country bring bottled water. The tropical climate of Equatorial Guinea provides the climate for the country's largest exports and source of economy; cacao, wood and coffee. Although the country, as a whole, has progressed towards developing a participatory political system, there are still problems of governmental corruption in the face of grave health and welfare conditions. In recent years, the country has received assistance from the World Bank and the United States to aid in its development.

  13. After the Rain: Rain.

    ERIC Educational Resources Information Center

    Old Elk, Arlene; Stoklas, Jackie

    The Heard Museum (Phoenix, Arizona) has developed and updated an integrated curriculum for use in grades K-3. The goals for this curriculum are to: (1) share museum resources with schools; (2) promote cross-cultural understanding through a focus on rain, a universal requirement for life; (3) help students understand that Native Americans are…

  14. Equatorial Guinea.

    PubMed

    1984-06-01

    Attention in this discussion of Equatorial Guinea is directed to the following: the people, history, geography, government, political conditions, the economy, foreign relations, and relations between the US and Equatorial Guinea. The population was estimated at 304,000 in 1983 and the annual growth rate was estimated in the range of 1.7-2.5. The infant mortality rate is 142.9/1000 with a life expectancy of 44.4 years for males and 47.6 years for females. The majority of the Equatoguinean people are of Bantu origin. The largest tribe, the Fang, is indigenous to the mainland, although many now also live on Bioko Island. Portuguese explorers found the island of Bioko in 1471, and the Portuguese retained control until 1778, when the island, adjacent islets, and the commercial rights to the mainland between the Niger and Ogooue Rivers were ceded to Spain. Spain lacked the wealth and the interest to develop an extensive economic infrastructure in Equatorial Guinea during the 1st half of this century, but the Spanish did help Equatorial Guinea achieve 1 of the highest literacy rates in Africa. They also founded a good network of health care facilities. In March 1968, under pressure from Guinean nationalists, Spain announced that it would grant independence to Equatorial Guinea as rapidly as possible. A referendum was held on August 11, 1968, and 63% of the electorate voted in favor of the constitution, which provided for a government with a general assembly and presidentially appointed judges in the Supreme Court. After the coup in August 1979, power was placed in the hands of a Supreme Military Council. A new constitution came into effect after a popular vote in August 1982, abolishing the Supreme Military Council. Under the terms of the constitution, the president was given extensive powers. By the end of 1983, a 60-member Chamber of Representatives of the people had been formed. The government, which is credited with restoring greater personal freedom, is regarded

  15. Acid rain

    SciTech Connect

    Elsworth, S.

    1985-01-01

    This book was written in a concise and readable style for the lay public. It's purpose was to make the public aware of the damage caused by acid rain and to mobilize public opinion to favor the elimination of the causes of acid rain.

  16. Acid rain

    SciTech Connect

    White, J.C. )

    1988-01-01

    This book presents the proceedings of the third annual conference sponsored by the Acid Rain Information Clearinghouse (ARIC). Topics covered include: Legal aspects of the source-receptor relationship: an energy perspective; Scientific uncertainty, agency inaction, and the courts; and Acid rain: the emerging legal framework.

  17. Acid Rain.

    ERIC Educational Resources Information Center

    Openshaw, Peter

    1987-01-01

    Provides some background information on acid deposition. Includes a historical perspective, describes some effects of acid precipitation, and discusses acid rain in the United Kingdom. Contains several experiments that deal with the effects of acid rain on water quality and soil. (TW)

  18. Age of Eocene/Oligocene boundary based on extrapolation from North American microtektite layer

    SciTech Connect

    Glass, B.P.; Crosbie, J.R.

    1982-04-01

    Microtektites believed to belong to the North American tektite strewn field have been found in upper Eocene sediments in cores from nine Deep Sea Drilling Project sites in the Caribbean Sea, Gulf of Mexico, equatorial Pacific, and eastern equatorial Indian Ocean. The microtektite layer has an age of 34.2 +- 0.6 m.y. based on fission-track dating of the microtektites and K-Ar and fission-track dating of the North American tektites. Extrapolation from the microtektite layer to the overlying Eocene/Oligocene boundary indicates an age of 32.3 +- 0.9 m.y. for the Eocene/Oligocene boundary as defined at each site in the Initial Reports of the Deep Sea Drilling Project. This age is approximately 5 m.y. younger than the age of 37.5 m.y. that is generally assigned to the boundary based on recently published Cenozoic time scales. 3 figures, 5 tables.

  19. Acid rain

    SciTech Connect

    Bess, F.D.

    1980-01-01

    The acid rain problem in the northeastern U.S. has been growing in severity and geographical areas affected. Acid rain has damaged, or will result in damage to visibility, physical structures and materials, aquatic life, timber, crops, and soils. The principal causes of acid rain in the northeastern U.S. are sulfur oxide and nitrogen oxide emissions from large power plants and smelters in the Ohio River Valley. Immediate corrective action and appropriate research are needed to reduce acid precipitation. Short-term programs that will define the rate of environmental deterioration, remaining environmental capacity to resist sudden deterioration, mechanisms of acid rain formation, and costs of various control options must be developed. (3 maps, 13 references, 1 table)

  20. Aerosol Transport Over Equatorial Africa

    NASA Technical Reports Server (NTRS)

    Gatebe, C. K.; Tyson, P. D.; Annegarn, H. J.; Kinyua, A. M.; Piketh, S.; King, M.; Helas, G.

    1999-01-01

    Long-range and inter-hemispheric transport of atmospheric aerosols over equatorial Africa has received little attention so far. Most aerosol studies in the region have focussed on emissions from rain forest and savanna (both natural and biomass burning) and were carried out in the framework of programs such as DECAFE (Dynamique et Chimie Atmospherique en Foret Equatoriale) and FOS (Fires of Savanna). Considering the importance of this topic, aerosols samples were measured in different seasons at 4420 meters on Mt Kenya and on the equator. The study is based on continuous aerosol sampling on a two stage (fine and coarse) streaker sampler and elemental analysis by Particle Induced X-ray Emission. Continuous samples were collected for two seasons coinciding with late austral winter and early austral spring of 1997 and austral summer of 1998. Source area identification is by trajectory analysis and sources types by statistical techniques. Major meridional transports of material are observed with fine-fraction silicon (31 to 68 %) in aeolian dust and anthropogenic sulfur (9 to 18 %) being the major constituents of the total aerosol loading for the two seasons. Marine aerosol chlorine (4 to 6 %), potassium (3 to 5 %) and iron (1 to 2 %) make up the important components of the total material transport over Kenya. Minimum sulfur fluxes are associated with recirculation of sulfur-free air over equatorial Africa, while maximum sulfur concentrations are observed following passage over the industrial heartland of South Africa or transport over the Zambian/Congo Copperbelt. Chlorine is advected from the ocean and is accompanied by aeolian dust recirculating back to land from mid-oceanic regions. Biomass burning products are transported from the horn of Africa. Mineral dust from the Sahara is transported towards the Far East and then transported back within equatorial easterlies to Mt Kenya. This was observed during austral summer and coincided with the dying phase of 1997/98 El

  1. Eocene cooling linked to early flow across the Tasmanian Gateway

    PubMed Central

    Bijl, Peter K.; Bendle, James A. P.; Bohaty, Steven M.; Pross, Jörg; Schouten, Stefan; Tauxe, Lisa; Stickley, Catherine E.; McKay, Robert M.; Röhl, Ursula; Olney, Matthew; Sluijs, Appy; Escutia, Carlota; Brinkhuis, Henk; Klaus, Adam; Fehr, Annick; Williams, Trevor; Carr, Stephanie A.; Dunbar, Robert B.; Gonzàlez, Jhon J.; Hayden, Travis G.; Iwai, Masao; Jimenez-Espejo, Francisco J.; Katsuki, Kota; Kong, Gee Soo; Nakai, Mutsumi; Passchier, Sandra; Pekar, Stephen F.; Riesselman, Christina; Sakai, Toyosaburo; Shrivastava, Prakash K.; Sugisaki, Saiko; Tuo, Shouting; van de Flierdt, Tina; Welsh, Kevin; Yamane, Masako

    2013-01-01

    The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52–50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica from 34 Ma onward. Whereas early studies attributed the Eocene transition from greenhouse to icehouse climates to the tectonic opening of Southern Ocean gateways, more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations (e.g., CO2). However, the scarcity of field data has prevented empirical evaluation of these hypotheses. We present marine microfossil and organic geochemical records spanning the early-to-middle Eocene transition from the Wilkes Land Margin, East Antarctica. Dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound Antarctic Counter Current began ∼49–50 Ma through a southern opening of the Tasmanian Gateway. This early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling (2–4 °C), evidenced by biomarker- and pollen-based paleothermometry. We interpret that the westbound flowing current flow across the Tasmanian Gateway resulted in cooling of Antarctic surface waters and coasts, which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes. Although atmospheric CO2 forcing alone would provide a more uniform middle Eocene cooling, the opening of the Tasmanian Gateway better explains Southern Ocean surface water and global deep ocean cooling in the apparent absence of (sub-) equatorial cooling. PMID:23720311

  2. Eocene cooling linked to early flow across the Tasmanian Gateway.

    PubMed

    Bijl, Peter K; Bendle, James A P; Bohaty, Steven M; Pross, Jörg; Schouten, Stefan; Tauxe, Lisa; Stickley, Catherine E; McKay, Robert M; Röhl, Ursula; Olney, Matthew; Sluijs, Appy; Escutia, Carlota; Brinkhuis, Henk

    2013-06-11

    The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52-50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica from 34 Ma onward. Whereas early studies attributed the Eocene transition from greenhouse to icehouse climates to the tectonic opening of Southern Ocean gateways, more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations (e.g., CO2). However, the scarcity of field data has prevented empirical evaluation of these hypotheses. We present marine microfossil and organic geochemical records spanning the early-to-middle Eocene transition from the Wilkes Land Margin, East Antarctica. Dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound Antarctic Counter Current began ~49-50 Ma through a southern opening of the Tasmanian Gateway. This early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling (2-4 °C), evidenced by biomarker- and pollen-based paleothermometry. We interpret that the westbound flowing current flow across the Tasmanian Gateway resulted in cooling of Antarctic surface waters and coasts, which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes. Although atmospheric CO2 forcing alone would provide a more uniform middle Eocene cooling, the opening of the Tasmanian Gateway better explains Southern Ocean surface water and global deep ocean cooling in the apparent absence of (sub-) equatorial cooling.

  3. Rain height statistics for satellite communication in Malaysia

    NASA Astrophysics Data System (ADS)

    Mandeep, J. S.

    2008-09-01

    The calculation of fade margin required for 99.99% of the time availability of satellite link requires the knowledge of rain height. There is a shortage of results on rain height over Malaysian equatorial stations. The results on rain height in relation to 0 °C isotherm height (Hi) over four stations are presented. The variations of 0 °C isotherm heights for two monsoon seasons have been studied based on an analysis of radiosonde. The exceedence probability statistics of rain height are compared between the two seasons.

  4. Estimating rainfall in the tropics using the fractional time raining

    NASA Technical Reports Server (NTRS)

    Morrissey, Mark L.; Krajewski, Witold F.; Mcphaden, Michael J.

    1994-01-01

    The relationship between the fractional time raining and tropical rainfall amount is investigated using raingage data and a point process model of tropical rainfall. Both the strength and the nature of the relationship are dependent upon the resolution of the data used to estimate the fractional time raining. It is found that highly accurate estimates of rainfall amounts over periods of one month or greater can be obtained from the fractional time raining so long as high-time-resolution data are used. It is demonstrated that the relationship between the fractional time raining and monthly atoll rainfall is quasi-homogeneous within the monsoon trough region of the equatorial western Pacific.

  5. Equatorial convergence of India and early Cenozoic climate trends.

    PubMed

    Kent, Dennis V; Muttoni, Giovanni

    2008-10-21

    India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO(2) concentration (pCO(2)) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-productivity equatorial belt resulted in a component flux of CO(2) delivery to the atmosphere capable to maintain high pCO(2) levels and warm climate conditions until the decarbonation factory shut down with the collision of Greater India with Asia at the Early Eocene climatic optimum at approximately 50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO(2) by efficient silicate weathering further perturbed the delicate equilibrium between CO(2) input to and removal from the atmosphere toward progressively lower pCO(2) levels, thus marking the onset of a cooling trend over the Middle and Late Eocene that some suggest triggered the rapid expansion of Antarctic ice sheets at around the Eocene-Oligocene boundary.

  6. Equatorial convergence of India and early Cenozoic climate trends

    PubMed Central

    Kent, Dennis V.; Muttoni, Giovanni

    2008-01-01

    India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO2 concentration (pCO2) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-productivity equatorial belt resulted in a component flux of CO2 delivery to the atmosphere capable to maintain high pCO2 levels and warm climate conditions until the decarbonation factory shut down with the collision of Greater India with Asia at the Early Eocene climatic optimum at ≈50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO2 by efficient silicate weathering further perturbed the delicate equilibrium between CO2 input to and removal from the atmosphere toward progressively lower pCO2 levels, thus marking the onset of a cooling trend over the Middle and Late Eocene that some suggest triggered the rapid expansion of Antarctic ice sheets at around the Eocene-Oligocene boundary. PMID:18809910

  7. Acid rain

    SciTech Connect

    Not Available

    1985-01-01

    This report has four parts: they discuss acid rain in relation to acid soils, agriculture, forests, and aquatic ecosystems. Among findings: modern sources of acid deposition from the atmosphere for all the acid soils in the world, nor even chiefly responsible for those of northern U.S. Agriculture has its problems, but acid precipitation is probably not one of them. More research is needed to determine to what extent acid precipitation is responsible for forest declines and for smaller detrimental effects on forest growth where no damage to the foliage is evident. Many lakes and streams are extremely sensitive to added acids.

  8. Eocene precipitation: How wet do greenhouse climates get? (Invited)

    NASA Astrophysics Data System (ADS)

    Greenwood, D. R.; Smith, R. Y.

    2010-12-01

    The Eocene was the warmest part of the Cenozoic due to CO2 being at 2x - 4x Holocene levels, with warm climates extending across North America into the Arctic. Substantive paleobotanical evidence for this greenhouse time shows the existence of extensive broadleaf and coniferous polar forests - a circumpolar rain forest. Similarly, Australia in the Eocene - while 25° south of its present position - was a well-forested and humid continent, in contrast to today where 2/3 of the continent is arid or semi-arid and lacks forest. Both of these regions reflect past climate states - mesothermal moist climates with low thermal seasonality at high latitudes - that have no analog in the modern world; undiscovered earth climates. Paleontological temperature proxies provide a basis for understanding early Paleogene climates; however, there is a lack of corresponding proxy data on precipitation. Paleobotanical proxies offer 2 methods for estimated paleo-precipitation; leaf physiognomy (including leaf area analysis), and quantitative analysis of nearest living relatives (‘NLRs’) of macrofloras. Presented here is an exploration of this former greenhouse world, through analyses of macrofloras from mid-latitude North America and the Canadian Arctic, as well as from Australia. Analysis of the Canadian Arctic floras indicate upper microthermal to lower mesothermal moist climates (MAT ~13-15 °C, CMMT ~4 °C, MAP >100cm/a) in the early and middle Eocene. Leaf-area analysis of Paleocene and Eocene Arctic floras demonstrates precipitation for the Paleogene western and eastern Arctic estimated as >100 cm/yr. Sites from the Okanagan Highlands early Eocene lake macrofloras of British Columbia and northern Washington indicate comparable conditions in the early Eocene to those reconstructed for the Arctic in the middle Eocene, with MAP ~100cm/a for most sites along a 1000km North-South transect from Republic in Washington State to Driftwood Canyon near Smithers in northern British

  9. Rain dance

    NASA Astrophysics Data System (ADS)

    Carlowicz, Michael

    The concept of altering weather soon may get some added credibility. Residents of Mexico's parched state of Coahuila just hope to get some rain.In a program that links scientists from the U.S. National Center for Atmospheric Research (NCAR) with others working for the Mexican government and agricultural and industrial labs, researchers will test a new technique to enhance and perhaps induce rainfall. In field trials planned for June through October for the next four years, scientists will use pyrotechnic flares mounted on aircraft to seed clouds: as the plane flies at the base of the cloud, the burning flares produce moisture-retaining particles that rise into the cloud and attract water vapor. When the technique succeeds, the water particles become droplets which can become bonafide precipitation.

  10. Acid rain

    SciTech Connect

    Sweet, W.

    1980-06-20

    Acid precipitation includes not only rain but also acidified snow, hail and frost, as well as sulfur and nitrogen dust. The principal source of acid precipitation is pollution emitted by power plants and smelters. Sulfur and nitrogen compounds contained in the emissions combine with moisture to form droplets with a high acid content - sometimes as acidic as vinegar. When sufficiently concentrated, these acids can kill fish and damage material structures. Under certain circumstances they may reduce crop and forest yields and cause or aggravate respiratory diseases in humans. During the summer, especially, pollutants tend to collect over the Great Lakes in high pressure systems. Since winds typically are westerly and rotate clockwise around high pressure systems, the pollutants gradually are dispersed throughout the eastern part of the continent.

  11. Characteristics of rain and rain systems

    NASA Astrophysics Data System (ADS)

    1981-12-01

    The description and measurement of the macroscopic and microscopic characteristics of rain and rain systems are discussed. The statistical relationships of these characteristics and their effect on polarization and attenuation are considered. Macroscopic characteristics include the size, distribution, and movements of rain cells, the height of melting layers, and the presence of ice crystals. Microscopic characteristics include the size distribution, density, and oblateness of rain drops and ice crystals. The estimation of a major propagation effect, specific attenuation, is described.

  12. Optical Rain Gauge Performance: Second Workshop on Optical Rain Gauge Measurements

    NASA Technical Reports Server (NTRS)

    Short, David A. (Editor); Thiele, Otto W. (Editor); Mcphaden, Michael J. (Editor)

    1994-01-01

    The primary focus of the workshop was on the performance and reliability of STi mini-Optical Rain Gauges in a number of environments, including deployments on ships and buoys in the western equatorial Pacific Ocean during the TOGA/COARE field experiment, deployments on buoys in U.S. coastal waters, and comparisons with other types of rain gauges on the Virginia coast and in Florida. The workshop was attended by 20 investigators, representing 10 different institutions, who gathered to present new results obtained since the first workshop (April 1993), to discuss problems, to consider solutions, and to chart future directions. Post-TOGA/COARE calibration studies were also presented.

  13. Equatorial MST radars: Further consideration

    NASA Technical Reports Server (NTRS)

    Lagos, P.

    1983-01-01

    The results presented give additional support to the need of equatorial MST radars in order to obtain more information on the nature of equatorial waves in the MST region. Radar deduced winds such as obtained at Jicamarca for periods of months indicate that with these data the full range of equatorial waves, with time scales of seconds to years, can be studied.

  14. Multiple Early Eocene Thermal Maximums

    NASA Astrophysics Data System (ADS)

    Roehl, U.; Zachos, J. C.; Thomas, E.; Kelly, D. C.; Donner, B.; Westerhold, T.

    2004-12-01

    Periodic dissolution horizons signifying abrupt shoaling of the lysocline and CCD are characteristic features of deep-sea sections and often attributed to Milankovitch forcing via their diagnostic frequencies. Prominent dissolution horizons also correspond to abrupt climate events, such as the Paleocene-Eocene thermal maximum (PETM), as a result of input of significant CH4 - CO2 into the ocean-atmosphere system. The question arises whether other significant dissolution horizons identified in sediments of late Paleocene and early Eocene age similar to the recently identified ELMO (Lourens et al., 2004) were formed as a result of greenhouse gas input, or whether they were related to cumulative effects of periodic changes in ocean chemistry and circulation. Here we report the discovery of a 3rd thermal maximum in early Eocene (about 52 Ma) sediments recovered from the South Atlantic during ODP Leg 208. The prominent clay layer was named the "X" event and was identified within planktonic foraminifer zone P7 and calcareous nannofossil zone CP10 at four Walvis Ridge Transect sites with a water depth range of 2000 m (Sites 1262 to 1267). Benthics assemblages are composed of small individuals, have low diversity and high dominance. Dominant taxa are Nuttallides truempyi and various abyssaminids, resembling the post PETM extinction assemblages. High-resolution bulk carbonate \\delta13C measurements of one of the more shallow Sites 1265 reveal a rapid about 0.6 per mill drop in \\delta13C and \\delta18O followed by an exponential recovery to pre-excursion \\delta13C values well known for the PETM and also observed for the ELMO. The planktonic foraminiferal \\delta13C records of Morozovella subbotina and Acaranina soldadoensis in the deepest Site 1262 show a 0.8 to 0.9 per mill drop, whereas the \\delta13C drop of benthic foraminifera Nuttallides truempyi is slightly larger (about 1 per mill). We are evaluating mechanisms for the widespread change in deep-water chemistry, its

  15. Orbitally tuned timescale and astronomical forcing in the middle Eocene to early Oligocene

    NASA Astrophysics Data System (ADS)

    Westerhold, T.; Röhl, U.; Pälike, H.; Wilkens, R.; Wilson, P. A.; Acton, G.

    2014-05-01

    Deciphering the driving mechanisms of Earth system processes, including the climate dynamics expressed as paleoceanographic events, requires a complete, continuous, and high-resolution stratigraphy that is very accurately dated. In this study, a robust astronomically calibrated age model was constructed for the middle Eocene to early Oligocene interval (31-43 Ma) in order to permit more detailed study of the exceptional climatic events that occurred during this time, including the middle Eocene climate optimum and the Eocene-Oligocene transition. A goal of this effort is to accurately date the middle Eocene to early Oligocene composite section cored during the Pacific Equatorial Age Transect (PEAT, IODP Exp. 320/321). The stratigraphic framework for the new timescale is based on the identification of the stable long eccentricity cycle in published and new high-resolution records encompassing bulk and benthic stable isotope, calibrated XRF core scanning, and magnetostratigraphic data from ODP Sites 171B-1052, 189-1172, 199-1218, and 207-1260 as well as IODP Sites 320-U1333, and 320-U1334 spanning magnetic polarity Chrons C12n to C20n. Subsequently orbital tuning of the records to the La2011 orbital solution was conducted. The resulting new timescale revises and refines the existing orbitally tuned age model and the geomagnetic polarity timescale from 31 to 43 Ma. The newly defined absolute age for the Eocene-Oligocene boundary validates the astronomical tuned age of 33.89 Ma identified at the Massignano, Italy, global stratotype section and point. The compilation of geochemical records of climate-controlled variability in sedimentation through the middle-to-late Eocene and early Oligocene demonstrates strong power in the eccentricity band that is readily tuned to the latest astronomical solution. Obliquity driven cyclicity is only apparent during 2.4 myr eccentricity cycle minima around 35.5, 38.3, and 40.1 Ma.

  16. Orbitally tuned time scale and astronomical forcing in the middle Eocene to early Oligocene

    NASA Astrophysics Data System (ADS)

    Westerhold, T.; Röhl, U.; Pälike, H.; Wilkens, R.; Wilson, P. A.; Acton, G.

    2013-12-01

    Deciphering the driving mechanisms of Earth system processes, including the climate dynamics expressed as paleoceanographic events, requires a complete, continuous, and high-resolution stratigraphy that is very accurately dated. In this study, we construct a robust astronomically calibrated age model for the middle Eocene to early Oligocene interval (31-43 Ma) in order to permit more detailed study of the exceptional climatic events that occurred during this time, including the Middle Eocene Climate Optimum and the Eocene/Oligocene transition. A goal of this effort is to accurately date the middle Eocene to early Oligocene composite section cored during the Pacific Equatorial Age Transect (PEAT, IODP Exp. 320/321). The stratigraphic framework for the new time scale is based on the identification of the stable long eccentricity cycle in published and new high-resolution records encompassing bulk and benthic stable isotope, calibrated XRF core scanning, and magnetostratigraphic data from ODP Sites 171B-1052, 189-1172, 199-1218, and 207-1260 as well as IODP Sites 320-U1333, and -U1334 spanning magnetic polarity Chrons C12n to C20n. Subsequently we applied orbital tuning of the records to the La2011 orbital solution. The resulting new time scale revises and refines the existing orbitally tuned age model and the Geomagnetic Polarity Time Scale from 31 to 43 Ma. Our newly defined absolute age for the Eocene/Oligocene boundary validates the astronomical tuned age of 33.89 Ma identified at the Massignano (Italy) global stratotype section and point. Our compilation of geochemical records of climate-controlled variability in sedimentation through the middle-to-late Eocene and early Oligocene demonstrates strong power in the eccentricity band that is readily tuned to the latest astronomical solution. Obliquity driven cyclicity is only apparent during very long eccentricity cycle minima around 35.5, 38.3 and 40.1 Ma.

  17. Study of equatorial scintillations

    NASA Technical Reports Server (NTRS)

    Pomalaza, J.; Woodman, R.; Tisnado, G.; Nakasone, E.

    1972-01-01

    Observations of the amplitude scintillations produced by the F-region in equatorial areas are presented. The equipment used for conducting the observations is described. The use of transmissions from the ATS-1, ATS-3, and ATS-5 for obtaining data is described. The two principal subjects discussed are: (1) correlation between satellite and incoherent radar observations of scintillations and (2) simultaneous observations of scintillations at 136 MHz and 1550 MHz.

  18. Integrated bio-magnetostratigraphy of ODP Site 709 (equatorial Indian Ocean).

    NASA Astrophysics Data System (ADS)

    Villa, Giuliana; Fioroni, Chiara; Florindo, Fabio

    2015-04-01

    Over the last decade, calcareous nannofossil biostratigraphy of the lower Eocene-Oligocene sediments has shown great potential, through identification of several new nannofossil species and bioevents (e.g. Fornaciari et al., 2010; Bown and Dunkley Jones, 2012; Toffanin et al., 2013). These studies formed the basis for higher biostratigraphic resolution leading to definition of a new nannofossil biozonation (Agnini et al., 2014). In this study, we investigate the middle Eocene-lower Oligocene sediments from ODP Hole 709C (ODP Leg 115) by means of calcareous nannofossils and magnetostratigraphy. Ocean Drilling Program (ODP) Site 709 was located in the equatorial Indian Ocean and biostratigraphy has been investigated in the nineties (Okada, 1990; Fornaciari et al., 1990) while paleomagnetic data from the Initial Report provided only a poorly constrained magnetostratigraphic interpretation, thus the cored succession was dated only by means of biostratigraphy. Our goal is to test the reliability in the Indian Ocean of the biohorizons recently identified at Site 711 (Fioroni et al., in press), by means of high resolution sampling, new taxonomic updates, quantitative analyses on calcareous nannofossils allowed to increase the number of useful bioevents and to compare their reliability and synchroneity. The new magnetostratigraphic analyses and integrated stratigraphy allow also to achieve an accurate biochronology of the time interval spanning Chrons C20 (middle Eocene) and C12 (early Oligocene). In addition, this equatorial site represents an opportunity to study the carbonate accumulation history and the large fluctuations of the carbonate compensation depth (CCD) during the Eocene (e.g. Pälike et al., 2012). The investigated interval encompasses the Middle Eocene Climatic Optimum (MECO), and the long cooling trend that leads to the Oligocene glacial state. By means of our new bio-magnetostratigraphic data and paleoecological results we provide further insights on

  19. Calcareous phytoplankton perturbations through the Eocene/Oligocene Transition

    NASA Astrophysics Data System (ADS)

    Bown, P. R.; Dunkley Jones, T.; Expedition 320/321 Shipboard Party

    2010-12-01

    The Eocene-Oligocene transition (E/OT) witnessed the most significant climatic change in the Cenozoic with a fundamental reordering of the planet’s oceanic and atmospheric circulation, the cooling of deep and high-latitude waters and the formation of continental scale ice sheets on Antarctica. Records from the equatorial Pacific show rapid and highly correlated increases in deep-ocean oxygen and carbon isotopes and a drop in the Calcium Carbonate Compensation Depth (CCD) of over a kilometre (Coxall et al. 2005). The role of surface ocean productivity changes, especially at low latitudes, within this carbon cycle perturbation remains open to question. Detailed micropalaeontological analyses from shelf-slope sections of Tanzania, which host exceptionally well preserved calcareous microfossils, indicate a significant reorganization of planktonic niches coincident with the E/OT (Pearson et al. 2008). These include major assemblage shifts within the calcareous phytoplankton closely coupled to the isotopic excursions (Dunkley Jones et al. 2008). Here, we integrate the Tanzanian records with patterns of calcareous nannofossil turnover observed in historic DSDP Site 242 (Davie Ridge, Indian Ocean), the US Gulf Coast and preliminary data from new E/OT successions recovered during the recent IODP Expedition 320 in the eastern equatorial Pacific and discuss their implications for nutrient cycling and surface ocean productivity across the E/OT. Coxall, H. K., Wilson, P. A., Palike, H., Lear, C. H. & Backman, J. 2005. Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean. Nature 433: 53-57. Dunkley Jones, T., Bown, P. R., Pearson, P. N., Wade, B. S., Coxall, H. K. & Lear, C. H. 2008. Major shifts in calcareous phytoplankton assemblages through the Eocene-Oligocene transition of Tanzania and their implications for low-latitude primary production, Paleoceanography, 23, PA4204, doi:10.1029/2008PA001640. Pearson, P.N, McMillan, I. K

  20. Rain Gauges Handbook

    SciTech Connect

    Bartholomew, M. J.

    2016-01-01

    To improve the quantitative description of precipitation processes in climate models, the Atmospheric Radiation Measurement (ARM) Climate Research Facility deployed rain gauges located near disdrometers (DISD and VDIS data streams). This handbook deals specifically with the rain gauges that make the observations for the RAIN data stream. Other precipitation observations are made by the surface meteorology instrument suite (i.e., MET data stream).

  1. Understanding Acid Rain

    ERIC Educational Resources Information Center

    Damonte, Kathleen

    2004-01-01

    The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

  2. Acid Rain Study Guide.

    ERIC Educational Resources Information Center

    Hunger, Carolyn; And Others

    Acid rain is a complex, worldwide environmental problem. This study guide is intended to aid teachers of grades 4-12 to help their students understand what acid rain is, why it is a problem, and what possible solutions exist. The document contains specific sections on: (1) the various terms used in conjunction with acid rain (such as acid…

  3. The Acid Rain Reader.

    ERIC Educational Resources Information Center

    Stubbs, Harriett S.; And Others

    A topic which is often not sufficiently dealt with in elementary school textbooks is acid rain. This student text is designed to supplement classroom materials on the topic. Discussed are: (1) "Rain"; (2) "Water Cycle"; (3) "Fossil Fuels"; (4) "Air Pollution"; (5) "Superstacks"; (6) "Acid/Neutral/Bases"; (7) "pH Scale"; (8) "Acid Rain"; (9)…

  4. No Rain, No Gain

    ERIC Educational Resources Information Center

    Perna, Mark C.

    2005-01-01

    Marketing is like the rain. Some people are quickly aware of it, while others take repeated and consistent drops for quite an extended period of time before they take action. Building on the marketing principles discussed in previous issues, the next key principle to smart marketing is the "Rain Effect." The Rain Effect is the use of consistent…

  5. The Children's Rain Forest.

    ERIC Educational Resources Information Center

    Thornton, Carol A.; And Others

    1995-01-01

    Describes a unit on rain forests in which first graders studied about rain forests, built a classroom rain forest, and created a bulletin board. They also graphed rainfall, estimated body water, and estimated the number of newspapers that could be produced from one canopy tree. (MKR)

  6. Equatorial Wave Line, Pacific Ocean

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This Equatorial Wave Line (2.0 N, 102.5W) seen in the Pacific Ocean is of great interest to oceanographers because of the twice annual upwelling of the oceans nutrients. As a result of nearly constant easterly winds, cool nutrient rich water wells up at the equator. The long narrow line is an equatorial front or boundry between warm surface equatorial water and cool recently upwelled water as the intermix of nutrients takes place.

  7. No extreme bipolar glaciation during the main Eocene calcite compensation shift.

    PubMed

    Edgar, Kirsty M; Wilson, Paul A; Sexton, Philip F; Suganuma, Yusuke

    2007-08-23

    Major ice sheets were permanently established on Antarctica approximately 34 million years ago, close to the Eocene/Oligocene boundary, at the same time as a permanent deepening of the calcite compensation depth in the world's oceans. Until recently, it was thought that Northern Hemisphere glaciation began much later, between 11 and 5 million years ago. This view has been challenged, however, by records of ice rafting at high northern latitudes during the Eocene epoch and by estimates of global ice volume that exceed the storage capacity of Antarctica at the same time as a temporary deepening of the calcite compensation depth approximately 41.6 million years ago. Here we test the hypothesis that large ice sheets were present in both hemispheres approximately 41.6 million years ago using marine sediment records of oxygen and carbon isotope values and of calcium carbonate content from the equatorial Atlantic Ocean. These records allow, at most, an ice budget that can easily be accommodated on Antarctica, indicating that large ice sheets were not present in the Northern Hemisphere. The records also reveal a brief interval shortly before the temporary deepening of the calcite compensation depth during which the calcite compensation depth shoaled, ocean temperatures increased and carbon isotope values decreased in the equatorial Atlantic. The nature of these changes around 41.6 million years ago implies common links, in terms of carbon cycling, with events at the Eocene/Oligocene boundary and with the 'hyperthermals' of the Early Eocene climate optimum. Our findings help to resolve the apparent discrepancy between the geological records of Northern Hemisphere glaciation and model results that indicate that the threshold for continental glaciation was crossed earlier in the Southern Hemisphere than in the Northern Hemisphere. PMID:17713530

  8. Eocene prevalence of monsoon-like climate over eastern China reflected by hydrological dynamics

    NASA Astrophysics Data System (ADS)

    Wang, Dehai; Lu, Shicong; Han, Shuang; Sun, Xiaoyan; Quan, Cheng

    2013-01-01

    Hydrological dynamics of sedimentary basins are essential for understanding regional climatic pattern in the geological past. In previous qualitative studies lithologically depending on the occurrence of featured sedimentary rocks, the Eocene climate of China had been subdivided into three latitudinal zones, with one subtropical high-controlled arid zone throughout middle China, and two humid zones respectively in the north and south. However, recent advances on mammalian fauna distribution, plant fossil-based quantitative paleoclimatic reconstruction, and modeling experiment jointly suggest that the relatively humid monsoonal climate might have prevailed over the territory. Here we examine and compare sedimentary sequences of 10 Eocene sections across eastern China, and hence the lake level fluctuations, to discuss the nature of climate type. Our results show that, instead of the categorically zonal pattern, the hydroclimate dynamics is intensified landward. This is demonstrated by the fact that, in contrast to the wide developed coal layers around the periphery, evaporites are growingly occurred endocentrically to the central part of middle China. However, although we have had assumed that all evaporites are indicator of extreme aridity, the highly oscillated climate in the central part of middle China was humid in the majority of the Eocene, distinct from permanent arid as seen in deserts or steppe along modern horse latitude. From the upcountry distribution pattern of the Eocene hydrological dynamics, it appears that the relatively dry climate in central China was caused by the impact of continentality or rain shadow effect under monsoonal, or monsoon-like climate.

  9. ACTS Rain Fade Compensation

    NASA Technical Reports Server (NTRS)

    Coney, Thom A.

    1996-01-01

    Performance status of the Adaptive Rain Fade Compensation includes: (1) The rain fade protocol is functional detecting fades, providing an additional 10 dB of margin and seamless transitions to and from coded operation; (2) The stabilization of the link margins and the optimization of rain fade decision thresholds has resulted in improved BER performance; (3) Characterization of the fade compensation algorithm is ongoing.

  10. Rain forest preservation

    SciTech Connect

    Weiner, R.F. )

    1989-01-01

    The author discusses the possible impact the destruction of the tropical rain forest in South America has had on the atmosphere. Slash-and-burn agricultural practices have caused laterization of the soils, because rain forest vegetation carries nutrients, rather than the soil. The fact that the vegetation of the rain forest can help metabolize the excess carbon dioxide in the atmosphere is also mentioned.

  11. Eocene ostracoda from Oshosun formation Southwestern Nigeria

    NASA Astrophysics Data System (ADS)

    Okosun, E. A.

    A biostratigraphic study of the phosphate-bearing Oshosun Formation in southwestern Nigeria (eastern Dahomey Embayment) gave ostracos which are diagnostic for the Eocene. The ostracod assemblage contains the early to middle Eocene zonal index Costa dahomeyi. The majority of the species are common to the phosphatic sequence in the western Dahomey Embayment. This paleontologic evidence, and the association of clay and shale with the phosphate occurrences in different parts of the basin, suggest that the phosphatic beds were deposited in the Dahomey Embayment under similar paleoenvironmental conditions. Phosphatic sedimentation in southwestern Nigeria is inferred to have occurred during an early to early middle Eocene minor marine transgression.

  12. USGS Tracks Acid Rain

    USGS Publications Warehouse

    Gordon, John D.; Nilles, Mark A.; Schroder, LeRoy J.

    1995-01-01

    The U.S. Geological Survey (USGS) has been actively studying acid rain for the past 15 years. When scientists learned that acid rain could harm fish, fear of damage to our natural environment from acid rain concerned the American public. Research by USGS scientists and other groups began to show that the processes resulting in acid rain are very complex. Scientists were puzzled by the fact that in some cases it was difficult to demonstrate that the pollution from automobiles and factories was causing streams or lakes to become more acidic. Further experiments showed how the natural ability of many soils to neutralize acids would reduce the effects of acid rain in some locations--at least as long as the neutralizing ability lasted (Young, 1991). The USGS has played a key role in establishing and maintaining the only nationwide network of acid rain monitoring stations. This program is called the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). Each week, at approximately 220 NADP/NTN sites across the country, rain and snow samples are collected for analysis. NADP/NTN site in Montana. The USGS supports about 72 of these sites. The information gained from monitoring the chemistry of our nation's rain and snow is important for testing the results of pollution control laws on acid rain.

  13. Paleogene equatorial penguins challenge the proposed relationship between biogeography, diversity, and Cenozoic climate change.

    PubMed

    Clarke, Julia A; Ksepka, Daniel T; Stucchi, Marcelo; Urbina, Mario; Giannini, Norberto; Bertelli, Sara; Narváez, Yanina; Boyd, Clint A

    2007-07-10

    New penguin fossils from the Eocene of Peru force a reevaluation of previous hypotheses regarding the causal role of climate change in penguin evolution. Repeatedly it has been proposed that penguins originated in high southern latitudes and arrived at equatorial regions relatively recently (e.g., 4-8 million years ago), well after the onset of latest Eocene/Oligocene global cooling and increases in polar ice volume. By contrast, new discoveries from the middle and late Eocene of Peru reveal that penguins invaded low latitudes >30 million years earlier than prior data suggested, during one of the warmest intervals of the Cenozoic. A diverse fauna includes two new species, here reported from two of the best exemplars of Paleogene penguins yet recovered. The most comprehensive phylogenetic analysis of Sphenisciformes to date, combining morphological and molecular data, places the new species outside the extant penguin radiation (crown clade: Spheniscidae) and supports two separate dispersals to equatorial (paleolatitude approximately 14 degrees S) regions during greenhouse earth conditions. One new species, Perudyptes devriesi, is among the deepest divergences within Sphenisciformes. The second, Icadyptes salasi, is the most complete giant (>1.5 m standing height) penguin yet described. Both species provide critical information on early penguin cranial osteology, trends in penguin body size, and the evolution of the penguin flipper.

  14. Paleogene equatorial penguins challenge the proposed relationship between biogeography, diversity, and Cenozoic climate change

    PubMed Central

    Clarke, Julia A.; Ksepka, Daniel T.; Stucchi, Marcelo; Urbina, Mario; Giannini, Norberto; Bertelli, Sara; Narváez, Yanina; Boyd, Clint A.

    2007-01-01

    New penguin fossils from the Eocene of Peru force a reevaluation of previous hypotheses regarding the causal role of climate change in penguin evolution. Repeatedly it has been proposed that penguins originated in high southern latitudes and arrived at equatorial regions relatively recently (e.g., 4–8 million years ago), well after the onset of latest Eocene/Oligocene global cooling and increases in polar ice volume. By contrast, new discoveries from the middle and late Eocene of Peru reveal that penguins invaded low latitudes >30 million years earlier than prior data suggested, during one of the warmest intervals of the Cenozoic. A diverse fauna includes two new species, here reported from two of the best exemplars of Paleogene penguins yet recovered. The most comprehensive phylogenetic analysis of Sphenisciformes to date, combining morphological and molecular data, places the new species outside the extant penguin radiation (crown clade: Spheniscidae) and supports two separate dispersals to equatorial (paleolatitude ≈14°S) regions during greenhouse earth conditions. One new species, Perudyptes devriesi, is among the deepest divergences within Sphenisciformes. The second, Icadyptes salasi, is the most complete giant (>1.5 m standing height) penguin yet described. Both species provide critical information on early penguin cranial osteology, trends in penguin body size, and the evolution of the penguin flipper. PMID:17601778

  15. An Early Cenozoic Ichthyolith Record from Demerara Rise (ODP Site 1258: Equatorial Atlantic Ocean)

    NASA Astrophysics Data System (ADS)

    Bryant, R. M.; Sibert, E. C.; Norris, R. D.

    2014-12-01

    Peak global warmth during the early Eocene is a partial analog to the future structure of marine ecosystems in a high pCO2 world. Early Eocene oceans are generally regarded as supporting warmer oceans with lower overall productivity than today owing to the low concentrations of preserved organic matter in pelagic sediments. It has also been proposed that Eocene oceans were about as productive as now, but higher respiration rates in a warmer-than-modern ocean more efficiently recycled organic matter and nutrients. We investigated Eocene export productivity and its link to taxonomic diversity using the pelagic ichthyolith record. Ichthyoliths are calcium phosphate microfossils including fish teeth and shark denticles and their fragments, and are a unique paleoceanographic proxy because they represent a fossil record for marine vertebrates, a charismatic and tangible part of the ecosystem that generally goes unrepresented in the fossil record. Analysis of the ichthyolith record in Ocean Drilling Program Site 1258 (NE South America) shows a remarkable increase in accumulation rate of ichthyoliths from the Paleocene into the Eocene, suggesting that onset of the Early Eocene Climatic Optimum in the equatorial Atlantic was favorable to fish production. Our results suggest that, if anything, the early Eocene maintained higher productivity than in the late Paleocene. These results compare favorably with a record of ichthyolith accumulation in the South Pacific (DSDP 596), which also indicates unusually high rates of fish productivity in the peak of Eocene warm climates. Low resolution data sets from the Pacific suggest an explosion of morphotypes during the warm period associated with an increase in ichthyolith mass accumulation rates. Peak global warmth, therefore, appears to be associated with both higher fish production and higher taxonomic diversity than suggested by previous reconstructions of Eocene primary production. Increasing the amount of continuous records of

  16. The Coudé Equatorials

    NASA Astrophysics Data System (ADS)

    Lequeux, James

    2011-11-01

    Between 1884 and 1892, no fewer than seven coudé equatorials were installed in France, Algeria and Austria. Invented by Maurice Loewy, these equatorials allowed the observer to sit comfortably in a closed room, with all the controls and readings at hand. However they were expensive, they required two flat mirrors, which were a source of concern because of their thermal distortion, and their mechanics was complex and delicate, so that they did not succeed in replacing the conventional equatorials in spite of their advantages. Only two are preserved, in Lyons and in Algiers. We describe in detail these instruments, their history and their use.

  17. What Is Acid Rain?

    ERIC Educational Resources Information Center

    Likens, Gene E.

    2004-01-01

    Acid rain is the collective term for any type of acidified precipitation: rain, snow, sleet, and hail, as well as the presence of acidifying gases, particles, cloud water, and fog in the atmosphere. The increased acidity, primarily from sulfuric and nitric acids, is generated as a by-product of the combustion of fossil fuels such as coal and oil.…

  18. Rain Forest Murals

    ERIC Educational Resources Information Center

    Kleiner, Cheryl

    2010-01-01

    The rain forest murals in the author's school began as a request from her principal to have students decorate the cafeteria with their own paintings. She decided to brainstorm ideas with her eighth-grade students. Taking into consideration the architectural space and the environmental concerns they wanted to convey, students chose the rain forest…

  19. After the Rain: Using the Rain.

    ERIC Educational Resources Information Center

    Old Elk, Arlene; Stoklas, Jackie

    The Heard Museum (Phoenix, Arizona) has developed and updated an integrated curriculum for use in grades K-3. The goals for this curriculum are to: (1) share museum resources with schools; (2) promote cross-cultural understanding through a focus on rain, a universal requirement for life; (3) help students understand that Native Americans are…

  20. Geologic mapping of Indonesian rain forest with analysis of multiple SIR-B incidence angles

    NASA Technical Reports Server (NTRS)

    Ford, J. P.; Sabins, F. F., Jr.; Asmoro, P., Jr.

    1984-01-01

    The discrimination and mapping capabilities are to be evaluated for shuttle imaging radar-B (SIR-B) images of geologic features in Indonesia that are covered by equatorial rain forest canopy. The SIR-B backscatter from the rain forest at L-band is to be compared to backscatter acquired by the SEASAT scatterometer system at Ku-band ever corresponding areas. The approach for data acquisition, handling, and analysis and the expected results of the investigation are discussed.

  1. A Cenozoic record of the equatorial Pacific carbonate compensation depth.

    PubMed

    Pälike, Heiko; Lyle, Mitchell W; Nishi, Hiroshi; Raffi, Isabella; Ridgwell, Andy; Gamage, Kusali; Klaus, Adam; Acton, Gary; Anderson, Louise; Backman, Jan; Baldauf, Jack; Beltran, Catherine; Bohaty, Steven M; Bown, Paul; Busch, William; Channell, Jim E T; Chun, Cecily O J; Delaney, Margaret; Dewangan, Pawan; Dunkley Jones, Tom; Edgar, Kirsty M; Evans, Helen; Fitch, Peter; Foster, Gavin L; Gussone, Nikolaus; Hasegawa, Hitoshi; Hathorne, Ed C; Hayashi, Hiroki; Herrle, Jens O; Holbourn, Ann; Hovan, Steve; Hyeong, Kiseong; Iijima, Koichi; Ito, Takashi; Kamikuri, Shin-ichi; Kimoto, Katsunori; Kuroda, Junichiro; Leon-Rodriguez, Lizette; Malinverno, Alberto; Moore, Ted C; Murphy, Brandon H; Murphy, Daniel P; Nakamura, Hideto; Ogane, Kaoru; Ohneiser, Christian; Richter, Carl; Robinson, Rebecca; Rohling, Eelco J; Romero, Oscar; Sawada, Ken; Scher, Howie; Schneider, Leah; Sluijs, Appy; Takata, Hiroyuki; Tian, Jun; Tsujimoto, Akira; Wade, Bridget S; Westerhold, Thomas; Wilkens, Roy; Williams, Trevor; Wilson, Paul A; Yamamoto, Yuhji; Yamamoto, Shinya; Yamazaki, Toshitsugu; Zeebe, Richard E

    2012-08-30

    Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.

  2. Life in Tropical Rain Forests.

    ERIC Educational Resources Information Center

    NatureScope, 1989

    1989-01-01

    Discusses the diversity of rain forest life, the adaptations of rain forest plants and animals, and ways these organisms interact. Includes activities on canopy critters with a copyable sheet, rain forest revue, design a plant, and jungle sleuths. (RT)

  3. Low-Latitude Ethane Rain on Titan

    NASA Technical Reports Server (NTRS)

    Dalba, Paul A.; Buratti, Bonnie J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-01-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years. These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally. Determining the composition of this rainfall is an important step in understanding the "methanological" cycle on Titan. I use data from Cassini VIMS to complete a spectroscopic investigation of multiple rain-wetted areas. I compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain. By comparing these spectral ratios to a model of liquid ethane, I find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. I show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, I show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form.

  4. The demise of the early Eocene greenhouse - Decoupled deep and surface water cooling in the eastern North Atlantic

    NASA Astrophysics Data System (ADS)

    Bornemann, André; D'haenens, Simon; Norris, Richard D.; Speijer, Robert P.

    2016-10-01

    Early Paleogene greenhouse climate culminated during the early Eocene Climatic Optimum (EECO, 50 to 53 Ma). This episode of global warmth is subsequently followed by an almost 20 million year-long cooling trend leading to the Eocene-Oligocene glaciation of Antarctica. Here we present the first detailed planktic and benthic foraminiferal isotope single site record (δ13C, δ18O) of late Paleocene to middle Eocene age from the North Atlantic (Deep Sea Drilling Project Site 401, Bay of Biscay). Good core recovery in combination with well preserved foraminifera makes this site suitable for correlations and comparison with previously published long-term records from the Pacific Ocean (e.g. Allison Guyot, Shatsky Rise), the Southern Ocean (Maud Rise) and the equatorial Atlantic (Demerara Rise). Whereas our North Atlantic benthic foraminiferal δ18O and δ13C data agree with the global trend showing the long-term shift toward heavier δ18O values, we only observe minor surface water δ18O changes during the middle Eocene (if at all) in planktic foraminiferal data. Apparently, the surface North Atlantic did not cool substantially during the middle Eocene. Thus, the North Atlantic appears to have had a different surface ocean cooling history during the middle Eocene than the southern hemisphere, whereas cooler deep-water masses were comparatively well mixed. Our results are in agreement with previously published findings from Tanzania, which also support the idea of a muted post-EECO surface-water cooling outside the southern high-latitudes.

  5. Understanding acid rain

    SciTech Connect

    Budiansky, S.

    1981-06-01

    The complexities of the phenomenon of acid rain are described. Many factors, including meteorology, geology, chemistry, and biology, all play parts. Varying weather, varying soils, the presence of other pollutants and species differences all act to blur the connections between industrial emissions, acid rain, and environmental damage. Some experts believe that the greatest pH shock to lakes occurs during snow melt and runoff in the spring; others believe that much of the plant damage ascribed to acid rain is actually due to the effects of ozone. Much work needs to be done in the area of sampling. Historical data are lacking and sampling methods are not sufficiently accurate. (JMT)

  6. Tethys’ Mysterious Equatorial Band

    NASA Astrophysics Data System (ADS)

    Elder, Catherine; Helfenstein, P.; Thomas, P.; Veverka, J.; Burns, J. A.; Denk, T.; Porco, C.

    2007-10-01

    We investigate a conspicuous equatorial albedo band on Tethys by analyzing Cassini Imaging Science Subsystem (ISS) Narrow Angle Camera (NAC) images obtained in several wavelengths. The band, first seen in Voyager data by Stooke (1989;2002) is symmetric 15° on either side of the equator and extends from 0° to 160°W that is, almost centered on the leading part of Tethys. There is no evidence that the band is topographically-based; margins are gradational and there is no visible difference in underlying geology. Because of the otherwise broadly-uniform albedo of Tethys, subtle albedo and color variations are easily detected and we sampled them after correcting each image for wavelength-dependent limb darkening effects using Hapke's (2002) photometric model. In the ISS CL1-CL2 filter (611nm), the average albedo contrast of the band with adjacent cratered plains is only about 3%. Compared to its surroundings, the band is about 2-3% brighter in the NAC CL1-UV3 filter (338nm), 2-3% darker in the NAC CL1-GRN (568nm) and 8% darker in the NAC CL1-IR3 filter (930nm). This may indicate that the band exposes regolith composed of cleaner ice with a different grain-size distribution than surrounding materials. The average global photometric properties of Tethys are affected by the E-Ring (Verbiscer et al. 2007). However, dynamical explanations for the narrow albedo band that involve E-ring particles so far are unlikely given the broad nature of the E-ring and the inclination of Tethys. References: Hapke, B. 2002. Icarus 157, 523-534; Stooke, P.J. 1989. Lunar and Planet. Sci. Conf. 20th, 1071-1072; Stooke, P.J. 2002, Lunar and Planet. Sci. Conf, 33rd, #1553; Verbiscer et al. 2007. Science 315, pp.815.

  7. The emergence of modern type rain forests and mangroves and their traces in the palaeobotanical record during the Late Cretaceous and early Tertiary

    NASA Astrophysics Data System (ADS)

    Mohr, Barbara; Coiffard, Clément

    2014-05-01

    The origin of modern rain forests is still very poorly known. This ecosystem could have potentially fully evolved only after the development of relatively high numbers of flowering plant families adapted to rain forest conditions. During the early phase of angiosperm evolution in the early Cretaceous the palaeo-equatorial region was located in a seasonally dry climatic belt, so that during this phase, flowering plants often show adaptations to drought, rather than to continuously wet climate conditions. Therefore it is not surprising that except for the Nymphaeales, the most basal members of extant angiosperm families have members that do not necessarily occur in the continuously wet tropics today. However, during the late Early Cretaceous several clades emerged that later would give rise to families that are typically found today mostly in (shady) moist places in warmer regions. This is especially seen among the monocotyledons, a group of the mesangiosperms, that developed in many cases large leaves often with very specific venation patterns that make these leaves very unique and well recognizable. Especially members of three groups are here of interest: the arum family (Araceae), the palms (Arecaceae) and the Ginger and allies (Zingiberales). The earliest fossil of Araceae are restricted to low latitudes during the lower Cretaceous. Arecaceae and Zingiberales do not appear in the fossil record before the early late Cretaceous and occur at mid latitudes. During the Late Cretaceous, Araceae are represented at mid latitudes by non-tropical early diverging members and at low latitudes by derived rainforest members. Palms became widespread during the Late Cretataceous and also Nypa, a typical element of tropical to subtropical mangrove environments evolved during this time period. During the Paleocene Arecaceae appear to be restricted to lower latitudes as well as Zingiberales. All three groups are again widespread during the Eocene, reaching higher latitudes and

  8. Late Paleocene-early Eocene carbon isotope stratigraphy from a near-terrestrial tropical section and antiquity of Indian mammals

    NASA Astrophysics Data System (ADS)

    Samanta, A.; Sarkar, A.; Bera, M. K.; Rai, Jyotsana; Rathore, S. S.

    2013-02-01

    Late Paleocene to early Eocene (~56 to 51 Ma) interval is characterized by five distinct transient warming (hyperthermal) events (Paleocene-Eocene thermal maximum (PETM), H1/ETM2/ELMO, H2, I1 and I2) in a super greenhouse globe associated with negative carbon isotope excursions (CIEs). Although well-documented marine records exist at different latitudes, terrestrial PETM sections are rare. In particular, almost no terrestrial records of either the PETM or early Eocene hyperthermals (EEHs) are yet available from the tropics. Further, evolution of modern order of mammals near the PETM has been recorded in many northern continents; however, the response of mammals in the tropics to these warming events is unknown. A tropical terrestrial record of these hyperthermal/CIE events, encompassing the earliest modern order mammal bearing horizon from India, can therefore be vital in understanding climatic and biotic evolution during the earliest Cenozoic time. Here, for the first time, we report high resolution carbon isotope ( δ 13C) stratigraphy, nannofossil, and Sr isotope ratio of marine fossil carbonate from the Cambay Shale Formation of Western India. The record shows complete preservation of all the above CIE events, including the PETM, hitherto unknown from the equatorial terrestrial records. δ 13C chemostratigraphy further suggests that at least the present early Eocene mammal-bearing horizon, recently discovered at Vastan, does not support the `out of India' hypothesis of earliest appearance of modern mammals and subsequent dispersal to the Holarctic continents.

  9. Difficult Decisions: Acid Rain.

    ERIC Educational Resources Information Center

    Miller, John A.; Slesnick, Irwin L.

    1989-01-01

    Discusses some of the contributing factors and chemical reactions involved in the production of acid rain, its effects, and political issues pertaining to who should pay for the clean up. Supplies questions for consideration and discussion. (RT)

  10. (Acid rain workshop)

    SciTech Connect

    Turner, R.S.

    1990-12-05

    The traveler presented a paper entitled Susceptibility of Asian Ecosystems to Soil-Mediated Acid Rain Damage'' at the Second Workshop on Acid Rain in Asia. The workshop was organized by the Asian Institute of Technology (Bangkok, Thailand), Argonne National Laboratory (Argonne, Illinois), and Resource Management Associates (Madison, Wisconsin) and was sponsored by the US Department of Energy, the United Nations Environment Program, the United Nations Economic and Social Commission for Asia and the Pacific, and the World Bank. Papers presented on the first day discussed how the experience gained with acid rain in North America and Europe might be applied to the Asian situation. Papers describing energy use projections, sulfur emissions, and effects of acid rain in several Asian countries were presented on the second day. The remaining time was allotted to discussion, planning, and writing plans for a future research program.

  11. Thinking in the Rain.

    ERIC Educational Resources Information Center

    Bartlett, Albert A.

    1989-01-01

    Four questions related to rain concerning aerodynamic drag force, pressure from the impact of raindrops, impact of wind on the pressure, and stopping force extended on the car by the water are proposed. (YP)

  12. Rain-Mapping Radar

    NASA Technical Reports Server (NTRS)

    Im, K. E.; Li, F. K.; Wilson, W. J.; Rosing, D.

    1988-01-01

    Orbiting radar system measures rates of rainfall from 0.5 to 60 mm/h. Radar waves scattered and absorbed by rainfall to extents depending on wavelength, polarization, rate of rainfall, and distribution of sizes and shapes of raindrops. Backscattered radar signal as function of length of path through rain used to infer detailed information about rain. Accumulated radar return signals processed into global maps of monthly average rainfall for use in climatological studies.

  13. Callisto's Equatorial Region

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This mosaic covers part of the equatorial region of Jupiter's moon, Callisto. The mosaic combines six separate image frames obtained by the solid state imaging (CCD) system on NASA's Galileo spacecraft during its ninth orbit around Jupiter. North is to the top of the picture. The mosaic shows several new features and characteristics of the surface revealed by Galileo. These include deposits that may represent landslides in the southern and southwestern floors of many craters. Two such deposits are seen in a 12 kilometer (7.3 mile) crater in the west-central part of the image, and in a 23 kilometer (14 mile) crater just north of the center of the image. Also notable are several sinuous valleys emanating from the southern rims of 10 to 15 kilometer (6.2 to 9.3 mile) irregular craters in the west-central part of the image. The pervasive local smoothing of Callisto's surface is well represented in the plains between the craters in the southeastern part of the image. Possible oblique impacts are suggested by the elongated craters in the northeastern and southeastern parts of the image.

    The mosaic, centered at 7.4 degrees south latitude and 6.6 degrees west longitude, covers an area of approximately 315 by 215 kilometers (192 by 131 miles). The sun illuminates the scene from the west (left). The smallest features that can be seen are about 300 meters (993 feet) across. The images were obtained on June 25, 1997, when the spacecraft was at a range of 15,200 kilometers (8,207 miles) from Callisto.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  14. The Eocene/Oligocene boundary event in the deep sea

    USGS Publications Warehouse

    Corliss, B.H.; Aubry, M.-P.; Berggren, W.A.; Fenner, J.M.; Keigwin, L.D.; Keller, G.

    1984-01-01

    Analysis of middle Eocene to early Oligocene calcareous and siliceous microfossils shows gradual biotic changes with no massive extinction event across the Eocene/Oligocene boundary. Biotic changes in the late Paleogene appear to reflect changing paleoclimatic and paleoceanographic conditions and do not support suggestions of a catastrophic biotic event caused by a bolide impact at the Eocene/Oligocene boundary.

  15. PMP-2: Equatorial wave dynamics

    NASA Technical Reports Server (NTRS)

    Hirota, I.

    1982-01-01

    After the discovery of the quasi-biennial oscillation (QBO) in the stratospheric zonal wind, there were, in the last two decades, a large number of observational and theoretical studies on the structure and behavior of the mean zonal wind and waves in the tropical stratosphere. Planetary-scale, vertically propagating equatorial waves play an important role in producing the QBO through the mechanism of wave-mean flow interaction. Concerning the dynamics of the equatorial upper stratosphere and mesosphere, however, little was known about the possible wave motions, except for tides, mainly because of the lack of adequate observations in this region. The main purpose is to provide the nature of various types of equatorial wave modes, with the aid of improved sounding techniques and sophisticated numerical modelings.

  16. Rain radar instrument definition

    NASA Astrophysics Data System (ADS)

    Vincent, Nicolas; Chenebault, J.; Suinot, Noel; Mancini, Paolo L.

    1996-12-01

    As a result of a pre-phase a study, founded by ESA, this paper presents the definition of a spaceborne Rain Radar, candidate instrument for earth explorer precipitation mission. Based upon the description of user requirements for such a dedicated mission, a mission analysis defines the most suitable space segment. At system level, a parametric analysis compares pros and cons of instrument concepts associated with rain rate retrieval algorithms in order to select the most performing one. Several trade-off analysis at subsystem level leads then to the definition of the proposed design. In particular, as pulse compression is implemented in order to increase the radar sensitivity, the selected method to achieve a pulse response with a side-lobe level below--60 dB is presented. Antenna is another critical rain radar subsystem and several designs are com pared: direct radiating array, single or dual reflector illuminated by single or dual feed arrays. At least, feasibility of centralized amplification using TWTA is compared with criticality of Tx/Rx modules for distributed amplification. Mass and power budgets of the designed instrument are summarized as well as standard deviations and bias of simulated rain rate retrieval profiles. The feasibility of a compliant rain radar instrument is therefore demonstrated.

  17. Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology

    PubMed Central

    Franzen, Jens L.; Gingerich, Philip D.; Habersetzer, Jörg; Hurum, Jørn H.; von Koenigswald, Wighart; Smith, B. Holly

    2009-01-01

    Background The best European locality for complete Eocene mammal skeletons is Grube Messel, near Darmstadt, Germany. Although the site was surrounded by a para-tropical rain forest in the Eocene, primates are remarkably rare there, and only eight fragmentary specimens were known until now. Messel has now yielded a full primate skeleton. The specimen has an unusual history: it was privately collected and sold in two parts, with only the lesser part previously known. The second part, which has just come to light, shows the skeleton to be the most complete primate known in the fossil record. Methodology/Principal Findings We describe the morphology and investigate the paleobiology of the skeleton. The specimen is described as Darwinius masillae n.gen. n.sp. belonging to the Cercamoniinae. Because the skeleton is lightly crushed and bones cannot be handled individually, imaging studies are of particular importance. Skull radiography shows a host of teeth developing within the juvenile face. Investigation of growth and proportion suggest that the individual was a weaned and independent-feeding female that died in her first year of life, and might have attained a body weight of 650–900 g had she lived to adulthood. She was an agile, nail-bearing, generalized arboreal quadruped living above the floor of the Messel rain forest. Conclusions/Significance Darwinius masillae represents the most complete fossil primate ever found, including both skeleton, soft body outline and contents of the digestive tract. Study of all these features allows a fairly complete reconstruction of life history, locomotion, and diet. Any future study of Eocene-Oligocene primates should benefit from information preserved in the Darwinius holotype. Of particular importance to phylogenetic studies, the absence of a toilet claw and a toothcomb demonstrates that Darwinius masillae is not simply a fossil lemur, but part of a larger group of primates, Adapoidea, representative of the early haplorhine

  18. Estimating Rain Rates from Tipping-Bucket Rain Gauge Measurements

    NASA Technical Reports Server (NTRS)

    Wang, Jianxin; Fisher, Brad L.; Wolff, David B.

    2007-01-01

    This paper describes the cubic spline based operational system for the generation of the TRMM one-minute rain rate product 2A-56 from Tipping Bucket (TB) gauge measurements. Methodological issues associated with applying the cubic spline to the TB gauge rain rate estimation are closely examined. A simulated TB gauge from a Joss-Waldvogel (JW) disdrometer is employed to evaluate effects of time scales and rain event definitions on errors of the rain rate estimation. The comparison between rain rates measured from the JW disdrometer and those estimated from the simulated TB gauge shows good overall agreement; however, the TB gauge suffers sampling problems, resulting in errors in the rain rate estimation. These errors are very sensitive to the time scale of rain rates. One-minute rain rates suffer substantial errors, especially at low rain rates. When one minute rain rates are averaged to 4-7 minute or longer time scales, the errors dramatically reduce. The rain event duration is very sensitive to the event definition but the event rain total is rather insensitive, provided that the events with less than 1 millimeter rain totals are excluded. Estimated lower rain rates are sensitive to the event definition whereas the higher rates are not. The median relative absolute errors are about 22% and 32% for 1-minute TB rain rates higher and lower than 3 mm per hour, respectively. These errors decrease to 5% and 14% when TB rain rates are used at 7-minute scale. The radar reflectivity-rainrate (Ze-R) distributions drawn from large amount of 7-minute TB rain rates and radar reflectivity data are mostly insensitive to the event definition.

  19. Equatorial zonal circulations: Historical perspectives

    NASA Astrophysics Data System (ADS)

    Hastenrath, Stefan

    2007-04-01

    The changing perceptions on zonal circulations in the equatorial belt are traced for (a) stratospheric wind regimes, and (b) vertical-zonal circulation cells in the troposphere. (a) Observations from the Krakatoa eruption 1883 and Berson's 1908 expedition to East Africa, along with later soundings over Batavia (Jakarta) led to the notion of "Krakatoa easterlies" around 30 km (10 mb) and "Berson westerlies" around 20 km (50 mb). Prompted by contrary observations since the late 1950s, this dogma was replaced by the notion of easterlies alternating with westerlies in the equatorial stratosphere at a rhythm of about 26 months. (b) Stimulated by Bjerknes' postulate of a "Walker circulation" along the Pacific Equator, a multitude of such cells have been hypothesized at other longitudes, in part from zonal contrasts of temperature and cloudiness. Essential for the diagnosis of equatorial zonal circulation cells is the continuity following the flow between the centers of ascending and subsiding motion. Evaluation of the recent NCEP-NCAR and ECMWF Reanalysis upper-air datasets reveals equatorial zonal circulation cells over the Pacific all year round, over the Atlantic only in boreal winter, and over the Indian Ocean only in autumn, all being seasons and oceanic longitudes with strong zonal flow in the lower troposphere.

  20. Rain sampling device

    DOEpatents

    Nelson, Danny A.; Tomich, Stanley D.; Glover, Donald W.; Allen, Errol V.; Hales, Jeremy M.; Dana, Marshall T.

    1991-01-01

    The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of said precipitation from said chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device.

  1. Whither acid rain?

    PubMed

    Brimblecombe, P

    2001-04-01

    Acid rain, the environmental cause célèbre of the 1980s seems to have vanished from popular conscience. By contrast, scientific research, despite funding difficulties, has continued to produce hundreds of research papers each year. Studies of acid rain taught much about precipitation chemistry, the behaviour of snow packs, long-range transport of pollutants and new issues in the biology of fish and forested ecosystems. There is now evidence of a shift away from research in precipitation and sulfur chemistry, but an impressive theoretical base remains as a legacy.

  2. Acid rain and soil.

    PubMed

    vanLoon, G W

    1984-08-01

    A summary of important chemical properties of soil is given and the way in which acid rain may affect these properties is discussed. Acid rain may suppress microbiological decomposition and nitrification processes, thus influencing the nutrient status of soils. It has also been found that soil organic matter is less soluble in more acid solutions. Changed nutrient availability patterns are predicted in a low pH environment and enhanced leaching of essential elements from the soil exchange complex has been observed. Increased solubility of potentially toxic elements such as aluminium may also occur from soils which have been exposed to acidified rainfall.

  3. Rain sampling device

    DOEpatents

    Nelson, D.A.; Tomich, S.D.; Glover, D.W.; Allen, E.V.; Hales, J.M.; Dana, M.T.

    1991-05-14

    The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of the precipitation from the chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device. 11 figures.

  4. Airborne rain mapping radar

    NASA Technical Reports Server (NTRS)

    Wilson, W. J.; Parks, G. S.; Li, F. K.; Im, K. E.; Howard, R. J.

    1988-01-01

    An airborne scanning radar system for remote rain mapping is described. The airborne rain mapping radar is composed of two radar frequency channels at 13.8 and 24.1 GHz. The radar is proposed to scan its antenna beam over + or - 20 deg from the antenna boresight; have a swath width of 7 km; a horizontal spatial resolution at nadir of about 500 m; and a range resolution of 120 m. The radar is designed to be applicable for retrieving rainfall rates from 0.1-60 mm/hr at the earth's surface, and for measuring linear polarization signatures and raindrop's fall velocity.

  5. Eocene-Oligocene proto-Cascades topography revealed by clumped (Δ47) and oxygen isotope (δ18O) geochemistry (Chumstick Basin, WA, USA)

    NASA Astrophysics Data System (ADS)

    Methner, Katharina; Fiebig, Jens; Wacker, Ulrike; Umhoefer, Paul; Chamberlain, C. Page; Mulch, Andreas

    2016-03-01

    The topography of the present-day Washington Cascades impacts atmospheric circulation and precipitation patterns in the Pacific Northwest, introducing a pronounced orographic rain shadow in the lee of the mountain range. The temporal development of Cascade topography, however, remains largely unconstrained for the early Cenozoic. Based on coupled carbonate clumped isotope (Δ47) and oxygen isotope (δ18O) measurements we reconstruct δ18O values of Eocene groundwater (δ18Owater) in the Chumstick basin (central Washington), today located in the Cascade rain shadow. Δ47 (paleo)thermometry indicates a systematic change in basin burial temperatures from 110°C to 70°C depending on burial depth in the basin. These data are in good agreement with low-T thermochronological and vitrinite reflectance data, and further constrain the basin burial and exhumation history. In concert with field observations, microstructural analysis, and δ18O values of the analyzed carbonates, we suggest that the Δ47 temperatures and δ18O values reflect open-system carbonate cement recrystallization in meteoric-derived groundwaters during early burial diagenesis. Assuming open-system behavior, reconstructed mean δ18Owater values of ~ -7‰ (middle Eocene) to -9‰ (late Eocene/early Oligocene) are consistent with a low-elevation origin of the corresponding meteoric waters that permeated the sandstone/conglomerate members of the Eocene sedimentary units. In light of the paleogeographic setting of the Chumstick basin, the reconstructed δ18Owater values agree well with Pacific-derived moisture that did not experience strong rainout. The absence of a rain shadow effect therefore permits only moderate Eocene/Oligocene elevations at least for the southern part of the Washington proto-Cascades.

  6. Acid Rain Investigations.

    ERIC Educational Resources Information Center

    Hugo, John C.

    1992-01-01

    Presents an activity in which students investigate the formation of solid ammonium chloride aerosol particles to help students better understand the concept of acid rain. Provides activity objectives, procedures, sample data, clean-up instructions, and questions and answers to help interpret the data. (MDH)

  7. The Acid Rain Debate.

    ERIC Educational Resources Information Center

    Oates-Bockenstedt, Catherine

    1997-01-01

    Details an activity designed to motivate students by incorporating science-related issues into a classroom debate. Includes "The Acid Rain Bill" and "Position Guides" for student roles as committee members, consumers, governors, industry owners, tourism professionals, senators, and debate directors. (DKM)

  8. Acid rain bibliography

    SciTech Connect

    Sayers, C.S.

    1983-09-01

    This bibliography identifies 900 citations on various aspects of Acid Rain, covering published bibliographies, books, reports, conference and symposium proceedings, audio visual materials, pamphlets and newsletters. It includes five sections: citations index (complete record of author, title, source, order number); KWIC index; title index; author index; and source index. 900 references.

  9. Acid Rain Classroom Projects.

    ERIC Educational Resources Information Center

    Demchik, Michael J.

    2000-01-01

    Describes a curriculum plan in which students learn about acid rain through instructional media, research and class presentations, lab activities, simulations, design, and design implementation. Describes the simulation activity in detail and includes materials, procedures, instructions, examples, results, and discussion sections. (SAH)

  10. The Acid Rain Debate.

    ERIC Educational Resources Information Center

    Bybee, Rodger; And Others

    1984-01-01

    Describes an activity which provides opportunities for role-playing as industrialists, ecologists, and government officials. The activity involves forming an international commission on acid rain, taking testimony, and, based on the testimony, making recommendations to governments on specific ways to solve the problem. Includes suggestions for…

  11. The Acid Rain Game.

    ERIC Educational Resources Information Center

    Rakow, Steven J.; Glenn, Allen

    1982-01-01

    Provides rationale for and description of an acid rain game (designed for two players), a problem-solving model for elementary students. Although complete instructions are provided, including a copy of the game board, the game is also available for Apple II microcomputers. Information for the computer program is available from the author.…

  12. Rain Forests: Tropical Treasures.

    ERIC Educational Resources Information Center

    Braus, Judy, Ed.

    1989-01-01

    Ranger Rick's NatureScope is a creative education series dedicated to inspiring in children an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. The topic of this issue is "Rain Forests: Tropical Treasures." Contents are organized into the following…

  13. Slouching in the Rain

    ERIC Educational Resources Information Center

    Bailey, Herb

    2013-01-01

    A number of papers find the velocity that minimizes the wetness of a traveler caught in the rain. In this capsule we determine, in addition, the necessary amount of forward bend (slouching) so that the traveler stays as dry as possible.

  14. After the Rain: Clouds.

    ERIC Educational Resources Information Center

    Old Elk, Arlene; Stoklas, Jackie

    The Heard Museum (Phoenix, Arizona) has developed and updated an integrated curriculum for use in grades K-3. The goals for this curriculum are to: (1) share museum resources with schools; (2) promote cross-cultural understanding through a focus on rain, a universal requirement for life; (3) help students understand that Native Americans are…

  15. After the Rain: Dryspell.

    ERIC Educational Resources Information Center

    Old Elk, Arlene; Stoklas, Jackie

    The Heard Museum (Phoenix, Arizona) has developed and updated an integrated curriculum for use in grades K-3. The goals for this curriculum are to: (1) share museum resources with schools; (2) promote cross-cultural understanding through a focus on rain, a universal requirement for life; (3) help students understand that Native Americans are…

  16. After the Rain: Rainbows.

    ERIC Educational Resources Information Center

    Old Elk, Arlene; Stoklas, Jackie

    The Heard Museum (Phoenix, Arizona) has developed and updated an integrated curriculum for use in grades K-3. The goals for this curriculum are to: (1) share museum resources with schools; (2) promote cross-cultural understanding through a focus on rain, a universal requirement for life; (3) help students understand that Native Americans are…

  17. After the Rain: Animals.

    ERIC Educational Resources Information Center

    Old Elk, Arlene; Stoklas, Jackie

    The Heard Museum (Phoenix, Arizona) has developed and updated an integrated curriculum for use in grades K-3. The goals for this curriculum are to: (1) share museum resources with schools; (2) promote cross-cultural understanding through a focus on rain, a universal requirement for life; (3) help students understand that Native Americans are…

  18. People & Tropical Rain Forests.

    ERIC Educational Resources Information Center

    NatureScope, 1989

    1989-01-01

    Discusses ways people who live in rain forests make a living and some of the products that enrich our lives. Provides activities covering forest people, tropical treats, jungle in the pantry, treetop explorers, and three copyable pages to accompany activities. (Author/RT)

  19. Torrential Rain in China

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Concentric ovals of red, orange, yellow, and green are draped over southern China, showing rainfall totals for the week of June 4 through June 11, 2007. The rainfall totals are from the Goddard Space Flight Center Multi-satellite Precipitation Analysis, which is based on rainfall measurements taken by the Tropical Rainfall Measuring Mission (TRMM) satellite. Though seasonal rains are not unexpected in the area, the rain that fell during the week was torrential and relentless. As the image shows, a broad stretch of China received up to 200 millimeters (8 inches) of rain, and some areas were inundated with up to 500 millimeters (20 inches). Floods and landslides resulted, destroying crops and forcing some 643,000 people from their homes, reported the Xinhua News Agency on ReliefWeb. As of June 11, 71 people had died and 13 were missing. The most affected area was the southern coast, where rainfall totals are highest in this image. Heavy tropical rains combined with steep mountains make southeastern China prone to devastating landslides. Monitoring landslide-producing conditions typically requires extensive networks of ground-based rain gauges and weather instruments. But many developing countries in high-risk areas lack the resources to maintain such systems; heavy rains and flooding often wash away ground-based instruments. Robert Adler, a senior scientist in the Laboratory for Atmospheres at Goddard Space Flight Center, and Yang Hong, a research scientist at Goddard Earth Sciences Technology Center, are confronting the problem by developing a satellite-based system for predicting landslides. The system relies on TRMM data to predict when rainfall in different areas has reached a landslide-triggering threshold. The system makes data available on the Internet just a few hours after the satellite makes its observations. To read more about the landslide-monitoring system, please read the feature article Satellite Monitors Rains That Trigger Landslides, http

  20. Rain Drop Charge Sensor

    NASA Astrophysics Data System (ADS)

    S, Sreekanth T.

    begin{center} Large Large Rain Drop Charge Sensor Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , S. Murali Das (2) *Atmospheric Sciences Division, Centre for Earth Science Studies, Thiruvananthapuram 695011 (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) Kavyam, Manacaud, Thiruvananthapuram 695009 begin{center} ABSTRACT To study the inter-relations with precipitation electricity and precipitation microphysical parameters a rain drop charge sensor was designed and developed at CESS Electronics & Instrumentation Laboratory. Simultaneous measurement of electric charge and fall speed of rain drops could be done using this charge sensor. A cylindrical metal tube (sensor tube) of 30 cm length is placed inside another thick metal cover opened at top and bottom for electromagnetic shielding. Mouth of the sensor tube is exposed and bottom part is covered with metal net in the shielding cover. The instrument is designed in such a way that rain drops can pass only through unhindered inside the sensor tube. When electrically charged rain drops pass through the sensor tube, it is charged to the same magnitude of drop charge but with opposite polarity. The sensor tube is electrically connected the inverted input of a current to voltage converter operational amplifier using op-amp AD549. Since the sensor is electrically connected to the virtual ground of the op-amp, the charge flows to the ground and the generated current is converted to amplified voltage. This output voltage is recorded using a high frequency (1kHz) voltage recorder. From the recorded pulse, charge magnitude, polarity and fall speed of rain drop are calculated. From the fall speed drop diameter also can be calculated. The prototype is now under test running at CESS campus. As the magnitude of charge in rain drops is an indication of accumulated charge in clouds in lightning, this instrument has potential application in the field of risk and disaster management. By knowing the charge

  1. Low-Latitude Ethane Rain on Titan

    NASA Astrophysics Data System (ADS)

    Dalba, Paul; Buratti, B. J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-10-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years (Barnes, J. W. et al. 2012, Icarus, submitted). These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally (Turtle, E. P. et al. 2011, Science, 331, 1414-1417). Determining the composition of this rainfall is an important step in understanding the “methanological” cycle that dominates Titan's surface and atmosphere. In this study, we use data from Cassini VIMS to complete a thorough spectroscopic investigation of rain-wetted areas near Yalaing Terra, Hetpet Regio and central Adiri on Titan. We compute “before-and-after” spectral ratios of any areas that show either deposition or evaporation of rain at any point in the time span of August 2009 to January 2012. By comparing these spectral ratios to a model of liquid ethane that was calculated to match the resolution and sampling interval of VIMS (Brown, R. H. et al. 2008, Nature, 454, 607-610), we find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fortunately fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. We show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, we show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form as well. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to the National Aeronautics and Space Administration. Copyright 2012. All rights reserved.

  2. Low-latitude ethane rain on Titan

    NASA Astrophysics Data System (ADS)

    Dalba, P. A.; Buratti, B. J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-12-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years (Barnes, J. W. et al. 2012, Icarus, submitted). These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally (Turtle, E. P. et al. 2011, Science, 331, 1414-1417). Determining the composition of this rainfall is an important step in understanding the "methanological" cycle that dominates Titan's surface and atmosphere. In this study, we use data from Cassini VIMS to complete a thorough spectroscopic investigation of rain-wetted areas near Yalaing Terra, Hetpet Regio and central Adiri on Titan. We compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain at any point in the time span of August 2009 to January 2012. By comparing these spectral ratios to a model of liquid ethane that was calculated to match the resolution and sampling interval of VIMS (Brown, R. H. et al. 2008, Nature, 454, 607-610), we find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fortunately fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. We show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, we show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form as well. Funded by NASA.

  3. Acid rain: Reign of controversy

    SciTech Connect

    Kahan, A.M.

    1986-01-01

    Acid Rain is a primer on the science and politics of acid rain. Several introductory chapters describe in simple terms the relevant principles of water chemistry, soil chemistry, and plant physiology and discuss the demonstrated or postulated effects of acid rain on fresh waters and forests as well as on statuary and other exposed objects. There follow discussions on the economic and social implications of acid rain (for example, possible health effects) and on the sources, transport, and distribution of air pollutants.

  4. The marine 187Os/ 188Os record of the Eocene-Oligocene transition: the interplay of weathering and glaciation

    NASA Astrophysics Data System (ADS)

    Ravizza, G.; Peucker-Ehrenbrink, B.

    2003-05-01

    Osmium (Os) isotope analyses of bulk sediments from the South Atlantic, Equatorial Pacific, and the Italian Apennines yield a well-dated and coherent pattern of 187Os/ 188Os variation from the late Eocene to the early Oligocene. The resulting composite record demonstrates the global character of two prominent features of the low-resolution LL44-GPC3 Os isotope record [Pegram and Turekian, Geochim. Cosmochim. Acta 63 (1999) 4053-4058]. These are: (1) a pronounced minimum in 187Os/ 188Os (0.22-0.27) in the late Eocene, between 34 and 34.5 Ma, and (2) a subsequent rapid increase in 187Os/ 188Os, to approximately 0.6 by 32 Ma. An ultramafic weathering event and an increased influx of extraterrestrial particles to the Earth are discussed as alternative explanations for the late Eocene 187Os/ 188Os minimum. Comparison of the 187Os/ 188Os to benthic foraminiferal oxygen isotope records demonstrates that the nearly three-fold increase in 187Os/ 188Os from the late Eocene minimum coincides with the growth and decay of the first large ice sheet of the Oligocene (Oi1 [Miller et al., J. Geophys. Res. 96 (1991) 6829-6848]). The fine structure of the Os isotope record indicates that enhanced release of radiogenic Os, unrelated to the recovery from late Eocene minimum, lagged the initiation of the Oi1 event by roughly 0.5 Myr. This record, in conjunction with weathering studies in modern glacial soils [Blum, in: W.F. Ruddiman (Ed.), Tectonic Uplift and Climate Change, Plenum Press, New York, 1997, pp. 259-288; Peucker-Ehrenbrink and Blum, Geochim. Cosmochim. Acta 62 (1998) 3193-3203], suggests that exposure of freshly eroded material during deglaciation following Oi1 enhanced chemical weathering rates, and may have contributed to ice sheet stabilization by drawing down atmospheric carbon dioxide. The improved temporal resolution and age control of the refined Eocene-Oligocene Os isotope record also makes it possible to illustrate the late Eocene Os isotope excursion as a tool for

  5. Lessons from the Rain Forest.

    ERIC Educational Resources Information Center

    Phillips, Shelley

    2002-01-01

    Presents a first-grade art project after students learned about the rain forest and heard the story, "The Great Kapok Tree: A Tale of the Amazon Rain Forest" (Lynn Cherry). Explains that the students created pictures of the rain forest. (CMK)

  6. When It Rains, It Pours

    ERIC Educational Resources Information Center

    Mills, Linda

    2012-01-01

    "It's raining, it's pouring, the old man is snoring!" "The itsy, bitsy spider crawled up the waterspout, down came the rain and washed the spider out. Out came the sun and dried up all the rain, and the itsy, bitsy spider went up the spout again." What do children's nursery rhymes have to do with the school library? The author begins by telling a…

  7. Pre-Eocene rocks of Java, Indonesia

    USGS Publications Warehouse

    Ketner, Keith B.; Kastowo,; Modjo, Subroto; Naeser, C.W.; Obradovich, J.D.; Robinson, Keith; Suptandar, Tatan; Wikarno,

    1976-01-01

    The exposed pre-Eocene rocks of Java can be divided into two compound units for purposes of reconnaissance mapping and structural interpretation: a sedimentary sequence and melange. The sedimentary sequence consists of moderately deformed and little-metamorphosed conglomerate, sandstone, mudstone, claystone, chert, and limestone. The melange consists of a chaotic mechanical mixture of rocks identical to those of the sedimentary sequence and their metamorphic equivalents, such as schist, phyllite, quartzite, and marble. In addition, it contains a large proportion of quartz porphyry and smaller amounts of granite, basalt, gabbro, peridotite, pyroxenite, and serpentinite. The sedimentary sequence is at least partly of Early Cretaceous age and the melange is of Early Cretaceous to very early Paleocene age. They are overlain unconformably by Eocene rocks. The presence in the melange of blocks of quartz porphyry and granite is not easily reconcilable with current plate tectonic concepts in which the sites of formation of melange and plutonic rocks should be hundreds of kilometres apart.

  8. The influence of extraterrestrial material on the late Eocene marine Os isotope record

    NASA Astrophysics Data System (ADS)

    Paquay, François S.; Ravizza, Greg; Coccioni, Rodolfo

    2014-11-01

    A reconstruction of seawater 187Os/188Os ratios during the late Eocene (∼36-34 Ma), based upon bulk sediment analyses from the sub-Antarctic Southern Atlantic Ocean (Ocean Drilling Program (ODP) Site 1090), Eastern Equatorial Pacific Ocean (ODP Sites 1218 and 1219) and the uplifted (land-based) Tethyan section (Massignano, Italy), confirms that the previously reported abrupt shift to lower 187Os/188Os is a unique global feature of the marine Os isotope record that occurs in magnetochron C16n.1n. This feature is interpreted to represent the change in seawater 187Os/188Os caused by the Popigai impact event. Higher in the Massignano section, two other iridium anomalies previously proposed to represent additional impact events do not show a comparable excursion to low 187Os/188Os, suggesting that these horizons do not record multiple large impacts. Comparison of records from three different ocean basins indicates that seawater 187Os/188Os begins to decline in advance of the Popigai impact event. At Massignano this decline coincides with a previously reported episode of elevated 3He flux, suggesting that increased influx of interplanetary dust particles (IDPs) contributed to the pre-impact shift in 187Os/188Os and not to the longer-term latest Eocene 187Os/188Os decline that occurred ∼1 million year after the Popigai impact event.

  9. The politics of acid rain

    SciTech Connect

    Wilcher, M.E. )

    1989-01-01

    This work examines and compares the acid rain policies through the different political systems of Canada, Great Britain and the United States. Because the flow of acid rain can transcend national boundaries, acid rain has become a crucial international problem. According to the author, because of differences in governmental institutions and structure, the extent of governmental intervention in the industrial economy, the degree of reliance on coal for power generation, and the extent of acid rain damage, national responses to the acid rain problem have varied.

  10. Adaptive rain fade compensation

    NASA Technical Reports Server (NTRS)

    Rautio, J. C.

    1980-01-01

    A large available margin must be provided for satellite communications systems operating near 20 GHz, which occasionally experience fades due to rain attenuation. It is proposed that this margin may be achieved in high-capacity FDMA satellites by dynamically providing a large margin to those links which are experiencing deep fades, while maintaining a small fade margin on all others. Single-beam SCPC operation and multiple-beam, satellite-switched FDMA systems are described, and the optimization of the dynamic FDMA links in a severely fading environment is investigated. A solution is derived which takes into account: (1) transponder intermodulation distortion, (2) cochannel and cross-polarization antenna interference, and (3) rain fade characteristics. The sample system configuration presented shows that such systems reach availability levels approaching 0.9999 at Ka-Band.

  11. Geochronology of Early Eocene strata, Baja California

    SciTech Connect

    Flynn, J.J.; Cipolletti, R.M.

    1985-01-01

    Recent discoveries clearly indicate a Wasatchian (Early Eocene) land mammal age for fossil vertebrates from the Punta Prieta area, Baja California North, Mexico. This fauna provides a rare test for discriminating the temporal significance of mammalian faunas over a broad geographic area. The authors sampled intertonguing, fossiliferous terrestrial and marine strata for paleomagnetic and biostratigraphic analyses to provide an independent age determination for the Punta Prieta area mammal fauna. The marine macroinvertebrate assemblage is most likely upper Meganos to lower Capay West Coast Molluscan Stage based on the temporal ranges of all the taxa; also, none of the taxa occur in pre-Meganos stages. Two genera of planktonic forams indicate a probably Eocene age. They sampled seventeen paleomagnetic sites over 50 meters in the terrestrial mammal-bearing section, and thirteen sites over 25 meters in the marine section. The entire terrestrial sequence is reversely magnetized; initial results indicate the marine sequence probably also is reversely magnetized. Based on all the available biochronologic evidence this reversed sequence most likely should be correlated with the long reversed polarity Chron C24R. Clarkforkian to Early Wasatchian faunas in Wyoming also are associated with Chron C24R. All the available biostratigraphic and magnetostratigraphic evidence strongly supports an Early Eocene age for the Punta Prieta mammalian fauna and temporal equivalence of the Punta Prieta Wasatchian fauna with Wasatchian faunas from the Western United States. Land mammal ages are synchronous and applicable across broad geographic areas.

  12. Late Eocene rings around the earth

    NASA Technical Reports Server (NTRS)

    King, E. A.

    1980-01-01

    The suggestion of O'Keefe (1980) that the terminal Eocene event was caused by rings of tektite material encircling the earth is discussed. It is argued that the assumption that the tektites are of lunar volcanic origin is unwarranted and contrary to existing data, including the lack of lunar rocks of suitable composition, the lack of lunar rocks of the correct age, the lack of evidence that the North American tektites fell throughout a sedimentary rock column of a few million years, and the nondetection of a tektite with a measurable cosmic ray exposure age. Alternatively, it is suggested that the terminal Eocene event may be associated with volcanic ash, air-fall tuff and bentonite in the late Eocene. O'Keefe replies that the hypothesis of the terrestrial origin of the tektites conflicts with the laws of physics, for example in the glass structure and shaping of the tektites. Furthermore, evidence is cited for lunar rocks of the proper major-element composition and ages, and it is noted that the proposed solar Poynting-Robertson effect would account for the particle fall distributions and cosmic ray ages.

  13. Interplay Between the Equatorial Geophysical Processes

    NASA Astrophysics Data System (ADS)

    Sridharan, R.

    2006-11-01

    r_sridharanspl@yahoo.com With the sun as the main driving force, the Equatorial Ionosphere- thermosphere system supports a variety of Geophysical phenomena, essentially controlled by the neutral dynamical and electro dynamical processes that are peculiar to this region. All the neutral atmospheric parameters and the ionospheric parameters show a large variability like the diurnal, seasonal semi annual, annual, solar activity and those that are geomagnetic activity dependent. In addition, there is interplay between the ionized and the neutral atmospheric constituents. They manifest themselves as the Equatorial Electrojet (EEJ), Equatorial Ionization Anomaly (EIA), Equatorial Spread F (ESF), Equatorial Temperature and Wind Anomaly (ETWA). Recent studies have revealed that these phenomena, though apparently might show up as independent ones, are in reality interlinked. The interplay between these equatorial processes forms the theme for the present talk.

  14. Equatorial refuge amid tropical warming

    NASA Astrophysics Data System (ADS)

    Karnauskas, Kristopher B.; Cohen, Anne L.

    2012-07-01

    Upwelling across the tropical Pacific Ocean is projected to weaken in accordance with a reduction of the atmospheric overturning circulation, enhancing the increase in sea surface temperature relative to other regions in response to greenhouse-gas forcing. In the central Pacific, home to one of the largest marine protected areas and fishery regions in the global tropics, sea surface temperatures are projected to increase by 2.8°C by the end of this century. Of critical concern is that marine protected areas may not provide refuge from the anticipated rate of large-scale warming, which could exceed the evolutionary capacity of coral and their symbionts to adapt. Combining high-resolution satellite measurements, an ensemble of global climate models and an eddy-resolving regional ocean circulation model, we show that warming and productivity decline around select Pacific islands will be mitigated by enhanced upwelling associated with a strengthening of the equatorial undercurrent. Enhanced topographic upwelling will act as a negative feedback, locally mitigating the surface warming. At the Gilbert Islands, the rate of warming will be reduced by 0.7+/-0.3°C or 25+/-9% per century, or an overall cooling effect comparable to the local anomaly for a typical El Niño, by the end of this century. As the equatorial undercurrent is dynamically constrained to the Equator, only a handful of coral reefs stand to benefit from this equatorial island effect. Nevertheless, those that do face a lower rate of warming, conferring a significant advantage over neighbouring reef systems. If realized, these predictions help to identify potential refuges for coral reef communities from anticipated climate changes of the twenty-first century.

  15. Radio wave scintillations at equatorial regions

    NASA Technical Reports Server (NTRS)

    Poularikas, A. D.

    1972-01-01

    Radio waves, passing through the atmosphere, experience amplitude and phase fluctuations know as scintillations. A characterization of equatorial scintillation, which has resulted from studies of data recorded primarily in South America and equatorial Africa, is presented. Equatorial scintillation phenomena are complex because they appear to vary with time of day (pre-and postmidnight), season (equinoxes), and magnetic activity. A wider and more systematic geographical coverage is needed for both scientific and engineering purposes; therefore, it is recommended that more observations should be made at earth stations (at low-geomagnetic latitudes) to record equatorial scintillation phenomena.

  16. Orbital control on carbon cycle alterations and hyperthermal events in a cooling world: the late Early to Mid Eocene record at Possagno (southern Alps, Italy)

    NASA Astrophysics Data System (ADS)

    Galeotti, Simone; Sprovieri, Mario; Moretti, Matteo; Rio, Domenico; Fornaciari, Eliana; Giusberti, Luca; Agnini, Claudia; Backman, Jan; Lanci, Luca; Luciani, Valeria

    2013-04-01

    The late Early Eocene to Middle Eocene ~50-45 Million years ago (Ma) time interval in the middle bathyal, pelagic/hemipelagic succession of the Western Tethys Possagno section (southern Alps, Veneto), contains several episodes of negative carbon isotope excursions (CIEs) and concomitant dissolution of carbonates. These episodes are superimposed on a long term global climate cooling that started at about 51 Ma following the Early Eocene Climatic Optimum (EECO). Spectral analysis indicates that CIEs and dissolution events are paced by orbital forcing, confirming the global significance of previous finding on the same interval from Western and Southern Atlantic and Equatorial Pacific sites. The frequency and magnitude of CIEs through time is controlled by long-term modulations of orbital parameters, including long eccentricity (400 kyr) and a 1.2 million year modulation. Highest frequency of events - at the orbital scale - is observed across the EECO, which provides an observational basis to validate theoretical models predicting a threshold effect resulting from orbital forcing superimposed on gradually changing mean global boundary conditions. The observation of the 1.2 million year beat (long-term modulation of obliquity) together with previously published observation of enhanced obliquity (41 kyr) forcing across major CIEs and dissolution intervals indicates that high latitude feedbacks to orbital forcing played a fundamental role in the emplacement of the hyperthermals. The observed orbital forcing signature closely match that of early Eocene hyperthermals, suggesting similar driving processes.

  17. Beyond acid rain

    SciTech Connect

    Gaffney, J.S.; Streit, G.E.; Spall, W.D.; Hall, J.H.

    1987-06-01

    This paper discussed the effects of the interactions of soluble oxidants and organic toxins with sulfur dioxide and nitrogen dioxide. It suggested that these chemical reactions in the atmosphere produced a more potent acid rain which was harmful not only because it had a low pH but because it contained oxidants and organic toxins which were harmful to surface vegetation and the organisms found in surface waters. It was stressed that air pollution is a global problem and that is is necessary to develop a better fundamental understanding of how air pollution is causing damage to the streams and forests of the world. 50 references.

  18. Missing organic carbon in Eocene marine sediments: Is metabolism the biological feedback that maintains end-member climates?

    NASA Astrophysics Data System (ADS)

    Olivarez Lyle, Annette; Lyle, Mitchell W.

    2006-06-01

    Ocean chemistry is affected by pCO2 in the atmosphere by increasing the dissolution of solid calcium carbonate and elevating the dissolved inorganic carbon concentrations in seawater. Positive feedbacks between the ocean and atmosphere can maintain high atmospheric pCO2 and affect global climate. We report evidence for changes in the oceanic carbon cycle from the first high-quality organic carbon (Corg) data set of Eocene sediments beneath the equatorial Pacific upwelling region (Leg 199 of the Ocean Drilling Program). Eocene Corg mass accumulation rates (MARs) are 10 times lower than Holocene rates, even though expected Corg MARs estimated from biogenic-barium MARs (an indicator of biological production) equal or exceed modern fluxes. What happened to the missing Corg? Recent advances in ecology and biochemical kinetics show that the metabolism of nearly all animals, marine and terrestrial, is positively correlated by first principles to environmental temperatures. The approximately 10°C abyssal temperature difference from Eocene to Holocene should have radically reduced pelagic Corg burial, as we observe. We propose that higher basal metabolism and nutrient utilization/recycling rates in the Eocene water column and surface sediments precluded Corg sediment burial in the pelagic ocean. Increased rates of metabolism, nutrient utilization, and lowered Corg sedimentation caused by increased temperature may have acted as a biological feedback to maintain high atmospheric pCO2 and hothouse climates. Conversely, these same parameters would reverse sign to maintain low pCO2 when temperatures decrease, thereby maintaining "icehouse" conditions during cold climate regimes.

  19. Simulated acid rain on crops

    SciTech Connect

    Plocher, M.D.; Perrigan, S.C.; Hevel, R.J.; Cooper, R.M.; Moss, D.N.

    1985-10-01

    In 1981, simulated H/sub 2/SO/sub 4/ acid rain was applied to alfalfa and tall fescue and a 2:1 ratio of H/sub 2/SO/sub 4/:HNO/sub 3/ acid rain was applied to alfalfa, tall fescue, barley, wheat, potato, tomato, radish, and corn crops growing in the open field at Corvallis, Oregon. Careful attention was given to effects of the acid rain on the appearance of the foliage, and the effects on yield were measured. Because the effect of pH 4.0 rain on corn yield was the only significant effect noted in the 1981 studies, in 1982, more-extensive studies of the effect of simulated H/sub 2/SO/sub 4//HNO/sub 3/ rain on corn were conducted. No significant effects of acid rain were found on foliage appearance, or on yield of grain or stover in the 1982 studies.

  20. Acid rain: effects on fish and wildlife

    SciTech Connect

    Mayer, K.S.; Multer, E.P.; Schreiber, R.K.

    1984-01-01

    The following questions concerning acid rain are discussed: what is acid rain; what causes acid rain; where do sulfur and nitrogen oxides originate; what areas in the U.S. are susceptible to acid rain; are there early warning signals of acidification to aquatic resources; how does acid rain affect fishery resources; does acid rain affect wildlife; and how can effects of acid rain be reduced.

  1. Central Equatorial Pacific Experiment (CEPEX)

    SciTech Connect

    Not Available

    1993-01-01

    The Earth's climate has varied significantly in the past, yet climate records reveal that in the tropics, sea surface temperatures seem to have been remarkably stable, varying by less than a few degrees Celsius over geologic time. Today, the large warm pool of the western Pacific shows similar characteristics. Its surface temperature always exceeds 27[degree]C, but never 31[degree]C. Heightened interest in this observation has been stimulated by questions of global climate change and the exploration of stabilizing climate feedback processes. Efforts to understand the observed weak sensitivity of tropical sea surface temperatures to climate forcing has led to a number of competing ideas about the nature of this apparent thermostat. Although there remains disagreement on the processes that regulate tropical sea surface temperature, most agree that further progress in resolving these differences requires comprehensive field observations of three-dimensional water vapor concentrations, solar and infrared radiative fluxes, surface fluxes of heat and water vapor, and cloud microphysical properties. This document describes the Central Equatorial Pacific Experiment (CEPEX) plan to collect such observations over the central equatorial Pacific Ocean during March of 1993.

  2. Acid rain: Rhetoric and reality

    SciTech Connect

    Park, C.C.

    1987-01-01

    Acid rain is now one of the most serious environmental problems in developed countries. Emissions and fallout were previously extremely localized, but since the introduction of tall stacks policies in both Britain and the US - pardoxically to disperse particulate pollutants and hence reduce local damage - emissions are now lifted into the upper air currents and carried long distances downwind. The acid rain debate now embraces many western countries - including Canada, the US, England, Scotland, Wales, Sweden, Norway, Denmark, West Germany, the Netherlands, Austria, Switzerland - and a growing number of eastern countries - including the Soviet Union, Poland, East Germany, and Czechoslovakia. The problem of acid rain arises, strictly speaking, not so much from the rainfall itself as from its effects on the environment. Runoff affects surface water and groundwater, as well as soils and vegetation. Consequently changes in rainfall acidity can trigger off a range of impacts on the chemistry and ecology of lakes and rivers, soil chemistry and processes, the health and productivity of plants, and building materials, and metallic structures. The most suitable solutions to the problems of acid rain require prevention rather than cure, and there is broad agreement in both the political scientific communities on the need to reduce emissions of sulfur and nitrogen oxides to the atmosphere. Book divisions discuss: the problem of acid rain, the science of acid rain, the technology of acid rain, and the politics of acid rain, in an effort to evaluate this growing global problem of acid rain.

  3. Micro-Halocline Enabled Nutrient Recycling May Explain Extreme Azolla Event in the Eocene Arctic Ocean

    PubMed Central

    van Kempen, Monique M. L.; Smolders, Alfons J. P.; Lamers, Leon P. M.; Roelofs, Jan G. M.

    2012-01-01

    In order to understand the physicochemical mechanisms that could explain the massive growth of Azolla arctica in the Eocene Arctic Ocean, we carried out a laboratory experiment in which we studied the interacting effects of rain and wind on the development of salinity stratification, both in the presence and in the absence of a dense Azolla cover. Additionally, we carried out a mesocosm experiment to get a better understanding of the nutrient cycling within and beneath a dense Azolla cover in both freshwater and brackish water environments. Here we show that Azolla is able to create a windproof, small-scale salinity gradient in brackish waters, which allows for efficient recycling of nutrients. We suggest that this mechanism ensures the maintenance of a large standing biomass in which additional input of nutrients ultimately result in a further expansion of an Azolla cover. As such, it may not only explain the extent of the Azolla event during the Eocene, but also the absence of intact vegetative Azolla remains and the relatively low burial efficiency of organic carbon during this interval. PMID:23166833

  4. Micro-halocline enabled nutrient recycling may explain extreme Azolla event in the Eocene Arctic Ocean.

    PubMed

    van Kempen, Monique M L; Smolders, Alfons J P; Lamers, Leon P M; Roelofs, Jan G M

    2012-01-01

    In order to understand the physicochemical mechanisms that could explain the massive growth of Azolla arctica in the Eocene Arctic Ocean, we carried out a laboratory experiment in which we studied the interacting effects of rain and wind on the development of salinity stratification, both in the presence and in the absence of a dense Azolla cover. Additionally, we carried out a mesocosm experiment to get a better understanding of the nutrient cycling within and beneath a dense Azolla cover in both freshwater and brackish water environments. Here we show that Azolla is able to create a windproof, small-scale salinity gradient in brackish waters, which allows for efficient recycling of nutrients. We suggest that this mechanism ensures the maintenance of a large standing biomass in which additional input of nutrients ultimately result in a further expansion of an Azolla cover. As such, it may not only explain the extent of the Azolla event during the Eocene, but also the absence of intact vegetative Azolla remains and the relatively low burial efficiency of organic carbon during this interval. PMID:23166833

  5. More rain compensation results

    NASA Technical Reports Server (NTRS)

    Sworder, D. D.; Vojak, R.

    1992-01-01

    To reduce the impact of rain-induced attenuation in the 20/30 GHz band, the attenuation at a specified signal frequency must be estimated and extrapolated forward in time on the basis of a noisy beacon measurement. Several studies have used model based procedures for solving this problem in statistical inference. Perhaps the most widely used model-based paradigm leads to the Kalman filter and its lineal variants. In this formulation, the dynamic features of the attenuation are represented by a state process (x(sub t)). The observation process (y(sub t)) is derived from beacon measurements. Some ideas relating to the signal processing problems related to uplink power control are presented. It is shown that some easily implemented algorithms hold promise for use in estimating rain induced fades. The algorithms were applied to actual data generated at the Virginia Polytechnic Institute and State University (VPI) test facility. Because only one such event was studied, it is not clear that the algorithms will have the same effectiveness when a wide range of events are studied.

  6. Early Eocene uplift of southernmost San Joaquin basin, California

    SciTech Connect

    Reid, S.A.; Cox, B.F.

    1989-04-01

    Stratigraphic studies in the southern San Joaquin basin and in the El Paso Mountains of the southwestern Great Basin corroborate a hypothesized early Eocene regional uplift event. Eocene uplift and erosion of the southernmost San Joaquin basin south of Bakersfield were recently proposed because an early Paleogene fluviodeltaic sequence in the El Paso Mountains (Goler Formation) apparently had no seaward counterpart to the southwest. New microfossil data (coccoliths) indicate that marine deposits near the top of the Goler Formation are uppermost Paleocene (nannofossil zone CP8) rather than lower Eocene, as reported previously. These data (1) confirm that the oldest known Tertiary strata south of Bakersfield (Eocene Tejon Formation) are younger than the uppermost Goler Formation and (2) seem to restrict uplift to the earliest Eocene. The authors propose that the uppermost Cretaceous and Paleocene deposits were eroded and the Mushrush trough was cut and filled mainly in response to earliest Eocene uplift. The uplift was transverse to the northwest-trending forearc basin. Thus, it was distinct from late early Eocene (pre-Comengine Formation) regional tilting and uplift, which produced northwest-trending structures. Early Eocene uplift probably played only a minor role in the southward termination of pre-Maastrichtian parts of the forearc basin, which they instead attribute to massive uplift of the southernmost Sierra Nevada during the early(.) Late Cretaceous.

  7. Possible role of oceanic heat transport in early Eocene climate.

    PubMed

    Sloan, L C; Walker, J C; Moore, T C

    1995-04-01

    Increased oceanic heat transport has often been cited as a means of maintaining warm high-latitude surface temperatures in many intervals of the geologic past, including the early Eocene. Although the excess amount of oceanic heat transport required by warm high latitude sea surface temperatures can be calculated empirically, determining how additional oceanic heat transport would take place has yet to be accomplished. That the mechanisms of enhanced poleward oceanic heat transport remain undefined in paleoclimate reconstructions is an important point that is often overlooked. Using early Eocene climate as an example, we consider various ways to produce enhanced poleward heat transport and latitudinal energy redistribution of the sign and magnitude required by interpreted early Eocene conditions. Our interpolation of early Eocene paleotemperature data indicate that an approximately 30% increase in poleward heat transport would be required to maintain Eocene high-latitude temperatures. This increased heat transport appears difficult to accomplish by any means of ocean circulation if we use present ocean circulation characteristics to evaluate early Eocene rates. Either oceanic processes were very different from those of the present to produce the early Eocene climate conditions or oceanic heat transport was not the primary cause of that climate. We believe that atmospheric processes, with contributions from other factors, such as clouds, were the most likely primary cause of early Eocene climate.

  8. A local index of Maritime Continent intraseasonal variability based on rain rates over the land and sea

    NASA Astrophysics Data System (ADS)

    Vincent, C. L.; Lane, T. P.; Wheeler, M. C.

    2016-09-01

    A local index for describing intraseasonal variability over the Maritime Continent is developed. The index is based on the ratio of area-averaged rain rate over the land to that over the sea. It takes advantage of the fact that the main convective envelope of intraseasonal variability events tends to modulate the diurnal precipitation cycle over the land over the entire Maritime Continent. Lagged analysis is used to create composite intraseasonal variability events, where "day 0" is chosen according to when the normalized rain rate over the sea becomes greater than that over the land. The index identifies intraseasonal variability events associated with the Madden Julian Oscillation as well as equatorial Kelvin waves and westward propagating equatorial Rossby waves. The results suggest a similar local impact of all such events in suppressing the rain rate over land relative to that over the sea when the main convective envelope approaches.

  9. Ozone measurements in the troposphere of an Amazonian rain forest environment

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.; Browell, E. V.; Gregory, G. L.

    1988-01-01

    Ozone concentration profiles from the ground to above the stratospheric peak were obtained in an equatorial rain forest environment near Manaus in the Amazon Basin between July and August of 1985. The peak ozone concentration (4.4 x 10 to the 22 molecules/cu cm) was found at 20 mbar (26.6 km). A major pollution (biomass-burning) event which occurred near the end of the experiment was responsible for large changes in ozone concentration.

  10. Industrial ecotoxicology "acid rain".

    PubMed

    Astolfi, E; Gotelli, C; Higa, J

    1986-01-01

    The acid rain phenomenon was studied in the province of Cordoba, Argentina. This study, based on a previously outlined framework, determined the anthropogenic origin of the low pH due to the presence of industrial hydrochloric acid wastage. This industrial ecotoxicological phenomenon seriously affected the forest wealth, causing a great defoliation of trees and shrubs, with a lower effect on crops. A survey on its effects on human beings has not been carried out, but considering the corrosion caused to different metals and its denouncing biocide effect on plants and animals, we should expect to find some kind of harm to the health of the workers involved or others engaged in farming, and even to those who are far away from the polluting agent. PMID:3758667

  11. Industrial ecotoxicology "acid rain".

    PubMed

    Astolfi, E; Gotelli, C; Higa, J

    1986-01-01

    The acid rain phenomenon was studied in the province of Cordoba, Argentina. This study, based on a previously outlined framework, determined the anthropogenic origin of the low pH due to the presence of industrial hydrochloric acid wastage. This industrial ecotoxicological phenomenon seriously affected the forest wealth, causing a great defoliation of trees and shrubs, with a lower effect on crops. A survey on its effects on human beings has not been carried out, but considering the corrosion caused to different metals and its denouncing biocide effect on plants and animals, we should expect to find some kind of harm to the health of the workers involved or others engaged in farming, and even to those who are far away from the polluting agent.

  12. Acid rain: a background report

    SciTech Connect

    Glustrom, L.; Stolzenberg, J.

    1982-07-08

    This Staff Brief was prepared for the Wisconsin Legislative Council's Special Committee on Acid Rain to provide an introduction to the issue of acid rain. It is divided into four parts. Part I provides an overview on the controversies surrounding the measurement, formation and effects of acid rain. As described in Part I, the term acid rain is used to describe the deposition of acidic components through both wet deposition (e.g., rain or snow) and dry deposition (e.g., direct contact between atmospheric constituents and the land, water or vegetation of the earth). Part II presents background information on state agency activities relating to acid rain in Wisconsin, describes what is known about the occurrence of, susceptibility to and effects of acid rain in Wisconsin, and provides information related to man-made sources of sulfur and nitrogen oxides in Wisconsin. Part III describes major policies and regulations relating to acid rain which have been or are being developed jointly by the United States and Canadian governments, by the United States government and by the State of Wisconsin. Part IV briefly discusses possible areas for Committee action.

  13. Acid Rain: An Educational Opportunity?

    ERIC Educational Resources Information Center

    Marion, James I.

    1984-01-01

    Deals with how educators can handle the subject of acid rain; illustrates suggestions with experiences of grade nine students visiting Frost Valley Environmental Education Center (Oliverea, New York) to learn scientific concepts through observation of outdoor phenomena, including a stream; and discusses acid rain, pH levels, and pollution control…

  14. Acid rain & electric utilities II

    SciTech Connect

    1997-12-31

    This document presents reports which were presented at the Acid Rain and Electric Utilities Conference. Topics include environmental issues and electric utilities; acid rain program overview; global climate change and carbon dioxide; emissions data management; compliance; emissions control; allowance and trading; nitrogen oxides; and assessment. Individual reports have been processed separately for the United States Department of Energy databases.

  15. An Umbrella for Acid Rain.

    ERIC Educational Resources Information Center

    Randal, Judith

    1979-01-01

    The Environmental Protection Agency has awarded several grants to study effects of and possible solutions to the problem of "acid rain"; pollution from atmospheric nitric and sulfuric acids. The research program is administered through North Carolina State University at Raleigh and will focus on biological effects of acid rain. (JMF)

  16. Acid Rain: The Scientific Challenge.

    ERIC Educational Resources Information Center

    Godfrey, Paul J.

    1991-01-01

    Documents the workings and findings of the Massachusetts Acid Rain Monitoring Project, which has pooled the volunteer efforts of more than 1,000 amateur and professional scientists since 1983. Reports on the origins of air pollution, the prediction of acid rain, and its effects on both water life and land resources. (JJK)

  17. A Demonstration of Acid Rain

    ERIC Educational Resources Information Center

    Fong, Man Wai

    2004-01-01

    A demonstration showing acid rain formation is described. Oxides of sulfur and nitrogen that result from the burning of fossil fuels are the major pollutants of acid rain. In this demonstration, SO[subscript 2] gas is produced by the burning of matches. An acid-base indicator will show that the dissolved gas turns an aqueous solution acidic.

  18. Acid Rain: What's the Forecast?

    ERIC Educational Resources Information Center

    Bybee, Rodger

    1984-01-01

    Discusses various types of acid rain, considered to be a century-old problem. Topics include: wet and dry deposition, effects on a variety of environments, ecosystems subject to detrimental effects, and possible solutions to the problem. A list of recommended resources on acid rain is provided. (BC)

  19. Status of heavy rain tests

    NASA Technical Reports Server (NTRS)

    Bezos, Gaudy

    1991-01-01

    The heavy rain effects program is presented in the form of the view-graphs. The following topics are covered: rain effects on airfoil performance; two-phase flow dynamics; wind tunnel test results; issues; large-scale results; and summary.

  20. Rain Gardens: Stormwater Infiltrating Systems

    EPA Science Inventory

    The hydrological dynamics and changes in stormwater nutrient concentrations within rain gardens were studied by introducing captured stormwater runoff to rain gardens at EPA’s Urban Water Research Facility in Edison, New Jersey. The runoff used in these experiments was collected...

  1. Acid rain and environmental policy

    SciTech Connect

    Jacobson, J.S.

    1981-10-01

    Various seemingly paradoxical scientific questions are posed which relate to the problem of acid rain and its effect on the environment and environmental policy. The first paradox discussed concerns the supposed increase in fossil fuel usage over the last several decades, with the resultant increases in emissions of pollutants from the combustion of fuels which cause acid rain. Despite these increases, experts do not agree on whether acidity of rain has increased in eastern North America. The second paradox concerns the effect of acid rain on vegetation. If the rain is supposedly harmful, why have some reports shown increases and others, decreases in the growth of crops and trees with the application of simulated acid rain. The third paradox concerns the effect of acid rains on fish life in lakes. If acid rain falls throughout eastern North America, why have some lakes become acid and lost fish populations while others have not. Since unequivocal answers to these scientific questions are not available, a systematic approach is needed for developing policy which can be useful for solving the problem. It appears that traditional cost-benefit analysis can not be the sole basis for decision-making, but that it will be helpful. Research needs must be identified, and the upper and lower limits for alternative strategies must be determined. 14 references, 1 table.

  2. Acid rain in Asia

    NASA Astrophysics Data System (ADS)

    Bhatti, Neeloo; Streets, David G.; Foell, Wesley K.

    1992-07-01

    Acid rain has been an issue of great concern in North America and Europe during the past several decades. However, due to the passage of a number of recent regulations, most notably the Clean Air Act in the United States in 1990, there is an emerging perception that the problem in these Western nations is nearing solution. The situation in the developing world, particularly in Asia, is much bleaker. Given the policies of many Asian nations to achieve levels of development comparable with the industrialized world—which necessitate a significant expansion of energy consumption (most derived from indigenous coal reserves)—the potential for the formation of, and damage from, acid deposition in these developing countries is very high. This article delineates and assesses the emissions patterns, meteorology, physical geology, and biological and cultural resources present in various Asian nations. Based on this analysis and the risk factors to acidification, it is concluded that a number of areas in Asia are currently vulnerable to acid rain. These regions include Japan, North and South Korea, southern China, and the mountainous portions of Southeast Asia and southwestern India. Furthermore, with accelerated development (and its attendant increase in energy use and production of emissions of acid deposition precursors) in many nations of Asia, it is likely that other regions will also be affected by acidification in the near future. Based on the results of this overview, it is clear that acid deposition has significant potential to impact the Asian region. However, empirical evidence is urgently needed to confirm this and to provide early warning of increases in the magnitude and spread of acid deposition and its effects throughout this part of the world.

  3. Snow or rain on early Mars?

    NASA Astrophysics Data System (ADS)

    Wordsworth, R. D.

    2015-12-01

    The climate of Mars during the late Noachian 3-4 Ga remains a long-standing mystery. Over the last three decades, the key debate has been whether the valley networks and other fluvial features were carved by rain in a warm, wet Earth-like climate or by snowmelt in a mainly cold climate. Recently, it has become clear that close intercomparison between the geology and 3D climate model predictions can be used to move this debate forward. Here I describe new work comparing three-dimensional simulations under warm and cold climate scenarios with the surface distribution of valley networks. I discuss how the lack of periglacial landforms at equatorial latitudes (the 'periglacial paradox') and destabilizing climate influence of Tharsis can be used to rule out scenarios where the surface water inventory was extremely high, indicating a mainly cold, snowmelt-driven scenario for valley network formation is most likely. Finally, I discuss plausible episodic warming mechanisms and the importance of early Mars to our conception of exoplanet habitability.

  4. Tectonic control of Eocene arkosic sediment deposition, Oregon and Washington

    SciTech Connect

    Armentrout, J.M.; Ulrich, A.R.

    1983-03-01

    Chronostratigraphic and geographic studies of Eocene arkosic sandstones suggest deposition during a volcanically quiet interval resulting from the westward jump of the Farallon-Kula plate subduction zone in Oregon and Washington. The Eocene arkosic sandstones were deposited as part of a broad fluvial plain-coastal plain-shelf margin basin complex extending throughout Oregon and Washington between uplands of Mesozoic rocks. Feldspathic-quartzose sediments were transported from the east by river systems draining granitic terrains perhaps as far away as the Idaho Batholith. Chronostratigraphic correlations suggest that the arkosic sandstones were deposited along the margins of the depositional system during the early Eocene, prograded westward during the middle Eocene, and then regressed during the latest Eocene and Oligocene simultaneously with the influx of abundant pyroclastic debris. During the early Eocene, a northwest-southeast seamount chain was extruded on the Farallon and Kula plates west of an eastward-dipping subduction zone. Subduction of the oceanic plates moved the seamount chain obliquely toward the subduction zone. In middle Eocene time-49 to 40 m.y.b.p-the seamount chain reached the subduction zone creating instability in the subduction system and resulting in the westward jump of the underthrust boundary between the Farallon-Kula and North American plates. Coincident with and continuing after the subduction zone jump and seamount accretion, eastwardly derived arkosic sediments prograded across Oregon and Washington spilling into the new fore-arc basin and enveloping the seamounts.

  5. EQUATORIAL SUPERROTATION ON TIDALLY LOCKED EXOPLANETS

    SciTech Connect

    Showman, Adam P.; Polvani, Lorenzo M.

    2011-09-01

    The increasing richness of exoplanet observations has motivated a variety of three-dimensional (3D) atmospheric circulation models of these planets. Under strongly irradiated conditions, models of tidally locked, short-period planets (both hot Jupiters and terrestrial planets) tend to exhibit a circulation dominated by a fast eastward, or 'superrotating', jet stream at the equator. When the radiative and advection timescales are comparable, this phenomenon can cause the hottest regions to be displaced eastward from the substellar point by tens of degrees longitude. Such an offset has been subsequently observed on HD 189733b, supporting the possibility of equatorial jets on short-period exoplanets. Despite its relevance, however, the dynamical mechanisms responsible for generating the equatorial superrotation in such models have not been identified. Here, we show that the equatorial jet results from the interaction of the mean flow with standing Rossby waves induced by the day-night thermal forcing. The strong longitudinal variations in radiative heating-namely intense dayside heating and nightside cooling-trigger the formation of standing, planetary-scale equatorial Rossby and Kelvin waves. The Rossby waves develop phase tilts that pump eastward momentum from high latitudes to the equator, thereby inducing equatorial superrotation. We present an analytic theory demonstrating this mechanism and explore its properties in a hierarchy of one-layer (shallow-water) calculations and fully 3D models. The wave-mean-flow interaction produces an equatorial jet whose latitudinal width is comparable to that of the Rossby waves, namely the equatorial Rossby deformation radius modified by radiative and frictional effects. For conditions typical of synchronously rotating hot Jupiters, this length is comparable to a planetary radius, explaining the broad scale of the equatorial jet obtained in most hot-Jupiter models. Our theory illuminates the dependence of the equatorial jet

  6. Acidification and Acid Rain

    NASA Astrophysics Data System (ADS)

    Norton, S. A.; Veselã½, J.

    2003-12-01

    endangers the existing biota. Concerns about acid (or acidic) rain in its modern sense were publicized by the Swedish soil scientist Svante Odén (1968). He argued, initially in the Swedish press, that long-term increases in the atmospheric deposition of acid could lower the pH of surface waters, cause a decline in fish stocks, deplete soils of nutrients, and accelerate damage to materials. By the 1970s, acidification of surface waters was reported in many countries in Europe as well as in North America. The late twentieth-century rush to understand the impact of acid rain was driven by: (i) reports of damaged or threatened freshwater fisheries and (ii) damaged forests. Perhaps the earliest linkage between acidic surface water and damage to fish was made by Dahl (1921) in southern Norway. There, spring runoff was sufficiently acidic to kill trout. It was not until the 1970s that a strong link was established between depressed pH, mobilization of aluminum from soil, and fish status ( Schofield and Trojnar,1980). The relationship between acidification of soils and forest health started with hypotheses in the 1960s and has slowly developed. Acid rain enhances the availability of some nutrients (e.g., nitrogen), and may either enhance or diminish the availability of others (e.g., calcium, magnesium, potassium, and phosphorus). Damage to anthropogenic structures, human health, and visibility have also raised concerns. The history of these early developments was summarized by Cowling (1982). Since the 1970s, sulfur and nitrogen emissions to the atmosphere have been reduced by 50-85% and 0-30%, respectively, both in North America and Europe. The emission reductions have occurred as a consequence of knowledge gained and economic factors. While recovery of water quality is underway in some areas, problems of acidification persist, and are now complicated by the effects of climate change ( Schindler, 1997).

  7. Seven Guideposts for Tropical Rain Forest Education.

    ERIC Educational Resources Information Center

    Rillero, Peter

    1999-01-01

    Identifies seven guideposts for tropical rain forest education. Aids teachers in finding structure and creating educational experiences that promote more complete understanding of tropical rain forests. (CCM)

  8. The Arctic Forest of the Middle Eocene

    NASA Astrophysics Data System (ADS)

    Jahren, A. Hope

    2007-05-01

    Lush forests, dominated by deciduous conifers, existed well north of the Arctic Circle during the middle Eocene (45 Ma). The Fossil Forest site, located on Axel Heiberg Island, Canada, has yielded a particularly rich assemblage of plant macro- and microfossils, as well as paleosols -- all exquisitely preserved. Methods ranging from classical paleobotany, to stable-isotope geochemistry, have been applied to materials excavated from the Fossil Forest and have revealed layers of diverse conifer forests with a rich angiosperm understory that successfully endured three months of continuous light and three months of continuous darkness. Paleoenvironmental reconstructions suggest a warm, ice-free environment, with high growing-season-relative humidity, and high rates of soil methanogenesis. Methods to evaluate intraseasonal variability highlight the switchover from stored to actively fixed carbon during the short annual growing season.

  9. Be an acid rain detective

    SciTech Connect

    Atwill, L.

    1982-07-01

    Acid rain is discussed in a question and answer format. The article is aimed at educating sport fishermen on the subject, and also to encourage them to write their congressmen, senators, and the President about the acid rain problem. The article also announces the availability of an acid rain test kit available through the magazine, ''Sports Afield.'' The kit consists of pH-test paper that turns different shades of pink and blue according to the pH of the water tested. The color of the test paper is then compared to a color chart furnished in the kit and an approximate pH can be determined.

  10. Can crops tolerate acid rain

    SciTech Connect

    Kaplan, J.K.

    1989-11-01

    This brief article describes work by scientists at the ARS Air Quality-Plant Growth and Development Laboratory in Raleigh, North Carolina, that indicates little damage to crops as a result of acid rain. In studies with simulated acid rain and 216 exposed varieties of 18 crops, there were no significant injuries nor was there reduced growth in most species. Results of chronic and acute exposures were correlated in sensitive tomato and soybean plants and in tolerant winter wheat and lettuce plants. These results suggest that 1-hour exposures could be used in the future to screen varieties for sensitivity to acid rain.

  11. Acid rain in Asia

    SciTech Connect

    Bhatti, N.; Streets, D.G. ); Foell, W.K. )

    1991-01-01

    Acid rain has been an issue of widespread concern in North America and Europe for more than fifteen years. However, there is an emerging feeling that the problem in Europe and North America is nearing solution, largely as a result of existing and newly enacted legislation, decreased energy use due to conservation and efficiency improvements, and/or trends in energy policy away from fossil fuels. The situation in Asia appears much bleaker. Fossil fuels are already used in large quantities, such that local air pollution is becoming a serious problem and high deposition levels are being measured. Emission regulations in most countries (with the notable exception of Japan) are not very stringent. Energy plans in many countries (particularly PRC, India, Thailand, and South Korea) call for very large increases in coal combustion in the future. Finally, there is not presently a strong scientific or public constituency for action to mitigate the potential effects of acid deposition. These factors imply potentially serious problems in the future for long-range transport and deposition of sulfur and nitrogen species and consequent damage to ecosystems and materials. The political ramifications of transboundary environmental pollution in this region are also potentially serious. The purpose of this paper is to provide background information on the acid deposition situation in Asia, with the intention of laying the foundation for the development of a possible research program for this region. 36 refs., 8 figs., 8 tabs.

  12. Was the Arctic Eocene 'rainforest' monsoonal? Estimates of seasonal precipitation from early Eocene megafloras from Ellesmere Island, Nunavut

    NASA Astrophysics Data System (ADS)

    West, Christopher K.; Greenwood, David R.; Basinger, James F.

    2015-10-01

    The early Eocene was the warmest interval of the Cenozoic, and included within it were several hyperthermal events, with the Paleocene-Eocene Thermal Maximum (PETM) the most pronounced of these. These globally warm climates extended into the Arctic and substantive paleobotanical evidence for high Arctic precipitation (MAP > 150 cm/yr) is indicative of an Arctic rainforest, which contradicts some climate models that show low Arctic precipitation. Prior studies of Arctic early Eocene wood stable-isotope chemistry, however, have shown a summer peak in precipitation, which suggests modern analogs are best sought on the summer-wet east coast of the Asia (e.g., China, Japan, South Korea), not the winter-wet west coasts of the Pacific Northwest of North America). Furthermore, some prior modeling data suggest that highly seasonal 'monsoon-type' summer-wet precipitation regimes (i.e., summer:MAP > 55%) characterized certain mid and lower latitude regions in the early to mid-Eocene. Presented here is a new analysis using leaf physiognomy of 3 leaf megafloras (Split Lake, Stenkul Fiord and Strathcona Fiord) and palynofloral Bioclimatic Analysis from the Margaret Formation from Ellesmere Island, placed stratigraphically as early Eocene, possibly occurring during or following one of the early Eocene hyperthermals. These new data indicate high summer precipitation in the Arctic during the early Eocene, which in part corroborates the results from Eocene wood chemistry. Nevertheless, in contradiction to the wood analysis, monsoonal conditions are not indicated by our analysis, consistent with current modeling studies. High summer (light season) and winter (dark season) precipitation in the Eocene Arctic during hyperthermals would have contributed to regional warmth.

  13. Ozone and Aitken nuclei over equatorial Africa - Airborne observations during DECAFE 88

    NASA Technical Reports Server (NTRS)

    Andreae, M. O.; Chapuis, A.; Cros, B.; Fontan, J.; Helas, G.; Justice, C.; Kaufman, Y. J.; Minga, A.; Nganga, D.

    1992-01-01

    Results of ozone and Aitken condensation nuclei measurements made over the rain forest in equatorial Africa during February 12-25, 1988 are presented. The results indicate the presence of a layer between 1 and 4 km altitude where these species are strongly enriched. Based on information derived from simultaneous measurements of other chemical and meteorological parameters, satellite imagery, and trajectory calculations, this enrichment is attributed to emissions from biomass burning in sub-Saharan Africa, from which ozone is formed by photochemical reactions.

  14. Dynamic, Large-Magnitude CCD Changes in the Atlantic During the Middle Eocene Climatic Optimum

    NASA Astrophysics Data System (ADS)

    Kordesch, W.; Bohaty, S. M.; Palike, H.; Wilson, P. A.; Edgar, K. M.; Agnini, C.; Westerhold, T.; Roehl, U.

    2015-12-01

    The Middle Eocene Climatic Optimum (MECO; ~40.1 Ma) is a transient global warming event that abruptly reversed the long-term Eocene cooling trend. The primary driving mechanism(s) must be linked to a CO2 increase; however, geochemical modeling experiments show that prevailing hypotheses are incompatible with the paleoclimate record. To further examine changes in deep-sea carbonate burial, we identify the MECO for the first time at ODP Site 929 (Equatorial Atlantic; ~3935 m paleodepth) and present new lithological and geochemical data for this site, including benthic foraminiferal stable isotopes (δ18O and δ13C), XRF scanning data, and an orbitally tuned age model. We combine these records with data from a suite of Atlantic sites to form a depth transect between ~2-4 km (DSDP Site 523, ODP Site 1260 and 1263, IODP Site U1404) representing the first detailed record of carbonate dissolution in the Atlantic spanning the MECO. This compilation reveals dissolution at water depths as shallow as ~2 km (>1 km shallower than previous estimates) with multiple and discrete short-lived (<100 kyr) phases of carbonate compensation depth (CCD) shoaling during and after the event. Careful reevaluation of the Pacific CCD records combined with new results suggests similar short-term variability and magnitude of shoaling globally. These data provide new constraints on carbon release history during the MECO and, potentially, the forcing mechanisms for warming. The transient CCD shoaling events indicate multiple pulses of carbon input and acidification decoupled from deep-sea δ18O and δ13C records, indicating that these events must not have been driven directly by changes in temperature or carbon burial/storage - potentially reconciling some of the data-model discrepancies.

  15. Stability of equatorial satellite orbits

    NASA Astrophysics Data System (ADS)

    Mioc, V.; Stavinschi, M.

    2004-09-01

    We study satellite orbits lying in the equatorial plane of a planet via the geometric methods of the theory of dynamical systems. To model the planetary gravitational potential, we expand it to the sixth zonal harmonic. The motion equations are regularized by means of McGehee-type transformations of the second kind. Naturally considering the motion to be collisionless and escapeless, we take into account the whole interplay among field parameters, total-energy level and angular momentum. This gives rise to various phase-portraits. In the most general case as regards the changes of sign of parameters, we meet: saddles generating simple or double homoclinic loops, double loops inside one loop of a larger double loop, centers surrounded by periodic and quasiperiodic trajectories, heteroclinic orbits, etc. Of course, less general cases lead to simpler phase portraits. Every type of phase orbit is translated in terms of physical motion. Such qualitative results are useful to the analysis of circumplanetary motion of major or infinitesimal satellites, rings, etc

  16. Longitudinal variations of the equatorial electojet

    NASA Astrophysics Data System (ADS)

    Shume, Esayas

    We have utilized a three dimensional electrostatic potential model to explain the longitudinal variations of the equatorial electrojet. The model runs were constrained by net H component magnetic field measurements from three equatorial stations, namely, Huancayo (Peru) 12.05 S, 284.67 E; Addis Ababa (Ethiopia) 9.8 N, 38.8 E; Tirunelveli (India) 8.42 N, 77.48 E. The model runs were done in an iterative fashion until the computed and measured H component magnetic field values come into a close agreement. The physical mechanisms for the longitudinal variations of the equatorial electrojet were inferred by comparing and contrasting the resulting computed vertical polarization electric field (which drives the equatorial electrojet), and zonal current density profiles for the three stations mentioned above.

  17. EQUATORIAL ZONAL JETS AND JUPITER's GRAVITY

    SciTech Connect

    Kong, D.; Liao, X.; Zhang, K.; Schubert, G.

    2014-08-20

    The depth of penetration of Jupiter's zonal winds into the planet's interior is unknown. A possible way to determine the depth is to measure the effects of the winds on the planet's high-order zonal gravitational coefficients, a task to be undertaken by the Juno spacecraft. It is shown here that the equatorial winds alone largely determine these coefficients which are nearly independent of the depth of the non-equatorial winds.

  18. The storm-time equatorial electrojet

    NASA Technical Reports Server (NTRS)

    Burrows, K.; Sastry, T. S. G.; Sampath, S.; Stolarik, J. D.; Usher, M. J.

    1976-01-01

    A Petrel rocket carrying a double cell rubidium magnetometer was launched from the Thumba Equatorial Rocket Launching Station during the early main phase of a magnetic storm. No ionospheric currents associated with the storm were observed and the large field depression, at the flight time, must therefore be attributed to currents at higher altitudes. The equatorial enhancement of ionospheric magnetic storm currents, predicted on the basis of theory and earlier ground data, was not observed.

  19. The storm-time equatorial electrojet

    NASA Technical Reports Server (NTRS)

    Burrows, K.; Sastry, T. S. G.; Sampath, S.; Stolarik, J. D.; Usher, M. J.

    1977-01-01

    A Petrel rocket carrying a double cell rubidium magnetometer was launched from the Thumba Equatorial Rocket Launching Station during the early main phase of a magnetic storm. No ionospheric currents associated with the storm were observed, and the large field depression at the flight time must therefore be attributed to currents at higher altitudes. The equatorial enhancement of ionospheric magnetic storm currents, predicted on the basis of theory and earlier ground data, was not observed.

  20. The Terrestrial Eocene-Oligocene Transition in North America

    NASA Astrophysics Data System (ADS)

    Prothero, Donald R.; Emry, Robert J.

    1996-06-01

    The transition from the Eocene to the Oligocene epoch, occurring approximately 47 to 30 million years ago, was the most dramatic episode of climatic and biotic change since the demise of the dinosaurs. The mild tropical climates of the Paleocene and early Eocene were replaced by modern climatic conditions and extremes, including glacial ice in Antarctica. The first part of this book summarizes the latest information in the dating and correlation of the strata of late middle Eocene through early Oligocene age in North America. The second part reviews almost all the important terrestrial reptiles and mammals found near the Eocene-Oligocene boundary, in the White River Chronofauna--from the turtles, snakes and lizards to the common rodents, carnivores, oreodonts and deer of the Badlands. This is the first comprehensive treatment of these topics in over sixty years, and will be invaluable to vertebrate paleontologists, geologists, mammalogists and evolutionary biologists.

  1. Swarm Equatorial Electric Field Inversion Chain

    NASA Astrophysics Data System (ADS)

    Alken, Patrick; Maus, Stefan; Vigneron, Pierre; Sirol, Olivier; Hulot, Gauthier

    2014-05-01

    The day-time eastward equatorial electric field (EEF) in the ionospheric E-region plays a crucial role in equatorial ionospheric dynamics. It is responsible for driving the equatorial electrojet (EEJ) current system, equatorial vertical ion drifts, and the equatorial ionization anomaly (EIA). Due to its importance, there is much interest in accurately measuring and modeling the EEF for both climatological and near real-time studies. The Swarm satellite mission offers a unique opportunity to estimate the equatorial electric field from measurements of the geomagnetic field. Due to the near-polar orbits of each satellite, the on-board magnetometers record a full profile in latitude of the ionospheric current signatures at satellite altitude. These latitudinal magnetic profiles are then modeled using a first principles approach with empirical climatological inputs specifying the state of the ionosphere, in order to recover the EEF. We will present preliminary estimates of the EEF using the first Swarm geomagnetic field measurements, and compare them with independently measured electric fields from the JULIA ground-based radar in Peru.

  2. Toward the camera rain gauge

    NASA Astrophysics Data System (ADS)

    Allamano, P.; Croci, A.; Laio, F.

    2015-03-01

    We propose a novel technique based on the quantitative detection of rain intensity from images, i.e., from pictures taken in rainy conditions. The method is fully analytical and based on the fundamentals of camera optics. A rigorous statistical framing of the technique allows one to obtain the rain rate estimates in terms of expected values and associated uncertainty. We show that the method can be profitably applied to real rain events, and we obtain promising results with errors of the order of ±25%. A precise quantification of the method's accuracy will require a more systematic and long-term comparison with benchmark measures. The significant step forward with respect to standard rain gauges resides in the possibility to retrieve measures at very high temporal resolution (e.g., 30 measures per minute) at a very low cost. Perspective applications include the possibility to dramatically increase the spatial density of rain observations by exporting the technique to crowdsourced pictures of rain acquired with cameras and smartphones.

  3. Climatic effects of an impact-induced equatorial debris ring

    NASA Astrophysics Data System (ADS)

    Fawcett, Peter J.; Boslough, Mark B. E.

    2002-08-01

    Several theoretical and laboratory studies suggest that some large impact events are capable of inserting material into space depending on mechanics of the impact. This material would quickly coalesce to form a temporary debris ring in orbit around the equator, which would cast its shadow on the winter hemisphere. The results of an atmospheric general circulation model (GCM) simulation where an orbiting equatorial debris ring is applied as a boundary condition to the model show how the longer-term effects of a major impact could affect the climate system. The primary effect is a severe cooling in the tropics and the subtropics, especially under the seasonally migrating ring shadow. The globe cools and becomes drier, with the exception of monsoonal regions that become wetter. The Hadley cell is weakened resulting in drier tropics and weaker subtropical high-pressure cells in the winter hemisphere. Because the tropics cool more than middle latitude regions, the equator-to-pole temperature gradient becomes shallower resulting in weaker tropospheric winds and less high-latitude storminess. We suggest that the late Eocene impact(s) (35.5 Ma) could have generated a geologically temporary orbiting debris ring based on the global distribution of tektites associated with these events and patterns of climate change immediately above the iridium/microtektite layer. The Cretaceous-Tertiary boundary event, while larger, did not produce a debris ring. We also suggest that an opaque debris ring could have acted as the trigger to at least one episode of global glaciation during the Neoproterozoic.

  4. Rain Rate Statistics in Southern New Mexico

    NASA Technical Reports Server (NTRS)

    Paulic, Frank J., Jr.; Horan, Stephen

    1997-01-01

    The methodology used in determining empirical rain-rate distributions for Southern New Mexico in the vicinity of White Sands APT site is discussed. The hardware and the software developed to extract rain rate from the rain accumulation data collected at White Sands APT site are described. The accuracy of Crane's Global Model for rain rate predictions is analyzed.

  5. Deep, cross-equatorial eddies

    NASA Astrophysics Data System (ADS)

    Borisov, Sergey; Nof, Doron

    The question of how deep ocean eddies can cross the equator is addressed with the aid of analytical and numerical models. We focus on the possibility that deep ocean (lens-like) eddies can cross the equator via deep cross equatorial channels on the ocean floor. We first examine the behavior of solid balls (i.e., free particles) in a meridional parabolic channel on a plane. Such balls are subject to similar topographical forcing and inertial forces that a lens is subject to, except that pressure forces and friction are absent. We examine both single isolated balls and a "cloud" of (noninteractive) balls. In general, the balls' trajectories have a chaotic character; a fraction of the cloud crosses the equator and ends up in the northern hemisphere, and a fraction is left behind. More realistic numerical experiments (with a fully nonlinear reduced-gravity isopycnic model of the Bleck and Boudra type) show similar behavior. In all cases the equator acts as an "eddy smasher" in the sense that it breaks the lens into at least two parts, one crosses the equator and ends up in the northern hemisphere, and the other is left behind. Here, however, the system is not chaotic. Despite the obvious differences between clouds of balls and eddies, there is a remarkable similarity between the percentage of balls that penetrate into the opposite hemisphere and the percentage of eddies' mass that ends up in the other hemisphere. This suggests that the geometry of the channel and the presence of the equator determine how the fluid will be partitioned among the two hemispheres.

  6. On the equatorial Ekman layer

    NASA Astrophysics Data System (ADS)

    Marcotte, Florence; Dormy, Emmanuel; Soward, Andrew

    2016-09-01

    The steady incompressible viscous flow in the wide gap between spheres rotating about a common axis at slightly different rates (small Ekman number E) has a long and celebrated history. The problem is relevant to the dynamics of geophysical and planetary core flows, for which, in the case of electrically conducting fluids, the possible operation of a dynamo is of considerable interest. A comprehensive asymptotic study, in the limit E<<1, was undertaken by Stewartson (J. Fluid Mech. 1966, vol. 26, pp. 131-144). The mainstream flow, exterior to the E^{1/2} Ekman layers on the inner/outer boundaries and the shear layer on the inner sphere tangent cylinder C, is geostrophic. Stewartson identified a complicated nested layer structure on C, which comprises relatively thick quasi-geostrophic E^{2/7} (inside C) and E^{1/4} (outside C) layers. They embed a thinner E^{1/3} ageostrophic shear layer (on C), which merges with the inner sphere Ekman layer to form the E^{2/5} Equatorial Ekman layer of axial length E^{1/5}. Under appropriate scaling, this $E^{2/5}$--layer problem may be formulated, correct to leading order, independent of E. Accordingly, the Ekman boundary layer and ageostrophic shear layer become features of the far-field (as identified by the large value of the scaled axial co-ordinate z) solution. We present a numerical solution, which uses a non-local integral boundary condition at finite $z$ to account for the far-field behaviour. Adopting z^{-1} as a small parameter we extend Stewartson's similarity solution for the ageostrophic shear layer to higher orders. This far-field solution agrees well with that obtained from our numerical model.

  7. Latitudinal comparisons of equatorial Pacific zooplankton

    NASA Astrophysics Data System (ADS)

    Roman, M. R.; Dam, H. G.; Le Borgne, R.; Zhang, X.

    Zooplankton biomass and rates of ingestion, egestion and production in the equatorial Pacific Ocean along 140°W and 180° exhibit maximum values in the High-Nutrient Low-Chlorophyll (HNLC) zone associated with equatorial upwelling (5°S-5°N) as compared to the more oligotrophic regions to the north and south. Zooplankton biomass and rates are not usually highest on the equator, but increase "downstream" of the upwelling center as the zooplankton populations exhibit a delayed response to enhanced phytoplankton production. The vertical distribution of zooplankton biomass in the equatorial HNLC area tends to be concentrated in surface waters and is more uniform with depth in oligotrophic regions to the north and south of the equatorial upwelling zone. In general, the amount of mesozooplankton (>200 μm) carbon biomass is approximately 25% of estimated phytoplankton biomass and 30% of bacterial biomass in the HNLC area of the equatorial Pacific Ocean. Zooplankton grazing on phytoplankton is low in the equatorial Pacific Ocean, generally <5% of the total chlorophyll-a standing stock grazed per day. Based on estimates of metabolic demand, it is apparent that zooplankton in the equatorial Pacific Ocean are omnivores, consuming primarily microzooplankton and detritus. Estimated zooplankton growth rates in the warm waters of the HNLC equatorial Pacific Ocean are high, ranging from 0.58 d -1 for 64-200 μm zooplankton to 0.08 d -1 for 1000-2000 μm zooplankton. Thus, the numerical and functional response of equatorial zooplankton to increases in phytoplankton production are more rapid than normally occurs in sub-tropical and temperate waters. Potential zooplankton fecal pellet production, estimated from metabolic demand, is approximately 1.6 times the estimated gravitational carbon flux at 150 m in the zone of equatorial upwelling (5°S-5°N) and 1.1 times the export flux in the more oligotrophic regions to the north and south. The active flux of carbon by diel migrant

  8. Seminal role of stratiform clouds in large-scale aggregation of tropical rain in boreal summer monsoon intraseasonal oscillations

    NASA Astrophysics Data System (ADS)

    Kumar, Siddharth; Arora, Anika; Chattopadhyay, R.; Hazra, Anupam; Rao, Suryachandra A.; Goswami, B. N.

    2016-04-01

    Modification of the vertical structure of non-adiabatic heating by significant abundance of the stratiform rain in the tropics has been known to influence the large-scale circulation. However, the role of the stratiform rain on the space-time evolution of the observed Boreal summer monsoon intraseasonal oscillations (MISO) has so far been ignored. In the present study, we unravel a feedback mechanism through which the stratiform component of the rain leads to aggregation (organization) of rain on the MISO scale, making it an indispensable component of the MISO evolution dynamics. Using TRMM 3A25 monthly mean data (between 1998 and 2013), the ratio between convective and stratiform rain (RCS) is shown to be strongly related to the total rainfall. Further, composites of rainfall and circulation anomalies corresponding to high (low) values of RCS over the Central India or over the Equatorial Indian Ocean show spatial structures remarkably similar to that associated with the MISOs. Analyzing lead-lag relationship between the convective rain, the stratiform rain and the large scale moisture convergence with respect to peak active (break) spells from daily modern era retrospective-analysis for research and applications data, we unravel that the initial isolated convective elements spawn the stratiform rain which in turn modifies the vertical distribution of heating and leads to stronger large scale moisture convergence thereby producing more convective elements and more stratiform rain ultimately leading to aggregation of rain on the MISO scale. Our finding indicates that large and persisting systematic biases in simulating the summer monsoon rainfall over the Asian monsoon region by climate models are likely to be related to the systematic biases in simulating the MISOs which in turn are related to the serious underestimation of stratiform rain in most climate models.

  9. The dynamics of rain-induced fades

    NASA Technical Reports Server (NTRS)

    Sweeney, Dennis G.; Bostian, Charles W.

    1992-01-01

    The dynamics of rain-induced fades on satellite radio links is studied by evaluating the rate at which the first Fresnel zone volume fills with rain. A compact expression for the fade slope on a terrestrial path is derived which shows that once the rain rate is specified, fade slope is very sensitive to differences in rain velocity. Thus, there is no unique relationship between fade slope and rain rate.

  10. Mercury in rain and throughfall in a tropical rain forest

    SciTech Connect

    Lindberg, S.E.; Harriss, R.C.

    1985-01-01

    The major hydrologic pathways from the atmosphere to the ground in a tropical rain forest were sampled to determine the wet deposition of mercury above and below the canopy. The concentrations of mercury in rain averaged 74 ng L/sup -1/ and were inversely proportional to rainfall amount. Concentrations in stemflow and throughfall were comparable, averaging approx.66 ng L/sup -1/. As a result of these lower concentrations and significant rainfall interception and evaporation in the canopy, the total wet fluxes below the canopy were lower than those above, suggesting in-canopy sorption of dissolved mercury. 7 refs., 1 fig., 2 tabs.

  11. Paleoclimatic analyses of middle Eocene through Oligocene planktic foraminiferal faunas

    USGS Publications Warehouse

    Keller, G.

    1983-01-01

    Quantitative faunal analyses and oxygen isotope ranking of individual planktic foraminiferal species from deep sea sequences of three oceans are used to make paleoceanographic and paleoclimatic inferences. Species grouped into surface, intermediate and deep water categories based on ??18O values provide evidence of major changes in water-mass stratification, and individual species abundances indicate low frequency cool-warm oscillations. These data suggest that relatively stable climatic phases with minor cool-warm oscillations of ???0.5 m.y. frequency are separated by rapid cooling events during middle Eocene to early Oligocene time. Five major climatic phases are evident in the water-mass stratification between middle Eocene through Oligocene time. Phase changes occur at P14/P15, P15/P16, P20/P21 and P21/P22 Zone boundaries and are marked by major faunal turnovers, rapid cooling in the isotope record, hiatuses and changes in the eustatic sea level. A general cooling trend between middle Eocene to early late Oligocene is indicated by the successive replacement of warm middle Eocene surface water species by cooler late Eocene intermediate water species and still cooler Oligocene intermediate and deep water species. Increased water-mass stratification in the latest Eocene (P17), indicated by the coexistence of surface, intermediate and deep dwelling species groups, suggest that increased thermal gradients developed between the equator and poles nearly coincident with the development of the psychrosphere. This pattern may be related to significant ice accumulation between late Eocene and early late Oligocene time. ?? 1983.

  12. Acid rain degradation of nylon

    SciTech Connect

    Kyllo, K.E.

    1984-01-01

    Acid rain, precipitation with a pH less than 5.6, is known to damage lakes, vegetation and buildings. Degradation of outdoor textiles by acid rain is strongly suspected but not well documented. This study reports the effects of sunlight, aqueous acid, heat and humidity (acid rain conditions) on spun delustered nylon 6,6 fabric. Untreated nylon and nylon treated with sulfuric acid of pH 2.0, 3.0, and 4.4 were exposed to light in an Atlas Xenon-arc fadeometer at 63/sup 0/C and 65% R.H. for up to 640 AATCC Fading Units. The untreated and acid treated nylon fabrics were also exposed to similar temperature and humidity condition without light. Nylon degradation was determined by changes in breaking strength, elongation, molecular weight, color, amino end group concentration (NH/sub 2/) and /sup 13/C NMR spectra. Physical damage was assessed using SEM.

  13. Atmospheric dust and acid rain

    SciTech Connect

    Hedin, L.O.; Likens, G.E.

    1996-12-01

    Why is acid rain still an environmental problem in Europe and North America despite antipollution reforms? The answer really is blowing in the wind: atmospheric dust. These airborne particles can help neutralize the acids falling on forests, but dust levels are unusually low these days. In the air dust particles can neutralize acid rain. What can we do about acid rain and atmospheric dust? Suggestions range from the improbable to the feasible. One reasonable suggestion is to reduce emissions of acidic pollutants to levels that can be buffered by natural quantities of basic compounds in the atmosphere; such a goal would mean continued reductions in sulfur dioxide and nitrogen oxides, perhaps even greater than those prescribed in the 1990 Amendments to the Clean Air Act in the U.S. 5 figs.

  14. Fertilizing the Amazon and equatorial Atlantic with West African dust

    NASA Astrophysics Data System (ADS)

    Bristow, Charlie S.; Hudson-Edwards, Karen A.; Chappell, Adrian

    2010-07-01

    Atmospheric mineral dust plays a vital role in Earth's climate and biogeochemical cycles. The Bodélé Depression in Chad has been identified as the single biggest source of atmospheric mineral dust on Earth. Dust eroded from the Bodélé is blown across the Atlantic Ocean towards South America. The mineral dust contains micronutrients such as Fe and P that have the potential to act as a fertilizer, increasing primary productivity in the Amazon rain forest as well as the equatorial Atlantic Ocean, and thus leading to N2 fixation and CO2 drawdown. We present the results of chemical analysis of 28 dust samples collected from the source area, which indicate that up to 6.5 Tg of Fe and 0.12 Tg of P are exported from the Bodélé Depression every year. This suggests that the Bodélé may be a more significant micronutrient supplier than previously proposed.

  15. Evolution and extinction of Afro-Arabian primates near the Eocene-Oligocene boundary.

    PubMed

    Seiffert, Erik R

    2007-01-01

    Revised age estimates for the primate-bearing localities of the Jebel Qatrani Formation (Fayum area, northern Egypt) have provided a new perspective on primate response to early Oligocene climate change in North Africa. Environmental changes associated with early Oligocene cooling might have driven the local extinction of at least 4 strepsirrhine primate clades (adapids, djebelemurines, plesiopithecids and galagids). Contrary to previous suggestions, oligopithecid (and possibly proteopithecid) anthropoids persisted beyond the Eocene-Oligocene boundary (EOB) in the Fayum area, and the former group evidently continued to diversify through the early Oligocene at lower latitudes. Propliopithecids and parapithecine parapithecids first appear in the Jebel Qatrani Formation millions of years after the EOB, so their derived dental and gnathic features can no longer be interpreted as sudden adaptive morphological responses to earliest Oligocene climatic events. Evidence for latitudinal contraction of Afro-Arabian primate distribution through the early Oligocene suggests that the profound late Oligocene restructuring of Afro-Arabian primate communities is most likely to have occurred in equatorial and low-latitude tropical Africa.

  16. The terminal Eocene event - Formation of a ring system around the earth

    NASA Technical Reports Server (NTRS)

    Okeefe, J. A.

    1980-01-01

    It is suggested that the formation of a ring system about the earth by particles and debris related to the North American strewn tektite field is responsible for the terminal Eocene event of 34 million years ago, in which severe climatic changes accompanied by widespread biological extinctions occurred. Botanical data is cited which implies a 20-C decrease in winter temperature with no change in summer temperature, and evidence of the correlation of the North American tektite fall, which is estimated to have a total mass of 10 to the 9th to 10 to the 10th tons, with the disappearance of five of the most abundant species of radiolaria is presented. The possible connection between the tektites and climatic change is argued to result from the screening of sunlight by an equatorial ring of trapped particles of extraterrestrial origin in geocentric orbit which would cut off sunlight only in the winter months. Such a ring, located at a distance of between 1.5 and 2.5 earth radii (the Roche limit) is estimated to have a lifetime of a few million years.

  17. Palynostratigraphy and depositional environment of Vastan Lignite Mine (Early Eocene), Gujarat, western India

    NASA Astrophysics Data System (ADS)

    Rao, M. R.; Sahni, Ashok; Rana, R. S.; Verma, Poonam

    2013-04-01

    Early Eocene sedimentary successions of south Asia, are marked by the development of extensive fossil-bearing, lignite-rich sediments prior to the collision of India with Asia and provide data on contemporary equatorial faunal and vegetational assemblages. One such productive locality in western India is the Vastan Lignite Mine representing approximately a 54-52 Ma sequence dated by the presence of benthic zone marker species, Nummulites burdigalensis burdigalensis. The present study on Vastan Lignite Mine succession is based on the spore-pollen and dinoflagellate cyst assemblages and documents contemporary vegetational changes. 86 genera and 105 species belonging to algal remains (including dinoflagellate cysts), fungal remains, pteridophytic spores and angiospermous pollen grains have been recorded. On the basis of first appearance, acme and decline of palynotaxa, three cenozones have been recognized and broadly reflect changing palaeodepositional environments. These are in ascending stratigraphic order (i) Proxapertites Spp. Cenozone, (ii) Operculodinium centrocarpum Cenozone and (iii) Spinizonocolpites Spp. Cenozone. The basal sequence is lagoonal, palm-dominated and overlain by more open marine conditions with dinoflagellate cysts and at the top, mangrove elements are dominant. The succession has also provided a unique record of fish, lizards, snakes, and mammals.

  18. Benefits of acid rain controls

    SciTech Connect

    Hawkins, D.G.

    1984-04-01

    The acid rain debate has been distorted by a mistaken political paradigm. This paradigm holds that acid rain controls will benefit only a few lakes and streams, mostly in the Adirondack Mountains in northeastern New York State. It holds that the costs of a control program will fall on the Midwest but that none of the benefits will occur there since no sensitive lakes and streams are found in that area. The author discussed this problem and pointed out that sulfur dioxide was responsible for several types of pollution damage and that all the states would benefit from the reduction of sulfur dioxide emissions.

  19. Equatorial waves in the stratosphere of Uranus

    NASA Technical Reports Server (NTRS)

    Hinson, David P.; Magalhaes, Julio A.

    1991-01-01

    Analyses of radio occultation data from Voyager 2 have led to the discovery and characterization of an equatorial wave in the Uranus stratosphere. The observed quasi-periodic vertical atmospheric density variations are in close agreement with theoretical predictions for a wave that propagates vertically through the observed background structure of the stratosphere. Quantitative comparisons between measurements obtained at immersion and at emersion yielded constraints on the meridional and zonal structure of the wave; the fact that the two sets of measurements are correlated suggests a wave of planetary scale. Two equatorial wave models are proposed for the wave.

  20. Constructing an Eocene Marine Ecosystem Sensitivity Scale

    NASA Astrophysics Data System (ADS)

    D'haenens, S.; Bornemann, A.; Speijer, R. P.; Hull, P. M.

    2014-12-01

    A key question in the face of current global environmental change is how marine ecosystems will respond and evolve in the future. To answer this, we first need to understand the relationship between environmental and ecosystem change - i.e., the ecosystem sensitivity. Addressing this question requires understanding of how biota respond to (a succession of) sudden environmental perturbations of varying sizes and durations in varying background conditions (i.e., climatic, oceanographic, biotic). Here, we compare new and published data from the Early to Middle Eocene greenhouse world to understand the sensitivity of marine ecosystems to background environmental change and hyperthermal events. This work focuses on the early Paleogene, because it is considered to be a good analog for a future high CO2 world. Newly generated high-resolution multiproxy datasets based on northern Atlantic DSDP Leg 48 and IODP Leg 342 material will allow us to compare the marine ecosystem responses (including bentho-pelagic systems) to abiotic drivers across climatic disruptions of differing magnitude. Initial results of a benthic foraminiferal community comparison including the PETM and ETM2 hyperthermals in the northeastern Atlantic DSDP sites 401 and 5501 suggest that benthic ecosystem sensitivity may actually be non-linearly linked to background climate states as reflected by a range of geochemical proxies (XRF, TOC, CaCO3, grain sizes, XRD clay mineralogy and foraminiferal δ18O, δ13C, Mg/Ca)2,3, in contrast to planktic communities4. Testing the type of scaling across different taxa, communities, initial background conditions and time scales may be the first big step to disentangle the often synergistic effects of environmental change on ecosystems5. References: 1D'haenens et al., 2012, in prep. 2Bornemann et al., 2014, EPSL 3D'haenens et al., 2014, PA 4Gibbs et al., 2012, Biogeosc. 5 Norris et al., 2013, Science

  1. Taxonomy, affinities, and paleobiology of the tiny metatherian mammal Minusculodelphis, from the early Eocene of South America

    NASA Astrophysics Data System (ADS)

    Oliveira, Édison Vicente; Zimicz, Natalia; Goin, Francisco J.

    2016-02-01

    With less than 3 g of estimated body mass, the early Eocene Minusculodelphis minimus Paula Couto (Mammalia, Metatheria, Jaskhadelphyidae) is one of the smallest mammals, living or extinct. It has alternatively been regarded as a didelphid or a derorhynchid "ameridelphian," or even as an eometatherian marsupial. Here, we describe a new species of Minusculodelphis coming from the same locality (Itaboraí Quarry, Brazil) and age (Itaboraian age) of the type species of the genus. It differs from M. minimus in its larger size and several dental characters. The new species offers data on the upper dentition and femur, which are unknown in the type species. Compared to other Paleogene metatherians, Minusculodelphis shows closer relationships with Jaskhadelphys, from the early Paleocene of Tiupampa, Bolivia, as well as with Kiruwamaq, from the late Eocene-early Oligocene of Perú. A cladistic analysis places all three genera within the family Jaskhadelphyidae (Metatheria, Order indet.), which includes small to tiny, insectivorous-like metatherians. We argue that insectivory (soft insects) is the best-supported diet for both species of Minusculodelphis, and that the most probable microhabitat for them was the understorey or leaf litter of tropical, rain forested environments.

  2. Taxonomy, affinities, and paleobiology of the tiny metatherian mammal Minusculodelphis, from the early Eocene of South America.

    PubMed

    Oliveira, Édison Vicente; Zimicz, Natalia; Goin, Francisco J

    2016-02-01

    With less than 3 g of estimated body mass, the early Eocene Minusculodelphis minimus Paula Couto (Mammalia, Metatheria, Jaskhadelphyidae) is one of the smallest mammals, living or extinct. It has alternatively been regarded as a didelphid or a derorhynchid "ameridelphian," or even as an eometatherian marsupial. Here, we describe a new species of Minusculodelphis coming from the same locality (Itaboraí Quarry, Brazil) and age (Itaboraian age) of the type species of the genus. It differs from M. minimus in its larger size and several dental characters. The new species offers data on the upper dentition and femur, which are unknown in the type species. Compared to other Paleogene metatherians, Minusculodelphis shows closer relationships with Jaskhadelphys, from the early Paleocene of Tiupampa, Bolivia, as well as with Kiruwamaq, from the late Eocene-early Oligocene of Perú. A cladistic analysis places all three genera within the family Jaskhadelphyidae (Metatheria, Order indet.), which includes small to tiny, insectivorous-like metatherians. We argue that insectivory (soft insects) is the best-supported diet for both species of Minusculodelphis, and that the most probable microhabitat for them was the understorey or leaf litter of tropical, rain forested environments. PMID:26743194

  3. Taxonomy, affinities, and paleobiology of the tiny metatherian mammal Minusculodelphis, from the early Eocene of South America.

    PubMed

    Oliveira, Édison Vicente; Zimicz, Natalia; Goin, Francisco J

    2016-02-01

    With less than 3 g of estimated body mass, the early Eocene Minusculodelphis minimus Paula Couto (Mammalia, Metatheria, Jaskhadelphyidae) is one of the smallest mammals, living or extinct. It has alternatively been regarded as a didelphid or a derorhynchid "ameridelphian," or even as an eometatherian marsupial. Here, we describe a new species of Minusculodelphis coming from the same locality (Itaboraí Quarry, Brazil) and age (Itaboraian age) of the type species of the genus. It differs from M. minimus in its larger size and several dental characters. The new species offers data on the upper dentition and femur, which are unknown in the type species. Compared to other Paleogene metatherians, Minusculodelphis shows closer relationships with Jaskhadelphys, from the early Paleocene of Tiupampa, Bolivia, as well as with Kiruwamaq, from the late Eocene-early Oligocene of Perú. A cladistic analysis places all three genera within the family Jaskhadelphyidae (Metatheria, Order indet.), which includes small to tiny, insectivorous-like metatherians. We argue that insectivory (soft insects) is the best-supported diet for both species of Minusculodelphis, and that the most probable microhabitat for them was the understorey or leaf litter of tropical, rain forested environments.

  4. THE ACID RAIN NOX PROGRAM

    EPA Science Inventory

    Between 350,000 and 400,000 tons of annual NOx emissions have been eliminated as a result of Phase I of the Acid Rain NOx Program. As expected. the utilities have chosen emissions averaging as the primary compliance option. This reflects that, in general, NO x reductions have ...

  5. Scientist, researchers, and acid rain

    SciTech Connect

    Alm, L.R. )

    1989-01-01

    The role of the hidden participants in agenda-setting for environmental issues is discussed. These personnel involve academics, researchers, career bureaucrats, congressional staffers, consultants, and administration appointees below the top level. Scientists have been publicly involved in the acid rain issue from the beginning, using the media to dramatize the possible catastrophic consequences of acid rain. Presently, the scientific community is not in consensus about the solutions to the problem. Since the initial enactment of the National Acid Precipitation Act in 1980, not a single acid rain law has been passed, although many bills have been proposed. Spokesman for the coal and utility industries and Reagan administration personnel have used the scientific disagreements to delay abatement actions and refute claims that acid rain is a severe problem. Another result of the confusion is a distrust and even disdain for academic work. One possible solution to the stalemate is an accurate form for resolving scientific disputes that have a strong political component and that the forum should have a mechanism for converging on accurate science. 19 refs.

  6. Voronoi Diagrams and Spring Rain

    ERIC Educational Resources Information Center

    Perham, Arnold E.; Perham, Faustine L.

    2011-01-01

    The goal of this geometry project is to use Voronoi diagrams, a powerful modeling tool across disciplines, and the integration of technology to analyze spring rainfall from rain gauge data over a region. In their investigation, students use familiar equipment from their mathematical toolbox: triangles and other polygons, circumcenters and…

  7. Rain gauge calibration and testing

    NASA Technical Reports Server (NTRS)

    Wilkerson, John

    1994-01-01

    Prior to the Tropical Oceans Global Atmosphere-Coupled Ocean Atmosphere Response Experiment (TOGA-COARE), 42 Model 100 series optical gauges were tested in the rain simulator facility at Wallops Island before shipment to the field. Baseline measurements at several rain rates were made simultaneously with collector cans, tipping bucket, and a precision weighing gauge and held for post-COARE evaluation with a repeat set of measurements that were to be recorded after the instruments were returned. This was done as a means of detecting any calibration changes that might have occurred while deployed. Although it was known that the artificial rain in the simulator did not contain the required exponential distribution for accurate optical rain gauge rate measurements, use of the facility was necessary because it was the only means available for taking controlled observations with instruments that were received, tested, and shipped out in groups over a period of months. At that point, it was believed that these measurements would be adequately precise for detecting performance changes over time. However, analysis of the data by STI now indicates that this may not be true. Further study of the data will be undertaken to resolve this.

  8. Impacts of acid rain legislation

    SciTech Connect

    Addison, E.L.

    1983-01-01

    The author warns against hasty acid rain legislation that would involve billions of dollars and affect thousands of jobs. He recommends further study into the causes of high acidity in lakes and streams. He states that there are too many uncertainties of whether the problem would be solved by reducing sulfur dioxide emissions from coal-fired power plants. (DMC)

  9. Asian monsoons in a late Eocene greenhouse world

    NASA Astrophysics Data System (ADS)

    Licht, A.; van Cappelle, M.; Abels, H. A.; Ladant, J.-B.; Trabucho-Alexandre, J.; France-Lanord, C.; Donnadieu, Y.; Vandenberghe, J.; Rigaudier, T.; Lécuyer, C.; Terry, D., Jr.; Adriaens, R.; Boura, A.; Guo, Z.; Soe, Aung Naing; Quade, J.; Dupont-Nivet, G.; Jaeger, J.-J.

    2014-09-01

    The strong present-day Asian monsoons are thought to have originated between 25 and 22 million years (Myr) ago, driven by Tibetan-Himalayan uplift. However, the existence of older Asian monsoons and their response to enhanced greenhouse conditions such as those in the Eocene period (55-34 Myr ago) are unknown because of the paucity of well-dated records. Here we show late Eocene climate records revealing marked monsoon-like patterns in rainfall and wind south and north of the Tibetan-Himalayan orogen. This is indicated by low oxygen isotope values with strong seasonality in gastropod shells and mammal teeth from Myanmar, and by aeolian dust deposition in northwest China. Our climate simulations support modern-like Eocene monsoonal rainfall and show that a reinforced hydrological cycle responding to enhanced greenhouse conditions counterbalanced the negative effect of lower Tibetan relief on precipitation. These strong monsoons later weakened with the global shift to icehouse conditions 34 Myr ago.

  10. Widespread formation of cherts during the early Eocene climate optimum

    NASA Astrophysics Data System (ADS)

    Muttoni, G.; Kent, D. V.

    2007-12-01

    Radiolarian cherts in the Tethyan realm of Jurassic age were recently interpreted as resulting from high biosiliceous productivity along upwelling zones in subequatorial paleolatitudes the locations of which were confirmed by revised paleomagnetic estimates. However, the widespread occurrence of cherts in the Eocene suggests that cherts may not always be reliable proxies of latitude and upwelling zones. In a new survey of the global spatiotemporal distribution of Cenozoic cherts in Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) sediment cores, we found that cherts occur most frequently in the Paleocene and early Eocene, with a peak in occurrences at ~50 Ma that is coincident with the time of highest bottom water temperatures of the early Eocene climatic optimum (EECO) when the global ocean was presumably characterized by reduced upwelling efficiency and biosiliceous productivity. Cherts occur less commonly during the subsequent Eocene global cooling trend. Primary paleoclimatic factors rather than secondary diagenetic processes seem therefore to control chert formation. This timing of peak Eocene chert occurrence, which is supported by detailed stratigraphic correlations, contradicts currently accepted models that involve an initial loading of large amounts of dissolved silica from enhanced weathering and/or volcanism in a supposedly sluggish ocean of the EECO, followed during the subsequent middle Eocene global cooling by more vigorous oceanic circulation and consequent upwelling that made this silica reservoir available for enhanced biosilicification, with the formation of chert as a result of biosilica transformation during diagenesis. Instead, we suggest that basin-basin fractionation by deep-sea circulation could have raised the concentration of EECO dissolved silica especially in the North Atlantic, where an alternative mode of silica burial involving widespread direct precipitation and/or absorption of silica by clay minerals could have

  11. Molecular phylogenetics reveal multiple tertiary vicariance origins of the African rain forest trees

    PubMed Central

    Couvreur, Thomas LP; Chatrou, Lars W; Sosef, Marc SM; Richardson, James E

    2008-01-01

    Background Tropical rain forests are the most diverse terrestrial ecosystems on the planet. How this diversity evolved remains largely unexplained. In Africa, rain forests are situated in two geographically isolated regions: the West-Central Guineo-Congolian region and the coastal and montane regions of East Africa. These regions have strong floristic affinities with each other, suggesting a former connection via an Eocene pan-African rain forest. High levels of endemism observed in both regions have been hypothesized to be the result of either 1) a single break-up followed by a long isolation or 2) multiple fragmentation and reconnection since the Oligocene. To test these hypotheses the evolutionary history of endemic taxa within a rain forest restricted African lineage of the plant family Annonaceae was studied. Molecular phylogenies and divergence dates were estimated using a Bayesian relaxed uncorrelated molecular clock assumption accounting for both calibration and phylogenetic uncertainties. Results Our results provide strong evidence that East African endemic lineages of Annonaceae have multiple origins dated to significantly different times spanning the Oligocene and Miocene epochs. Moreover, these successive origins (c. 33, 16 and 8 million years – Myr) coincide with known periods of aridification and geological activity in Africa that would have recurrently isolated the Guineo-Congolian rain forest from the East African one. All East African taxa were found to have diversified prior to Pleistocene times. Conclusion Molecular phylogenetic dating analyses of this large pan-African clade of Annonaceae unravels an interesting pattern of diversification for rain forest restricted trees co-occurring in West/Central and East African rain forests. Our results suggest that repeated reconnections between the West/Central and East African rain forest blocks allowed for biotic exchange while the break-ups induced speciation via vicariance, enhancing the levels of

  12. Rain Hampers Tsunami Relief Efforts

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The cleanup and relief efforts from the recent tsunamis continue in coastal communities that were ravaged by the waves all across the Indian Ocean. Heavy rains have further complicated the matter and added to the misery in parts of eastern Sri Lanka. Between December 28, 2004, and January 5, 2005, up to 10 to 15 inches of rain may have fallen along the southeast coast of the island, and as much as 20 inches (red areas) fell just offshore. This rainfall map was created by the TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center, which monitors rainfall over the global tropics. The map shows that many other regions around the Indian Ocean were also affected by the rains, including Malaysia and parts of Sumatra. The heaviest rains fell on December 31 and January 4. The rains were likely the result of a combination of the northeast monsoon interacting with the topography and an active phase of what is known as the Madden-Julian Oscillation (MJO) (or 30-60 day oscillation). The MJO is a large-scale disturbance that propagates eastward from the Indian Ocean into the West Pacific Ocean, bringing extended periods of unsettled weather with it. Individual convective complexes within the MJO can last on the order of a day. TRMM is a joint mission between NASA and the Japanese space agency JAXA. NASA image produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC).

  13. Nature in the Classroom: Acid Rain.

    ERIC Educational Resources Information Center

    Doyle, Charles

    1982-01-01

    As a lesson topic, acid rain is defined, its chemistry given, and its development since the 1950s described. The worldwide effects of acid rain are discussed along with the available technology for controlling the problem. (CM)

  14. Acid Rain: The Silent Environmental Threat.

    ERIC Educational Resources Information Center

    Zmud, Mia

    1992-01-01

    Describes the silent environmental threat posed by acid rain. Caused mainly by manmade pollutants, acid rain damages water and trees, decreases visibility, corrodes monuments, and threatens public health. The article includes guidelines for action. (SM)

  15. Inter-comparison of automatic rain gauges

    NASA Technical Reports Server (NTRS)

    Nystuen, Jeffrey A.

    1994-01-01

    The Ocean Acoustics Division (OAD) of the Atlantic Oceanographic and Meteorological Laboratory (AOML), in cooperation with NOAA/NESDIS and NASA, has deployed six rain gauges for calibration and intercomparison purposes. These instruments include: (1) a weighing rain gauge, (2) a RM Young Model 50202 capacitance rain gauge, (3) a ScTI ORG-705 (long path) optical rain gauge, (4) a ScTI ORG-105 (mini-ORG) optical rain gauge, (5) a Belfort Model 382 tipping bucket rain gauge, and (6) a Distromet RD-69 disdrometer. The system has been running continuously since July 1993. During this time period, roughly 150 events with maximum rainfall rate over 10 mm/hr and 25 events with maximum rainfall rates over 100 mm/hr have been recorded. All rain gauge types have performed well, with intercorrelations 0.9 or higher. However, limitations for each type of rain gauge have been observed.

  16. PMP-2 Report: Equatorial Wave Dynamics

    NASA Technical Reports Server (NTRS)

    Hirota, I.

    1982-01-01

    The activities of the pre-MAP project 2 (PMP-2) from 1978 through 1981 are described. The following topics relating to the equatorial middle atmosphere are discussed briefly: (1) the semi-annual oscillation and Kelvin waves; (2) planetary Rossby waves; (3) upper mesospheric waves; and (4) gravity waves.

  17. High plant diversity in Eocene South America: Evidence from Patagonia

    USGS Publications Warehouse

    Wilf, P.; Cuneo, N.R.; Johnson, K.R.; Hicks, J.F.; Wing, S.L.; Obradovich, J.D.

    2003-01-01

    Tropical South America has the highest plant diversity of any region today, but this richness is usually characterized as a geologically recent development (Neogene or Pleistocene). From caldera-lake beds exposed at Laguna del Hunco in Patagonia, Argentina, paleolatitude ???47??S, we report 102 leaf species. Radioisotopic and paleomagnetic analyses indicate that the flora was deposited 52 million years ago, the time of the early Eocene climatic optimum, when tropical plant taxa and warm, equable climates reached middle latitudes of both hemispheres. Adjusted for sample size, observed richness exceeds that of any other Eocene leaf flora, supporting an ancient history of high plant diversity in warm areas of South America.

  18. An analysis of issues concerning acid rain

    SciTech Connect

    Not Available

    1984-01-01

    GAO examines the implications of current scientific knowledge for policy decisions on acid rain and offers a series of observations on the following issues involved in the debate: to what extent has it been scientifically demonstrated that acid rain is resulting in damage to the environment. What are the causes of acid rain and where is it most prevalent. What alternatives exist for controlling acid rain and what are their economic effects.

  19. Acid rain control: the costs of compliance

    SciTech Connect

    Gilleland, D.S.; Swisher, J.H.

    1985-01-01

    This document is the proceedings from a conference sponsored by the Illinois Energy Resources Commission and the Coal Extraction and Utilization Research Center, Southern Illinois University at Carbondale and held in Carbondale on March 18, 1984. Topics addressed include: the sources and impacts of acid rain, the problems inherent in modeling the impacts of acid rain legislation, the effects of acid rain legislation on the socio-economic sector, compliance costs, and the impact of acid rain legislation on related industries (railroads).

  20. Wave Forcing of Saturn's Equatorial Oscillation

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Schlinder, P. J.; Guerlet, S.; Fouchet, T.

    2011-01-01

    Ground-based measurements and Cassini data from CIRS thermal-infrared spectra and radio-occultation soundings have characterized the spatial structure and temporal behavior of a 15-year equatorial oscillation in Saturn's stratosphere. The equatorial region displays a vertical pattern of alternating warm and cold anomalies and, concomitantly, easterly and westerly winds relative to the cloud-top winds, with a peak-to-peak amplitude of 200 m/s. Comparison of the Cassini data over a four-year period has established that the pattern of mean zonal winds and temperatures descends at a rate of roughly I scale height over 4 years. This behavior is reminiscent of the equatorial oscillations in Earth's middle atmosphere. Here the zonal-mean spatial structure and descending pattern are driven by the absorption of vertically propagating waves. The maximum excursions in the pattern of easterly and westerly winds is determined by the limits of the zonal phase velocities of the waves. Here we report on the characterization of the waves seen in the temperature profiles retrieved from the Cassini radio-occultation soundings. The equatorial profiles exhibit a complex pattern of wavelike structure with dimensions one pressure scale height and smaller. We combine a spectral decomposition with a WKBJ analysis, where the vertical wavelength is assumed to vary slowly with the ambient static stability and doppler-shifted phase velocity of the wave. Use of the temperature and zonal wind maps from CIRS makes this approach viable. On Earth, the wave forcing associated with the equatorial oscillations generates secondary meridional circulations that affect the mean flow and planetary wave ducting well away from the equator. This may relate to the triggering of the recently reported mid-latitude storms on Saturn.

  1. Internal gravity waves in the equatorial Pacific

    SciTech Connect

    Skyllingstad, E.D.; Denbo, D.W. )

    1992-09-01

    Mixing in the ocean surface layer is an important process in the transport of heat, momentum, and CO[sub 2] into the deep ocean, For example, the flux of heat into the cold, upwelling water in equatorial regions provides one of the major heat sources driving the ocean circulation. Direct measurements of the ocean mixed layer have provided good estimates of the bulk layer properties. However, estimates of the small-scale effects of intenial waves and related turbulence have remained ambiguous because of the difficulty in observing these processes. Until more detailed measurements become available, numerical models can provide a convenient and cost-effective way to analyze the details of the surface mixed layer. Modeling the surface layer of the equatorial Pacific Ocean is challenging because of the strong vertical current shear and density stratification common to the region. The primary zonal current is the eastward flowing Equatorial Undercurrent (EUC) centered at roughly 120 m depth, with a speed of about 1.5 ms[sup [minus]1] as shown in Figure 1. The EUC is forced by a zonal pressure gradient resulting from the westward directed surface wind stress. Above the EUC, the wind stress directly forces thee South Equatorial Current (SEC), which flows westward with a speed of about 0.5 ms[sup [minus]1]. The shear zone generated by these currents is marginally stable and exhibits a diurnal cycle of turbulence dependent on convection forced by surface cooling. In addition, surface convection forces internal gravity waves, which can transport momentum away from the surface current to deeper waters. In this report, we discuss recent modeling results for the equatorial Pacific showing the generation of convection, turbulence, and internal waves.

  2. Internal gravity waves in the equatorial Pacific

    SciTech Connect

    Skyllingstad, E.D.; Denbo, D.W.

    1992-09-01

    Mixing in the ocean surface layer is an important process in the transport of heat, momentum, and CO{sub 2} into the deep ocean, For example, the flux of heat into the cold, upwelling water in equatorial regions provides one of the major heat sources driving the ocean circulation. Direct measurements of the ocean mixed layer have provided good estimates of the bulk layer properties. However, estimates of the small-scale effects of intenial waves and related turbulence have remained ambiguous because of the difficulty in observing these processes. Until more detailed measurements become available, numerical models can provide a convenient and cost-effective way to analyze the details of the surface mixed layer. Modeling the surface layer of the equatorial Pacific Ocean is challenging because of the strong vertical current shear and density stratification common to the region. The primary zonal current is the eastward flowing Equatorial Undercurrent (EUC) centered at roughly 120 m depth, with a speed of about 1.5 ms{sup {minus}1} as shown in Figure 1. The EUC is forced by a zonal pressure gradient resulting from the westward directed surface wind stress. Above the EUC, the wind stress directly forces thee South Equatorial Current (SEC), which flows westward with a speed of about 0.5 ms{sup {minus}1}. The shear zone generated by these currents is marginally stable and exhibits a diurnal cycle of turbulence dependent on convection forced by surface cooling. In addition, surface convection forces internal gravity waves, which can transport momentum away from the surface current to deeper waters. In this report, we discuss recent modeling results for the equatorial Pacific showing the generation of convection, turbulence, and internal waves.

  3. Rain, fog, and clouds for aircraft simulators

    NASA Technical Reports Server (NTRS)

    Chase, W. D.

    1981-01-01

    Environmental chamber creates realistic fog and rain effects in aircraft simulator. It reproduces clouds, homogeneous fog, patches of fog, rain and fog, and rain only. It is used with real time digital computer, color computer generated image display that simulates airport lights, or color television camera that produces moving display of airport runway as depicted on model terrain board.

  4. Acid Rain: What We Must Do.

    ERIC Educational Resources Information Center

    Gorham, Eville

    1983-01-01

    Addresses questions about the nature, source, and history of acid rain. In addition, discusses the questions: Why is acid rain a problem? Is acid rain getting worse? What is the threat of further problems? Concludes that it is time to act on the problem and recommends an appropriate course of action. (JN)

  5. A Walk in the Rain Forest.

    ERIC Educational Resources Information Center

    Gustafson, Glenn

    2001-01-01

    Presents a learning project in which students prepare a guided, multisensory rain forest tour representing its ecology. Develops five stop points presenting a theme or an important aspect of the rain forest. Includes a list of selected resources for rain forest studies. (YDS)

  6. Create a Rain Forest in the Gym.

    ERIC Educational Resources Information Center

    Kane, Karen

    1995-01-01

    Describes a creative interdisciplinary program for K-3 students that involves setting up a rain forest in the gymnasium to teach students gymnastic skills in the context of the Amazon rain forest. The paper describes how to set up the rain forest and teach a variety of classes. Rainforest resources are included. (SM)

  7. Rain, Snow, and Spring Runoff Revisited.

    ERIC Educational Resources Information Center

    Bohren, Craig F.

    1995-01-01

    Explores the theory behind the correlation between warm rain, rapid snowmelt, and the subsequent runoff using the concepts of enthalpy, thermal transfer, and energy transfer. Concludes that rapid runoff is not a consequence of rain per se but of the high humidities associated with the rain. (JRH)

  8. Rain cell size statistics as a function of rain rate for attenuation modeling

    NASA Technical Reports Server (NTRS)

    Goldhirsh, J.

    1983-01-01

    Rain cell size statistics as a function of rain rate have been deduced by employing a radar data base of rain reflectivity data acquired over a three-year period at Wallops Island, VA. These cell statistics have important applications in slant path rain attenuation modeling and remote sensing of the earth's surface from space at frequencies above 10 GHz.

  9. Living on the edge: The oxygen isotope record of Eocene Basins at the margin of the Cenozoic North American plateau

    NASA Astrophysics Data System (ADS)

    Methner, Katharina; Mulch, Andreas; Chamberlain, Page

    2013-04-01

    the site or within close proximity. However, paleofloral data from e.g. the Chumstick basin to the E of the modern Cascades indicate moderate elevations and montane rain forest conditions during a warm (MAT = 14°C) and rather wet, seasonal Eocene climate. Therefore, we tentatively suggest that these basins were at moderate elevations, allowing dense vegetation and seasonal drying of soils, but were fed by isotopically highly 18O-depleted runoff and groundwater from elevated catchment areas in the vicinity of the basins. This requires Eocene highlands of the North American Cordillera to be laterally extensive already during the Eocene and places important constraints on the impact of the plateau region on atmospheric circulation patterns.

  10. A new Late Eocene anthropoid primate from Thailand.

    PubMed

    Chaimanee, Y; Suteethorn, V; Jaeger, J J; Ducrocq, S

    1997-01-30

    The fossil record of anthropoid primates from the Middle Eocene of South Asia is so far restricted to two genera (Pondaungia cotteri Pilgrim, 1937 and Amphipithecus mogaungensis Colbert, 1937 from the Eocene Pondaung deposits of Burma) whose anthropoid status and phylogenetic position have long been under debate because they represent the oldest highly derived fossil primates of anthropoid grade. Moreover, several new African taxa, some of which are even older, have been recently included in the suborder Anthropoidea, suggesting an African origin for this group. Conversely, new fossil primates recently discovered in China (Eosimias) have been related to the most primitive representatives of Anthropoidea, alternatively suggesting an Asian origin and a probable Asian radiation centre. We report here the discovery of a new anthropoid from the Thai Late Eocene locality of Krabi, which displays several additional anthropoid characters with regard to those of the Eocene Burmese genera. This species, which is about the size of the Fayum Aegyptopithecus, can be related to the Burmese forms, and it further provides strong additional evidence for a southeast Asian evolutionary centre for anthropoids.

  11. High bat (Chiroptera) diversity in the Early Eocene of India

    NASA Astrophysics Data System (ADS)

    Smith, Thierry; Rana, Rajendra S.; Missiaen, Pieter; Rose, Kenneth D.; Sahni, Ashok; Singh, Hukam; Singh, Lachham

    2007-12-01

    The geographic origin of bats is still unknown, and fossils of earliest bats are rare and poorly diversified, with, maybe, the exception of Europe. The earliest bats are recorded from the Early Eocene of North America, Europe, North Africa and Australia where they seem to appear suddenly and simultaneously. Until now, the oldest record in Asia was from the Middle Eocene. In this paper, we report the discovery of the oldest bat fauna of Asia dating from the Early Eocene of the Cambay Formation at Vastan Lignite Mine in Western India. The fossil taxa are described on the basis of well-preserved fragments of dentaries and lower teeth. The fauna is highly diversified and is represented by seven species belonging to seven genera and at least four families. Two genera and five species are new. Three species exhibit very primitive dental characters, whereas four others indicate more advanced states. Unexpectedly, this fauna presents strong affinities with the European faunas from the French Paris Basin and the German Messel locality. This could result from the limited fossil record of bats in Asia, but could also suggest new palaeobiogeographic scenarios involving the relative position of India during the Early Eocene.

  12. Warm ocean processes and carbon cycling in the Eocene.

    PubMed

    John, Eleanor H; Pearson, Paul N; Coxall, Helen K; Birch, Heather; Wade, Bridget S; Foster, Gavin L

    2013-10-28

    Sea surface and subsurface temperatures over large parts of the ocean during the Eocene epoch (55.5-33.7 Ma) exceeded modern values by several degrees, which must have affected a number of oceanic processes. Here, we focus on the effect of elevated water column temperatures on the efficiency of the biological pump, particularly in relation to carbon and nutrient cycling. We use stable isotope values from exceptionally well-preserved planktonic foraminiferal calcite from Tanzania and Mexico to reconstruct vertical carbon isotope gradients in the upper water column, exploiting the fact that individual species lived and calcified at different depths. The oxygen isotope ratios of different species' tests are used to estimate the temperature of calcification, which we converted to absolute depths using Eocene temperature profiles generated by general circulation models. This approach, along with potential pitfalls, is illustrated using data from modern core-top assemblages from the same area. Our results indicate that, during the Early and Middle Eocene, carbon isotope gradients were steeper (and larger) through the upper thermocline than in the modern ocean. This is consistent with a shallower average depth of organic matter remineralization and supports previously proposed hypotheses that invoke high metabolic rates in a warm Eocene ocean, leading to more efficient recycling of organic matter and reduced burial rates of organic carbon.

  13. Possible methane-induced polar warming in the early Eocene.

    PubMed

    Sloan, L C; Walker, J C; Moore, T C; Rea, D K; Zachos, J C

    1992-05-28

    Reconstructions of early Eocene climate depict a world in which the polar environments support mammals and reptiles, deciduous forests, warm oceans and rare frost conditions. At the same time, tropical sea surface temperatures are interpreted to have been the same as or slightly cooler than present values. The question of how to warm polar regions of Earth without noticeably warming the tropics remains unresolved; increased amounts of greenhouse gases would be expected to warm all latitudes equally. Oceanic heat transport has been postulated as a mechanism for heating high latitudes, but it is difficult to explain the dynamics that would achieve this. Here we consider estimates of Eocene wetland areas and suggest that the flux of methane, an important greenhouse gas, may have been substantially greater during the Eocene than at present. Elevated methane concentrations would have enhanced early Eocene global warming, and also might specifically have prevented severe winter cooling of polar regions because of the potential of atmospheric methane to promote the formation of optically thick, polar stratospheric ice clouds.

  14. Arctic plant diversity in the Early Eocene greenhouse

    PubMed Central

    Harrington, Guy J.; Eberle, Jaelyn; Le-Page, Ben A.; Dawson, Mary; Hutchison, J. Howard

    2012-01-01

    For the majority of the Early Caenozoic, a remarkable expanse of humid, mesothermal to temperate forests spread across Northern Polar regions that now contain specialized plant and animal communities adapted to life in extreme environments. Little is known on the taxonomic diversity of Arctic floras during greenhouse periods of the Caenozoic. We show for the first time that plant richness in the globally warm Early Eocene (approx. 55–52 Myr) in the Canadian High Arctic (76° N) is comparable with that approximately 3500 km further south at mid-latitudes in the US western interior (44–47° N). Arctic Eocene pollen floras are most comparable in richness with today's forests in the southeastern United States, some 5000 km further south of the Arctic. Nearly half of the Eocene, Arctic plant taxa are endemic and the richness of pollen floras implies significant patchiness to the vegetation type and clear regional richness of angiosperms. The reduced latitudinal diversity gradient in Early Eocene North American plant species demonstrates that extreme photoperiod in the Arctic did not limit taxonomic diversity of plants. PMID:22072610

  15. Lower Eocene carbonate facies of Egypt: paleogeographic and tectonic implications

    SciTech Connect

    Garrison, R.E.

    1983-03-01

    The northern Arabo-Nubian craton witnessed a major Late Cretaceous-early Tertiary marine transgression that culminated in the deposition of widespread shelf-sea carbonates during Early Eocene (Ypresian) time. Outer shelf facies characterize exposures in central Egypt (Assiut, Luxor, Kharga), and are composed primarily of rhythmically interbedded chalk and micritic limestone with minor intercalated marine hardgrounds. To the south (Kurkur-Dungul), these fine-grained lithologies give way to inner shelf foraminiferal wackestones and grainstones, typical Tethyan Nummulitic facies. Missing in southern Egypt is the restricted dolomitic evaporitic facies predicted by the Irwin model and observed in the lower Eocene of the Sirte basin to the west and the Arabian Platform to the east. Comparing the areal distribution of these lower Eocene carbonates to coeval facies developed across the remained of northern Africa and Arabia reveals the presence of a broad marine embayment which extended through central and eastern Egypt into northern Sudan during Ypresian time. The widespread subsidence that resulted in the development of this features may have been an effect of regional crustal attenuation preceding the rifting of the Red Sea. Concomitant with this regional subsidence were localized uplift and extensional block faulting in the vicinity of the incipient Red Sea rift (the Safaga-Quseir coastal plain). Here, lower Eocene carbonate facies are indicative of shallow water platforms developed on horst blocks, and deeper water, turbidite-fed basins in intervening grabens.

  16. New taxa of Tanyderidae (Diptera) from Eocene Baltic amber.

    PubMed

    Krzeminski, Wiesław; Krzeminska, Ewa; Kania, Iwona; Ross, Andrew J

    2013-01-01

    Macrochile hornei sp. nov. from Baltic amber (Upper Eocene) is described and illustrated. Podemacrochile gen. nov. is described with Podemacrochile baltica (Podenas, 1997) as type species. A key to the genera and species of Tanyderidae known from Baltic amber is presented. PMID:24583815

  17. The rain-powered cart

    NASA Astrophysics Data System (ADS)

    Mungan, Carl E.; Lipscombe, Trevor C.

    2016-09-01

    A frictionless cart in the shape of a right triangle (with the vertical side forward) is elastically impacted by vertically falling raindrops. The speed of the cart as a function of time can be analytically deduced as an exercise in the use of trigonometric and hyperbolic functions. A characteristic time defines the approach to a terminal speed which is a sizeable fraction of the speed of the rain. The treatment is accessible to a student in a calculus-based mechanics course.

  18. Equatorial Electrojet Observations in the African Continent

    NASA Astrophysics Data System (ADS)

    Yizengaw, E.; Moldwin, M. B.; Mebrahtu, A.; Damtie, B.; Pfaff, R.; Zesta, E.

    2008-12-01

    Although Satellite observations in the African sector show unique equatorial ionospheric structures that can severely impact navigation and communication systems, the study of ionospheric disturbances in this region is difficult due to the lack of ground-based instruments. This has created a gap in global understanding of the physics behind the evolution and formation of plasma irregularities in the equatorial region, which imposes limitations on ionospheric density modeling efforts. Therefore, in order to have a more complete global understanding of equatorial ionosphere motion, the international space science community has begun to develop an observational infrastructure in the African sector. This includes the deployment of a number of arrays of small instruments, including the AMBER magnetometer array, through the International Heliophysical Year (IHY) cooperative program with the United Nations Basic Space Science (UNBSS) program. Two AMBER magnetometers have been deployed successfully at Adigrat (~6°N magnetic) in Ethiopia and at Medea in Algeria (28°N magnetic), and became fully operational on 03 August 2008. The remaining two AMBER magnetometers will be deployed soon in Cameroon and Namibia. One of the prime scientific objectives of AMBER is to understand the processes governing electrodynamics of the equatorial ionosphere as a function of latitude, local time, magnetic activity, and season in the African region. The most credible driving mechanism of ionospheric plasma (E × B drift) can be estimated using two magnetometers, one right at the equator and the other about 6 off the equator. Therefore, using the AMBER magnetometer at Adigrat and the INTERMAGNET magnetometer located at Addis Ababa (0.9°N magnetic) in Ethiopia, the equatorial electrojet (E × B drift) activities in that longitudinal sector of the African continent is estimated. The paper also presents the comparison between the estimated vertical drift and the drift values obtained from the

  19. Early Oligocene glaciation and productivity in the eastern equatorial Pacific: Insights into global carbon cycling

    NASA Astrophysics Data System (ADS)

    Coxall, Helen K.; Wilson, Paul A.

    2011-06-01

    The onset of sustained Antarctic glaciation across the Eocene-Oligocene transition (EOT) marks a pivotal change in Earth's climate, but our understanding of this event, particularly the role of the carbon cycle, is limited. To help address this gap we present the following paleoceanographic proxy records from Ocean Drilling Program Site 1218 in the eastern equatorial Pacific (EEP): (1) stable isotope (δ18O and δ13C) records generated in epifaunal benthic foraminifera (Cibicidoides spp.) to improve (double the resolution) the previously published records; (2) δ18O and δ13C records measured on Oridorsalis umbonatus, a shallow infaunal species; and (3) a record of benthic foraminifera accumulation rate (BFAR). Our new isotope data sets confirm the existence at Site 1218 of a two-step δ18O increase. They also lend support to the hypothesized existence of a late Eocene transient δ18O increase and early Oligocene Oi-1a and Oi-1b glacial maxima. Our record of BFAR indicates a transient (˜500 kyr) twofold to threefold peak relative to baseline Oligocene values associated with the onset of Antarctic glaciation that we attribute to enhanced biological export production in the EEP. This takes the same general form as the history of opal accumulation in the Southern Ocean, suggesting strong high-to-low-latitude oceanic coupling. These findings appear to lend support to the idea that the EOT δ13C excursion is traceable to increased organic carbon (Corg) burial. Paradoxically, early Oligocene sediments in the EEP are extremely Corg-poor, and proxy records of atmospheric pCO2 indicate a transient increase associated with the EOT.

  20. Acid Rain: What It Is -- How You Can Help!

    ERIC Educational Resources Information Center

    National Wildlife Federation, Washington, DC.

    This publication discusses the nature and consequences of acid precipitation (commonly called acid rain). Topic areas include: (1) the chemical nature of acid rain; (2) sources of acid rain; (3) geographic areas where acid rain is a problem; (4) effects of acid rain on lakes; (5) effect of acid rain on vegetation; (6) possible effects of acid rain…

  1. The Rise of Flowering Plants and Land Surface Physics: The Cretaceous and Eocene Were Different

    NASA Astrophysics Data System (ADS)

    Upchurch, G. R.; Feild, T.

    2010-12-01

    The Cretaceous and Eocene have served as the poster children of past greenhouse climates. One difference between the two time periods is that angiosperms (flowering plants) underwent a major diversification and rise to dominance during the mid-Cretaceous to Paleocene. Flowering plants differ from all other living and fossil plants in having significantly higher rates of transpiration and photosynthesis, which in modern leaves correlate with the density of venation (Dv), a feature that can be measured directly from fossils. This increase in Dv, coupled with an increase in the abundance of angiosperms, is thought to have had major impact on the climate system. This is, in part, because transpiration plays an important role in determining the ratio of sensible to latent heat flux from the land surface and in determining precipitation rate in regions such as the equatorial rainforest. Analysis of Dv in fossil leaves indicates two phases of increase in transpiration rate for angiosperms during the Cretaceous-Paleocene. The oldest known angiosperms (Aptian-early Albian) have a low Dv characteristic of extant and fossil ferns and gymnosperms. At this time angiosperms are low-stature plants of minor importance in terms of relative abundance and diversity (<5%). The first phase of Dv increase occurs during the Late Albian to Cenomanian, where average Dv is 40% greater than that of conifers and ferns, and maximum Dv reaches levels characteristic of many trees from the temperate zone. This first phase coincides with the first local dominance of angiosperms, the first occurrence of moderate to large angiosperm trees (up to 1 m in diameter) , and the first common occurrence of angiosperms in the Arctic. The second phase of Dv increase occurs during the Maastrichtian to Paleocene, where average Dv reaches levels characteristic of modern tropical forests and maximum Dv reaches the level found in highly productive modern vegetation. This second phase coincides with the rise to

  2. Equatorial Spread F Variability Investigations in Brazil: Preliminary Results from Conjugate Point Equatorial Experiments Campaign - COPEX

    NASA Astrophysics Data System (ADS)

    Abdu, M. A.; Batista, I. S.; Reinisch, B. W.; Souza, J. R.; Paula, E. R.; Sobral, J. H.; Bullett, T. W.

    2004-05-01

    Equatorial spread F variability can result from diverse conditions of the coupling processes that control the dynamic state of the ambient ionosphere-atmosphere system of the evening hours. While the sunset associated prereversal electric field enhancement (PRE) is known to be the most basic prerequisite for initiating ESF development, the intensity of an event seems to be controlled also by other factors, such as the symmetry/asymmetry of the ionization anomaly, flux tube integrated conductivities, and a possible (but largely unknown) perturbation source. An evaluation of the possible contributions from some of these factors to the observed ESF variability can be possible from measurements carried out over equatorial and conjugate points locations. A conjugate point equatorial observational campaign (COPEX) was conducted in Brazil during October to December 2002. The COPEX used digital ionosondes, all-sky imagers, GPS receivers, and other complementary instruments at the magnetic equatorial and conjugate point stations in the western longitude sector of Brazil. The campaign objective was to investigate the equatorial spread F/plasma bubble irregularity (ESF) generation conditions in terms of the ambient ionosphere-thermosphere properties along the magnetic flux tubes in which they occur. The COPEX digisonde observations permitted field line mapping of the conjugate E layers to dip equatorial F layer peak/bottomside. Other digisondes at eastern longitudes in Brazil complemented these measurements . Our results are based on the analysis of selected data sets, and we address the questions concerning: Trans-equatorial thermospheric winds and their effect on the ESF development; ESF variability under magnetospheric forcing through disturbance electric fields and winds; and the possible role of sporadic E layers on the ESF variability

  3. Rapid Middle Eocene temperature change in western North America

    NASA Astrophysics Data System (ADS)

    Methner, Katharina; Mulch, Andreas; Fiebig, Jens; Wacker, Ulrike; Gerdes, Axel; Graham, Stephan A.; Chamberlain, C. Page

    2016-09-01

    Eocene hyperthermals are among the most enigmatic phenomena of Cenozoic climate dynamics. These hyperthermals represent temperature extremes superimposed on an already warm Eocene climate and dramatically affected the marine and terrestrial biosphere, yet our knowledge of temperature and rainfall in continental interiors is still rather limited. We present stable isotope (δ18O) and clumped isotope temperature (Δ47) records from a middle Eocene (41 to 40 Ma) high-elevation mammal fossil locality in the North American continental interior (Montana, USA). Δ47 paleotemperatures of soil carbonates delineate a rapid +9/-11 °C temperature excursion in the paleosol record. Δ47 temperatures progressively increase from 23 °C ± 3 °C to peak temperatures of 32 °C ± 3 °C and subsequently drop by 11 °C. This hyperthermal event in the middle Eocene is accompanied by low δ18O values and reduced pedogenic carbonate concentrations in paleosols. Based on laser ablation U/Pb geochronology of paleosol carbonates in combination with magnetostratigraphy, biostratigraphy, stable isotope, and Δ47 evidence, we suggest that this pronounced warming event reflects the Middle Eocene Climatic Optimum (MECO) in western North America. The terrestrial expression of northern hemisphere MECO in western North America appears to be characterized by warmer and wetter (sub-humid) conditions, compared to the post-MECO phase. Large and rapid shifts in δ18O values of precipitation and pedogenic CaCO3 contents parallel temperature changes, indicating the profound impact of the MECO on atmospheric circulation and rainfall patterns in the western North American continental interior during this transient warming event.

  4. Seasonal variability in Arctic temperatures during the early Eocene

    NASA Astrophysics Data System (ADS)

    Eberle, J. J.; Fricke, H. C.; Humphrey, J.; Hackett, L.; Newbrey, M.; Hutchison, H.

    2009-12-01

    As a deep time analog for today’s rapidly warming Arctic region, early Eocene (~53 Ma) rocks on Ellesmere Island, Arctic Canada (~79° N.) preserve evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions that at present, quantitative estimates of Eocene Arctic climate are rare. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we provide estimates of early Eocene Arctic temperature, including mean annual temperature (MAT) of ~ 8° C, mean annual range in temperature (MART) of ~ 16.5° C, warm month mean temperature (WMMT) of 16 - 19° C, and cold month mean temperature (CMMT) of 0 - 1° C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, unusually high estimates of early Eocene Arctic MAT and sea surface temperature (SST) by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and marine Crenarchaeota fall within our range of WMMT, suggesting a bias towards summer values. Consequently, caution should be taken when using these methods to infer MAT and SST that, in turn, are used to constrain climate models. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although in both of these reptiles, past temperature tolerances were greater than in their living descendants.

  5. Seasonal variability in Arctic temperatures during early Eocene time

    NASA Astrophysics Data System (ADS)

    Eberle, Jaelyn J.; Fricke, Henry C.; Humphrey, John D.; Hackett, Logan; Newbrey, Michael G.; Hutchison, J. Howard

    2010-08-01

    As a deep time analog for today's rapidly warming Arctic region, early Eocene (52-53 Ma) rock on Ellesmere Island in Canada's High Arctic (˜ 79°N.) preserves evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, the quantification of Eocene Arctic climate has been more elusive. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we infer early Eocene Arctic temperatures, including mean annual temperature (MAT) of ˜ 8 °C, mean annual range in temperature of ˜ 16.5-19 °C, warm month mean temperature of 19-20 °C, and cold month mean temperature of 0-3.5 °C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, relatively high estimates of early Eocene Arctic MAT and SST by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine Crenarchaeota fall close to our warm month temperature, suggesting a bias towards summer values. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although for both of these reptilian groups, past temperature tolerances probably were greater than in living descendants.

  6. A Geostatistical Framework for Estimating Rain Intensity Fields Using Dense Rain Gauge Networks

    NASA Astrophysics Data System (ADS)

    Benoit, L.; Mariethoz, G.

    2015-12-01

    Rain gauges provide direct and continuous observations of rain accumulation with a high time resolution (up to 1min). However the representativeness of these measurements is restricted to the funnel where rainwater is collected. Due to the high spatial heterogeneity of rainfall, this poor spatial representativeness is a strong limitation for the detailed reconstruction of rain intensity fields. Here we propose a geostatistical framework that is able to generate an ensemble of simulated rain fields based on data from a dense rain gauge network. When the density of rain gauges is high (sensor spacing in the range 500m to 1km), the spatial correlation between precipitation time series becomes sufficient to identify and track the rain patterns observed at the rain gauge sampling rate. Rain observations derived from such networks can thus be used to reconstruct the rain field with a high resolution in both space and time (i.e. 1min in time, 100m in space). Our method produces an ensemble of realizations that honor the rain intensities measured throughout the rain gauge network and preserve the main features of the rain intensity field at the considered scale, i.e.: the advection and morphing properties of rain cells over time, the intermittency and the skewed distribution of rainfall, and the decrease of the rain rate near the rain cell borders (dry drift). This allows to image the observed rain field and characterize its main features, as well as to quantify the related uncertainty. The obtained reconstruction of the rainfall are continuous in time, and therefore can complement weather radar observations which are snapshots of the rain field. In addition, the application of this method to networks with a spatial extent comparable to the one of a radar pixel (i.e. around 1km2) could allow exploration of the rain field within a single radar pixel.

  7. AMISR-14: Observations of equatorial spread F

    NASA Astrophysics Data System (ADS)

    Rodrigues, F. S.; Nicolls, M. J.; Milla, M. A.; Smith, J. M.; Varney, R. H.; Strømme, A.; Martinis, C.; Arratia, J. F.

    2015-07-01

    A new, 14-panel Advanced Modular Incoherent Scatter Radar (AMISR-14) system was recently deployed at the Jicamarca Radio Observatory. We present results of the first coherent backscatter radar observations of equatorial spread F(ESF) irregularities made with the system. Colocation with the 50 MHz Jicamarca Unattended Long-term studies of the Ionosphere and Atmosphere (JULIA) radar allowed unique simultaneous observations of meter and submeter irregularities. Observations from both systems produced similar Range-Time-Intensity maps during bottom-type and bottomside ESF events. We were also able to use the electronic beam steering capability of AMISR-14 to "image" scattering structures in the magnetic equatorial plane and track their appearance, evolution, and decay with a much larger field of view than previously possible at Jicamarca. The results suggest zonal variations in the instability conditions leading to irregularities and demonstrate the dynamic behavior of F region scattering structures as they evolve and drift across the radar beams.

  8. Equatorial Kelvin waves do not vanish

    NASA Technical Reports Server (NTRS)

    O'Brien, James J.; Parham, Fred

    1992-01-01

    In the last several years many scientists have been using poorly resolved coupled models to study the ENSO. It has been very common to state that an ENSO cycle found in a model cannot have oceanic Kelvin waves as a mechanism because such waves do not exist in an ocean model with coarse grid spaing. In this note it is demonstrated that equatorial Kelvin waves can exist in models with coarse grids.

  9. Electromagnetic induction by the equatorial electrojet

    NASA Astrophysics Data System (ADS)

    Rastogi, R. G.

    2004-07-01

    This paper discusses the effects of currents induced inside the Earth at equatorial latitudes due to the currents in the ionosphere and the magnetosphere. The horizontal (H), vertical (Z) and eastward (Y) components of the geomagnetic field at equatorial and low-latitude stations around the world are examined for effects due to solar daily (Sq) variations during normal as well as counter electrojet days, during solar flares, during storm sudden commencements (SSCs) and during the main phase of the magnetic storms. The Sq(Z) variations show an abnormally large positive peak at Indian electrojet stations and to a lesser extent at Koror in the forenoon hours when the temporal gradient of Sq(H) is largest. At Indian longitudes this abnormality is largest during equinoxes and December solstices. The nighttime bay disturbance, solar flares and SSC produce large impulses in the Z field at Indian stations and at Koror. The latitudinal extent of this abnormality is larger for events with shorter periods. The disturbance equatorial ring current produces a large decrease of Z field around the period in the middle of main phase of the storm when the Dst index is rapidly decreasing and not when Dst is most negative. A strong decrease in the Z field is observed at Yauca in the American sector during the main phase of the storm. The induction effects on the equatorial electrojet seem to be absent in central and eastern parts of South America, and in the African region. The significant induction effects observed in the recording of the Z field at Peredinia in Sri Lanka suggest a wide latitude of abnormal conductivity anomaly distribution in the Indo-Sri Lanka longitude sector. Our present understanding of the conductor being in Palk Strait between India and Sri Lanka needs to be revised on the basis of results described in this paper.

  10. Evidence of trends in rain event size effecting trends in rain fade

    NASA Astrophysics Data System (ADS)

    Paulson, Kevin S.

    2016-03-01

    Rain gauge studies have shown that the incidence of rain at rates associated with outage on terrestrial links has shown an increasing trend in several countries over the last 30 years. However, no evidence is available from microwave links to show whether outage rates, or the incidence of fade, is similarly increasing. This paper presents evidence of fade trends, derived from a decade of rain radar data. Although a decade is too short a period to observe rain rate trends, evidence is presented that trends in the size of rain events is leading to changes in the relationship between point rain rates and rain fade. Furthermore, these trends are shown to vary significantly across the UK. Temporal trends in both rain rates and their link to rain fade, make it more difficult to adapt International Telecommunication Union Radiocommunication Reccomendations to a changing climate.

  11. Jupiter's Equatorial Zone in Exaggerated Color

    NASA Technical Reports Server (NTRS)

    1979-01-01

    This special color composite made from Voyager 2 narrow-angle frames taken on June 28, 1979, has been processed to exaggerate color differences within the naturally colorful Jovian atmosphere. Such processing makes detailed structure in the clouds more apparent. The dark belt across the upper portion of the photograph is the North Equatorial Belt. One of the largest of the long-lived dark features found along the northern edge of this belt is seen in the upper middle of the photograph. Jupiter's Equatorial Zone, which lies across the middle of the photograph, is characterized by a series of wisp-like plume features. The northern bluish edges of these plumes are thought to lie within deeper, warmer levels of the atmosphere. South of the Equatorial Zone lies the chaotic region of whiter clouds found west of the Great Red Spot. kilometers (6.4 million miles) from Jupiter. The smallest features visible in this photograph are about 190 kilometers (119 miles) across.

  12. Equatorial scintillations: advances since ISEA-6

    SciTech Connect

    Not Available

    1985-01-01

    Our understanding of the morphology of equatorial scintillations has advanced due to more intensive observations at the equatorial anomaly locations in the different longitude zones. The unmistakable effect of the sunspot cycle in controlling irregularity belt width and electron concentration responsible for strong scintillation in the controlling the magnitude of scintillations has been recognized by interpreting scintillation observations inthe light of realistic models of total electron content at various longitudes. A hypothesis based on the alignment of the solar terminator with the geomagnetic flux tubes as an indicator of enhanced scintillation occurrence and another based on the influence of a transequatorial thermospheric neutral wind have been postulated to describe the observed longitudinal variation. A distinct class of equatorial irregularities known as the bottomside sinusoidal (BSS) type was identified. These irregularities occur in very large patches, sometimes in excess of several thousand kilometers in the E-W direction and are associated with frequency spread on ionograms. Scintillations caused by such irregularities exist only in the VHF band, exhibit Fresnel oscillations in intensity spectra and are found to give rise to extremely long durations (approx. several hours) of uninterrrupted scintillations.

  13. Eastern Equatorial Pacific Dust Provenance on Deglacial Timescales

    NASA Astrophysics Data System (ADS)

    Xie, R.; Marcantonio, F.

    2008-12-01

    Changing patterns of eolian dust deposition preserved in deep-sea sediments have the potential to provide us with a better understanding of changes in past atmospheric circulation. One way in which to determine the provenance of dust in deep-sea sediments is to use radiogenic isotopic tracers which can fingerprint potential dust sources. Models (e.g., [1]) suggest that sources of dust to the Eastern Equatorial Pacific (EEP) are from areas as diverse as Asia, North, Central, and South America, and, perhaps, even Africa. Here, we investigate spatial and temporal changes in the provenance of the eolian component in the EEP by measuring Pb, Sr, and Nd isotope ratios in dust extracted from sediments along a transect at 110oW from 7oN to 3oS (ODP sites 853 - 848). In this region, although fluxes of dust were higher during the last glacial maximum (LGM) than those in the Holocene by up to 100%, the glacial flux of dust displayed a shallower meridional gradient [2]. However, it is unclear whether this shallower gradient is due to a mean southerly displacement of the Intertropical Convergence Zone (ITCZ). Most of the dust trying to pass through the ITCZ will be scavenged and rained out at the ITCZ. Along the meridional gradient, therefore, temporal variations in the Pb, Sr, and Nd isotopic fingerprints of the distinct dust sources will determine the extent to which the position of the ITCZ changes on deglacial timescales. [1] Mahowald et al., 2005, Global Biogeochemical Cycles 19, GB4025. [2] McGee et al., 2007, EPSL 257, 215-230.

  14. Sudden intrusion of corrosive bottom water into the South Atlantic during the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Meissner, K. J.; Alexander, K.; Bralower, T. J.

    2015-12-01

    The Paleocene-Eocene Thermal Maximum, ˜55 million years before present, was a period of rapid warming marked by a negative carbon isotope excursion and widespread dissolution of seafloor carbonate. These changes have been attributed to a massive release of carbon into the exogenic carbon cycle, and thus, the event provides an analog for future climate and environmental changes given the current anthropogenic CO2 emissions. Previous attempts to constrain the amount of carbon released have produced widely diverging results, between 2000 and 10,000 gigatons carbon (GtC). Sediment records indicate that acidification of deep waters was generally more extensive and severe in the Atlantic and Caribbean regions, with more modest changes in the Southern and Pacific Oceans. Here we compare simulations integrated with the UVic Earth System Climate Model with reconstructions of temperature and dissolution to present a mechanism that might explain the observed spatial differences and to constrain the total mass of carbon released. Due to the late Paleocene topography, highly corrosive waters accumulate in the deep North Atlantic before the PETM in our simulations. Several thousand years into the event, deep ocean warming destabilizes the North Atlantic water column and triggers deep water formation. This causes the corrosive bottom water to spill over an equatorial sill into the South Atlantic and through the Southern and Pacific Oceans, progressively gaining alkalinity. The simulated pattern of sediment dissolution along the path taken by this corrosive water is consistent with most dissolution estimates made from CaCO3 measurements in the Paleocene-Eocene sediment record. We find two scenarios that agree best with proxy data: a carbon release of 7000 GtC in combination with pre-event atmospheric carbon dioxide concentrations of 840 ppm and a carbon release of 7000-10,000 GtC with pre-event CO2 concentrations of 1680 ppm.

  15. ODP Hole 689B spherules and upper Eocene microtektite and clinopyroxene-bearing spherule strewn fields

    NASA Astrophysics Data System (ADS)

    Glass, B. P.; Koeberl, C.

    1999-03-01

    Montanari et al. (1993) reported a positive Ir anomaly in the upper Eocene sediments from Ocean Drilling Program Hole 689B on the Maud Rise, Southern Ocean. Vonhof (1998) described microtektites and clinopyroxene-bearing (cpx) spherules associated with the Ir anomaly in Hole 689B and suggested that they belong to the North American and equatorial Pacific cpx strewn fields, respectively. We searched a suite of 27 samples taken through the spherule layer from Hole 689B and we recovered 386 microtektites and 667 cpx spherules. We studied the petrography of the microtektites and cpx spherules and determined the major element compositions of 31 microtektites and 14 cpx spherules using energy dispersive x-ray analysis. We also determined the minor element compositions of eight microtektites using instrumental neutron activation analysis. We found that the peak abundance of cpx spherules is ~2 cm below the peak abundance of the microtektites (~128.7 m below sea floor), suggesting that the cpx spherule layer may be slightly older (~3-5 ka). The microtektites are mostly spherical and are generally transparent and colorless. They are similar to the North American microtektites in composition; the biggest differences being their generally lower Na2O and generally higher Zr, Ba, and Ir (up to 0.3 ppb) contents. We agree with Vonhof (1998) that the Hole 689B microtektites probably belong to the North American tektite strewn field. We calculate that the number of microtektites (>125 microns)/cm2 at Hole 689B is 52. This number is close to the concentration predicted by extrapolation of the trend of concentration versus distance from the Chesapeake Bay structure based on data from other North American microtektite-bearing sites. Thus, the North American strewn field may be at least four times larger than previously mapped. The Hole 689B cpx spherules range from translucent yellow to opaque black, but most are opaque tan to dark brown. They are generally spherical in shape and all

  16. Acid rain. Rhetoric and reality

    SciTech Connect

    Park, C.

    1988-01-01

    The book examines the implications of recent scientific studies, and sets the political debate in the main 'polluting' countries--Britain and the United States--into its proper international context. It provides a wealth of U.S. data, including a history of the development of U.S. acid rain policy. The author presents a review of the evidence for damage and the statistics of change. Data is drawn from around the world, with particular emphasis on damage in Scandinavia and West Germany.

  17. First fossil record of Discocephalinae (Insecta, Pentatomidae): a new genus from the middle Eocene of Río Pichileufú, Patagonia, Argentina

    PubMed Central

    Petrulevičius, Julián F.; Popov, Yuri A.

    2014-01-01

    Abstract A new genus and species of Discocephalini, Acanthocephalonotum martinsnetoi gen. n. et sp. n. is described from Río Pichileufú, middle Eocene of Patagonia, Argentina at palaeolatitude ~ 46°S. The new species is the first fossil representative of the Discocephalinae. This taxon is extant in equatorial to subtropical America, and some species reach warm temperate latitudes (Buenos Aires province). The new genus is distinguished from the other genera of Discocephalini by the combination of these characters: interocular width greater than head length; head massive and quadrangular with the anterior margin almost straight; juga touching each other; labrum thick and curved; triangular ante-ocular process extending beyond the eye; broad spine-like antero-lateral process of the pronotum; pronotum explanate and bean shaped; scutellum triangular with a circular tongue reaching the anterior side of abdominal segment 7; and wings well developed with membrane just surpassing end of abdomen. PMID:25061387

  18. Two groups challenge US acid rain efforts

    SciTech Connect

    Not Available

    1987-11-01

    In its report, Acid Rain Invades Our National Parks, the National Parks and Conservation Association (NPCA) says acid rain is being detected at all 27 national park monitoring sites. In 1980, 87 national parks expressed concern in a NPCA survey over acid rain. Repolled in 1986, more than half of the respondents reported that no research on acid rain was under way. The NPCA report concludes that the alarm that was sounded in 1980 fell largely on deaf ears, and calls for the structural and scientific reorganization of the National Park Service. The National Audubon Society shares NPCA's dissatisfaction with federal efforts to tackle the problem of acid rain and has taken testing into its own hands. Through its Citizens Acid Rain Monitoring Network, Audubon volunteers have collected readings of acidity at 64 monitoring stations in 31 states since July.

  19. Analysis of issues concerning acid rain

    SciTech Connect

    Bowsher, C.A.

    1984-12-11

    Although science has largely determined that man-made emissions cause acid rain, there is uncertainty concerning the extent and timing of its anticipated effects. Thus, at the present time scientific information alone does not lead unequivocally to a conclusion on whether it is appropriate to begin control actions now or to await better understanding. Given this uncertainty, decisionmakers must weigh the risks of further, potentially avoidable environmental damage against the risks of economic impacts from acid rain control actions which may ultimately prove to be unwarranted. GAO examines the implications of current scientific knowledge for policy decisions on acid rain and offers a series of observations on the following issues involved in the debate: To what extent has it been scientifically demonstrated that acid rain is resulting in damage to the environment. What are the causes of acid rain and where is it most prevalent. What alternatives exist for controlling acid rain and what are their economic effects. 5 figures, 20 tables.

  20. Acid rain said to threaten Bay

    SciTech Connect

    Not Available

    1988-04-29

    A report on April 25, 1988 by the Environmental Defense Fund blames acid rain for pollution of Chesapeake Bay. The nitrates in the rain are reported to account for 25% of the nitrogen load of the bay. This increases the acidity of the bay, thereby acting as a fertilizer to promote algal growth. It is postulated that acid rain contributes as much nitrogen to the bay as point sources, which include raw sewage and industrial plants.

  1. Acid rain information book. Draft final report

    SciTech Connect

    1980-12-01

    Acid rain is one of the most widely publicized environmental issues of the day. The potential consequences of increasingly widespread acid rain demand that this phenomenon be carefully evaluated. Reveiw of the literature shows a rapidly growing body of knowledge, but also reveals major gaps in understanding that need to be narrowed. This document discusses major aspects of the acid rain phenomenon, points out areas of uncertainty, and summarizes current and projected research by responsible government agencies and other concerned organizations.

  2. Variability of the TRMM-PR total and convective and stratiform rain fractions over the Indian region during the summer monsoon

    NASA Astrophysics Data System (ADS)

    Pokhrel, Samir; Sikka, D. R.

    2013-07-01

    Level 3 (3A25) TRMM Precipitation Radar (PR) data are used for 13 years period (1998-2010) to prepare climatology of TRMM PR derived near surface rain (Total rain) and rain fractions for the 4-months duration of Indian Summer Monsoon season (June-September) as well as for individual months. It is found that the total rain is contributed mostly (99 %) by two rain fractions i.e. stratiform and convective rain fractions for the season as well as on the monthly basis. It is also found that total rain estimates by PR are about 65 % of the gauge measured rain over continental India as well as on sub-regional basis. Inter-annual variability of TRMM-PR rain estimates for India mainland and its sub-regions as well as over the neighboring oceanic regions, in terms of coefficient of variability (CV) is discussed. The heaviest rain region over north Bay of Bengal (BoB) is found to have the lowest CV. Another sub-region of low CV lies over the eastern equatorial Indian ocean (EEIO). The CVs of total rain as well as its two major constituents are found to be higher on monthly basis compared to seasonal basis. Existence of a well known dipole between the EEIO and the north BoB is well recognized in PR data also. Significant variation in PR rainfall is found over continental India between excess and deficit monsoon seasons as well as between excess and deficit rainfall months of July and August. Examination of rainfall fractions between the BoB and Central India on year to year basis shows that compensation in rainfall fractions exists on monthly scale on both the regions. Also on the seasonal and monthly scales, compensation is observed in extreme monsoon seasons between the two regions. However, much less compensation is observed between the north BoB and EEIO belts in extreme rain months. This leads to speculation that the deficit and excess seasons over India may result from slight shift of the rainfall from Central India to the neighboring oceanic regions of north Bo

  3. Late Eocene diatomite from the Peruvian coastal desert, coastal upwelling in the eastern Pacific, and Pacific circulation before the terminal Eocene event

    SciTech Connect

    Marty, R.; Dunbar, R.; Martin, J.B.; Baker, P.

    1988-09-01

    Previously undocumented late Eocene diatomaceous sediments are present near Fundo Desbarrancado (FD) in southern Peru. These sediments are similar to Miocene diatomite from the same area but, unlike the Miocene diatomite, the FD sediments contain cherty layers, are enriched in CaCO/sub 3/, have a diverse and abundant radiolarian fauna, and possess varved-massive and millimeter- and meter-scale biogenic-terrigenous alternations. The FD sediments are part of an Eocene sequence that includes the clastic sediments of the Paracas Formation, and they are correlative to the Chira Formation of northern Peru. The Paleogene biogenic sediments of western South America show that coastal upwelling developed in the eastern Pacific before the latest Eocene, argue for the existence of a proto-Humboldt current at this time, and suggest that the terminal Eocene event was the culmination of gradual changes and not a catastrophic event at the Eocene/Oligocene boundary.

  4. Vibration (?) spikes during natural rain events

    NASA Technical Reports Server (NTRS)

    Short, David A.

    1994-01-01

    Limited analysis of optical rain gauge (ORG) data from shipboard and ground based sensors has shown the existence of spikes, possibly attributable to sensor vibration, while rain is occurring. An extreme example of this behavior was noted aboard the PRC#5 on the evening of December 24, 1992 as the ship began repositioning during a rain event in the TOGA/COARE IFA. The spikes are readily evident in the one-second resolution data, but may be indistinguishable from natural rain rate fluctuations in subsampled or averaged data. Such spikes result in increased rainfall totals.

  5. Rain from Tropical Storm Noel

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Though not the most powerful storm of the 2007 Atlantic Hurricane season, Tropical Storm Noel was among the most deadly. Only Category 5 Hurricane Felix and its associated flooding had a higher toll. The slow-moving Tropical Storm Noel inundated the Dominican Republic, Haiti, Jamaica, Cuba, and the Bahamas with heavy rain between October 28 and November 1, 2007. The resulting floods and mudslides left at least 115 dead and thousands homeless throughout the Caribbean, reported the Associated Press on November 2, 2007. This image shows the distribution of the rainfall that made Noel a deadly storm. The image shows rainfall totals as measured by the Multi-satellite Precipitation Analysis (MPA) at NASA Goddard Space Flight Center from October 26 through November 1, 2007. The analysis is based on measurements taken by the Tropical Rainfall Measuring Mission (TRMM) satellite. The heaviest rainfall fell in the Dominican Republic and the Bahamas, northeast of Noel's center. Areas of dark red show that rainfall totals over the south-central Dominican Republic and parts of the Bahamas were over 551 millimeters (21 inches). Much of eastern Hispaniola, including both the Dominican Republic and Haiti received at least 200 mm (about 8 inches) of rain, shown in yellow. Rainfall totals over Haiti and Cuba were less, with a range of at least 50 mm (2 inches) to over 200 mm (8 inches).

  6. Acid rain threatens marine life

    SciTech Connect

    Not Available

    1988-09-01

    In freshwater, acid rain harms aquatic organisms because one of its components, sulfur dioxide, lowers the water's pH. In seawater, the damage comes from other components of acid precipitation: nitrogen oxides. Acting as a nutrient, nitrogen promotes excessive algal growth, which blocks sunlight and depletes dissolved oxygen, thereby suffocating other plants and animals. Known as eutrophication, this phenomenon has been increasing in both frequency and intensity on the Atlantic coast during the past few years. The New York City-based Environmental Defense Fund (EDF), study focused on the Chesapeake Bay, the nation's largest estuary and an important spawning ground for many species of economic importance. It has long been known that the bay is suffering from nitrogen pollution. Until now, it was assumed that most of the nitrogen was coming from sewage and agricultural runoff. However, based on data collected from both federal and state agencies, EDF scientists estimated that nitrates from acid rain are responsible for 25% of the nitrogen entering the bay. The report says that if present trends continue, airborne nitrates will contribute 42% of annual nitrogen deposits into the Chesapeake Bay by the year 2030.

  7. Environment and evolution through the Paleocene-Eocene thermal maximum.

    PubMed

    Gingerich, Philip D

    2006-05-01

    The modern orders of mammals, Artiodactyla, Perissodactyla and Primates (APP taxa), first appear in the fossil record at the Paleocene-Eocene boundary, c. 55 million years ago. Their appearance on all three northern continents has been linked to diversification and dispersal in response to rapid environmental change at the beginning of a worldwide 100 000-200 000-year Paleocene-Eocene thermal maximum (PETM) and carbon isotope excursion. As I discuss here, global environmental events such as the PETM have had profound effects on evolution in the geological past and must be considered when modeling the history of life. The PETM is also relevant when considering the causes and consequences of global greenhouse warming.

  8. Cretaceous and Eocene lignite deposits, Jackson Purchase, Kentucky

    USGS Publications Warehouse

    Hower, J.C.; Rich, F.J.; Williams, D.A.; Bland, A.E.; Fiene, F.L.

    1990-01-01

    Lignites occur in the Cretaceous McNairy Formation and the Eocene Claiborne Formation in the Jackson Purchase region of western Kentucky. The lone Cretaceous lignite sample has over 18 percent inertodetrinite and 32 percent humodetrinite which, along with the abundant mineral matter, suggests a possible allochthonous origin for the deposit. The Claiborne Formation lignites have higher humic maceral contents than the Cretaceous lignites. Palynology suggests that there was considerable variation in the plant communities responsible for the Claiborne deposits. Differences in the preservation of the various plants is also seen in the variations between the humic types, particularly in the ulminite and humodetrinite contents. Potter and Dilcher (1980) suggested that the Claiborne lignites in the Jackson Purchase and west Tennessee developed in the abandoned oxbows of Eocene rivers. Significant short-distance changes in the peat thickness, flora, and other depositional elements should be expected in such an environment and could easily account for the observed variations in composition. ?? 1990.

  9. Late Eocene impact microspherules - Stratigraphy, age and geochemistry

    NASA Astrophysics Data System (ADS)

    Keller, G.; D'Hondt, S. L.; Orth, C. J.; Gilmore, J. S.; Oliver, P. Q.; Shoemaker, E. M.; Molina, E.

    1987-03-01

    The stratigraphy, faunal changes, and geochemistry of deep-sea sediments associated with late Eocene microtektite and microspherule layers are reported. Microprobe analyses of major element compositions of microspherules show that, although there is some compositional overlap in all three late Eocene layers as well as with the Pleistocene Australasian and Ivory Coast microtektites, each microspherule population has characteristic compositional features. All three microspherule layers are associated with decreased carbonate, possibly due to a sudden productivity change, increased dissolution as a result of sea-level and climate fluctuations, or impact events. A discovery of microtektites in the Gl. cerroazulensis Zone off the New Jersey coast extends the North American strewn field from the Caribbean to the northwest Atlantic.

  10. The Middle Eocene flora of Csordakút (N Hungary)

    NASA Astrophysics Data System (ADS)

    Erdei, Boglárka; Rákosi, László

    2009-02-01

    The Middle Eocene fossil plant assemblage from Csordakút (N Hungary) comprises plant remains preserved exclusively as impressions. Algae are represented by abundant remains of Characeae, including both vegetative fragments and gyrogonites. Remains of angiosperms comprise Lauraceae (Daphnogene sp.), Fagaceae (cf. Eotrigonobalanus furcinervis), Ulmaceae (Cedrelospermum div. sp.), Myricaceae (Myrica sp., Comptonia div. sp.), Leguminosae (leaves and fruit), Rhamnaceae (?Zizyphus zizyphoides), Elaeocarpaceae (Sloanea nimrodi, Sloanea sp. fruit), Smilacaceae (Smilax div. sp.). The absence of gymnosperms is indicative of a floristic similarity to the coeval floras of Tatabánya (N Hungary) and Girbou in Romania. Sloanea nimrodi (Ettingshausen) Kvaček & Hably, a new element for the Hungarian fossil record indicates a floristic relation to the Late Eocene flora of Kučlin (Bohemia).

  11. Impact ejecta at the Paleocene-Eocene boundary

    NASA Astrophysics Data System (ADS)

    Schaller, Morgan F.; Fung, Megan K.; Wright, James D.; Katz, Miriam E.; Kent, Dennis V.

    2016-10-01

    Extraterrestrial impacts have left a substantial imprint on the climate and evolutionary history of Earth. A rapid carbon cycle perturbation and global warming event about 56 million years ago at the Paleocene-Eocene (P-E) boundary (the Paleocene-Eocene Thermal Maximum) was accompanied by rapid expansions of mammals and terrestrial plants and extinctions of deep-sea benthic organisms. Here, we report the discovery of silicate glass spherules in a discrete stratigraphic layer from three marine P-E boundary sections on the Atlantic margin. Distinct characteristics identify the spherules as microtektites and microkrystites, indicating that an extraterrestrial impact occurred during the carbon isotope excursion at the P-E boundary.

  12. Response of the Pacific inter-tropical convergence zone to global cooling and initiation of Antarctic glaciation across the Eocene Oligocene Transition.

    PubMed

    Hyeong, Kiseong; Kuroda, Junichiro; Seo, Inah; Wilson, Paul A

    2016-08-10

    Approximately 34 million years ago across the Eocene-Oligocene transition (EOT), Earth's climate tipped from a largely unglaciated state into one that sustained large ice sheets on Antarctica. Antarctic glaciation is attributed to a threshold response to slow decline in atmospheric CO2 but our understanding of the feedback processes triggered and of climate change on the other contents is limited. Here we present new geochemical records of terrigenous dust accumulating on the sea floor across the EOT from a site in the central equatorial Pacific. We report a change in dust chemistry from an Asian affinity to a Central-South American provenance that occurs geologically synchronously with the initiation of stepwise global cooling, glaciation of Antarctica and aridification on the northern continents. We infer that the inter-tropical convergence zone of intense precipitation extended to our site during late Eocene, at least four degrees latitude further south than today, but that it migrated northwards in step with global cooling and initiation of Antarctic glaciation. Our findings point to an atmospheric teleconnection between extratropical cooling and rainfall climate in the tropics and the mid-latitude belt of the westerlies operating across the most pivotal transition in climate state of the Cenozoic Era.

  13. Response of the Pacific inter-tropical convergence zone to global cooling and initiation of Antarctic glaciation across the Eocene Oligocene Transition.

    PubMed

    Hyeong, Kiseong; Kuroda, Junichiro; Seo, Inah; Wilson, Paul A

    2016-01-01

    Approximately 34 million years ago across the Eocene-Oligocene transition (EOT), Earth's climate tipped from a largely unglaciated state into one that sustained large ice sheets on Antarctica. Antarctic glaciation is attributed to a threshold response to slow decline in atmospheric CO2 but our understanding of the feedback processes triggered and of climate change on the other contents is limited. Here we present new geochemical records of terrigenous dust accumulating on the sea floor across the EOT from a site in the central equatorial Pacific. We report a change in dust chemistry from an Asian affinity to a Central-South American provenance that occurs geologically synchronously with the initiation of stepwise global cooling, glaciation of Antarctica and aridification on the northern continents. We infer that the inter-tropical convergence zone of intense precipitation extended to our site during late Eocene, at least four degrees latitude further south than today, but that it migrated northwards in step with global cooling and initiation of Antarctic glaciation. Our findings point to an atmospheric teleconnection between extratropical cooling and rainfall climate in the tropics and the mid-latitude belt of the westerlies operating across the most pivotal transition in climate state of the Cenozoic Era. PMID:27507793

  14. A New Eocene Casquehead Lizard (Reptilia, Corytophanidae) from North America.

    PubMed

    Conrad, Jack L

    2015-01-01

    A new fossil showing affinities with extant Laemanctus offers the first clear evidence for a casquehead lizard (Corytophanidae) from the Eocene of North America. Along with Geiseltaliellus from roughly coeval rocks in central Europe, the new find further documents the tropical fauna present during greenhouse conditions in the northern mid-latitudes approximately 50 million years ago (Ma). Modern Corytophanidae is a neotropical clade of iguanian lizards ranging from southern Mexico to northern South America.

  15. Climate directly influences Eocene mammal faunal dynamics in North America

    PubMed Central

    Woodburne, Michael O.; Gunnell, Gregg F.; Stucky, Richard K.

    2009-01-01

    The modern effect of climate on plants and animals is well documented. Some have cautioned against assigning climate a direct role in Cenozoic land mammal faunal changes. We illustrate 3 episodes of significant mammalian reorganization in the Eocene of North America that are considered direct responses to dramatic climatic events. The first episode occurred during the Paleocene–Eocene Thermal Maximum (PETM), beginning the Eocene (55.8 Ma), and earliest Wasatchian North American Land Mammal Age (NALMA). The PETM documents a short (<170 k.y.) global temperature increase of ≈5 °C and a substantial increase in first appearances of mammals traced to climate-induced immigration. A 4-m.y. period of climatic and evolutionary stasis then ensued. The second climate episode, the late early Eocene Climatic Optimum (EECO, 53–50 Ma), is marked by a temperature increase to the highest prolonged Cenozoic ocean temperature and a similarly distinctive continental interior mean annual temperature (MAT) of 23 °C. This MAT increase [and of mean annual precipitation (MAP) to 150 cm/y) promoted a major increase in floral diversity and habitat complexity under temporally unique, moist, paratropical conditions. Subsequent climatic deterioration in a third interval, from 50 to 47 Ma, resulted in major faunal diversity loss at both continental and local scales. In this Bridgerian Crash, relative abundance shifted from very diverse, evenly represented, communities to those dominated by the condylarth Hyopsodus. Rather than being “optimum,” the EECO began the greatest episode of faunal turnover of the first 15 m.y. of the Cenozoic. PMID:19666605

  16. Climate directly influences Eocene mammal faunal dynamics in North America.

    PubMed

    Woodburne, Michael O; Gunnell, Gregg F; Stucky, Richard K

    2009-08-11

    The modern effect of climate on plants and animals is well documented. Some have cautioned against assigning climate a direct role in Cenozoic land mammal faunal changes. We illustrate 3 episodes of significant mammalian reorganization in the Eocene of North America that are considered direct responses to dramatic climatic events. The first episode occurred during the Paleocene-Eocene Thermal Maximum (PETM), beginning the Eocene (55.8 Ma), and earliest Wasatchian North American Land Mammal Age (NALMA). The PETM documents a short (<170 k.y.) global temperature increase of approximately 5 degrees C and a substantial increase in first appearances of mammals traced to climate-induced immigration. A 4-m.y. period of climatic and evolutionary stasis then ensued. The second climate episode, the late early Eocene Climatic Optimum (EECO, 53-50 Ma), is marked by a temperature increase to the highest prolonged Cenozoic ocean temperature and a similarly distinctive continental interior mean annual temperature (MAT) of 23 degrees C. This MAT increase [and of mean annual precipitation (MAP) to 150 cm/y) promoted a major increase in floral diversity and habitat complexity under temporally unique, moist, paratropical conditions. Subsequent climatic deterioration in a third interval, from 50 to 47 Ma, resulted in major faunal diversity loss at both continental and local scales. In this Bridgerian Crash, relative abundance shifted from very diverse, evenly represented, communities to those dominated by the condylarth Hyopsodus. Rather than being "optimum," the EECO began the greatest episode of faunal turnover of the first 15 m.y. of the Cenozoic. PMID:19666605

  17. Asian Eocene monsoons as revealed by leaf architectural signatures

    NASA Astrophysics Data System (ADS)

    Spicer, Robert A.; Yang, Jian; Herman, Alexei B.; Kodrul, Tatiana; Maslova, Natalia; Spicer, Teresa E. V.; Aleksandrova, Galina; Jin, Jianhua

    2016-09-01

    The onset and development of the Asian monsoon systems is a topic that has attracted considerable research effort but proxy data limitations, coupled with a diversity of definitions and metrics characterizing monsoon phenomena, have generated much debate. Failure of geological proxies to yield metrics capable of distinguishing between rainfall seasonality induced by migrations of the Inter-tropical Convergence Zone (ITCZ) from that attributable to topographically modified seasonal pressure reversals has frustrated attempts to understand mechanisms underpinning monsoon development and dynamics. Here we circumvent the use of such single climate parameter metrics in favor of detecting directly the distinctive attributes of different monsoon regimes encoded in leaf fossils. Leaf form adapts to the prevailing climate, particularly under the extreme seasonal stresses imposed by monsoons, so it is likely that fossil leaves carry a unique signature of past monsoon regimes. Leaf form trait spectra obtained from fossils from Eocene basins in southern China were compared with those seen in modern leaves growing under known climate regimes. The fossil leaf trait spectra, including those derived from previously published fossil floras from northwestern India, were most similar to those found in vegetation exposed to the modern Indonesia-Australia Monsoon (I-AM), which is largely a product of seasonal migrations of the ITCZ. The presence of this distinctive leaf physiognomic signature suggests that although a monsoon climate existed in Eocene time across southern Asia the characteristics of the modern topographically-enhanced South Asia Monsoon had yet to develop. By the Eocene leaves in South Asia had become well adapted to an I-AM type regime across many taxa and points to the existence of a pervasive monsoon climate prior to the Eocene. No fossil trait spectra typical of exposure to the modern East Asia monsoon were seen, suggesting the effects of this system in southern

  18. A New Eocene Casquehead Lizard (Reptilia, Corytophanidae) from North America

    PubMed Central

    Conrad, Jack L.

    2015-01-01

    A new fossil showing affinities with extant Laemanctus offers the first clear evidence for a casquehead lizard (Corytophanidae) from the Eocene of North America. Along with Geiseltaliellus from roughly coeval rocks in central Europe, the new find further documents the tropical fauna present during greenhouse conditions in the northern mid-latitudes approximately 50 million years ago (Ma). Modern Corytophanidae is a neotropical clade of iguanian lizards ranging from southern Mexico to northern South America. PMID:26131767

  19. Temperate Pollen Genera in the Eocene (Claiborne) Flora, Alabama.

    PubMed

    Gray, J

    1960-09-23

    Pollen, spores, hystrichospherids, dinoflagellates, and the fresh-water alga Pediastrum occur in marine clays at the classic Claiborne Bluffs locality, Alabama. The presence of Ephedra pollen provides the first documented Tertiary record of this genus from the southeastern states. The occurrence of several characteristically temperate genera lends support to the idea that a deciduous hardwood forest was present in the Appalachian uplands during the Eocene.

  20. MACSAT - A Near Equatorial Earth Observation Mission

    NASA Astrophysics Data System (ADS)

    Kim, B. J.; Park, S.; Kim, E.-E.; Park, W.; Chang, H.; Seon, J.

    MACSAT mission was initiated by Malaysia to launch a high-resolution remote sensing satellite into Near Equatorial Orbit (NEO). Due to its geographical location, Malaysia can have large benefits from NEO satellite operation. From the baseline circular orbit of 685 km altitude with 7 degrees of inclination, the neighboring regions around Malaysian territory can be frequently monitored. The equatorial environment around the globe can also be regularly observed with unique revisit characteristics. The primary mission objective of MACSAT program is to develop and validate technologies for a near equatorial orbit remote sensing satellite system. MACSAT is optimally designed to accommodate an electro-optic Earth observation payload, Medium-sized Aperture Camera (MAC). Malaysian and Korean joint engineering teams are formed for the effective implementation of the satellite system. An integrated team approach is adopted for the joint development for MACSAT. MAC is a pushbroom type camera with 2.5 m of Ground Sampling Distance (GSD) in panchromatic band and 5 m of GSD in four multi-spectral bands. The satellite platform is a mini-class satellite. Including MAC payload, the satellite weighs under 200 kg. Spacecraft bus is designed optimally to support payload operations during 3 years of mission life. The payload has 20 km of swath width with +/- 30 o of tilting capability. 32 Gbits of solid state recorder is implemented as the mass image storage. The ground element is an integrated ground station for mission control and payload operation. It is equipped with S- band up/down link for commanding and telemetry reception as well as 30 Mbps class X-band down link for image reception and processing. The MACSAT system is capable of generating 1:25,000-scale image maps. It is also anticipated to have capability for cross-track stereo imaging for Digital elevation Model (DEM) generation.

  1. Ionospheric Storms in Equatorial Region: Digisonde Observations

    NASA Astrophysics Data System (ADS)

    Paznukhov, V.; Altadill, D.; Blanch, E.

    2011-12-01

    We present a study of the ionospheric storms observed in the low-latitude and equatorial ionosphere at several digisonde stations: Jicamarca (Geomagnetic Coordinates: 2.0 S, 355.3 E), Kwajalein Island (3.8 N, 238.2 E), Ascension Island (2.5 S, 56.8 E), Fortaleza (4.8 N, 33.7 W), and Ramey (28.6 N, 5.2 E). The strongest geomagnetic storms from years 1995-2009 have been analyzed. The main ionospheric characteristics, hmF2 and foF2 were used in the study, making it possible to investigate the changes in the ionosphere peak density and height during the storms. All digisonde data were manually processed to assure the accuracy of the measurements. Solar wind data, geomagnetic field variations, and auroral activity indices have been used to characterize the geomagnetic environment during the events. It was found in our analysis that the major drivers for the ionospheric storms, electric field and neutral wind have approximately equal importance at the low-latitude and equatorial latitudes. This is noticeably different from the behavior of the ionsphere in the middle latitudes, where the neutral wind is usually a dominant factor. It was found that the auroral index, AE is the best precursor of the ionospheric effects observed during the storms in this region. We analyze the difference between time delays of the storm effects observed at the stations located in different local time sectors. The overall statistics of the time delays of the storms as a function of the local time at the stations is also presented. Several very interesting cases of sudden very strong ionospheric uplifting and their possible relation to the equatorial super fountain effect are investigated in greater details.

  2. Eocene-Oligocene boundary problems, west coast, North America

    SciTech Connect

    Armentrout, J.M.

    1983-03-01

    Correlation of the international Eocene-Oligocene boundary with the provincial biostratigraphic framework of the northeast Pacific margin has been and continues to be controversial. The controversy centers about historical nomenclature and correlations, and current correlations based on planktonic fossil group. The Geological Society of America's C.E. Weaver Committee published the first interdisciplinary correlation chart for the Cenozoic rocks of the western United States in 1944. The committee placed the Eocene-Oligocene boundary at the base of the Keasey Molluscan Stage and Refugian Benthic Foraminiferal Stage. The most useful provincial boundaries of Late Eocene to Oligocene age are the Narizian-Refugian and Refugian-Zemorrian Benthic Foraminiferal Stage boundaries. Reevaluation of the Refugian Stage has recently been completed. The stage boundaries have been correlated to the international geologic time scale using planktonic microfossils. Planktonic assemblages are rare in samples from above and below the Refugian-Zemorrian Benthic Foraminiferal Stage boundary. In California this boundary is commonly at an unconformity or without superposition of diagnostic faunas. In southwestern Washington the Refugian-Zemorrian boundary occurs in continuously deposited and foraminiferally rich sections. Radiometric calibration of the provincial boundaries is not yet possible. Whole rock potassium-argon and fission track dates are available but both have very large error bars or lack adequate biostratigraphic control to be useful. Fossiliferous stratigraphic sections have rocks with sufficient remanent magnetism for magnetostratigraphic studies but to date only reconnaissance data are available.

  3. Late Eocene white pines (Pinus subgenus Strobus) from southern China

    PubMed Central

    Xu, Qingqing; Zhou, Wenjun; Kodrul, Tatiana M.; Naugolnykh, Serge V.; Jin, Jianhua

    2015-01-01

    Fossil records indicate that the genus Pinus L. split into two subgenera by the Late Cretaceous, although subgenus Strobus (D. Don) Lemmon is less well documented than subgenus Pinus L., especially in eastern Asia. In this paper, Pinus maomingensis sp. nov. is established based on a compressed seed cone from the upper Eocene of the Maoming Basin of southern China. This species is attributed to genus Pinus, subgenus Strobus, section Quinquefoliae Duhamel, subsection Strobus Loudon based on the combination of morphological characters obtained from the cone scales, specifically from the terminal umbo, rhombic apophysis, and cuticle structure. Associated fascicles of needle leaves with deciduous sheaths and bulbous bases are recognized as Pinus sp. and also represent Pinus subgenus Strobus. This new discovery from the Maoming Basin constitutes the first megafossil record of subgenus Strobus from southern China and implies that the members of this subgenus arrived in the southern region of China by the late Eocene. The extant species of subgenus Strobus are mainly distributed in northern temperate and tropical to subtropical mountainous regions. We propose that the Maoming Basin was adjacent to a mountainous region during the late Eocene. PMID:26548658

  4. Late Eocene white pines (Pinus subgenus Strobus) from southern China.

    PubMed

    Xu, Qingqing; Zhou, Wenjun; Kodrul, Tatiana M; Naugolnykh, Serge V; Jin, Jianhua

    2015-11-09

    Fossil records indicate that the genus Pinus L. split into two subgenera by the Late Cretaceous, although subgenus Strobus (D. Don) Lemmon is less well documented than subgenus Pinus L., especially in eastern Asia. In this paper, Pinus maomingensis sp. nov. is established based on a compressed seed cone from the upper Eocene of the Maoming Basin of southern China. This species is attributed to genus Pinus, subgenus Strobus, section Quinquefoliae Duhamel, subsection Strobus Loudon based on the combination of morphological characters obtained from the cone scales, specifically from the terminal umbo, rhombic apophysis, and cuticle structure. Associated fascicles of needle leaves with deciduous sheaths and bulbous bases are recognized as Pinus sp. and also represent Pinus subgenus Strobus. This new discovery from the Maoming Basin constitutes the first megafossil record of subgenus Strobus from southern China and implies that the members of this subgenus arrived in the southern region of China by the late Eocene. The extant species of subgenus Strobus are mainly distributed in northern temperate and tropical to subtropical mountainous regions. We propose that the Maoming Basin was adjacent to a mountainous region during the late Eocene.

  5. Asian monsoons in a late Eocene greenhouse world.

    PubMed

    Licht, A; van Cappelle, M; Abels, H A; Ladant, J-B; Trabucho-Alexandre, J; France-Lanord, C; Donnadieu, Y; Vandenberghe, J; Rigaudier, T; Lécuyer, C; Terry, D; Adriaens, R; Boura, A; Guo, Z; Soe, Aung Naing; Quade, J; Dupont-Nivet, G; Jaeger, J-J

    2014-09-25

    The strong present-day Asian monsoons are thought to have originated between 25 and 22 million years (Myr) ago, driven by Tibetan-Himalayan uplift. However, the existence of older Asian monsoons and their response to enhanced greenhouse conditions such as those in the Eocene period (55-34 Myr ago) are unknown because of the paucity of well-dated records. Here we show late Eocene climate records revealing marked monsoon-like patterns in rainfall and wind south and north of the Tibetan-Himalayan orogen. This is indicated by low oxygen isotope values with strong seasonality in gastropod shells and mammal teeth from Myanmar, and by aeolian dust deposition in northwest China. Our climate simulations support modern-like Eocene monsoonal rainfall and show that a reinforced hydrological cycle responding to enhanced greenhouse conditions counterbalanced the negative effect of lower Tibetan relief on precipitation. These strong monsoons later weakened with the global shift to icehouse conditions 34 Myr ago.

  6. Asian monsoons in a late Eocene greenhouse world.

    PubMed

    Licht, A; van Cappelle, M; Abels, H A; Ladant, J-B; Trabucho-Alexandre, J; France-Lanord, C; Donnadieu, Y; Vandenberghe, J; Rigaudier, T; Lécuyer, C; Terry, D; Adriaens, R; Boura, A; Guo, Z; Soe, Aung Naing; Quade, J; Dupont-Nivet, G; Jaeger, J-J

    2014-09-25

    The strong present-day Asian monsoons are thought to have originated between 25 and 22 million years (Myr) ago, driven by Tibetan-Himalayan uplift. However, the existence of older Asian monsoons and their response to enhanced greenhouse conditions such as those in the Eocene period (55-34 Myr ago) are unknown because of the paucity of well-dated records. Here we show late Eocene climate records revealing marked monsoon-like patterns in rainfall and wind south and north of the Tibetan-Himalayan orogen. This is indicated by low oxygen isotope values with strong seasonality in gastropod shells and mammal teeth from Myanmar, and by aeolian dust deposition in northwest China. Our climate simulations support modern-like Eocene monsoonal rainfall and show that a reinforced hydrological cycle responding to enhanced greenhouse conditions counterbalanced the negative effect of lower Tibetan relief on precipitation. These strong monsoons later weakened with the global shift to icehouse conditions 34 Myr ago. PMID:25219854

  7. Stable warm tropical climate through the Eocene Epoch

    NASA Astrophysics Data System (ADS)

    Pearson, Paul N.; van Dongen, Bart E.; Nicholas, Christopher J.; Pancost, Richard D.; Schouten, Stefan; Singano, Joyce M.; Wade, Bridget S.

    2007-03-01

    Earth's climate cooled from a period of extreme warmth in the early Eocene Epoch (ca. 50 Ma) to the early Oligocene (ca. 33 Ma), when a large ice cap first appeared on Antarctica. Evidence from the planktonic foraminifer oxygen isotope record in deep-sea cores has suggested that tropical sea-surface temperatures declined by 5-10 degrees over this interval, eventually becoming much cooler than modern temperatures. Here we present paleotemperature estimates from foraminifer isotopes and the membrane lipids of marine Crenarcheota from new drill cores in Tanzania that indicate a warm and generally stable tropical climate over this period. We reinterpret the previously published isotope records in the light of comparative textural analysis of the deep-sea foraminifer shells, which shows that in contrast to the Tanzanian material, they have been diagenetically recrystallized. We suggest that increasingly severe alteration of the deep-sea plankton shells through the Eocene produced a diagenetic overprint on their oxygen isotope ratios that imparts the false appearance of a tropical sea-surface cooling trend. This implies that the long-term Eocene climatic cooling trend occurred mainly at the poles and had little effect at lower latitudes.

  8. Eocene Diversification of Crown Group Rails (Aves: Gruiformes: Rallidae)

    PubMed Central

    García–R, Juan C.; Gibb, Gillian C.; Trewick, Steve A.

    2014-01-01

    Central to our understanding of the timing of bird evolution is debate about an apparent conflict between fossil and molecular data. A deep age for higher level taxa within Neoaves is evident from molecular analyses but much remains to be learned about the age of diversification in modern bird families and their evolutionary ecology. In order to better understand the timing and pattern of diversification within the family Rallidae we used a relaxed molecular clock, fossil calibrations, and complete mitochondrial genomes from a range of rallid species analysed in a Bayesian framework. The estimated time of origin of Rallidae is Eocene, about 40.5 Mya, with evidence of intrafamiliar diversification from the Late Eocene to the Miocene. This timing is older than previously suggested for crown group Rallidae, but fossil calibrations, extent of taxon sampling and substantial sequence data give it credence. We note that fossils of Eocene age tentatively assigned to Rallidae are consistent with our findings. Compared to available studies of other bird lineages, the rail clade is old and supports an inference of deep ancestry of ground-dwelling habits among Neoaves. PMID:25291147

  9. Hydrocarbon potential of Middle Eocene carbonates, Sirt Basin, Libya

    NASA Astrophysics Data System (ADS)

    Swei, Giuma H.; Tucker, Maurice E.

    2015-11-01

    Deposition of Middle Eocene carbonates in the Sirt Basin in Libya has been the subject of considerable study in recent years because of the importance of sediments of this age as hydrocarbon reservoirs. The Gialo Formation is an important gas-producing reservoir in the Assumood, Sahl and other nearby fields. The gas which is generated from the gas-prone Sirt Shale source rock of the northern Ajdabiya Trough probably migrated in to the Assumood Ridge from the northeast through late Cretaceous, Paleocene and early Eocene carbonates, before being trapped beneath the Augila Shale (Upper Eocene) which is the principal regional seal in the area. This integrated study has enhanced our understanding of reservoir heterogeneity and hydrocarbon potential of the Gialo carbonates and should lead to improved exploration in the future. Reservoir quality in the Gialo Formation is a function of grain types, pore types, grain size, sorting, cementation and compaction, and predicting areas of high reservoir quality has proved difficult; exploration should be oriented to positioning wells into the main trend of the mid-ramp, nummulite accumulation. Different nummulite facies can be reservoirs depending on their diagenetic history. A diagenetic reduction in porosity must be distinguished from a lack of porosity resulting from an unfavourable depositional environment, so that exploration alternatives can be assessed. This integrated study has demonstrated the presence of suitable reservoir rocks, hydrocarbon traps and the close proximity of potential source rocks. These features should encourage further hydrocarbon exploration in the area.

  10. The terminal eocene event and the polish connection

    USGS Publications Warehouse

    Van Couvering, J. A.; Aubry, M.-P.; Berggren, W.A.; Bujak, J.P.; Naeser, C.W.; Wieser, T.

    1981-01-01

    The Eocene/Oligocene boundary in Europe is marked by major discontinuities in all environments: the "Grande Coupure" in continental mammals; the elimination of semitropical elements from high-latitude floras; the virtually complete replacement of the shallow-marine malacofauna; and an extraordinary downslope excursion of carbonate deposition in deep-ocean basins (drop in the CCD). These phenomena collectively represent the "Terminal Eocene Event" (TEE). In the Carpathian Mountains, the TEE is manifested in the thin but regionally persistent Globigerina Marl, a calcareous unit containing abundant cool-water microplankton that occurs within very thick, siliceous, bathyal flysch sequences. In southern Poland, the marl is of very latest Eocene age, within planktonic foraminifera zone P17, calcareous nannoplankton zone NP19/20, and the zone of the dinoflagellate Rhomdodinium perforatum. Zircons from bentonites bracketing the marl are dated by fission-track analysis; at Polany, two underlying bentonites are 41.7 and 39.8 Ma, and at Znamirowice two overlying bentonites are 34.6 and 28.9 Ma, in sequence. This accords with glauconite K/Ar ages in Western Europe by which the Eo/Oligocene boundary age is estimated at 37-38 Ma. Global correlations indicate that the TEE corresponds to a major glacio-eustatic regression with a duration of about 0.5 Ma, in which a large Antarctic ice cap was formed, the ocean circulation was permanently changed to the psychrospheric condition, and world climate shifted irreversibly towards the modern state. ?? 1981.

  11. Late Eocene impact events recorded in deep-sea sediments

    NASA Technical Reports Server (NTRS)

    Glass, B. P.

    1988-01-01

    Raup and Sepkoski proposed that mass extinctions have occurred every 26 Myr during the last 250 Myr. In order to explain this 26 Myr periodicity, it was proposed that the mass extinctions were caused by periodic increases in cometary impacts. One method to test this hypothesis is to determine if there were periodic increases in impact events (based on crater ages) that correlate with mass extinctions. A way to test the hypothesis that mass extinctions were caused by periodic increases in impact cratering is to look for evidence of impact events in deep-sea deposits. This method allows direct observation of the temporal relationship between impact events and extinctions as recorded in the sedimentary record. There is evidence in the deep-sea record for two (possibly three) impact events in the late Eocene. The younger event, represented by the North American microtektite layer, is not associated with an Ir anomaly. The older event, defined by the cpx spherule layer, is associated with an Ir anomaly. However, neither of the two impact events recorded in late Eocene deposits appears to be associated with an unusual number of extinctions. Thus there is little evidence in the deep-sea record for an impact-related mass extinction in the late Eocene.

  12. An equatorial coronal hole at solar minimum

    NASA Technical Reports Server (NTRS)

    Bromage, B. J. I.; DelZanna, G.; DeForest, C.; Thompson, B.; Clegg, J. R.

    1997-01-01

    The large transequatorial coronal hole that was observed in the solar corona at the end of August 1996 is presented. It consists of a north polar coronal hole called the 'elephant's trunk or tusk'. The observations of this coronal hole were carried out with the coronal diagnostic spectrometer onboard the Solar and Heliospheric Observatory (SOHO). The magnetic field associated with the equatorial coronal hole is strongly connected to that of the active region at its base, resulting in the two features rotating at almost the same rate.

  13. Equatorial Oscillations in Jupiter's and Saturn's Atmospheres

    NASA Technical Reports Server (NTRS)

    Flasar, F. Michael; Guerlet, S.; Fouchet, T.; Schinder, P. J.

    2011-01-01

    Equatorial oscillations in the zonal-mean temperatures and zonal winds have been well documented in Earth's middle atmosphere. A growing body of evidence from ground-based and Cassini spacecraft observations indicates that such phenomena also occur in the stratospheres of Jupiter and Saturn. Earth-based midinfrared measurements spanning several decades have established that the equatorial stratospheric temperatures on Jupiter vary with a cycle of 4-5 years and on Saturn with a cycle of approximately 15 years. Spectra obtained by the Composite Infrared Spectrometer (CIRS) during the Cassini swingby at the end of 2000, with much better vertical resolution than the ground-based data, indicated a series of vertically stacked warm and cold anomalics at Jupiter's equator; a similar structurc was seen at Saturn's equator in CIRS limb measurements made in 2005, in the early phase of Cassini's orbital tour. The thermal wind equation implied similar patterns of mean zonal winds increasing and decreasing with altitude. On Saturn the peak-to-pcak amplitude of this variation was nearly 200 meters per second. The alternating vertical pattern of wanner and colder cquatorial tcmperatures and easterly and westerly tendencies of the zonal winds is seen in Earth's equatorial oscillations, where the pattern descends with time, The Cassini Jupiter and early Saturn observations were snapshots within a limited time interval, and they did not show the temporal evolution of the spatial patterns. However, more recent Saturn observations by CIRS (2010) and Cassini radio-occultation soundings (2009-2010) have provided an opportunity to follow the change of the temperature-zonal wind pattern, and they suggest there is descent, at a rate of roughly one scale height over four years. On Earth, the observed descent in the zonal-mean structure is associated with the absorption of a combination of vertically propagating waves with easlerly and westerly phase velocities. The peak-to-peak zonal wind

  14. The equatorial electrojet satellite and surface comparison

    NASA Technical Reports Server (NTRS)

    Cain, J. C. (Editor); Sweeney, R. E. (Editor)

    1972-01-01

    The OGO 4 and 6 (POGO) magnetic field results for the equatorial electrojet indicate that while the present models are approximately correct, the possibility of a westward component must be incorporated. The scatter diagrams of POGO amplitudes and surface data show a correlation. The ratios between the amplitudes estimated from surface data and those at 400 km altitude are as follows: India 5 to 8, East Africa (Addis Ababa) 4, Central Africa 3, West Africa (Nigeria) 3, South America (Huancayo) 5, and Philippines 5. The variation in the ratio is due to the conductivity structure of the earth in various zones.

  15. Evaluation of TRMM Ground-Validation Radar-Rain Errors Using Rain Gauge Measurements

    NASA Technical Reports Server (NTRS)

    Wang, Jianxin; Wolff, David B.

    2009-01-01

    Ground-validation (GV) radar-rain products are often utilized for validation of the Tropical Rainfall Measuring Mission (TRMM) spaced-based rain estimates, and hence, quantitative evaluation of the GV radar-rain product error characteristics is vital. This study uses quality-controlled gauge data to compare with TRMM GV radar rain rates in an effort to provide such error characteristics. The results show that significant differences of concurrent radar-gauge rain rates exist at various time scales ranging from 5 min to 1 day, despite lower overall long-term bias. However, the differences between the radar area-averaged rain rates and gauge point rain rates cannot be explained as due to radar error only. The error variance separation method is adapted to partition the variance of radar-gauge differences into the gauge area-point error variance and radar rain estimation error variance. The results provide relatively reliable quantitative uncertainty evaluation of TRMM GV radar rain estimates at various times scales, and are helpful to better understand the differences between measured radar and gauge rain rates. It is envisaged that this study will contribute to better utilization of GV radar rain products to validate versatile spaced-based rain estimates from TRMM, as well as the proposed Global Precipitation Measurement, and other satellites.

  16. Rain Attenuation Analysis using Synthetic Storm Technique in Malaysia

    NASA Astrophysics Data System (ADS)

    Lwas, A. K.; Islam, Md R.; Chebil, J.; Habaebi, M. H.; Ismail, A. F.; Zyoud, A.; Dao, H.

    2013-12-01

    Generated rain attenuation time series plays an important role for investigating the rain fade characteristics in the lack of real fade measurements. A suitable conversion technique can be applied to measured rain rate time series to produce rain attenuation data and be utilized to understand the rain fade characteristics. This paper focuses on applicability of synthetic storm technique (SST) to convert measured rain rate data to rain attenuation time series. Its performance is assessed for time series generation over a tropical location Kuala Lumpur, in Malaysia. From preliminary analysis, it is found that SST gives satisfactory results to estimate the rain attenuation time series from the rain rate measurements over this region.

  17. Pollen selection under acid rain stress

    SciTech Connect

    Zhang, Y.

    1994-01-01

    To investigate whether acid rain stress induces pollen selection in nature, three different approaches were used, based on the assumption that the response of pollen grains to acid rain is controlled by an acid sensitive gene product. Germination of pollen from homozygous and heterozygous individuals under acid rain stress was examined to detect any differences in rate of germination between populations of homogeneous and heterogeneous pollen grains. In vitro and in vivo bulked segregant analysis using RAPDs was used to search for differences in DNA constitution between the survivors of acid rain stressed and non-acid rain stressed pollen populations in vitro and between the progenies of acid rain stressed and non-acid rain stressed populations during pollination, respectively. No evidence for the pollen selection under acid rain stress was obtained in any of the test systems. Inhibition of protein synthesis using cycloheximide led to significant reduction of tube elongation at 4 hr and had no effect on pollen germination at any time interval tested. Total proteins extracted from control and acid rain stressed pollen grain populations exhibited no differences. The reduction of corn pollen germination in vitro under acid rain stress was mainly due to pollen rupture. The present data indicates the reduction of pollen germination and tube growth under acid rain stress may be a physiological response rather than a genetic response. A simple, nontoxic, and effective method to separate germinated from ungerminated pollen grains has been developed using pollen from corn (Zea mays, L. cv. Pioneer 3747). The separated germinated pollen grains retained viability and continued tube growth when placed in culture medium.

  18. Modulation of Cenozoic climate by weathering of large igneous provinces on continents drifting through equatorial humid belt

    NASA Astrophysics Data System (ADS)

    Muttoni, G.; Kent, D. V.

    2011-12-01

    The small reservoir of CO2 in the atmosphere (pCO2) that modulates climate through the greenhouse effect is a delicate balance between large fluxes of sources and sinks. The major long-term source of CO2 is global degassing from sea-floor spreading, subduction, hotspot activity, and metamorphism; the ultimate sink is through weathering of continental silicates. Most carbon cycle models are driven by changes in the source flux, in particular, variable rates of ocean floor production (and concomitant subduction) but the area/age versus age distribution of the modern ocean is compatible with a steady rate since 180 Ma (Rowley, 2002 GSA Bulletin). We previously suggested (2008 PNAS) that evidence of high pCO2 and warm climates in the Cretaceous-early Cenozoic could be explained by the subduction of Tethyan ocean crust loaded with equatorial carbonate-rich pelagic (more readily subductable) sediments since the onset of India's northward flight at ~120 Ma up until the CO2-producing decarbonation factory slowed down with collision of India and Asia at the Early Eocene Climate Optimum at 50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO2 by efficient silicate weathering would further lower the level of pCO2. Continued weathering uptake was influenced by the southerly extrusion of SE Asia in response to the Indian indentor starting at ~40 Ma (Molnar & Tapponnier, 1975 Science) as well as the emplacement of the Ethiopian traps near the Equator at 30 Ma. The ongoing impingement of India into Asia and resultant southerly tectonic extrusion of SE Asia (Replumaz & Tapponnier, 2003 JGR) makes it the dominant new area in the equatorial humid belt. Moreover, SE Asia presently accounts for 25% of CO2 consumption of all basaltic provinces, which account for ~1/3 of the total consumption by continental silicate weathering (Dessert et al., 2003 Chemical Geology) that is within the range of

  19. Modern Mammals dispersion linked to the Paleocene Eocene thermal maximum (PETM) and early Eocene climatic optimum, new insights from India

    NASA Astrophysics Data System (ADS)

    Khozyem, H. M.; Adatte, T.; Keller, G.; Spangenberg, J.; Bajpai, S.; Samant, B.

    2012-12-01

    The Paleocene Eocene Thermal Maximum (PETM, 55.9Ma)) is globally related with the extinction of deep benthic foraminifera, the diversification of both planktic foraminifera and modern mammals. In India, the tempo and timing of modern mammal dispersion, their association with the PETM or EECO (Early Eocene Climatic Optimum) and the India-Asia collision remain uncertain. Four Indian sections (Giral, Bhavnagar, Vastan and Tadkeshware lignite mines) have been studied using sedimentology, micropaleontology, mineralogy (bulk and clay mineralogy) and geochemistry (stable isotopes, major and trace elements, organic matter). Both PETM and ETM2 (second Eocene Thermal Maximum, 53.7Ma), a short-lived warming episode that followed the PETM, are globally marked by a pronounced δ13Ccarb and δ13Corg negative excursion. Both isotopic excursions have been recognized in the Vastan and Tarkeswhar lignite mines (Cambay basin, Gujarat) associated with the main mammal bearing level. The lower shift is located above the first lignite seam and corresponds to the transition from continental to shallow marine conditions. The upper excursion appears to be linked to the ETM2 and corresponds to a second marine incursion containing bivalves, benthic (Nummulites burdigalensis) and planktic foraminifera located below the second lignite seam. A very pronounced δ13Corg peak has been detected in the Giral lignite mine (Barmer, Rajhastan) around 6m above the vertebrate bearing level and may correspond to the PETM. This correlation is confirmed by palynological data and more particularly by a dinoflagellate acme that globally characterizes the PETM interval. Our micropaleontological data combined with stable carbone isotopes indicate the presence of both PETM and ETM2 events and constrain the age of the early mammals in northwestern India in between these two thermal events in the early Eocene. These new data will significantly improve the ongoing debate on whether mammals originated in or out of

  20. Iridium and Spherules in Late Eocene Impact Deposits

    NASA Technical Reports Server (NTRS)

    Kyte, F. T.; Liu, S.

    2002-01-01

    We have been independently examining the Ir (FTK) and spherule (SL) contents of recently discovered late Eocene impact deposits from the south Atlantic and western Indian oceans. These include ODP Sites 1090 [14,15], 709 [lo], and 699 [Liu in prep.]. Iridium abundances at these sites are within the typical range reported for late Eocene deposits, with peak concentrations between 100 and 1000 pg/g. In Table 1 we present estimated net Ir fluences (in ng Ir/cm ) for these and nine other sites. Although there are fewer sites than the K/T boundary, the average of 9 ng Ir/cm2 is probably a good estimate of the late Eocene global flux. This is enough Ir for a 6 km comet (assuming 250 ng/g Ir, p=1.5), is sufficient to produce the Popigai or Chesapeake Bay structures, and is 16% of the flux estimated for the K/T boundary (55 ng/cm2 [ 161). Figure 1 shows the relative abundances of Ir, glassy microtektites and cpx-bearing spherules in sediments from Sites 699 and 1090, which are separated by only 3100 km. Although these two sites have similar Ir anomalies, the abundances of spherules are quite different. Site 1090 has well-defined peaks for both types of spherules, with a peak of 562 cpx spheruledg, while Site 699 contains only a few glassy microtektites and no cpx spherules. While the different abundances of spherules may reflect a heterogeneous distribution of spherules on the Earth s surface, an equally likely cause of this difference may be differential preservation of spherules in the sediment. recovered are only a trace residue of the initial impact deposit. Earlier work found 0.22 ng/g Ir in glassy microtektites from Site 689 [17], an insufficient concentration to support 0.16 ng/g in the bulk sediment at this site. We measured 15 ng/g Ir in a group of 95 cpx spherules from Site 1090 with sizes from 63 to -200 pm, a set typical of the size distribution at this site. Although this is a significant concentration it also cannot support the Ir peak. We presently lack

  1. New Eocene damselflies and first Cenozoic damsel-dragonfly of the isophlebiopteran lineage (Insecta: Odonata).

    PubMed

    Garrouste, Romain; Nel, André

    2015-01-01

    The study of a new specimen of Petrolestes hendersoni from the Eocene Green Formation allows a more precise description of the enigmatic damselfly and the diagnosis of the Petrolestini. Petrolestes messelensis sp. nov. is described from the Eocene Messel Formation in Germany, extending the distribution of the Petrolestini to the European Eocene. The new damsel-dragonfly family Pseudostenolestidae is described for the new genus and species Pseudostenolestes bechlyi, from the Eocene Messel Formation. It is the first Cenozoic representative of the Mesozoic clade Isophlebioptera. PMID:26624314

  2. New Eocene damselflies and first Cenozoic damsel-dragonfly of the isophlebiopteran lineage (Insecta: Odonata).

    PubMed

    Garrouste, Romain; Nel, André

    2015-10-09

    The study of a new specimen of Petrolestes hendersoni from the Eocene Green Formation allows a more precise description of the enigmatic damselfly and the diagnosis of the Petrolestini. Petrolestes messelensis sp. nov. is described from the Eocene Messel Formation in Germany, extending the distribution of the Petrolestini to the European Eocene. The new damsel-dragonfly family Pseudostenolestidae is described for the new genus and species Pseudostenolestes bechlyi, from the Eocene Messel Formation. It is the first Cenozoic representative of the Mesozoic clade Isophlebioptera.

  3. Palaeotectonic implications of increased late Eocene-early Oligocene volcanism from South Pacific DSDP sites

    USGS Publications Warehouse

    Kennett, J.P.; Von Der Borch, C.; Baker, P.A.; Barton, C.E.; Boersma, A.; Cauler, J.P.; Dudley, W.C.; Gardner, J.V.; Jenkins, D.G.; Lohman, W.H.; Martini, E.; Merrill, R.B.; Morin, R.; Nelson, Campbell S.; Robert, C.; Srinivasan, M.S.; Stein, R.; Takeuchi, A.; Murphy, M.G.

    1985-01-01

    Late Eocene-early Oligocene (42-35 Myr) sediments cored at two DSDP sites in the south-west Pacific contain evidence of a pronounced increase in local volcanic activity, particularly in close association with the Eocene-Oligocene boundary. This pulse of volcanism is coeval with that in New Zealand and resulted from the development of an Indo- Australian / Pacific Plate boundary through the region during the late Eocene. The late Eocene / earliest Oligocene was marked by widespread volcanism and tectonism throughout the Pacific and elsewhere, and by one of the most important episodes of Cenozoic climatic cooling. ?? 1985 Nature Publishing Group.

  4. Eocene to Miocene biostratigraphy of New Jersey core ACGS #4; implications for regional stratigraphy

    USGS Publications Warehouse

    Poore, Richard Z.; Bybell, Laurel M.

    1988-01-01

    A time versus depth plot controlled primarily by nannofossil zone boundaries shows that sediment accumulation rates during the early and middle Eocene were in the range of 6 to 15 feet per million years. During the late Eocene, accumulation rates were much higher, perhaps exceeding 70 feet per million years. The only clear hiatus detected in the Paleogene part of ACGS #4 on the basis of microfossils is between the early and (?)late Oligocene. However, hiatuses are suspected at the early-middle Eocene boundary and within the late Eocene. Occurrences of calcareous nannofossils and planktic foraminifers are documented, and a number of key taxa are illustrated.

  5. Rain underscores need for injection

    SciTech Connect

    Stelling, K.F.

    1996-01-01

    Since 1987, steam production totals at The Geysers Geothermal field have fallen and water injection totals have remained quite stable, except for the unusually dry winter months of 1994 when injection fell by a record amount. The heavy rainfall in the first half of 1995 altered the long-term production and injection patterns and underscored the need to increase injection in the field. From January to June 1995, steam production at The Geysers was reduced by 37 percent form the amount produced during the same period in 1994--because the rain increased availability of hydroelectric power. At the same time, water injection in the field rose by 25 percent because more rainwater was available for injection. Consequently, both reservoir pressure and available steam reserves grew, and most power plants that returned on line in the second half of the year produced more megawatts with less steam. This confirmed findings form several injection studies at The Geyser`s.

  6. Desert Dust and Monsoon Rain

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, Kyu-Myong

    2014-01-01

    For centuries, inhabitants of the Indian subcontinent have know that heavy dust events brought on by strong winds occur frequently in the pre-monsoon season, before the onset of heavy rain. Yet scientists have never seriously considered the possibility that natural dust can affect monsoon rainfall. Up to now, most studies of the impacts of aerosols on Indian monsoon rainfall have focused on anthropogenic aerosols in the context of climate change. However, a few recent studies have show that aerosols from antropogenic and natural sources over the Indian subcontinent may affect the transition from break to active monsoon phases on short timescales of days to weeks. Writing in Nature Geoscience, Vinoj and colleagues describe how they have shown that desert dust aerosols over the Arabian Sea and West Asia can strenghten the summer monsoon over the Indial subcontinent in a matter of days.

  7. Nighttime ionospheric D region: Equatorial and nonequatorial

    NASA Astrophysics Data System (ADS)

    Thomson, Neil R.; McRae, Wayne M.

    2009-08-01

    Nighttime ionospheric D region parameters are found to be generally well modeled by the traditional H‧ and β as used by Wait and by the U.S. Navy in their Earth-ionosphere VLF radio waveguide programs. New comparisons with nonequatorial, mainly all-sea VLF path observations reported over several decades are shown to be consistent with the previously determined height H‧ ˜ 85.0 km and sharpness β ˜ 0.63 km-1. These paths include NPM (Hawaii) to Washington, D. C., Omega Hawaii and NLK (Seattle) to Japan, NWC (N.W. Australia) to Madagascar, and NBA (Panama) to Colorado. In marked contrast, transequatorial path observations (even when nearly all-sea) are found to be often not well modeled: for example, for Omega Japan and JJI (Japan) to Dunedin, New Zealand, the observed amplitudes are markedly lower than those which would be expected from H‧ ˜ 85.0 km and β ˜ 0.63 km-1, or any other realistic values of H‧ and β. Other transequatorial observations compared with modeling include NWC to Japan, Omega Hawaii to Dunedin, and NPM (Hawaii) to Dunedin. It is suggested that the effects of irregularities in the equatorial electrojet may extend down into the nighttime D region and so account for the observed equatorial VLF perturbations through scattering or mode conversion.

  8. Topside sounder observations of equatorial bubbles

    NASA Technical Reports Server (NTRS)

    Dyson, P. L.; Benson, R. F.

    1978-01-01

    Large scale regions of depleted equatorial ionospheric plasma, called equatorial bubbles, are investigated using topside sounder data. The sounder's unique remote measuring capability enables the magnetic field-aligned nature of the bubbles to be investigated. A search of all available Alouette 2 and ISIS 1 ionograms during nighttime perigee passes near the magnetic equator has revealed a variety of echo signatures associated with bubbles. In addition to a sudden drop in electron density, these signatures usually include in situ spread F and ducted traces. The ducted traces have been used to determine the electron density distribution and to infer changes in ion composition along the magnetic field line within the duct associated with the bubble. In some cases it can be determined that the bubble is asymmetric with respect to the magnetic equator. Even though such features require 3 dimensional models for their explanation, the great field-aligned extent of the bubbles (relative to their cross section) suggests that current theories, which ignore variations along the magnetic field, are still applicable.

  9. Fading of Jupiter's South Equatorial Belt

    NASA Technical Reports Server (NTRS)

    Sola, Michael A.; Orton, Glenn; Baines, Kevin; Yanamandra-Fisher, Padma

    2011-01-01

    One of Jupiter's most dominant features, the South Equatorial Belt, has historically gone through a "fading" cycle. The usual dark, brownish clouds turn white, and after a period of time, the region returns to its normal color. Understanding this phenomenon, the latest occurring in 2010, will increase our knowledge of planetary atmospheres. Using the near infrared camera, NSFCAM2, at NASA's Infrared Telescope Facility in Hawaii, images were taken of Jupiter accompanied by data describing the circumstances of each observation. These images are then processed and reduced through an IDL program. By scanning the central meridian of the planet, graphs were produced plotting the average values across the central meridian, which are used to find variations in the region of interest. Calculations using Albert4, a FORTRAN program that calculates the upwelling reflected sunlight from a designated cloud model, can be used to determine the effects of a model atmosphere due to various absorption, scattering, and emission processes. Spectra that were produced show ammonia bands in the South Equatorial Belt. So far, we can deduce from this information that an upwelling of ammonia particles caused a cloud layer to cover up the region. Further investigations using Albert4 and other models will help us to constrain better the chemical make up of the cloud and its location in the atmosphere.

  10. Gravity Wave Seeding of Equatorial Plasma Bubbles

    NASA Technical Reports Server (NTRS)

    Singh, Sardul; Johnson, F. S.; Power, R. A.

    1997-01-01

    Some examples from the Atmosphere Explorer E data showing plasma bubble development from wavy ion density structures in the bottomside F layer are described. The wavy structures mostly had east-west wavelengths of 150-800 km, in one example it was about 3000 km. The ionization troughs in the wavy structures later broke up into either a multiple-bubble patch or a single bubble, depending upon whether, in the precursor wavy structure, shorter wavelengths were superimposed on the larger scale wavelengths. In the multiple bubble patches, intrabubble spacings vaned from 55 km to 140 km. In a fully developed equatorial spread F case, east-west wavelengths from 690 km down to about 0.5 km were present simultaneously. The spacings between bubble patches or between bubbles in a patch appear to be determined by the wavelengths present in the precursor wave structure. In some cases, deeper bubbles developed on the western edge of a bubble patch, suggesting an east-west asymmetry. Simultaneous horizontal neutral wind measurements showed wavelike perturbations that were closely associated with perturbations in the plasma horizontal drift velocity. We argue that the wave structures observed here that served as the initial seed ion density perturbations were caused by gravity waves, strengthening the view that gravity waves seed equatorial spread F irregularities.

  11. Central Equatorial Pacific Experiment (CEPEX). Design document

    SciTech Connect

    Not Available

    1993-04-01

    The Earth`s climate has varied significantly in the past, yet climate records reveal that in the tropics, sea surface temperatures seem to have been remarkably stable, varying by less than a few degrees Celsius over geologic time. Today, the large warm pool of the western Pacific shows similar characteristics. Its surface temperature always exceeds 27{degree}C, but never 31{degree}C. Heightened interest in this observation has been stimulated by questions of global climate change and the exploration of stabilizing climate feedback processes. Efforts to understand the observed weak sensitivity of tropical sea surface temperatures to climate forcing has led to a number of competing ideas about the nature of this apparent thermostat. Although there remains disagreement on the processes that regulate tropical sea surface temperature, most agree that further progress in resolving these differences requires comprehensive field observations of three-dimensional water vapor concentrations, solar and infrared radiative fluxes, surface fluxes of heat and water vapor, and cloud microphysical properties. This document describes the Central Equatorial Pacific Experiment (CEPEX) plan to collect such observations over the central equatorial Pacific Ocean during March of 1993.

  12. GREEN INFRASTRUCTURE RESEARCH PROGRAM: Rain Gardens

    EPA Science Inventory

    the National Risk Management Research Laboratory (NRMRL) rain garden evaluation is part of a larger collection of long-term research that evaluates a variety of stormwater management practices. The U.S. EPA recognizes the potential of rain gardens as a green infrastructure manag...

  13. Rain garden guidelines for southwest Ohio

    EPA Science Inventory

    Rain gardens are a unique and practical landscape feature that can enhance the beauty of home gardens. When properly installed, they are one method of limiting the negative effects of rainfall runoff in urban areas. Indeed, rain gardens turn a "negative" into a "positive" by capt...

  14. Acid Rain Students Do Original Research.

    ERIC Educational Resources Information Center

    Outdoor Communicator, 1984

    1984-01-01

    At Park Senior High School (Cottage Grove, Minnesota), 46 juniors and seniors planted 384 red pine seedlings in connection with their original research on acid rain, with advice from Dr. Harriet Stubbs, director of the Acid Precipitation Awareness Program (West Saint Paul), which has been developing acid rain teaching materials. (MH)

  15. Acid Rain: Activities for Science Teachers.

    ERIC Educational Resources Information Center

    Johnson, Eric; And Others

    1983-01-01

    Seven complete secondary/college level acid rain activities are provided. Activities include overview; background information and societal implications; major concepts; student objectives; vocabulary/material lists; procedures; instructional strategies; and questions/discussion and extension suggestions. Activities consider effects of acid rain on…

  16. Acid Rain. LC Science Tracer Bullet.

    ERIC Educational Resources Information Center

    Hollmann, Pauline, Comp.

    The term "acid rain," also called "acid precipitation," generally refers to any precipitation having a pH value of less than 5.6. This guide to the literature on acid rain in the collections of the Library of Congress is not necessarily intended to be a comprehensive bibliography. It is designed to provide the reader with a set of resources that…

  17. Human Ecology: Acid Rain and Public Policy.

    ERIC Educational Resources Information Center

    Bybee, Rodger W.

    1983-01-01

    A connection between science and society can be seen in the human and ecological dimensions of one contemporary problem: acid rain. Introduces a human ecological theme and relationships between acid rain and public policy, considering scientific understanding and public awareness, scientific research and public policy, and national politics and…

  18. Rainy Day Fun: Rain-Inspired Activities.

    ERIC Educational Resources Information Center

    Stanger, Annie Moretz

    1999-01-01

    Rainy days are opportunities to teach campers about weather and to plan activities around a rain theme. Indoor and outdoor science-based activities concerned with rain, water, or water conservation are suggested for specific age groups from ages 5-7 through 11-14. Campers can also develop ideas for activities using questions provided. (CDS)

  19. Acid Thunder: Acid Rain and Ancient Mesoamerica

    ERIC Educational Resources Information Center

    Kahl, Jonathan D. W.; Berg, Craig A.

    2006-01-01

    Much of Mesoamerica's rich cultural heritage is slowly eroding because of acid rain. Just as water dissolves an Alka-Seltzer tablet, acid rain erodes the limestone surfaces of Mexican archaeological sites at a rate of about one-half millimeter per century (Bravo et al. 2003). A half-millimeter may not seem like much, but at this pace, a few…

  20. Acid rain and pollen germination in corn.

    PubMed

    Wertheim, F S; Craker, L E

    1987-01-01

    The properties of an acid rain episode that could influence the germination of pollen in corn, Zea mays L., were evaluated by treating silks with a simulated acid rain and measuring the subsequent germination of pollen on the silks. The data indicated that acid rain creates an inhospitable environment for pollen germination on the silk surface. Reduced germination appeared directly related to the acidity of the rain, but not the sulphate concentration. Rinsing silks with a pH 5.6 rain after treatment with a pH 2.6 rain did not increase pollen germination above that on silks treated only with a pH 2.6 rain, suggesting the reduced germination was due to physical and/or chemical modifications of the silk surface and not to residual acid on the tissue. Pollen germination on silks was inhibited even when silk tissue was exposed to a simulated rain of pH 2.6 for <1.5min.

  1. Environmental Education about the Rain Forest.

    ERIC Educational Resources Information Center

    Berkmuller, Klaus

    Designed to help in the development of an educational program about the value of rain forests, this handbook presents a condensation of issues, facts, and concepts. The handbook is divided into three parts. Part one introduces the rain forest ecosystem and provides conceptual background material needed in the determination of problems, the…

  2. New palynology-based astronomical and revised 40Ar/39Ar ages for the Eocene maar lake of Messel (Germany)

    NASA Astrophysics Data System (ADS)

    Lenz, Olaf K.; Wilde, Volker; Mertz, Dieter F.; Riegel, Walter

    2015-04-01

    The annually laminated oil shale from the Eocene maar lake at Messel (Federal State of Hessen, Germany) provides unique paleoenvironmental data for a time interval of ~640 ka during the Paleogene greenhouse phase. As a consequence of orbitally controlled changes in the vegetation in the vicinity of the lake, the lacustrine laminites can now be astronomically tuned. Dating is based on the short eccentricity amplitude modulations of the regional pollen rain and their correlation to the astronomical La2010a/La2010d solutions in combination with a revised 40Ar/39Ar age of a basalt fragment from a lapilli tuff section below the first lacustrine sediments. Depending on different newly suggested ages for the Fish Canyon sanidine used as monitor for neutron irradiation, the age for the eruption at Messel is between 48.27 ± 0.22 and 48.11 ± 0.22 Ma. This allows for the first time the exact correlation of a Paleogene lacustrine sequence to the marine record in Central Europe. The Messel oil shale becomes now slightly older than previously assumed and includes the Ypresian/Lutetian boundary that moves the base of the European Land Mammal Age Geiseltalian (MP 11) into the Lower Eocene. This opens a window for establishing an independent chronostratigraphic framework for Paleogene terrestrial records and their correlation to the marine realm. Furthermore, the study reveals that higher amounts of pollen from "wet" and thermophilous plants indicate less seasonal and more balanced precipitation and slightly higher temperatures during a well-expressed eccentricity minimum.

  3. Scale Dependence of Spatiotemporal Intermittence of Rain

    NASA Technical Reports Server (NTRS)

    Kundu, Prasun K.; Siddani, Ravi K.

    2011-01-01

    It is a common experience that rainfall is intermittent in space and time. This is reflected by the fact that the statistics of area- and/or time-averaged rain rate is described by a mixed distribution with a nonzero probability of having a sharp value zero. In this paper we have explored the dependence of the probability of zero rain on the averaging space and time scales in large multiyear data sets based on radar and rain gauge observations. A stretched exponential fannula fits the observed scale dependence of the zero-rain probability. The proposed formula makes it apparent that the space-time support of the rain field is not quite a set of measure zero as is sometimes supposed. We also give an ex.planation of the observed behavior in tenus of a simple probabilistic model based on the premise that rainfall process has an intrinsic memory.

  4. Acid rain in Laos and Thailand.

    PubMed

    Halpern, M

    1996-09-01

    Acid rain has an impact on forestry and human health. Forest degradation was noticed in the early 90's in Laos, a country without polluting industries nor intense automobile traffic. Therefore, in 1993-1994, we collected rain in one location in Thailand (Bangkok) and 4 in Laos (Luang Prabang, Vientiane, Savannaketh, Pakse); measured pH in each sample and resistivity in 2 locations. We obtained sequential meteorological satellite pictures showing the far motion of clouds, their location and course, and ultimately rain over Indochina. We conclude that acid rain forms over Thailand and falls in Laos (Vientiane, Pakse). We also measured peak flows in large groups of children, adults both non-smokers and chronic heavy smokers, in all five locations. Except for a small number of individual variations, we could not correlate the presence of acid rain and deterioration of pulmonary function in these subjects. However, we recommend active measures to curb pollution both in Thailand and Laos.

  5. Acid Rain: A Teaching Focus for the Intermediate Grades.

    ERIC Educational Resources Information Center

    Adams, Renee B.; Adams, Neil D.

    1992-01-01

    The study of acid rain provides ample opportunities for active, interdisciplinary learning. This article describes 12 hands-on activities designed to expand students' understanding of acid rain. Background information on acid rain is included. (LB)

  6. Phytochelatin concentrations in the equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Ahner, Beth A.; Lee, Jennifer G.; Price, Neil M.; Morel, François M. M.

    1998-11-01

    Phytochelatin, an intracellular metal-binding polypeptide synthesized in eucaryotic algae in response to metals such as Cd and Cu, was measured in particulate samples collected from the equatorial Pacific. The concentrations in these samples (normalized to total particulate chl a) were unexpectedly high compared to laboratory culture data and were on average slightly more than in coastal areas where the metal concentrations are typically much greater. In part, the high field concentrations can be explained by the low cellular concentrations of chlorophyll a resulting from very low ambient Fe, but laboratory experiments provide a possible explanation for the rest of the difference. At low concentrations of inorganic Cd (Cd'=3 pM), increasing amounts of phytochelatin were induced by decreasing Zn concentrations in the culture medium of two diatoms: Thalassiosira weissflogii, a coastal species, and T. parthenaia, an isolate from the equatorial Pacific. In all previous studies, phytochelatin production has been directly correlated with increasing metal concentrations. Decreasing Co also resulted in higher phytochelatin concentrations in T. weissflogii and Emiliania huxleyi. Replicating the field concentrations of Zn, Co, and Cd in the laboratory results in cellular concentrations (amol -1 cell) that are very similar to those estimated for the field. Contrary to the expectation that high metal concentrations in the equatorial upwelling would cause elevated phytochelatin concentrations, there was no increase in phytochelatin concentrations from 20° S to 10° N—near surface samples were roughly the same at all stations. Also, most of the depth profiles had a distinct subsurface maximum. Neither of these features is readily explained by the available Zn and Cd data. Incubations with additions of Cd and Cu performed on water sampled at four separate stations induced significantly higher concentrations of phytochelatins than those in controls in a majority of the samples

  7. The Eastern Equatorial Pacific Chlorophyll Dynamics: Update of the `Equatorial Box' Project

    NASA Astrophysics Data System (ADS)

    Westberry, T.; Wang, X.; Murtugudde, R.; Behrenfeld, M.; Roesler, C.

    2006-12-01

    The `Equatorial Box' Project utilizes the mooring observations along the 125 and 140 TAO lines to provide carbon component data, including chlorophyll, primary production, POC and DOC. These parameters together with other oceanographic properties can be used to validate ocean circulation-ecosystem models. In turn, a validated model can offer considerable promise for not only filling the gaps in the spatial and temporal coverage from the available observations, but also enhancing our understanding of the mechanisms underlying the variability. Here, we present both measured and simulated vertical-meridional chlorophyll distributions and primary production along 125W and 140W. While there is a permanent layer of deep chlorophyll maximum at 30-60 m, there is no deep maximum in phytoplankton carbon biomass or primary production. Our analyses focus on impact of nutrient stress and light conditions on chlorophyll dynamics in the eastern equatorial Pacific. We also compare modeled primary productivity with ocean color derived rates.

  8. Alkylmercury species in the equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Mason, R. P.; Fitzgerald, W. F.

    1990-10-01

    HIGH levels of mercury in piscivorous fish constitute a long-standing health hazard1-6. Monomethyl mercury, the main form of mercury in fish, is more toxic than inorganic mercury. But although something is known of the ability of organisms to methylate mercury7,8, the sources, synthesis and fate of methyl mercury in aquatic waters are not well understood. Inorganic and alkylated mercury has been studied in natural waters9-11, precipitation and the atmosphere12,13. We now report evidence of monomethyl and dimethyl mercury in the low-oxygen waters of the equatorial Pacific. The presence of these species has important implications for our understanding of the biogeochemical cycling of mercury in the marine environment. Although the source of monomethyl mercury in open-ocean fish is still unknown, our data show that a pathway exists for the accumulation of methylated mercury in marine pelagic fish.

  9. Three dimensional Visualization of Jupiter's Equatorial Region

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

    This frame is a view to the west, from between the cloud layers and over the patchy white clouds to the east of the hotspot. This is probably an area where moist convection is occurring over large horizontal distances, similar to the atmosphere over the equatorial ocean on Earth. The clouds are high and thick, and are observed to change rapidly over short time scales.

    Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

    The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756

  10. Interior models of Mercury with equatorial ellipticity

    NASA Astrophysics Data System (ADS)

    Dumberry, M.

    2012-09-01

    The combination of planetary rotation observations and gravity field measurements by the MESSENGER spacecraft can be used to constrain the internal structure of Mercury. A recently published model suggests a mean mantle density of ρm = 3650 ± 225 kg m-3, substantially larger than that expected of a silicate mantle (3300 kg m-3) and possibly hinting at the presence of an FeS-rich layer at the base of the mantle. Here, we show that a large ρm is only required if the core-mantle boundary (CMB) of the planet is assumed axially-symmetric. An equatorial ellipticity of CMB of the order of 2 · 10-5 allows to satisfy gravity and rotation constraints with a mean mantle density typical of silicate material. Possible origin of such topography include past mantle convection, aspherical planetary shrinking, remnant tidal deformation, or a combination thereof.

  11. Dynamical variability in Saturn Equatorial Atmosphere

    NASA Astrophysics Data System (ADS)

    Sánchez-Lavega, A.; Pérez-Hoyos, S.; Hueso, R.; Rojas, J. F.; French, R. G.; Grupo Ciencias Planetarias Team

    2003-05-01

    Historical ground-based and recent HST observations show that Saturn's Equatorial Atmosphere is the region where the most intense large-scale dynamical variability took place at cloud level in the planet. Large-scale convective storms (nicknamed the ``Great White Spots") occurred in 1876, 1933 and 1990. The best studied case (the 1990 storm), produced a dramatic change in the cloud aspect in the years following the outburst of September 1990. Subsequently, a new large storm formed in 1994 and from 1996 to 2002 our HST observations showed periods of unusual cloud activity in the southern part of the Equator. This contrast with the aspect observed during the Voyager 1 and 2 encounters in 1980 and 1981 when the Equator was calm, except for some mid-scale plume-like features seen in 1981. Cloud-tracking of the features have revealed a dramatic slow down in the equatorial winds from maximum velocities of ˜ 475 m/s in 1980-1981 to ˜ 275 m/s during 1996-2002, as we have recently reported in Nature, Vol. 423, 623 (2003). We discuss the possibility that seasonal and ring-shadowing effects are involved in generating this activity and variability. Acknowledgements: This work was supported by the Spanish MCYT PNAYA 2000-0932. SPH acknowledges a PhD fellowship from the Spanish MECD and RH a post-doc fellowship from Gobierno Vasco. RGF was supported in part by NASA's Planetary Geology and Geophysics Program NAG5-10197 and STSCI Grant GO-08660.01A.

  12. Climatic trends of the equatorial undercurrent: A backup mechanism for sustaining the equatorial Pacific production

    NASA Astrophysics Data System (ADS)

    Ruggio, Raffaele; Vichi, Marcello; Paparella, Francesco; Masina, Simona

    2013-07-01

    The Equatorial Undercurrent (EUC) is the major source of iron to the equatorial Pacific and it is sensitive to climatic changes as other components of the tropical Pacific. This work proposes a methodology based on a Lagrangian approach aimed at understanding the changes in the transport of iron rich waters to the EUC in a future climate change scenario, using climate model data from an Earth system model. A selected set of regions from the northern and southern extra-equatorial Pacific has been chosen. These regions are characterized by the presence of iron sources from continental shelf processes like the Papua New Guinea region and atmospheric deposition like the northern subtropical gyre. The trajectories that reach the EUC during the 20th and the 21st century departing from these areas have been analyzed using a set of statistics designed to determine variations in the amount of transport and in the travel times of the water masses. The transport of waters to the EUC from the north Pacific subtropical gyre and from the Bismarck Sea is projected to increase during the 21st century. The increase is particularly significant for water masses from the northern subtropical gyre, with travel times lower than 10 years in the second half of the 21st century. This increased interaction between the extra-tropics and the EUC may bring additional iron-rich waters in the high-nutrient low-chlorophyll region of the equatorial Pacific compatibly with the significant increase of the simulated net primary production found in the biogeochemical model, thus partly offsetting the anticipated decrease of production implied by the surface warming.

  13. Comet or asteroid shower in the late Eocene?

    PubMed

    Tagle, Roald; Claeys, Philippe

    2004-07-23

    The passage of a comet shower approximately 35 million years ago is generally advocated to explain the coincidence during Earth's late Eocene of an unusually high flux of interplanetary dust particles and the formation of the two largest craters in the Cenozoic, Popigai and the Chesapeake Bay. However, new platinum-group element analyses indicate that Popigai was formed by the impact of an L-chondrite meteorite. Such an asteroidal projectile is difficult to reconcile with a cometary origin. Perhaps instead the higher delivery rate of extraterrestrial matter, dust, and large objects was caused by a major collision in the asteroid belt. PMID:15273387

  14. Exploring Terrestrial Temperature Changes during the Early Eocene Hyperthermals

    NASA Astrophysics Data System (ADS)

    Snell, K. E.; Clyde, W. C.; Fricke, H. C.; Eiler, J. M.

    2012-12-01

    The Early Eocene is marked by a number of rapid global warming events called hyperthermals. These hyperthermals are associated with negative carbon isotope excursions (CIE) in both marine and terrestrial records. Multiple theories exist to explain the connection of these hyperthermals with the CIEs and each theory predicts different responses by the climate system. Characterizing the timing, duration and magnitude of temperature change that is associated with these hyperthermals is important for determining whether the hyperthermals are all driven by the same underlying climate dynamics or perhaps differ from one another in cause and climatic consequences. In the simplest case, all share a common underlying mechanism; this predicts that the associated temperature changes scale in a predictable way with the magnitude of the CIE (and perhaps exhibit other similarities, such as the relative amplitudes of marine and terrestrial temperature change). To our knowledge, however, the only hyperthermal with paleotemperature data from land is the Paleocene-Eocene Thermal Maximum (PETM). Here we present preliminary carbonate clumped isotope paleotemperature estimates for Early Eocene hyperthermal ETM2/H2 from paleosol carbonates from the Bighorn Basin in Wyoming, USA. We compare the results to existing clumped isotope paleotemperature estimates for the PETM in the Bighorn Basin. Temperatures recorded by paleosol carbonates (which likely reflect near-peak summer ground temperatures) prior to each CIE are ~30°C and increase to ~40-43°C during the apex of each CIE. Following both CIEs, temperatures drop back to pre-CIE values. In the case of ETM2/H2, temperatures begin to rise again immediately, possibly in association with a later hyperthermal, though further work needs to be done to establish this with certainty. These preliminary data suggest that both the absolute values and the magnitudes of temperature changes associated with the PETM and ETM2/H2 are similar; the

  15. Comet or asteroid shower in the late Eocene?

    PubMed

    Tagle, Roald; Claeys, Philippe

    2004-07-23

    The passage of a comet shower approximately 35 million years ago is generally advocated to explain the coincidence during Earth's late Eocene of an unusually high flux of interplanetary dust particles and the formation of the two largest craters in the Cenozoic, Popigai and the Chesapeake Bay. However, new platinum-group element analyses indicate that Popigai was formed by the impact of an L-chondrite meteorite. Such an asteroidal projectile is difficult to reconcile with a cometary origin. Perhaps instead the higher delivery rate of extraterrestrial matter, dust, and large objects was caused by a major collision in the asteroid belt.

  16. Acid rain and drinking water degradation.

    PubMed

    Middleton, P; Rhodes, S L

    1984-03-01

    Acid deposition-induced drinking water degradation is discussed with respect to the geographical extent of and the potential for dealing with possibly adverse human health impacts. Qualitative evidence from the northeastern United States and Sweden strongly suggests the existence of a linkage between these two environmental concerns. It is argued that water treatment and reduction of acid rain as solutions to the problem of water toxicity need closer evaluation. More research into the causal link is warranted since the addition of human health impacts to acid rain's environmental insults could have a significant bearing on discussions relating to acid rain controls.

  17. Acid rain: dousing community resources

    SciTech Connect

    Anderberg, K.

    1985-02-01

    While almost everyone agrees that there is a problem regarding acid rain, the differences occur in whether to implement control measures now, or wait for several more years of study to be completed. Most observers are convinced that coal-burning power plants are the major contributors to the problem. In the West, large smelter operations are also identified as sources. Usually, the areas affected are far removed from the actual source. Northeastern states have perhaps the greatest concern about acid precipitation's effect on water quality, since water distribution systems in this region often have been in place for decades and lead piping is far from uncommon. Combined with the historically corrosive nature of the region's water sources and the low buffering capacity of the soil acid precipitation is cited by many experts as an added burden impacting water quality. The challenge to water system operators focuses on the corrosive water's effect on the distribution system. Treatment can be very expensive, but must be addressed. Only 25% of the water systems in New England currently treat water for corrosivity. The most effective method of protecting consumers from corrosive water and associated contaminants is through corrosion control at the treatment plant. Large-scale plans for sulfur emission control still seem to be a long way off. 2 figures.

  18. Mass-movement deposits in the lacustrine Eocene Green River Formation, Piceance Basin, western Colorado

    USGS Publications Warehouse

    Johnson, Ronald C.; Birdwell, Justin E.; Brownfield, Michael E.; Mercier, Tracey J.

    2015-01-01

    The Eocene Green River Formation was deposited in two large Eocene saline lakes, Lake Uinta in the Uinta and Piceance Basins and Lake Gosiute in the Greater Green River Basin. Here we will discuss mass-movement deposits in just the Piceance Basin part of Lake Uinta.

  19. The oldest accurate record of Scenopinidae in the Lowermost Eocene amber of France (Diptera: Brachycera).

    PubMed

    Garrouste, Romain; Azar, Dany; Nel, Andre

    2016-01-01

    Eocenotrichia magnifica gen. et sp. nov. (Diptera: Scenopinidae: Metatrichini) is described and illustrated from the Lowermost Eocene amber of Oise (France) and represents the oldest definitive window fly fossil. The present discovery in the Earliest Eocene supports the Late Cretaceous-Paleocene age currently proposed for the emergence of Metatrichini. PMID:27394507

  20. Provenance of the Eocene Soebi Blanco formation, Bonaire, Leeward Antilles: Correlations with post-Eocene tectonic evolution of northern South America

    NASA Astrophysics Data System (ADS)

    Zapata, S.; Cardona, A.; Montes, C.; Valencia, V.; Vervoort, J.; Reiners, P.

    2014-07-01

    Middle to upper Eocene fluvial strata in the island of Bonaire contain detrital components that were tracked to Precambrian to Triassic massifs in northern Colombia and Venezuela. These detrital components confirm previous hypothesis suggesting that Bonaire and the Leeward Antilles were attached to South American basement massifs (SABM). These are composed of different fragmented South American blocks (Paraguana, Falcon, Maracaibo, Guajira, Perija, and Santa Marta) representing an Eocene, right-laterally displaced tectonic piercing point along the southern Caribbean plate margin. U-Pb LA-ICP-MS from the metamorphic boulders of the Soebi Blanco Formation in Bonaire yield Grenvillian peaks ages (1000-1200 Ma), while detrital zircons recovered from the sandy matrix of the conglomerates contain populations with peaks of 1000 Ma-1200 Ma, 750-950 Ma, and 200-300 Ma. These populations match with geochronological data reported for the northern South American massifs. Thermochronological results from the metamorphic clasts yield Paleocene-middle Eocene ages (65-50 Ma) that confirm a regional-scale cooling event in this time. These data imply a land connection between the SABM and the Leeward Antilles in late Eocene times, followed by a significant strike slip right-lateral displacement and transtensional basin opening starting in latest Eocene times. The succession of Eocene tectonic events recorded by the Soebi Blanco Formation and adjacent basins is a major tracer of the oblique convergence of the Caribbean plate against the South American margin.

  1. Air pollution, acid rain and the environment

    SciTech Connect

    Mellanby, K.

    1988-01-01

    This book reports on the Watt Committee's working group on acid rain, which was set up in 1981. The authors consider the relationship between natural and the man-made factors and the effects of possible remedial strategies. In the first phase of the study, the group looked at the fate of airborne pollution, vegetation and soils, freshwater and remedial strategy. In this report, which contains the results of a further phase of study, these topics are included and have been brought up to date. The scope of the report is extended to include buildings and non-living materials. Consideration is given to the problem of acid rain and air pollution worldwide. Emphasis is placed on the United Kingdom. The main conclusion is that more research is necessary on some aspects of acid rain and air pollution, but that some of the reports widespread damage caused by acid rain cannot be confirmed.

  2. TECHNOLOGICAL OPTIONS FOR ACID RAIN CONTROL

    EPA Science Inventory

    Discussed are acid rain control options available to the electric utility industry. They include coal switching, flue gas desulfurization, and such emerging lower cost technologies as Limestone Injection Multistage Burners (LIMB) and Advanced Silicate (ADVACATE), both developed ...

  3. Early Eocene cyclicity at the Wilkes Land Margin, Antarctica: Orbital forcing and environmental response

    NASA Astrophysics Data System (ADS)

    Roehl, U.; Bijl, P.; Jiménez, F.; Pross, J.; Contreras, L.; Tauxe, L.; Bohaty, S. M.; Bendle, J.; Brinkhuis, H.; IODP Expedition 318 Scientists

    2011-12-01

    The early Eocene Greenhouse interval (~56-49 Ma) was punctuated by multiple transient global warming events, or hyperthermals - the most prominent of which was the Paleocene-Eocene Thermal Maximum (PETM). Additional thermal maxima identified in Eocene records exhibit negative carbon isotope excursions (CIEs), carbonate dissolution horizons, and biotic perturbations, although of reduced magnitude and duration relative to the PETM. Many hyperthermals have been identified or postulated in the early Eocene, but it is unclear which of these events are normal carbon-cycle variations that occurred at orbital frequencies and which are exceptional events outside the normal range of Eocene carbon-cycle variability. Here we present a high-resolution cyclostratigraphy for a new early Eocene drillcore from the Wilkes Land Margin in direct proximity to the Antarctic continent (Site U1356 drilled during IODP Expedition 318). Site U1356 was situated in a mid-shelf setting during the early Eocene and is characterized by a superb magnetostratigraphy and a robust biostratigraphic age control. Our investigation includes XRF core scanning and ICP-MS data as well as bulk organic carbon isotope ratios (delta13Corg) in combination with the concentration of the total organic carbon (TOC). The early Eocene at Site U1356 consists of well developed cyclic claystones including the interval of magnetochron C24 which is ideal to re-evaluate the early Eocene part of the Geomagnetic Polarity Time Scale (GPTS) and to provide new insights into the environmental responses as well as orbital configuration of early Eocene climatic cycles.

  4. Simulating Rain Fade In A Communication System

    NASA Technical Reports Server (NTRS)

    Shalkhauser, Kurt A.; Nagy, Lawrence A.; Svoboda, James K.

    1994-01-01

    Automated, computer-controlled assembly of electronic equipment developed for use in simulation testing of downlink portion of Earth/satellite microwave digital communication system. Designed to show effects upon performance of system of rain-induced fading in received signal and increases in transmitted power meant to compensate for rain-induced fading. Design of communication system improved iteratively in response to results of simulations, leading eventually to design ensuring clear, uninterrupted transmission of digital signals.

  5. Capabilities for research on acid rain

    SciTech Connect

    Manowitz, B.

    1981-05-01

    Acid rain studies at Brookhaven National Laboratory (BNL) are conducted within the Department of Energy and Environment, in the divisions of Atmospheric Sciences, Environmental Chemistry, Land and Freshwater Environmental Sciences, and Biomedical and Environmental Assessment of the National Center for the Analysis of Energy Systems. The capabilities and ongoing activities of each of these organizations which relate to the acid rain problem are summarized here.

  6. NASA's DC-8 With Rain Mapping Radar

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In a joint venture between NASA and Japan's NASDA, scientists have been using satellites, airplanes, and boats to measure rain physics in and under thunderstorms over open water. This Quick Time movie shows NASA's DC-8 jet with the instruments like the airborne rain mapping radar, i.e., the Advanced Microwave Precipitation Radiometer (AMPR) and a lightening imaging sensor. Earth science and weather studies are an important ongoing function of NASA and its affiliates.

  7. Foraminiferal repopulation of the late Eocene Chesapeake Bay impact crater

    USGS Publications Warehouse

    Poag, C. Wylie

    2012-01-01

    The Chickahominy Formation is the initial postimpact deposit in the 85km-diameter Chesapeake Bay impact crater, which is centered under the town of Cape Charles, Virginia, USA. The formation comprises dominantly microfossil-rich, silty, marine clay, which accumulated during the final ~1.6myr of late Eocene time. At cored sites, the Chickahominy Formation is 16.8-93.7m thick, and fills a series of small troughs and subbasins, which subdivide the larger Chickahominy basin. Nine coreholes drilled through the Chickahominy Formation (five inside the crater, two near the crater margin, and two ~3km outside the crater) record the stratigraphic and paleoecologic succession of 301 indigenous species of benthic foraminifera, as well as associated planktonic foraminifera and bolboformids. Two hundred twenty of these benthic species are described herein, and illustrated with scanning electron photomicrographs. Absence of key planktonic foraminiferal and Bolboforma species in early Chickahominy sediments indicates that detrimental effects of the impact also disturbed the upper oceanic water column for at least 80-100kyr postimpact. After an average of ~73kyr of stressed, rapidly fluctuating paleoenvironments, which were destabilized by after-effects of the impact, most of the cored Chickahominy subbasins maintained stable, nutrient-rich, low-oxygen bottom waters and interstitial microhabitats for the remaining ~1.3myr of late Eocene time.

  8. Eocene Podocarpium (Leguminosae) from South China and its biogeographic implications.

    PubMed

    Xu, Qingqing; Qiu, Jue; Zhou, Zhekun; Jin, Jianhua

    2015-01-01

    Podocarpium A. Braun ex Stizenberger is one of the most common legumes in the Neogene of Eurasia, including fossil fruits, seeds, leaves, and possible flower and pollen grains. This genus is not completely consistent with any extant genera according to gross morphological characters and poorly preserved cuticular structures reported in previous studies. The fossil pods collected from the coal-bearing series of the Changchang Basin of Hainan Island and Maoming Basin of Guangdong, South China, are examined by morphologically comparative work, with special reference to venation patterns and placental position. These distinctive features, as well as the ovule development of pods from different developmental stages and the epidermal structure of the pods, as distinguished from previous records lead to the conclusion that these fossils can be recognized as a new species of Podocarpium, P. eocenicum sp. nov. This new discovery indicates that Podocarpium had arrived in South China by the Eocene. Investigation on the fossil records of this extinct genus shows that P. eocenicum is the earliest and lowest latitude fossil data. The possible occurrence pattern of this genus is revealed as follows: Podocarpium had distributed in the South China at least in the middle Eocene, and then migrated to Europe during the Oligocene; in the Miocene this genus reached its peak in Eurasia, spreading extensively across subtropical areas to warm temperate areas; finally, Podocarpium shrank rapidly and became extinct in Eurasia during the Pliocene. PMID:26579179

  9. Eocene Podocarpium (Leguminosae) from South China and its biogeographic implications

    PubMed Central

    Xu, Qingqing; Qiu, Jue; Zhou, Zhekun; Jin, Jianhua

    2015-01-01

    Podocarpium A. Braun ex Stizenberger is one of the most common legumes in the Neogene of Eurasia, including fossil fruits, seeds, leaves, and possible flower and pollen grains. This genus is not completely consistent with any extant genera according to gross morphological characters and poorly preserved cuticular structures reported in previous studies. The fossil pods collected from the coal-bearing series of the Changchang Basin of Hainan Island and Maoming Basin of Guangdong, South China, are examined by morphologically comparative work, with special reference to venation patterns and placental position. These distinctive features, as well as the ovule development of pods from different developmental stages and the epidermal structure of the pods, as distinguished from previous records lead to the conclusion that these fossils can be recognized as a new species of Podocarpium, P. eocenicum sp. nov. This new discovery indicates that Podocarpium had arrived in South China by the Eocene. Investigation on the fossil records of this extinct genus shows that P. eocenicum is the earliest and lowest latitude fossil data. The possible occurrence pattern of this genus is revealed as follows: Podocarpium had distributed in the South China at least in the middle Eocene, and then migrated to Europe during the Oligocene; in the Miocene this genus reached its peak in Eurasia, spreading extensively across subtropical areas to warm temperate areas; finally, Podocarpium shrank rapidly and became extinct in Eurasia during the Pliocene. PMID:26579179

  10. Episodic fresh surface waters in the Eocene Arctic Ocean

    USGS Publications Warehouse

    Brinkhuis, H.; Schouten, S.; Collinson, M.E.; Sluijs, A.; Damste, J.S.S.; Dickens, G.R.; Huber, M.; Cronin, T. M.; Onodera, J.; Takahashi, K.; Bujak, J.P.; Stein, R.; Van Der Burgh, J.; Eldrett, J.S.; Harding, I.C.; Lotter, A.F.; Sangiorgi, F.; Cittert, H.V.K.V.; De Leeuw, J. W.; Matthiessen, J.; Backman, J.; Moran, K.

    2006-01-01

    It has been suggested, on the basis of modern hydrology and fully coupled palaeoclimate simulations, that the warm greenhouse conditions that characterized the early Palaeogene period (55-45 Myr ago) probably induced an intensified hydrological cycle with precipitation exceeding evaporation at high latitudes. Little field evidence, however, has been available to constrain oceanic conditions in the Arctic during this period. Here we analyse Palaeogene sediments obtained during the Arctic Coring Expedition, showing that large quantities of the free-floating fern Azolla grew and reproduced in the Arctic Ocean by the onset of the middle Eocene epoch (???50 Myr ago). The Azolla and accompanying abundant freshwater organic and siliceous microfossils indicate an episodic freshening of Arctic surface waters during an ???800,000-year interval. The abundant remains of Azolla that characterize basal middle Eocene marine deposits of all Nordic seas probably represent transported assemblages resulting from freshwater spills from the Arctic Ocean that reached as far south as the North Sea. The termination of the Azolla phase in the Arctic coincides with a local sea surface temperature rise from ???10??C to 13??C, pointing to simultaneous increases in salt and heat supply owing to the influx of waters from adjacent oceans. We suggest that onset and termination of the Azolla phase depended on the degree of oceanic exchange between Arctic Ocean and adjacent seas. ?? 2006 Nature Publishing Group.

  11. Continental ice in Greenland during the Eocene and Oligocene

    NASA Astrophysics Data System (ADS)

    Eldrett, James S.; Harding, Ian C.; Wilson, Paul A.; Butler, Emily; Roberts, Andrew P.

    2007-03-01

    The Eocene and Oligocene epochs (~55 to 23 million years ago) comprise a critical phase in Earth history. An array of geological records supported by climate modelling indicates a profound shift in global climate during this interval, from a state that was largely free of polar ice caps to one in which ice sheets on Antarctica approached their modern size. However, the early glaciation history of the Northern Hemisphere is a subject of controversy. Here we report stratigraphically extensive ice-rafted debris, including macroscopic dropstones, in late Eocene to early Oligocene sediments from the Norwegian-Greenland Sea that were deposited between about 38 and 30million years ago. Our data indicate sediment rafting by glacial ice, rather than sea ice, and point to East Greenland as the likely source. Records of this type from one site alone cannot be used to determine the extent of ice involved. However, our data suggest the existence of (at least) isolated glaciers on Greenland about 20million years earlier than previously documented, at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher.

  12. Cretaceous to Eocene passive margin sedimentation in Northeastern Venezuela

    SciTech Connect

    Erikson, J.P. )

    1993-02-01

    Twenty two palinspastic paleogeographic maps are presented for the Cretaceous to Eocene strata of the Serrania del Interior of northeastern Venezuela. The mapped lithologies, environmental conditions, and evolving depositional systems record [approximately]90 m.y. of dominantly marine sedimentation on the only observable Mesozoic passive margin in the Western Hemisphere. The depositional systems of the passive margin are heterogeneous at lateral (i.e., along-margin) length scales greater than [approximately]40 km. The primary lateral heterogeneity is caused by a major Lower Cretaceous deltaic system that emanated southwest of the Serrania del Interior. All important intervals, such as the laterally variable Aptian-Albian El Cantil platform limestone and the hydrocarbon source rocks of the Upper Cretaceous Querecual and San Antonio formations, are related to probable causal mechanisms and environmental conditions. Stratigraphic events have been interpreted as of either local or regional extent; based on a combination of outcrop sedimentologic analyses and regional depositional systems interpretation. The 3-dimensional distribution of depositional systems and systems tracts reveals 4-6 regional sequence boundaries separated by 4-20 m.y. Subsidence analyses support the facies interpretation of a passive margin by showing continuous, thermally dominated subsidence during the Cretaceous to Eocene interval. Subsidence and accumulation rates increased and facies changed significantly in the Oligocene, indicating the end of passive margin sedimentation and the initiation of foredeep subsidence and accumulation associated with overthrusting the eastward-advancing Caribbean Plate.

  13. How many upper Eocene microspherule layers: More than we thought

    NASA Technical Reports Server (NTRS)

    Hazel, Joseph E.

    1988-01-01

    The scientific controversy over the origin of upper Eocene tektites, microtektites and other microspherules cannot be logically resolved until it is determined just how many events are involved. The microspherule-bearing beds in marine sediments have been dated using standard biozonal techniques. Although a powerful stratigraphic tool, zonal biostratigraph has its limitations. One is that if an event, such as a microspherule occurrence, is observed to occur in a zone at one locality and then a similar event observed in the same zone at another locality, it still may be unwarranted to conclude that these events exactly correlate. To be in a zone a sample only need be between the fossil events that define the zone boundaries. It is often very difficult to accurately determine where within a zone one might be. Further, the zone defining events do not everywhere occur at the same points in time. That is, the ranges of the defining taxa are not always filled. Thus, the length of time represented by a zone (but not, of course, its chronozone) can vary from place to place. These problems can be offset by use of chronostratigraphic modelling techniques such as Graphic Correlation. This technique was used to build a Cretaceous and Cenozoic model containing fossil, magnetopolarity, and other events. The scale of the model can be demonstrated to be linear with time. This model was used to determine the chronostratigraphic position of upper Eocene microspherule layers.

  14. Eocene Arctic Ocean and earth's Early Cenozoic climate

    SciTech Connect

    Clark, D.L.

    1985-01-01

    Seasonal changes of the Arctic Ocean are an approximate microcosm of the present advanced interglacial climate of the Earth. A similar relationship has existed for several million years but was the Early Cenozoic Arctic Ocean an analog of Earth's climate, as well. Absence of polar ice during the Cretaceous is relatively well established. During the Cenozoic a worldwide decrease in mean annual ocean temperature resulted from such factors as altered oceanic circulation and lower atmospheric CO/sub 2/ levels. Limited Arctic Ocean data for the middle or late Eocene indicate the presence of upwelling conditions and accompanying high productivity of diatoms, ebridians, silicoflagellates and archaeomonads. During this interval, some seasonality is suggested from the varve-like nature of a single sediment core. However, the absence of drop stones or any ice-rafted sediment supports the idea of an open water, ice-free central Arctic Ocean during this time. Latest Cretaceous Arctic Ocean sediment is interpreted to represent approximately the same conditions as those suggested for the Eocene and together with that data suggest that the central Arctic Ocean was ice-free during part if not all of the first 20 my of the Cenozoic. Sediment representing the succeeding 30 my has not been recovered but by latest Miocene or earl Pliocene, ice-rafted sediment was accumulating, both pack ice and icebergs covered the Arctic Ocean reflecting cyclic glacial climate.

  15. A Phororhacoid bird from the Eocene of Africa

    NASA Astrophysics Data System (ADS)

    Mourer-Chauviré, Cécile; Tabuce, Rodolphe; Mahboubi, M'hammed; Adaci, Mohammed; Bensalah, Mustapha

    2011-10-01

    The bird fossil record is globally scarce in Africa. The early Tertiary evolution of terrestrial birds is virtually unknown in that continent. Here, we report on a femur of a large terrestrial new genus discovered from the early or early middle Eocene (between ˜52 and 46 Ma) of south-western Algeria. This femur shows all the morphological features of the Phororhacoidea, the so-called Terror Birds. Most of the phororhacoids were indeed large, or even gigantic, flightless predators or scavengers with no close modern analogs. It is likely that this extinct group originated in South America, where they are known from the late Paleocene to the late Pleistocene (˜59 to 0.01 Ma). The presence of a phororhacoid bird in Africa cannot be explained by a vicariant mechanism because these birds first appeared in South America well after the onset of the mid-Cretaceous Gondwana break up (˜100 million years old). Here, we propose two hypotheses to account for this occurrence, either an early dispersal of small members of this group, which were still able of a limited flight, or a transoceanic migration of flightless birds from South America to Africa during the Paleocene or earliest Eocene. Paleogeographic reconstructions of the South Atlantic Ocean suggest the existence of several islands of considerable size between South America and Africa during the early Tertiary, which could have helped a transatlantic dispersal of phororhacoids.

  16. Continental ice in Greenland during the Eocene and Oligocene.

    PubMed

    Eldrett, James S; Harding, Ian C; Wilson, Paul A; Butler, Emily; Roberts, Andrew P

    2007-03-01

    The Eocene and Oligocene epochs (approximately 55 to 23 million years ago) comprise a critical phase in Earth history. An array of geological records supported by climate modelling indicates a profound shift in global climate during this interval, from a state that was largely free of polar ice caps to one in which ice sheets on Antarctica approached their modern size. However, the early glaciation history of the Northern Hemisphere is a subject of controversy. Here we report stratigraphically extensive ice-rafted debris, including macroscopic dropstones, in late Eocene to early Oligocene sediments from the Norwegian-Greenland Sea that were deposited between about 38 and 30 million years ago. Our data indicate sediment rafting by glacial ice, rather than sea ice, and point to East Greenland as the likely source. Records of this type from one site alone cannot be used to determine the extent of ice involved. However, our data suggest the existence of (at least) isolated glaciers on Greenland about 20 million years earlier than previously documented, at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher.

  17. Composition of Eocene Ice-Rafted Debris, Central Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Ramstad, C.; St. John, K.

    2007-12-01

    IODP Expedition 302 drilled a 400-m sediment record which contains physical evidence of ice-rafting in the Eocene and Neogene in the Arctic (Backman et al., 2006; Moran et al., 2006, St. John, in press). An increase in the terrigenous sand abundance occurs above 246 mcd (~46 Ma), with a flux similar to that in the Neogene. Higher resolution sampling in an interval of good recovery from 246-236 mcd shows evidence of cyclic input of IRD and biogenic components that fits with Milankovitch forcing at the obliquity period (Sangiorgi et al., in press). The question remains - what areas of the Arctic were ice-covered at this early stage in the Cenozoic? To address this provenance issue the composition of the terrigenous sands (250 micron fraction) in cores 55-56X is being quantified. Grains in 75 samples are being point-counted and their compositions categorized. Quartz grains are the dominant component (greater than 10,000 grains per gram), with some being hematite-stained, and there are lesser amounts of mafic minerals. No carbonate grains are identified so far in this study. Possible sources areas for Eocene IRD are the Eastern European and Russian Arctic margins. Tracking compositional variations of the IRD over the interval of cyclic deposition, should indicate whether the cyclic IRD deposition was consistently derived from one source region or multiple regions during this time.

  18. Diversity of Scydmaeninae (Coleoptera: Staphylinidae) in Upper Eocene Rovno amber.

    PubMed

    Jałoszyński, Paweł; Perkovsky, Evgeny

    2016-01-01

    Among nearly 1270 inclusions of Coleoptera found in Upper Eocene Rovno amber, 69 were identified as ant-like stone beetles (Scydmaeninae); 34 were possible to unambiguously determine to the tribal level and were studied in detail. Rovnoleptochromus ableptonoides gen. & sp. n. (Mastigitae: Clidicini), Vertheia quadrisetosa gen. & sp. n. (Cephenniitae: Eutheiini), Cephennomicrus giganteus sp. n. (Cephenniitae: Cephenniini), Glaesoconnus unicus gen. & sp. n. (Scydmaenitae: Glandulariini), Rovnoscydmus frontalis gen. & sp. n. (Scydmaenitae: Glandulariini; type species of Rovnoscydmus), Rovnoscydmus microscopicus sp. n., Euconnus (incertae sedis, near Cladoconnus) palaeogenus sp. n. (Scydmaenitae: Glandulariini), and Stenichnus (s. str.) proavus sp. n. (Scydmaenitae: Glandulariini) are described. Additionally, specimens representing one undescribed species of Vertheia, one of Cephennodes, five of Cephennomicrus, one of Euconnus, one of Microscydmus are recorded, and nine specimens representing an unknown number of species of Rovnoscydmus (and two putative Rovnoscydmus), one Euconnus (and one putative Euconnus), two putative Microscydmus and one putative Scydmoraphes were found in the studied material. The composition of Scydmaeninae fauna in Rovno amber is discussed in the context of ecological preferences and distribution of extant taxa. It is concluded that subtropical and tropical taxa were present in the region where Rovno amber has formed, most notably the second genus and species of the extant tribe Clidicini known from the Eocene of Europe, and six species of the extant genus Cephennomicrus, for the first time found in the fossil record. An annotated catalog of nominal species of Scydmaeninae known in the fossil record is given. PMID:27615867

  19. Eocene paleosols of King George Island, Maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Spinola, Diogo; Portes, Raquel; Schaefer, Carlos; Kühn, Peter

    2016-04-01

    Red layers between lava flows on King George Island, Maritime Antarctica, were formed during the Eocene, which was one of the warmest periods on Earth in the Cenozoic. Our hypothesis is that these red layers are paleosols formed in periods of little or no volcanic activity. Therefore, our main objective was to identify the main pedogenic properties and features to distinguish these from diagenetic features formed after the lava emplacement. Additionally, we compared our results with volcanic soils formed under different climates to find the best present analogue. The macromorphological features indicate a pedogenic origin, because of the occurrence of well-defined horizons based on colour and structure. Micromorphological analyses showed that most important pedogenic features are the presence of biological channels, plant residues, anisotropic b-fabric, neoformed and illuvial clay and distinct soil microstructure. Although the paleosols are not strongly weathered, the geochemical data also support the pedogenic origin despite of diagenetic features as the partial induration of the profiles and zeolites filling nearly all voids in the horizons in contact with the overlying lava flow, indicating circulation of hydrothermal fluids. The macromorphological and micromorphological features of these paleosols are similar to the soils formed under seasonal climates. Thus, these paleosol features do not correspond to the other proxies (e.g. sediment, plant fossils), which indicate a wet, non-seasonal climate, as in Valdivian Forest, Chile, during the Eocene in King George Island

  20. Dependency of rain integral parameters on specific rain drop sizes and its seasonal behaviour

    NASA Astrophysics Data System (ADS)

    Das, Saurabh; Ghosh, Debaleena

    2016-11-01

    This paper investigates the variability of raindrop size distribution (DSD) and rain integral parameters at Ahmedabad, a tropical location, in relation to the radar estimation of rainfall. Rain DSDs for the years 2006-2007 at Ahmedabad (23°04‧N, 72°38‧E) have been measured using a disdrometer. Variability of DSD is evaluated for different seasons and its effect on the integral rain parameters like radar reflectivity, rainfall intensity and attenuation are examined. A percentage contribution of different drop diameters on rain integral parameters is studied to understand the seasonal behaviour of rain attenuation and radar reflectivity. It is observed that drops with diameter around 3 mm contribute maximum to the radar reflectivity while drops having a diameter around 2 mm contribute the maximum to the rainfall intensity for the present location. The critical diameter range responsible for the maximum contribution in rain attenuation found to shift towards large drops with an increase in rain rate for a fixed frequency. Linear and non-linear regression analysis between radar reflectivity and rainfall intensity show significant variations in different seasons but does not differ much for different regression techniques. Results point to the necessity of considering the seasonal variability of rain DSD in radar remote sensing and will be helpful for better characterizing of rain parameters from radar measurements.

  1. Lidar Observation of Tropopause Ozone Profiles in the Equatorial Region

    NASA Astrophysics Data System (ADS)

    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    Tropospheric ozone in the tropics zone is significant in terms of the oxidizing efficiency and greenhouse effect. However, in the upper troposphere, the ozone budget in the tropics has not been fully understood yet because of the sparsity of the range-resolved observations of vertical ozone concentration profiles. A DIAL (differential absorption lidar) system for vertical ozone profiles have been installed in the equatorial tropopause region over Kototabang, Indonesia (100.3E, 0.2S). We have observed large ozone enhancement in the upper troposphere, altitude of 13 - 17 km, concurring with a zonal wind oscillation associated with the equatorial Kelvin wave around the tropopause at equatorial region.

  2. Phase and coherence of longitudinally separated equatorial ionospheric scintillation

    NASA Astrophysics Data System (ADS)

    Shume, E. B.; Mannucci, A. J.

    2013-12-01

    This paper presents the first calculation of phase and coherence of cross-wavelet transform applied on longitudinally separated VHF and L-band equatorial ionospheric scintillation. The cross-wavelet analysis has utilized scintillation observations made over equatorial South America and Christmas Island. Part of the results of this study has been reported recently in the Geophysical Research Letters by Shume and Mannucci (2013). The phase and coherence analysis were employed on pairs of scintillation observations separated by longitudes thereby to develop VHF and L-band scintillation (and equatorial spread F) forecast tools west of observation sites.

  3. Presenting the Rain-Sea Interaction Facility

    NASA Technical Reports Server (NTRS)

    Bliven, Larry F.; Elfouhaily, Tonas M.

    1993-01-01

    The new Rain-Sea Interaction Facility (RSIF) was established at GSFC/WFF and the first finds are presented. The unique feature of this laboratory is the ability to systematically study microwave scattering from a water surface roughened by artificial rain, for which the droplets are at terminal velocity. The fundamental instruments and systems (e.g., the rain simulator, scatterometers, and surface elevation probes) were installed and evaluated during these first experiments - so the majority of the data were obtained with the rain simulator at 1 m above the water tank. From these initial experiments, three new models were proposed: the square-root function for NCS vs. R, the log Gaussian model for ring-wave elevation frequency spectrum, and the Erland probability density distribution for back scattered power. Rain rate is the main input for these models, although the coefficients may be dependent upon other factors (drop-size distribution, fall velocity, radar configuration, etc.). The facility is functional and we foresee collaborative studies with investigators who are engaged in measuring and modeling rain-sea interaction processes.

  4. Effects of acid rain on grapevines

    SciTech Connect

    Forsline, P.L.; Musselman, R.C.; Dee, R.J.; Kender, W.J.

    1983-01-01

    Mature vineyard-growing Concord grapevines (Vitis labrusca, Bailey) were sprayed with simulated acid rain solutions ranging from pH 2.5 to pH 5.5 both as acute treatments at anthesis and chronically throughout the season in 1980 and 1981. In 1981, eight additional varieties were also treated with simulated acid rain solutions at pH 2.75 and pH 3.25. With Concord in 1981, few foliar lesions on leaves were visible at pH 2.75. In contrast, many leaf lesions with decreased fruit soluble solids in the absence of acid rain leaf lesions at pH>2.5 remains unclear. Acute sprays (pH 2.75) at anthesis reduced pollen germination in four grape cultivars. However, fruit set was reduced in only one of these. Only the cultivars de Chaunac and Ives had reduced berry soluble solids with chronic weekly sprays at pH 2.75. Reduction in soluble solids was not associated with increased oxidant stipple (ozone injury) in Concord and de Chaunac cultivars, but this association was observed in Ives. There was no evidence that acid rain in combination with ozone increased oxidant stipple as occurs when ozone and SO/sub 2/ are combined. Grape yields were not influenced by acid rain treatments. There was no evidence that acid rain at ambient pH levels had negative effects on grape production or fruit quality.

  5. Effects of acid rain on grapevines

    SciTech Connect

    Forsline, P.L.; Musselman, R.C.; Dee, R.J.; Kender, W.J.

    1983-01-01

    Mature vineyard-growing Concord grapevines were sprayed with simulated acid rain solutions ranging from pH 2.5 to 5.5 both as acute treatments at anthesis and chronically throughout the season in 1980 and 1981. In 1981, 8 additional varieties were also treated with simulated acid rain solutions at pH 2.75 and 3.25. With Concord in 1981, few foliar lesions on leaves were visible at pH 2.75. In contrast, many leaf lesions with decreased fruit soluble solids were observed at pH 2.5 in 1980. The relationship between acid-rain and oxidant stipple, chlorosis, and soluble solids in the absence of acid rain leaf lesions at pH>2.5 remains unclear. Acute sprays (pH2.75) at anthesis reduced pollen germination in four grape cultivars. However, fruit set was reduced in only one of these. Grape yields were not influenced by acid rain treatments. There was no evidence that acid-rain at ambient pH levels had negative effects on grape production or fruit quality.

  6. Three dimensional Visualization of Jupiter's Equatorial Region

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

    This frame is a view from the southwest looking northeast, from an altitude just above the high haze layer. The streaks in the lower cloud leading towards the hotspot are visible. The upper haze layer is mostly flat, with notable small peaks that can be matched with features in the lower cloud. In reality, these areas may represent a continuous vertical cloud column.

    Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

    The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756

  7. Three dimensional Visualization of Jupiter's Equatorial Region

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

    This frame is a view to the northeast, from between the cloud layers and above the streaks in the lower cloud leading towards the hotspot. The upper haze layer has some features that match the lower cloud, such as the bright streak in the foreground of the frame. These are probably thick clouds that span several tens of vertical kilometers.

    Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

    The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly

  8. Three dimensional Visualization of Jupiter's Equatorial Region

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

    This frame is a view from above and to the south of the visualized area, showing the entire model. The entire region is overlain by a thin, transparent haze. In places the haze is high and thick, especially to the east (to the right of) the hotspot.

    Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

    The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on more sophisticated studies of Jupiter's cloud structure. The upper

  9. Three dimensional Visualization of Jupiter's Equatorial Region

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

    This frame is a view to the northeast, from between the cloud layers and above the streaks in the lower cloud leading towards the hotspot. The hotspot is clearly visible as a deep blue feature. The cloud streaks end near the hotspot, consistent with the idea that clouds traveling along these streak lines descend and evaporate as they approach the hotspot. The upper haze layer is slightly bowed upwards above the hotspot.

    Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

    The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional

  10. Three dimensional Visualization of Jupiter's Equatorial Region

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

    This frame is a view to the southeast, from between the cloud layers and over the north center of the region. The tall white clouds in the lower cloud deck are probably much like large terrestrial thunderclouds. They may be regions where atmospheric water powers vertical convection over large horizontal distances.

    Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

    The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on

  11. Equatorial cloud level convection on Venus

    NASA Astrophysics Data System (ADS)

    Lee, Yeon Joo; Imamura, Takeshi; Sugiyama, Koichiro; Sato, Takao M.; Maejima, Yasumitsu

    2016-10-01

    In the equatorial region on Venus, a clear cloud top morphology difference depending on solar local time has been observed through UV images. Laminar flow shaped clouds are shown on the morning side, and convective-like cells on the afternoon side (Titov et al. 2012). Baker et al. (1998) suggested that deep convective motions in the low-to-middle cloud layers at the 40–60 km range can explain cellular shapes. Imamura et al. (2014), however argued that this cannot be a reason, as convection in the low-to-middle cloud layers can be suppressed near sub solar regions due to a stabilizing effect by strong solar heating. We suggest that the observed feature may be related to strong solar heating at local noon time (Lee et al. 2015). Horizontal uneven distribution of an unknown UV absorber and/or cloud top structure may trigger horizontal convection (Toigo et al. 1994). In order to examine these possibilities, we processed 1-D radiative transfer model calculations from surface to 100 km altitude (SHDOM, Evans 1998), which includes clouds at 48-71 km altitudes (Crisp et al. 1986). The results on the equatorial thermal cooling and solar heating profiles were employed in a 2D fluid dynamic model calculation (CReSS, Tsuboki and Sakakibara 2007). The calculation covered an altitude range of 40-80 km and a 100-km horizontal distance. We compared three conditions; an 'effective' global circulation condition that cancels out unbalanced net radiative energy at equator, a condition without such global circulation effect, and the last condition assumed horizontally inhomogeneous unknown UV absorber distribution. Our results show that the local time dependence of lower level cloud convection is consistent with Imamura et al.'s result, and suggest a possible cloud top level convection caused by locally unbalanced net energy and/or horizontally uneven solar heating. This may be related to the observed cloud morphology in UV images. The effective global circulation condition, however

  12. Variation of slant path Ka/V-band rain attenuation over seven tropical locations in Nigeria using synthetic storm techniques

    NASA Astrophysics Data System (ADS)

    Ojo, J. S.; Adediji, A. T.; Mandeep, J. S.; Ismail, M.

    2016-04-01

    In this paper, rain characteristics and slant path rain attenuation at 30 and 40 GHz using synthetic storm techniques over seven tropical locations in Nigeria have been presented. The technique can be used to predict the local first-order statistical rain attenuation to mitigate the severe fade experienced at higher frequency bands by employing local rainfall rate statistics. Three years rain rate data at seven tropical and equatorial locations in Nigeria were utilized for the purpose of this work. The predicted statistics are in good agreement with those obtained from the propagation beacon measurement (EUTELSAT W4/W7 satellite-12.245 GHz) It could be observed that at 99.99 % link availability over these locations, the fade margin of higher dB (74 and 81 dB) are required at 30 and 40 GHz frequency bands, respectively. When diurnal variation was observed for four time intervals: 00:00-06:00, 06:00-12:00, 12:00-18:00, and 18:00-24:00, there is a variation of the fade margin over the hours of the day. The overall results will be needed for an acceptable planning that can effectively reduce the fade margin to a very low value for an optimum data communication over the studied locations.

  13. Increased carbonate ion saturation in shallow deep waters at the Eocene-Oligocene Transition

    NASA Astrophysics Data System (ADS)

    Bohaty, S. M.; Lear, C. H.; Paelike, H.

    2013-12-01

    Global cooling and growth of large ice sheets across the Eocene-Oligocene Transition (EOT) were associated with a two-stage deepening of the calcite compensation depth (CCD) in the equatorial Pacific Ocean. It is uncertain, however, if changes in carbonate chemistry in the deep Pacific were mirrored in other ocean basins and in higher levels of the water column. In conjunction with CCD histories, geochemical records from benthic foraminifera can provide information on the timing and nature of changes in deep-water carbonate chemistry and may pinpoint mechanisms of EOT climate change and related shifts in global carbon cycling. We use benthic foraminiferal boron/calcium (B/Ca) ratios to reconstruct changes in carbonate ion saturation (Δ[CO32-]) at multiple drillsites in the Atlantic and Indian Ocean basins occupying a range of paleodepths (~1000 to 3500 m). In shallow deep waters of the Indian Ocean (ODP Site 763; ~1000 m), a pronounced increase in Δ[CO32-] is evident at the onset of the EOT that corresponds to the first step of the positive global shift in benthic δ18O values (EOT-1). More subdued increases in Δ[CO32-] occurred synchronously at deeper sites in both the Atlantic and Indian basins (ODP Sites 522 and 711). These results, in conjunction with observed multi-site patterns of CCD change, indicate that the initial phase of climate change during the EOT was associated with major fluctuations in deep-ocean carbonate chemistry that were sustained for ~150 kyr immediately prior to and during EOT-1. Earth system and carbon-cycle box models are currently being employed to help interpret these results. Combined information from both proxy data and models suggest that destabilization of deep-ocean carbonate chemistry at the onset of the EOT resulted from a perturbation in the long-term carbon cycle involving changes in continental weathering rates and/or shifting patterns of marine carbonate burial. We further hypothesize that the shift to more alkaline deep

  14. Acid rain: a primer on what, where, and how much

    SciTech Connect

    Barchet, W.R.

    1985-04-01

    Acid rain is introduced by defining its components: wet and dry deposition. Data bases on precipitation chemistry from several monitoring networks are used to show where acid rain occurs. Precipitation chemistry and air quality data are used to discuss what is in acid rain. Maps of the deposition of the major constituents of wet deposition are presented to contrast the amount of material deposited (deposition) in acid rain with its composition (concentration). The interactions of acid rain with the surfaces on which it falls are used to trace the paths by which acid rain reaches surface and soil waters. Implications of acid rain effects are introduced but not discussed in detail.

  15. Large-scale modeling of rain fields from a rain cell deterministic model

    NASA Astrophysics Data System (ADS)

    FéRal, Laurent; Sauvageot, Henri; Castanet, Laurent; Lemorton, JoëL.; Cornet, FréDéRic; Leconte, Katia

    2006-04-01

    A methodology to simulate two-dimensional rain rate fields at large scale (1000 × 1000 km2, the scale of a satellite telecommunication beam or a terrestrial fixed broadband wireless access network) is proposed. It relies on a rain rate field cellular decomposition. At small scale (˜20 × 20 km2), the rain field is split up into its macroscopic components, the rain cells, described by the Hybrid Cell (HYCELL) cellular model. At midscale (˜150 × 150 km2), the rain field results from the conglomeration of rain cells modeled by HYCELL. To account for the rain cell spatial distribution at midscale, the latter is modeled by a doubly aggregative isotropic random walk, the optimal parameterization of which is derived from radar observations at midscale. The extension of the simulation area from the midscale to the large scale (1000 × 1000 km2) requires the modeling of the weather frontal area. The latter is first modeled by a Gaussian field with anisotropic covariance function. The Gaussian field is then turned into a binary field, giving the large-scale locations over which it is raining. This transformation requires the definition of the rain occupation rate over large-scale areas. Its probability distribution is determined from observations by the French operational radar network ARAMIS. The coupling with the rain field modeling at midscale is immediate whenever the large-scale field is split up into midscale subareas. The rain field thus generated accounts for the local CDF at each point, defining a structure spatially correlated at small scale, midscale, and large scale. It is then suggested that this approach be used by system designers to evaluate diversity gain, terrestrial path attenuation, or slant path attenuation for different azimuth and elevation angle directions.

  16. Equatorial Staphyloma Associated with Neurofibromatosis Type 1

    PubMed Central

    Shimada, Yoshiaki; Horiguchi, Masayuki

    2016-01-01

    We report a case of a 38-year-old man who presented with a recently self-detected lump under his left eyebrow. Previous ophthalmological history was unremarkable except for unilateral high myopia (left eye) since childhood. The appearance of the left eye was seemingly normal; however, with the top lid pulled up on downward gaze, a dark brown bulge emerged. The bulge was 10 × 7 mm and approximately 4 mm in height, and was covered by the extended superior rectus muscle. The diagnosis of equatorial staphyloma was made after coronal T1-weighted magnetic resonance imaging of the orbit revealed the dilatation of the vitreous cavity. Ocular movements were fully maintained and visual acuity was largely spared: 20/15 in the right eye without correction and 20/25 in the left eye with −10.00 spheres and −4.00 × 80 degrees cylinders. His past and family histories were unremarkable; however, small neurofibromas and café au lait spots all over his body led to the diagnosis of neurofibromatosis type 1 (NF1). From this case, similar to previous reports, we suggest that manifestations of NF1 are extremely variable and unpredictable. PMID:27721788

  17. Onset conditions for equatorial spread F

    NASA Astrophysics Data System (ADS)

    Mendillo, Michael; Baumgardner, Jeffrey; Pi, Xiaoqing; Sultan, Peter J.; Tsunoda, Roland

    1992-09-01

    The problem of day-to-day variability in the occurrence of equatorial spread F (ESF) is addressed using multidiagnostic observations and semiempirical modeling. The observational results are derived from a two-night case study of ESF onset conditions observed at Kwajalein Atoll (Marshall Islands) using the ALTAIR incoherent scatter radar and all-sky optical imaging techniques. The major difference between nights when ESF instabilities did not occur (August 14, 1988) and did occur (August 15, 1988) in the Kwajalein sector was that the northern meridional gradient of 6300-A airglow was reduced on the night of limited ESF activity. Modeling results suggest that this unusual airglow pattern is due to equatorward neutral winds. Previous researchers have shown that transequatorial thermospheric winds can exert a control over ESF seasonal and longitudinal occurrence patterns by inhibiting Rayleigh-Taylor instability growth rates. Evidence is presented to suggest that this picture can be extended to far shorter time scales, namely, that 'surges' in transequatorial winds acting over characteristic times of a few hours to a day can result in a stabilizing influence upon irregularity growth rates. The seemingly capricious nature of ESF onset may thus be controlled, in part, by the inherent variability of low-latitude thermospheric winds.

  18. Condor equatorial electrojet campaign: Radar results

    SciTech Connect

    Kudeki, E.; Fejer, B.G.; Farley, D.T.; Hanuise, C.

    1987-12-01

    A review of the experimental and theoretical background to the Condor equatorial electrojet compaign is followed by the presentation and discussion of VHF radar interferometer and HF radar backscatter data taken concurrently with two rocket in situ experiments reported in companion papers (Pfaff et al., this issue (a, b). Both experiments were conducted in strongly driven periods with the on-line radar interferometer displaying signatures of what has been interpreted in earlier radar work (Kudeki et al., 1982) as kilometer scale gradient drift waves. Low-frequency density fluctuations detected by in situ rocket sensors confirm the earlier interpretation. VHF radar/rocket data comparisons also indicate the existence of a turbulent layer in the upper portion of the daytime electrojet at about 108 km altitude driven purely by the two-stream instability. Nonlinear mode coupling of linearly growing two-stream waves to linearly damped 3-m vertical modes could account for the radar echoes scattered from this layer, which showed no indication of large-scale gradient drift waves. Nonlinear mode coupling may therefore compete with the wave-induced anomalous diffusion mechanism proposed recently by Sudan (1983) for the saturation of directly excited two-stream waves. Nighttime radar data show a bifurcated layer with the two parts having comparable echo strength but oppositely directed zonal drift velocities. The lower layer shows narrow backscatter spectra; the upper layer is characterized by kilometer scale waves and vertically propagating type 1 waves.

  19. Periodic spacing between consecutive equatorial plasma bubbles

    NASA Astrophysics Data System (ADS)

    Makela, J. J.; Vadas, S. L.; Muryanto, R.; Duly, T.; Crowley, G.

    2010-07-01

    We analyze three-years of data collected by a field-aligned airglow imaging system located at the Cerro Tololo Inter-American Observatory near La Serena, Chile to determine the occurrence of equatorial plasma bubbles (EPBs). On 317 of the 552 predominately clear nights of observations, structure indicative of EPBs is present. On 123 of these nights, multiple EPBs with periodic spacings were recorded with 88 nights showing 3 or more consecutive bubbles. We suggest that the periodic spacing of EPBs could be related to the properties of an underlying seed mechanism, namely gravity waves (GWs). The distribution of spacings compares favorably to the spectrum of GW induced traveling ionospheric disturbances (TIDs) measured by Vadas and Crowley (2010) from a similar geographic latitude in the northern hemisphere. Furthermore, the distribution of spacings decreases from 2006 through 2009, tracking the corresponding decrease in the thermospheric neutral temperature, Tn. As Tn decreases, GWs with larger horizontal wavelengths have smaller initial amplitudes and cannot propagate as easily to EPB seeding altitudes. Thus, our observations are consistent with GW theory.

  20. Tilts of the Master Equatorial Tower

    NASA Astrophysics Data System (ADS)

    Ahlstrom, H. G., Jr.; Gawronski, W.; Girdner, D.; Noskoff, E.; Sommerville, J. N.

    2000-07-01

    At the center of the DSS-14 antenna, a tower reaches to the focal point of the antenna dish. The master equatorial (ME) instrument is located at the top of the tower. This instrument precisely (with an accuracy that exceeds that of the antenna) follows the commanded trajectory. Through the optical coupling, the antenna focal point follows the ME. One factor of the antenna pointing precision is the movement of the ME base, i.e., the top of the tower. For this reason, measurements of the ME tower tilts have been taken in order to quantify the tilts, to determine possible causes of the tilting, and to update the antenna pointing budget. They were conducted under three antenna operating modes: during tracking, slewing, and antenna stowing. The measurements indicate that the ME tower tilts introduce significant pointing errors that exceed the required 32-GHz (Ka-band) pointing precision (estimated as 0.8 mdeg for a 0.1-dB gain loss). Four different sources of tilt were identified and require verification.

  1. Vertical motions in the equatorial middle atmosphere

    NASA Technical Reports Server (NTRS)

    Weisman, M. L.

    1979-01-01

    A single station vertical velocity equation which considers ageostrophic and diabatic effects derived from the first law of thermodynamics and a generalized thermal wind relation is presented. An analysis and verification procedure which accounts for measurement and calculation errors as well as time and space continuity arguments and theoretical predictions are described. Vertical velocities are calculated at every kilometer between 25 and 60 km and for approximately every three hours for the above diurnal period at Kourou (French Guiana), Fort Sherman (Panama Canal Zone), Ascension Island, Antigua (British West Indies) and Natal (Brazil). The results, plotted as time series cross sections, suggest vertical motions ranging in magnitude from 1 or 2 cm/sec at 30 km to as much as 15 cm/sec at 60 km. Many of the general features of the results agree well with atmospheric tidal predictions but many particular features suggest that both smaller time scale gravity waves (periods less than 6 hours) and synoptic type waves (periods greater than 1 day) may be interacting significantly with the tidal fields. The results suggest that vertical motions can be calculated for the equatorial middle atmosphere and must be considered a significant part of the motion for time scales from 8 to 24 hours.

  2. Onset conditions for equatorial spread F

    SciTech Connect

    Mendillo, M.; Baumgardner, J.; Xiaoqing Pi; Sultan, P.J. ); Tsunoda, R. )

    1992-09-01

    The problem of day-to-day variability in the occurrence of equatorial spread F (ESF) is addressed using multidiagnostic observations and semiempirical modeling. The observational results are derived from a two-night case study of ESF onset conditions observed at Kwajalein Atoll (Marshall Islands) using the ALTAIR incoherent scatter radar and all-sky optical imaging techniques. The major difference between nights when ESF instabilities did not occur (August 14, 1988) and did occur (August 15, 1988) in the Kwajalein sector was that the northern meridional gradient of 6300-[angstrom] airglow was reduced on the night of limited ESF activity. Modeling results suggest that this unusual airglow pattern is due to equatorward neutral winds. Previous researchers have shown that transequatorial thermospheric winds can exert a control over ESF seasonal and longitudinal occurrence patterns by inhibiting Rayleigh-Taylor instability growth rates. They present evidence to suggest that this picture can be extended to far shorter time scales, namely, that 'surges' in transequatoral winds acting over characteristic times of a few hours to a day can result in a stabilizing influence upon irregularity growth rates. The seemingly capricious nature of ESF onset may thus be controlled, in part, by the inherent variability of low-latitude thermospheric winds.

  3. Onset conditions for equatorial spread F

    NASA Technical Reports Server (NTRS)

    Mendillo, Michael; Baumgardner, Jeffrey; Pi, Xiaoqing; Sultan, Peter J.; Tsunoda, Roland

    1992-01-01

    The problem of day-to-day variability in the occurrence of equatorial spread F (ESF) is addressed using multidiagnostic observations and semiempirical modeling. The observational results are derived from a two-night case study of ESF onset conditions observed at Kwajalein Atoll (Marshall Islands) using the ALTAIR incoherent scatter radar and all-sky optical imaging techniques. The major difference between nights when ESF instabilities did not occur (August 14, 1988) and did occur (August 15, 1988) in the Kwajalein sector was that the northern meridional gradient of 6300-A airglow was reduced on the night of limited ESF activity. Modeling results suggest that this unusual airglow pattern is due to equatorward neutral winds. Previous researchers have shown that transequatorial thermospheric winds can exert a control over ESF seasonal and longitudinal occurrence patterns by inhibiting Rayleigh-Taylor instability growth rates. Evidence is presented to suggest that this picture can be extended to far shorter time scales, namely, that 'surges' in transequatorial winds acting over characteristic times of a few hours to a day can result in a stabilizing influence upon irregularity growth rates. The seemingly capricious nature of ESF onset may thus be controlled, in part, by the inherent variability of low-latitude thermospheric winds.

  4. Exact and Explicit Internal Equatorial Water Waves with Underlying Currents

    NASA Astrophysics Data System (ADS)

    Kluczek, Mateusz

    2016-07-01

    In this paper we present an exact and explicit solution to the geophysical governing equations in the Equatorial region, which represents internal oceanic waves in the presence of a constant underlying current.

  5. Diachronous ranges of benthonic Foraminifera in the Eocene of Alabama and South Carolina

    SciTech Connect

    Willard, G.D.; Fallaw, W.C. . Dept. of Geology); Price, V. ); Snipes, D.S. . Dept. of Earth Sciences)

    1994-03-01

    Seventeen species of benthonic Foraminifera reported by Bandy (1949) from the Eocene of Little Stave Creek in Clarke County, Alabama were identified from the middle eocene Santee Limestone and the upper Eocene Dry Branch Formation in Aiken and Barnwell counties, South Carolina. Of the 17 species, seven occurred in South Carolina stratigraphically above or below the ranges listed by Bandy. Bandy made a detailed study of Foraminifera from the Claibornian and Jacksonian Tallahatta, Lisbon, Gosport, Moodys Branch, and Yazoo formations exposed on Little Stave Creek and plotted the stratigraphic ranges within the section of numerous species. The authors' samples came from well cores at the Savannah River Site in South Carolina. Of 13 species from the middle Eocene Santee and also reported by Bandy, four are stratigraphically below the lowest occurrence listed by Bandy, and one is stratigraphically above the highest occurrence. Of four species from the upper Eocene Dry Branch Formation and also listed by Bandy, two are stratigraphically above his highest occurrence. Dockery and Nystrom (1992) and Campbell (1993) have described diachroneity among mollusks in the Eocene of South Carolina. Caution should be used in relying on a small number of species in correlating Eocene deposits in the Atlantic and Gulf coastal plains.

  6. Lagrangian sources of frontogenesis in the equatorial Atlantic front

    NASA Astrophysics Data System (ADS)

    Giordani, Hervé; Caniaux, Guy

    2014-12-01

    Estimating the processes that control the north equatorial sea surface temperature (SST)-front on the northern edge of the cold tongue in the tropical Atlantic is a key issue for understanding the dynamics of the oceanic equatorial Atlantic and the West African Monsoon. Diagnosis of the frontogenetic forcings on a realistic high-resolution simulation was used to identify the processes involved in the formation and evolution of the equatorial SST-front. The turbulent forcing associated with the mixed-layer turbulent heat flux was found to be systematically frontolytic while the dynamic forcing associated with currents was found to be frontogenetic for the equatorial SST-front. Nevertheless, the low-frequency component of the turbulent forcing was frontogenetic and initiated the SST-front which was then amplified and maintained by the leading dynamic forcing. This forcing was mainly driven by the meridional convergence of the northern South Equatorial Current (nSEC) and the Guinea Current, which points out the essential role played by the circulation in the equatorial SST-front evolution. The quasi-biweekly variability of the equatorial SST-front and its forcings were found to be more strongly coupled to the wind energy flux ( WEF) than to the surface wind stress. In fact the WEF controlled the convergence/divergence of the nSEC and Guinea Current and thus the meridional component of the leading dynamic forcing. The WEF explains the equatorial SST-front development better than the wind does because it is a coupled ocean-atmosphere process.

  7. On Irrotational Flows Beneath Periodic Traveling Equatorial Waves

    NASA Astrophysics Data System (ADS)

    Quirchmayr, Ronald

    2016-08-01

    We discuss some aspects of the velocity field and particle trajectories beneath periodic traveling equatorial surface waves over a flat bed in a flow with uniform underlying currents. The system under study consists of the governing equations for equatorial ocean waves within a non-inertial frame of reference, where Euler's equation of motion has to be suitably adjusted, in order to account for the influence of the earth's rotation.

  8. First Record of Eocene Bony Fishes and Crocodyliforms from Canada’s Western Arctic

    PubMed Central

    Eberle, Jaelyn J.; Gottfried, Michael D.; Hutchison, J. Howard; Brochu, Christopher A.

    2014-01-01

    Background Discovery of Eocene non-marine vertebrates, including crocodylians, turtles, bony fishes, and mammals in Canada’s High Arctic was a critical paleontological contribution of the last century because it indicated that this region of the Arctic had been mild, temperate, and ice-free during the early – middle Eocene (∼53–50 Ma), despite being well above the Arctic Circle. To date, these discoveries have been restricted to Canada’s easternmost Arctic – Ellesmere and Axel Heiberg Islands (Nunavut). Although temporally correlative strata crop out over 1,000 km west, on Canada’s westernmost Arctic Island – Banks Island, Northwest Territories – they have been interpreted as predominantly marine. We document the first Eocene bony fish and crocodyliform fossils from Banks Island. Principal Findings We describe fossils of bony fishes, including lepisosteid (Atractosteus), esocid (pike), and amiid, and a crocodyliform, from lower – middle Eocene strata of the Cyclic Member, Eureka Sound Formation within Aulavik National Park (∼76°N. paleolat.). Palynology suggests the sediments are late early to middle Eocene in age, and likely spanned the Early Eocene Climatic Optimum (EECO). Conclusions/Significance These fossils extend the geographic range of Eocene Arctic lepisosteids, esocids, amiids, and crocodyliforms west by approximately 40° of longitude or ∼1100 km. The low diversity bony fish fauna, at least at the family level, is essentially identical on Ellesmere and Banks Islands, suggesting a pan-High Arctic bony fish fauna of relatively basal groups around the margin of the Eocene Arctic Ocean. From a paleoclimatic perspective, presence of a crocodyliform, gar and amiid fishes on northern Banks provides further evidence that mild, year-round temperatures extended across the Canadian Arctic during early – middle Eocene time. Additionally, the Banks Island crocodyliform is consistent with the phylogenetic hypothesis of a Paleogene divergence

  9. Sources of frontogenesis in the Equatorial Atlantic Front

    NASA Astrophysics Data System (ADS)

    Giordani, Hervé; Caniaux, Guy

    2014-05-01

    The Equatorial Atlantic front is located along 1°N in the eastern equatorial Atlantic basin, at the northern boundary of the cold tongue. It separates the cold waters of the southern cold tongue from the warmest, tropical waters circulating in the Gulf of Guinea. This seasonal front appears every year from May to August, and is characterized by meridional SST gradients up to 2 to 3°C/20 km. It is thought to play an important role for the circulation in the marine atmospheric boundary layer and influence the coastal precipitation and the western African monsoon onset. In this presentation the processes at the origin of the equatorial front were investigated. For that, diagnosis of the frontogenesis forcings were applied on a realistic high-resolution simulation of the equatorial Atlantic in 2006. It is found that the turbulent forcing term associated with the mixed layer turbulent heat fluxes is frontolitic (meaning a destruction of the front). However, a splitting of the turbulent forcing into its low and high-frequency (wavy) components, indicates that the low-frequency forcing may initiate the equatorial front, a forcing that is finally amplified and fully maintained by dynamical effects. Finally, the dynamic forcing has a leading frontogenetic role (meaning a reinforcement of the front) and is fully driven by the meridional convergence between the Guinea Current and the South Equatorial Current.

  10. AN EQUATORIAL PACIFIC RAIN EVENT: INFLUENCE ON THE DISTRIBUTION OF IRON AND HYDROGEN PEROXIDE IN SURFACE WATERS

    EPA Science Inventory

    Methods are described for measuring changes in atmospheric O2 concentration with emphasis on gas handling procedures. Cryogenically dried air samples are collected in 5 L glass flasks at ambient pressure and analyzed against reference gases derived from high-pressure aluminum tan...

  11. Rain rate duration statistics derived from the Mid-Atlantic coast rain gauge network

    NASA Technical Reports Server (NTRS)

    Goldhirsh, Julius

    1993-01-01

    A rain gauge network comprised of 10 tipping bucket rain gauges located in the Mid-Atlantic coast of the United States has been in continuous operation since June 1, 1986. Rain rate distributions and estimated slant path fade distributions at 20 GHz and 30 GHz covering the first five year period were derived from the gauge network measurements, and these results were described by Goldhirsh. In this effort, rain rate time duration statistics are presented. The rain duration statistics are of interest for better understanding the physical nature of precipitation and to present a data base which may be used by modelers to convert to slant path fade duration statistics. Such statistics are important for better assessing optimal coding procedures over defined bandwidths.

  12. Influence of Assimilation of Subsurface Temperature Measurements on Simulations of Equatorial Undercurrent and South Equatorial Current Along the Pacific Equator

    NASA Technical Reports Server (NTRS)

    Halpern, David; Leetmaan, Ants; Reynolds, Richard W.; Ji, Ming

    1997-01-01

    Equatorial Pacific current and temperature fields were simulated with and without assimilation of subsurface temperature measurements for April 1992 - March 1995, and compared with moored bouy and research vessel current measurements.

  13. Paleocene and Lower Eocene sections in the southern part of the Crimean Peninsula

    NASA Astrophysics Data System (ADS)

    Bugrova, I. Yu.; Bugrova, E. M.

    2015-11-01

    This work summarizes updated data on Paleocene and Lower Eocene deposits of the Crimean Peninsula concerning the systematics of assemblages of small foraminifers (and partly data on other microfossils) and results of biostratigraphic subdivision of sections. It is shown that Lower Paleocene and Lower-Middle Eocene deposits accumulated during two cycles of carbonate sedimentation in a warm-water shallow basin. These deposits are separated by Upper Paleocene deep-water deposits. The systematic composition of foraminifers testifies that there were different facies conditions in different parts of the Crimean basin and its connection to Western European and Tethyan basins during the Paleocene-early Eocene.

  14. Biochronology and paleoclimatic implications of Middle Eocene to Oligocene planktic foraminiferal faunas

    USGS Publications Warehouse

    Keller, G.

    1983-01-01

    Planktic foraminiferal assemblages have been analyzed quantitatively in six DSDP sites in the Atlantic (Site 363), Pacific (Sites 292, 77B, 277), and Indian Ocean (Sites 219, 253) in order to determine the nature of the faunal turnover during Middle Eocene to Oligocene time. Biostratigraphic ranges of taxa and abundance distributions of dominant species are presented and illustrate striking similarities in faunal assemblages of low latitude regions in the Atlantic, Pacific and Indian oceans. A high resolution biochronology, based on dominant faunal characteristics and 55 datum events, permits correlation between all three oceans with a high degree of precision. Population studies provide a view of the global impact of the paleoclimatic and paleoceanographic changes occurring during Middle Eocene to Oligocene time. Planktic foraminiferal assemblage changes indicate a general cooling trend between Middle Eocene to Oligocene time, consistent with previously published oxygen isotope data. Major faunal changes, indicating cooling episodes, occur, however, at discrete intervals: in the Middle Eocene 44-43 Ma (P13), the Middle/Late Eocene boundary 41-40 Ma ( P14 P15), the Late Eocene 39-38 Ma ( P15 P16), the Eocene/Oligocene boundary 37-36 Ma (P18), and the Late Oligocene 31-29 Ma ( P20 P21). With the exception of the E 0 boundary, faunal changes occur abruptly during short stratigraphic intervals, and are characterized by major species extinctions and first appearances. The Eocene/Oligocene boundary cooling is marked primarily by increasing abundances of cool water species. This suggests that the E 0 boundary cooling, which marks a major event in the oxygen isotope record affected planktic faunas less than during other cooling episodes. Planktic foraminiferal faunas indicate that the E 0 boundary event is part of a continued cooling trend which began during the Middle Eocene. Two hiatus intervals are recognized in low and high latitude sections at the Middle/Late Eocene

  15. Multidimensional Modeling of Coronal Rain Dynamics

    NASA Astrophysics Data System (ADS)

    Fang, X.; Xia, C.; Keppens, R.

    2013-07-01

    We present the first multidimensional, magnetohydrodynamic simulations that capture the initial formation and long-term sustainment of the enigmatic coronal rain phenomenon. We demonstrate how thermal instability can induce a spectacular display of in situ forming blob-like condensations which then start their intimate ballet on top of initially linear force-free arcades. Our magnetic arcades host a chromospheric, transition region, and coronal plasma. Following coronal rain dynamics for over 80 minutes of physical time, we collect enough statistics to quantify blob widths, lengths, velocity distributions, and other characteristics which directly match modern observational knowledge. Our virtual coronal rain displays the deformation of blobs into V-shaped features, interactions of blobs due to mostly pressure-mediated levitations, and gives the first views of blobs that evaporate in situ or are siphoned over the apex of the background arcade. Our simulations pave the way for systematic surveys of coronal rain showers in true multidimensional settings to connect parameterized heating prescriptions with rain statistics, ultimately allowing us to quantify the coronal heating input.

  16. Acid rain and its ecological consequences.

    PubMed

    Singh, Anita; Agrawal, Madhoolika

    2008-01-01

    Acidification of rain-water is identified as one of the most serious environmental problems of transboundary nature. Acid rain is mainly a mixture of sulphuric and nitric acids depending upon the relative quantities of oxides of sulphur and nitrogen emissions. Due to the interaction of these acids with other constituents of the atmosphere, protons are released causing increase in the soil acidity Lowering of soil pH mobilizes and leaches away nutrient cations and increases availability of toxic heavy metals. Such changes in the soil chemical characteristics reduce the soil fertility which ultimately causes the negative impact on growth and productivity of forest trees and crop plants. Acidification of water bodies causes large scale negative impact on aquatic organisms including fishes. Acidification has some indirect effects on human health also. Acid rain affects each and every components of ecosystem. Acid rain also damages man-made materials and structures. By reducing the emission of the precursors of acid rain and to some extent by liming, the problem of acidification of terrestrial and aquatic ecosystem has been reduced during last two decades.

  17. MULTIDIMENSIONAL MODELING OF CORONAL RAIN DYNAMICS

    SciTech Connect

    Fang, X.; Xia, C.; Keppens, R.

    2013-07-10

    We present the first multidimensional, magnetohydrodynamic simulations that capture the initial formation and long-term sustainment of the enigmatic coronal rain phenomenon. We demonstrate how thermal instability can induce a spectacular display of in situ forming blob-like condensations which then start their intimate ballet on top of initially linear force-free arcades. Our magnetic arcades host a chromospheric, transition region, and coronal plasma. Following coronal rain dynamics for over 80 minutes of physical time, we collect enough statistics to quantify blob widths, lengths, velocity distributions, and other characteristics which directly match modern observational knowledge. Our virtual coronal rain displays the deformation of blobs into V-shaped features, interactions of blobs due to mostly pressure-mediated levitations, and gives the first views of blobs that evaporate in situ or are siphoned over the apex of the background arcade. Our simulations pave the way for systematic surveys of coronal rain showers in true multidimensional settings to connect parameterized heating prescriptions with rain statistics, ultimately allowing us to quantify the coronal heating input.

  18. Rain-induced spring wheat harvest losses

    NASA Technical Reports Server (NTRS)

    Bauer, A.; Black, A. L. (Principal Investigator)

    1983-01-01

    When rain or a combination of rain and high humidity delay wheat harvest, losses can occur in grain yield and/or grain quality. Yield losses can result from shattering, from reduction in test weight, and in the case of windrowed grain, from rooting of sprouting grain at the soil: windrow contact. Losses in grain quality can result from reduction in test weight and from sprouting. Sprouting causes a degradation of grain proteins and starches, hence flour quality is reduced, and the grain price deteriorates to the value of feed grain. Although losses in grain yield and quality are rain-induced, these losses do not necessarily occur because a standing or windrowed crop is wetted by rain. Spike water concentration in hard red spring wheat must be increased to about 45-49% before sprouting is initiated in grain that has overcome dormancy. The time required to overcome this dormancy after the cultivar has dried to 12 to 14% water concentration differs with hard red spring cultivars. The effect of rain on threshing-ready standing and windrowed hard red spring wheat grain yeild and quality was evaluated. A goal was to develop the capability to forecast the extent of expected loss of grain yield and quality from specific climatic events that delay threshing.

  19. Acid rain and its ecological consequences.

    PubMed

    Singh, Anita; Agrawal, Madhoolika

    2008-01-01

    Acidification of rain-water is identified as one of the most serious environmental problems of transboundary nature. Acid rain is mainly a mixture of sulphuric and nitric acids depending upon the relative quantities of oxides of sulphur and nitrogen emissions. Due to the interaction of these acids with other constituents of the atmosphere, protons are released causing increase in the soil acidity Lowering of soil pH mobilizes and leaches away nutrient cations and increases availability of toxic heavy metals. Such changes in the soil chemical characteristics reduce the soil fertility which ultimately causes the negative impact on growth and productivity of forest trees and crop plants. Acidification of water bodies causes large scale negative impact on aquatic organisms including fishes. Acidification has some indirect effects on human health also. Acid rain affects each and every components of ecosystem. Acid rain also damages man-made materials and structures. By reducing the emission of the precursors of acid rain and to some extent by liming, the problem of acidification of terrestrial and aquatic ecosystem has been reduced during last two decades. PMID:18831326

  20. Geochemical evidence for a comet shower in the late Eocene.

    PubMed

    Farley, K A; Montanari, A; Shoemaker, E M; Shoemaker, C S

    1998-05-22

    Analyses of pelagic limestones indicate that the flux of extraterrestrial helium-3 to Earth was increased for a 2.5-million year (My) period in the late Eocene. The enhancement began approximately 1 My before and ended approximately 1.5 My after the major impact events that produced the large Popigai and Chesapeake Bay craters approximately 36 million years ago. The correlation between increased concentrations of helium-3, a tracer of fine-grained interplanetary dust, and large impacts indicates that the abundance of Earth-crossing objects and dustiness in the inner solar system were simultaneously but only briefly enhanced. These observations provide evidence for a comet shower triggered by an impulsive perturbation of the Oort cloud. PMID:9596575

  1. Eocene Hyperthermal Event Offers Insight Into Greenhouse Warming

    NASA Astrophysics Data System (ADS)

    Bowen, Gabriel J.; Bralower, Timothy J.; Delaney, Margaret L.; Dickens, Gerald R.; Kelly, Daniel C.; Koch, Paul L.; Kump, Lee R.; Meng, Jin; Sloan, Lisa C.; Thomas, Ellen; Wing, Scott L.; Zachos, James C.

    2006-04-01

    What happens to the Earth's climate, environment, and biota when thousands of gigatons of greenhouse gases are rapidly added to the atmosphere? Modern anthropogenic forcing of atmospheric chemistry promises to provide an experiment in such change that has not been matched since the early Paleogene, more than 50 million years ago (Ma),when catastrophic release of carbon to the atmosphere drove abrupt, transient, hyperthermal events. Research on the Paleocene-Eocene Thermal Maximum (PETM)-the best documented of these events, which occurred about 55 Ma-has advanced significantly since its discovery 15 years ago. During the PETM, carbon addition to the oceans and atmosphere was of a magnitude similar to that which is anticipated through the 21st century. This event initiated global warming, biotic extinction and migration, and fundamental changes in the carbon and hydrological cycles that transformed the early Paleogene world.

  2. Identification of Late Eocene Impact Deposits at ODP Site 1090

    NASA Technical Reports Server (NTRS)

    Kyte, Frank T.

    2001-01-01

    Anomalous concentrations of Ir have been found in upper Eocene sediments from Ocean Drilling Program (ODP) Hole 1090B. Clear and dark-colored spherules that are believed to be microtektites and clinopyroxene- bearing microkrystites, respectively, were found in the samples with highest Ir. The peak Ir concentration in Sample 177- 1090B-30X-5,105-106 cm (954 pg/g) and the net Ir fluence (14 ng/cm2) at this site are higher that at most other localities except for Caribbean site RC9-58. The Ir anomaly and impact debris are probably correlative with similar deposits found at ODP Site 689 on the Maude Rise and at other localities around the world.

  3. High latitude hydrological changes during the Eocene Thermal Maximum 2

    NASA Astrophysics Data System (ADS)

    Krishnan, Srinath; Pagani, Mark; Huber, Matthew; Sluijs, Appy

    2014-10-01

    The Eocene hyperthermals, including the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM2), represent extreme global warming events ∼56 and 54 million years ago associated with rapid increases in atmospheric greenhouse gas concentrations. An initial study on PETM characteristics in the Arctic region argued for intensification of the hydrological cycle and a substantial increase in poleward moisture transport during global warming based on compound-specific carbon and hydrogen isotopic (2H/1H) records from sedimentary leaf-wax lipids. In this study, we apply this isotopic and hydrological approach on sediments deposited during ETM2 from the Lomonosov Ridge (Integrated Ocean Drilling Program Expedition 302). Our results show similar 2H/1H changes during ETM2 as during the PETM, with a period of 2H-enrichment (∼20‰) relative to “pre-event” values just prior to the negative carbon isotope shift (CIE) that is often taken as the onset of the hyperthermal, and more negative lipid δ2H values (∼-15‰) during peak warming. Notably, lipid 2H-enrichment at the base of the event is coeval with colder TEX86H temperatures. If 2H/1H values of leaf waxes primarily reflect the hydrogen isotopic composition of precipitation, the observed local relationship between temperature and 2H/1H values for the body of ETM2 is precisely the opposite of what would be predicted using a simple Rayleigh isotope distillation model, assuming a meridional vapor trajectory and a reduction in equator-pole temperature gradients. Overall, a negative correlation exists between the average chain length of n-alkanes and 2H/1H suggesting that local changes in ecology could have impacted the hydrogen isotopic compositions of leaf waxes. The negative correlation falls across three separate intervals - the base of the event, the initial CIE, and during the H2 hyperthermal (of which the assignment is not fully certain). Three possible mechanisms potentially explain 2H

  4. Geochemical evidence for a comet shower in the late Eocene.

    PubMed

    Farley, K A; Montanari, A; Shoemaker, E M; Shoemaker, C S

    1998-05-22

    Analyses of pelagic limestones indicate that the flux of extraterrestrial helium-3 to Earth was increased for a 2.5-million year (My) period in the late Eocene. The enhancement began approximately 1 My before and ended approximately 1.5 My after the major impact events that produced the large Popigai and Chesapeake Bay craters approximately 36 million years ago. The correlation between increased concentrations of helium-3, a tracer of fine-grained interplanetary dust, and large impacts indicates that the abundance of Earth-crossing objects and dustiness in the inner solar system were simultaneously but only briefly enhanced. These observations provide evidence for a comet shower triggered by an impulsive perturbation of the Oort cloud.

  5. Geochemical evidence for a comet shower in the late Eocene

    USGS Publications Warehouse

    Farley, K.A.; Montanari, A.; Shoemaker, E.M.; Shoemaker, C.S.

    1998-01-01

    Analyses of pelagic limestones indicate that the flux of extraterrestrial helium-3 to Earth was increased for a 2.5-million year (My) period in the late Eocene. The enhancement began ~1 My before and ended ~1.5 My after the major impact events that produced the large Popigai and Chesapeake Bay craters ~36 million years ago. The correlation between increased concentrations of helium-3, a tracer of fine-grained interplanetary dust, and large impacts indicates that the abundance of Earth-crossing objects and dustiness in the inner solar system were simultaneously but only briefly enhanced. These observations provide evidence for a comet shower triggered by an impulsive perturbation of the Oort cloud.

  6. Isotopic interrogation of a suspected late Eocene glaciation

    NASA Astrophysics Data System (ADS)

    Scher, Howie D.; Bohaty, Steven M.; Smith, Brian W.; Munn, Gabrielle H.

    2014-06-01

    Ephemeral polar glaciations during the middle-to-late Eocene (48-34 Ma) have been proposed based on far-field ice volume proxy records and near-field glacigenic sediments, although the scale, timing, and duration of these events are poorly constrained. Here we confirm the existence of a transient cool event within a new high-resolution benthic foraminiferal δ18O record at Ocean Drilling Program (ODP) Site 738 (Kerguelen Plateau; Southern Ocean). This event, named the Priabonian oxygen isotope maximum (PrOM) Event, lasted ~140 kyr and is tentatively placed within magnetochron C17n.1n (~37.3 Ma) based on the correlation to ODP Site 689 (Maud Rise, Southern Ocean). A contemporaneous change in the provenance of sediments delivered to the Kerguelen Plateau occurs at the study site, determined from the <63 µm fraction of decarbonated and reductively leached sediment samples. Changes in the mixture of bottom waters, based on fossil fish tooth ɛNd, were less pronounced and slower relative to the benthic δ18O and terrigenous ɛNd changes. Terrigenous sediment ɛNd values rapidly shifted to less radiogenic signatures at the onset of the PrOM Event, indicating an abrupt change in provenance favoring ancient sources such as the Paleoproterozoic East Antarctic craton. Bottom water ɛNd reached a minimum value during the PrOM Event, although the shift begins much earlier than the terrigenous ɛNd excursion. The origin of the abrupt change in terrigenous sediment provenance is compatible with a change in Antarctic terrigenous sediment flux and/or source as opposed to a reorganization of ocean currents. A change in terrigenous flux and/or source of Antarctic sediments during the oxygen isotope maximum suggests a combination of cooling and ice growth in East Antarctica during the early late Eocene.

  7. Cretaceous and Eocene poroid hymenophores from Vancouver Island, British Columbia.

    PubMed

    Smith, Selena Y; Currah, Randolph S; Stockey, Ruth A

    2004-01-01

    Two fossil poroid hymenophore fragments, one from the Cretaceous Period and the other from the Eocene Epoch, are described. The permineralized specimens were obtained from marine calcareous concretions on Vancouver Island, British Columbia, Canada, and were studied using the cellulose acetate peel technique. Size and distribution of pores in the hymenophores, as well as the hyphal anatomy of the dissepiments and some hymenial elements, were examined. In the Cretaceous specimen, Quatsinoporites cranhamii sp. nov., pores are round to elliptical, three per mm, and 130-540 μm diam. Dissepiments consist of narrow, simple septate, hyphae. Neither basidia nor basidiospores are present, but acuminate hymenial cystidia, up to 54 μm in length, are common. The Eocene specimen, Appianoporites vancouverensis sp. nov., has a pore density of six per mm and pores are 130-163 μm in diam. Dissepiments consist of narrow, simple septate, thin-walled hyphae. Neither basidia nor basidiospores are present, but acuminate, thick-walled hymenial cystidia, up to 32 μm in length, are common. The poroid hymenophore is a characteristic of a number of extant basidiomycete taxa, including the Boletales, Polyporales and Hymenochaetales. It is unlikely that the fleshy, ephemeral, terrestrial basidiomata of the Boletales would be preserved in a marine environment, and thus the specimens are interpreted as belonging to basidiomycete lineages, with persistent, leathery or corky basidiomata. The simple septate hyphae, the minute pores and presence of cystidia most closely resemble taxa of the Hymenochaetales. These fossils unequivocally push back the minimum age of homobasidiomycetes and extend their paleogeographical range.

  8. Equatorial Kelvin Waves: A UARS MLS View.

    NASA Astrophysics Data System (ADS)

    Canziani, Pablo O.; Holton, James R.; Fishbein, Evan; Froidevaux, Lucien; Waters, Joe W.

    1994-10-01

    Data from the Microwave Limb Sounder instrument on the Upper Atmosphere Research Satellite are used to compare two periods of Kelvin wave activity during different stages of the equatorial quasi-biennial oscillation. The analysis is carried out using an asynoptic mapping technique. A wide bandpass filter is used to isolate the frequency bands where Kelvin waves have been identified in previous studies. Time-height and time-latitude plots of the bandpassed data are used to identify Kelvin wave activity in the temperature and ozone fields. Frequency spectra of temperature and ozone amplitudes are constructed to further analyze the latitudinal and meridional distribution of Kelvin wave activity in zonal wavenumbers 1 and 2. The characteristics identified in these plots agree well with theoretical predictions and previous observations of middle atmosphere Kelvin waves.The time-height and time-latitude plots support the existence of Kelvin waves in discrete frequency bands; the slow, fast, and ultrafast Kelvin modes are all identified in the data. The characteristics of these modes do not vary much despite different mean flow conditions in the two periods examined.For the Kelvin wave-induced perturbations in ozone, the change from a transport-dominated regime below 10 hPa to a photochemically controlled regime above 10 hPa is clearly apparent in the height dependence of the phase difference between temperature and ozone. The ratios of the ozone perturbation amplitude to the temperature perturbation amplitude for the various observed Kelvin wave modes are in agreement with model estimates and LIMS (Limb Infrared Monitor of the Stratosphere) observations in the lower half of the region sampled but appear to be too large in the upper stratosphere and lower mesosphere.

  9. Climatology of equatorial stratosphere over Lagos, Nigeria

    NASA Astrophysics Data System (ADS)

    Oyekola, Oyedemi Samuel

    We have used 12 complete calendar years (January 1993-December 2004) of monthly averages of measurements made by the Dobson spectrophotometer instrument over an urban site, Lagos (6.6oN, 3.3oE), southwest Nigeria, to study equatorial stratospheric column ozone variations and trends. Our results indicate that the time-averaged total column ozone has a seasonal cy-cle, which maximizes in June and July with a value of 259 Dobson units (DU) and minimizes in February with a magnitude of 250 DU. Statistical analysis of the climatological mean monthly total Dobson O3 record for 1993-2004 show that the local trend is approximately +0.041±0.0011 DU/year (+0.49±0.013% per decade). Spectral analysis was applied to the monthly averages series. The significant periodicity at 95% confidence level demonstrate prominent spectra peaks near 1.9 and 3.6 years, representative of quasi-biennial oscillation (QBO) and quasi-triennial oscillation (QTO), respectively. Signal due to semiannual variation is also identified at Lagos sounding site. Comparison with the ozone observations from Total Ozone Mapping Spectrom-eter (TOMS) on board the Earth-Probe (EP) satellite for the period from 1997 to 2002 reveal that EP/TOMS instrument consistently larger than the ground-based measurement from Dob-son station. Percentage mean relative disparity ranges from -11% to 15%. The root mean square error (RMSE) between satellite and ground-based observations over Lagos ranges be-tween ˜35-83 DU with largest and lowest variability occurring during the ascending phase of solar activity (1999, 10.7 cm radio flux, F10.7 equals 154 flux units) and during the peak phase of solar activity (2001, F10.7 equals 181), respectively.

  10. Neotectonics in the northern equatorial Brazilian margin

    NASA Astrophysics Data System (ADS)

    Rossetti, Dilce F.; Souza, Lena S. B.; Prado, Renato; Elis, Vagner R.

    2012-08-01

    An increasing volume of publications has addressed the role of tectonics in inland areas of northern Brazil during the Neogene and Quaternary, despite its location in a passive margin. Hence, northern South America plate in this time interval might have not been as passive as usually regarded. This proposal needs further support, particularly including field data. In this work, we applied an integrated approach to reveal tectonic structures in Miocene and late Quaternary strata in a coastal area of the Amazonas lowland. The investigation, undertaken in Marajó Island, mouth of the Amazonas River, consisted of shallow sub-surface geophysical data including vertical electric sounding and ground penetrating radar. These methods were combined with morphostructural analysis and sedimentological/stratigraphic data from shallow cores and a few outcrops. The results revealed two stratigraphic units, a lower one with Miocene age, and an upper one of Late Pleistocene-Holocene age. An abundance of faults and folds were recorded in the Miocene deposits and, to a minor extent, in overlying Late Pleistocene-Holocene strata. In addition to characterize these structures, we discuss their origin, considering three potential mechanisms: Andean tectonics, gravity tectonics related to sediment loading in the Amazon Fan, and rifting at the continental margin. Amongst these hypotheses, the most likely is that the faults and folds recorded in Marajó Island reflect tectonics associated with the history of continental rifting that gave rise to the South Atlantic Ocean. This study supports sediment deposition influenced by transpression and transtension associated with strike-slip divergence along the northern Equatorial Brazilian margin in the Miocene and Late Pleistocene-Holocene. This work records tectonic evidence only for the uppermost few ten of meters of this sedimentary succession. However, available geological data indicate a thickness of up to 6 km, which is remarkably thick for

  11. Little is plain about acid rain

    SciTech Connect

    Wantuck, M.M.

    1984-11-01

    Control of forest fires, which supplied alkaline ash to naturally acidic forest floors and neighboring lakes, may be part of the current acid rain problem. Researchers know that acid rain is not new, but they don't know how much sulfur dioxide (SO/sub 2/) emissions from fossil fuels contributes or how far those emissions travel. The debate over Clean Air Act provisions surrounds this lack of certainty over the effectiveness of pollution regulations at a time when the administration seeks to reduce the government role and cost. Studies of the effects of acid rain on lakes, forests, and crops are inconclusive, making it difficult for Congress to legislate emission standards. Utility plants will be able to choose among coal cleaning, wet and dry scrubbing, and fluidized-bed combustion technologies if Congress reduces emission levels.

  12. Acid rain: solving a transborder problem

    SciTech Connect

    Roberts, J.

    1981-01-01

    The problem of air pollution drifting across the border into Canada and falling as acid rain is discussed. This acid rain is having a great variety of negative impacts on lakes, streams, groundwater, soil, building surfaces, and on forests and certain crops. Between seven and eight million tons of SO/sub 2/ falling on Canada every year, along with four million tons of No/sub x/. At least half of this amount originates from emissions released in the US. The US and Canada took the first step towards reducing the transborder flow of acid rain in 1980, with the signing of a Memorandum of Intent between the two governments. The agreement pledges both countries to negotiate an air pollution agreement. In the interim, the two countries are committed to an enforcement of existing rules and regulations, and to cooperate in studies aimed at gaining information needed to draft an effective agreement.

  13. Optical rain gauge using a divergent beam.

    PubMed

    Wang, T I; Lawrence, R S; Tsay, M K

    1980-11-01

    We have shown that path-averaged rain rates can be obtained from the raindrop-induced amplitude scintillations of a divergent laser beam (spherical wave case). We found that the rain rate obtained from a divergent beam is less sensitive to drop-size distribution than that from a collimated beam. However, the path-weighting function is heavily weighted toward the receiving end in the spherical wave case, whereas in the plane wave case, it is almost uniformly weighted along the optical path. The theory was confirmed by observations on two optical paths, one using a collimated beam on a 200-m path, the other using a divergent beam on a 1000-m path. The results for the longer path show a saturation effect for rain rates higher than 12 mm/h.

  14. Equatorial hydrology studies by satellite telemetry

    SciTech Connect

    Clegg, B.; Koranda, J.; Robison, W.; Holladay, G.

    1980-12-30

    We are using a geostationary satellite functioning as a transponder to collect surface environmental data to describe the fate of soil-borne radionuclides. The remote, former atomic testing grounds at the Enewetak and Bikini Atolls present a difficult environment in which to collect continuous field data. Our land-based, solar-powered microprocessor and environmental data systems remotely measure net and total solar radiation, rain, humidity, temperature, and soil-water potentials. For the past year, our water-flux model predicted wet season plant-transpiration rates nearly equal to the 6- to 7-mm/d evaporation-pan rate, which decreases to 2 to 3 mm/d for the dry season. From the microclimate data we estimated a 1:3 and 1:20 /sup 137/Cs dry-matter concentration ratio, which was later confirmed by radioisotopic analysis. This ratio exacerbates the dose to man from intake of food plants. Nephelometer measurements of airborne particulates presently indicate a minimum respiratory radiological dose.

  15. Rain in the U.S. Midwest

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The powerful storms that moved across the U.S. Midwest during the first week of May 2007 brought wind, hail, tornadoes, and drenching rain. This image shows rainfall totals over parts of Oklahoma, Kansas, and Nebraska between May 1 and May 8, based in part on measurements made by the Tropical Rainfall Measuring Mission (TRMM) satellite. More than 400 millimeters (15.7 inches) of rain fell over some regions, corresponding with locations where the National Weather Service reported severe weather. A wide swath of red and orange (between 240 and 400 millimeters of rain) arcs in a clockwise direction from western Oklahoma, through central Kansas, and into southeastern Nebraska. The reddish-orange bull's-eye over southeastern Louisiana is evidence of the torrential rains that pounded visitors to the annual New Orleans Jazz Festival. South-central Texas' Edward Plateau was soaked with more than 240 millimeters of rain during the period, as well. From May 4 to May 8, the National Weather Service received approximately 683 reports of severe weather, 140 of which were reports of tornadoes, including the massive F5 tornado that devastated the city of Greensburg, Kansas. Beyond the damaging winds and tornadoes, the torrential rain triggered extensive flooding throughout the Central Plains. On the evening of May 7, flood warnings were in effect from South Dakota to southern Texas, and by May 8, the Hydrologic Information Center reported moderate to major flooding at 53 stream gauge sites in South Dakota, Iowa, Kansas, Nebraska, Missouri, and Arkansas. The floods could be as severe as the 1993 flood, one of the costliest floods in U.S. history, reported the Associated Press.

  16. Acid rain and electric utilities 2

    SciTech Connect

    1997-12-31

    This proceedings contains more than 100 technical presentations dealing with a variety of topics concerning the Title IV acid rain provisions of the Clean Air Act Amendments of 1990. Some of the major topics addressed include: emerging environmental issues impacting electric utilities (proposed revisions to the ozone and particulate matter NAAQS), acid rain program overview, continuous emissions monitoring rule revisions, global climate change and CO{sub 2}, emissions data management, Clean Air Power Initiative and regional issues, compliance/designated representative, flow monitoring, emissions control technology, allowance and trading, emission reductions, NO{sub x} control issues, hazardous air pollutants, and CEMS advances.

  17. Materials degradation caused by acid rain

    SciTech Connect

    Baboian, R.

    1986-01-01

    This book presents the papers given at a symposium on acid rain. Topics considered at the symposium included acidification, wet deposition, dry deposition, the corrosion of metals, corrosion products, the weathering of steel, environmental effects, automotive corrosion, effects on indoor surfaces, the degradation of organics, effects on wood surfaces, effects on plants, the acid rain degradation of nylon, the legal aspects of materials damage, the economic features of materials degradation, the economic assessment of acid damage to building materials, and the application of a theory for the economic assessment of corrosion damage.

  18. Nonlinear bounce resonances between magnetosonic waves and equatorially mirroring electrons

    NASA Astrophysics Data System (ADS)

    Chen, Lunjin; Maldonado, Armando; Bortnik, Jacob; Thorne, Richard M.; Li, Jinxing; Dai, Lei; Zhan, Xiaoya

    2015-08-01

    Equatorially mirroring energetic electrons pose an interesting scientific problem, since they generally cannot resonate with any known plasma waves and hence cannot be scattered down to lower pitch angles. Observationally it is well known that the flux of these equatorial particles does not simply continue to build up indefinitely, and so a mechanism must necessarily exist that transports these particles from an equatorial pitch angle of 90° down to lower values. However, this mechanism has not been uniquely identified yet. Here we investigate the mechanism of bounce resonance with equatorial noise (or fast magnetosonic waves). A test particle simulation is used to examine the effects of monochromatic magnetosonic waves on the equatorially mirroring energetic electrons, with a special interest in characterizing the effectiveness of bounce resonances. Our analysis shows that bounce resonances can occur at the first three harmonics of the bounce frequency (nωb, n = 1, 2, and 3) and can effectively reduce the equatorial pitch angle to values where resonant scattering by whistler mode waves becomes possible. We demonstrate that the nature of bounce resonance is nonlinear, and we propose a nonlinear oscillation model for characterizing bounce resonances using two key parameters, effective wave amplitude à and normalized wave number k~z. The threshold for higher harmonic resonance is more strict, favoring higher à and k~z, and the change in equatorial pitch angle is strongly controlled by k~z. We also investigate the dependence of bounce resonance effects on various physical parameters, including wave amplitude, frequency, wave normal angle and initial phase, plasma density, and electron energy. It is found that the effect of bounce resonance is sensitive to the wave normal angle. We suggest that the bounce resonant interaction might lead to an observed pitch angle distribution with a minimum at 90°.

  19. Differing Eocene floral histories in southeastern North America and Western Europe: influence of paleogeography

    USGS Publications Warehouse

    Frederiksen, N.O.

    1995-01-01

    Pollen data show that in southeastern North America, the Eocene angiosperm flora attained its maximum relative diversity some 8 m.y. after the late early Eocene to earliest middle Eocene to earliest middle Eocene climatic maximum. Increasing diversity resulted in part from the flora's position on a large continent which allowed easy migration. In western Europe, the floral diversity began decreasing even before the climatic maximum. Paleogeography played large roles in this diversity decrease. In western Europe, terrestrial floras were on islands and peninsulas in the sea, so that the floras underwent increasing isolation and partial local extermination. Temperate plants generally did not migrate to western Europe, because of a lack of nearby uplands, lack of northern terrestrial source areas for these plants, and presence of the Turgai Straights barrier. -from Authors

  20. Fossil palm beetles refine upland winter temperatures in the Early Eocene Climatic Optimum

    PubMed Central

    Archibald, S. Bruce; Morse, Geoffrey E.; Greenwood, David R.; Mathewes, Rolf W.

    2014-01-01

    Eocene climate and associated biotic patterns provide an analog system to understand their modern interactions. The relationship between mean annual temperatures and winter temperatures—temperature seasonality—may be an important factor in this dynamic. Fossils of frost-intolerant palms imply low Eocene temperature seasonality into high latitudes, constraining average winter temperatures there to >8 °C. However, their presence in a paleocommunity may be obscured by taphonomic and identification factors for macrofossils and pollen. We circumvented these problems by establishing the presence of obligate palm-feeding beetles (Chrysomelidae: Pachymerina) at three localities (a fourth, tentatively) in microthermal to lower mesothermal Early Eocene upland communities in Washington and British Columbia. This provides support for warmer winter Eocene climates extending northward into cooler Canadian uplands. PMID:24821798

  1. Fragments of Late Eocene Earth-Impacting Asteroids Linked to Disturbance of Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Schmitz, B.; Boschi, S.; Cronholm, A.; Heck, P. R.; Monechi, S.; Montanari, A.; Terfelt, F.

    2015-07-01

    The impactors that created the large Popigai and Chesapeake Bay craters represent two different meteorite types. A Late Eocene multi-type asteroid shower may reflect solar-system instability and indicate an astronomical trigger of ice-house climate.

  2. Response To The Paleocene-Eocene Thermal Maximum Of Calcareous Nannofossils: Observations On Composition, Preservation And Calcification In Sediments From ODP Reference Cores

    NASA Astrophysics Data System (ADS)

    Raffi, I.; de Bernardi, B.

    2007-12-01

    Studies on a climate extreme as the Paleocene-Eocene Thermal Maximum (PETM, ~ 55 myrs ago) have shown the effects of these critical conditions on global biogeochemical cycles and ecosystem, including the marine and terrestrial biota. A prominent negative shift (~ 3 ‰) in marine δ13C, the Carbon Isotope Excursion (CIE) reflects the input of a large amount of isotopically depleted carbon in the ocean- atmosphere system. Studies of the few complete deep-sea sections recovered to date have shown how global climate, atmospheric CO2 levels, marine carbonate chemistry and continental weathering were dynamically related during the PETM. Together, these changes should have strongly influenced the calcifying organisms living in the surface (photic zone) of the oceans. For this reason, recent investigations have focus on the planktonic community response to the shifts in oceanic environments during the PETM, specifically the response of calcifying microplankton to higher CO2 and lower pH, as well as the possible role of plankton in drawing down CO2. Calcareous nannofossils seem to play an important role in these interrelated mechanisms. For this reason we have performed detailed micropaleontologic analysis (using a SEM) of calcareous nannofossil assemblages in selected samples from selected Paleocene/Eocene deep-sea sediment cores with the purpose of documenting possible influence on assemblage composition and preservation. The sediments studied in detail are from ODP Site 1263 (from Southern East Atlantic, Walvis Ridge) that has been chosen as representative of one of the few complete PETM deep-sea cores. Comparative analyses were performed in few selected samples from sections located at different latitudes in the Atlantic and Pacific oceans (ODP Site 929, paleo-equatorial Atlantic, Ceara Rise; ODP Site 689, high-latitude Southern Atlantic, Maud Rise; ODP Sites 1215 and 1221, Eastern equatorial Pacific; ODP Site 1209, central Pacific, Shatsky Rise). This study documents

  3. Late Eocene- Oligocene magnetostratigraphy and biostratigraphy at South Atlantic DSDP site 522.

    USGS Publications Warehouse

    Poore, R.Z.; Tauxe, L.; Percival, S.F., Jr.; Labrecque, J.L.

    1982-01-01

    Upper Eocene to lowest Miocene sediments recovered at DSDP Site 522 in the S Atlantic Ocean allow direct calibration of magnetostratigraphy and calcareous plankton biostratigraphy. The results from Site 522 show that the Eocene/Oligocene boundary occurs in the reversed interval of magnetic Chron C13 (= C13R) and that the Oligocene/Miocene boundary probably occurs in the upper part of Chron C6C.-Authors

  4. Benthic foraminifera at the Paleocene/Eocene thermal maximum in the western Tethys (Forada section): variability in climate and productivity

    NASA Astrophysics Data System (ADS)

    Giusberti, L.; Boscolo Galazzo, F.; Thomas, E.

    2015-09-01

    overall arid climate, characterized by strong winds and intense upwelling, with an overall humid climate, with abundant rains and high sediment delivery (including refractory organic carbon) from land. Precessionally paced marl-limestone couplets occur throughout the recovery interval of the CIE and up to ten meters above it, suggesting that these wet-dry cycles persisted, though at declining intensity, after the peak PETM. Enhanced climate extremes at mid-latitudes might have been a direct response to the massive CO2 input in the ocean atmosphere system at the Paleocene-Eocene transition, and may have had a primary role in restoring the Earth system to steady state.

  5. Variability in climate and productivity during the Paleocene-Eocene Thermal Maximum in the western Tethys (Forada section)

    NASA Astrophysics Data System (ADS)

    Giusberti, L.; Boscolo Galazzo, F.; Thomas, E.

    2016-02-01

    arid climate, characterized by strong winds and intense upwelling, and an overall humid climate, with abundant rains and high sediment delivery (including refractory organic carbon) from land. Precessionally paced marl-limestone couplets occur throughout the recovery interval of the carbon isotope excursion (CIE) and up to 10 m above it, suggesting that these wet-dry cycles persisted, though at declining intensity, after the peak PETM. Enhanced climate extremes at mid-latitudes might have been a direct response to the massive CO2 input in the ocean atmosphere system at the Paleocene-Eocene transition, and may have had a primary role in restoring the Earth system to steady state.

  6. Seasonal influence of ENSO on the Atlantic ITCZ and equatorial South America

    NASA Astrophysics Data System (ADS)

    Münnich, M.; Neelin, J. D.

    2005-11-01

    In late boreal spring, especially May, a strong relationship exists in observations among precipitation anomalies over equatorial South America and the Atlantic intertropical convergence zone (ITCZ), and eastern equatorial Pacific and central equatorial Atlantic sea surface temperature anomalies (SSTA). A chain of correlations of equatorial Pacific SSTA, western equatorial Atlantic wind stress (WEA), equatorial Atlantic SSTA, sea surface height, and precipitation supports a causal chain in which El Niño/Southern Oscillation (ENSO) induces WEA stress anomalies, which in turn affect Atlantic equatorial ocean dynamics. These correlations show strong seasonality, apparently arising within the atmospheric links of the chain. This pathway and the influence of equatorial Atlantic SSTA on South American rainfall in May appear independent of that of the northern tropical Atlantic. Brazil's Nordeste is affected by the northern tropical Atlantic. The equatorial influence lies further to the north over the eastern Amazon and the Guiana Highlands.

  7. Equatorial superrotation in a thermally driven zonally symmetric circulation

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Harris, I.

    1981-01-01

    Near the equator where the Coriolis force vanishes, the momentum balance for the axially symmetric circulation is established between horizontal and vertical diffusion, which, a priori, does not impose constraints on the direction or magnitude of the zonal winds. Solar radiation absorbed at low latitudes is a major force in driving large scale motions with air rising near the equator and falling at higher latitudes. In the upper leg of the meridional cell, angular momentum is redistributed so that the atmosphere tends to subrotate (or corotate) at low latitudes and superrotate at high latitudes. In the lower leg, however, the process is reversed and produces a tendency for the equatorial region to superrotate. The outcome depends on the energy budget which is closely coupled to the momentum budget through the thermal wind equation; a pressure (temperature) maximum is required to sustain equatorial superrotation. Such a condition arises in regions which are convectively unstable and the temperature lapse rate is superadiabatic. It should arise in the tropospheres of Jupiter and Saturn; planetary energy from the interior is carried to higher altitudes where radiation to space becomes important. Upward equatorial motions in the direct and indirect circulations (Ferrel-Thomson type) imposed by insolation can then trap dynamic energy for equatorial heating which can sustain the superrotation of the equatorial region.

  8. Equatorial Winds on Saturn and the Stratospheric Oscillation

    NASA Technical Reports Server (NTRS)

    Li, Liming; Jian, Xun; Ingersoll, Andrew P.; DelGenio, Anthony D.; Porco, Carolyn C.; West, Robert A.; Vasavada, Ashwin R.; Ewald, Shawn P.; Conrath, Barney J.; Gierasch, Peter J.; Simon-Miller, Amy A.; Nixon, Conor A.; Achterberg, Richard K.; Orton, Glenn S.; Fletcher, Leigh N.; Baines, Kevin H.

    2011-01-01

    The zonal jets on the giant planets are generally thought to be stable with time. Recently, there are still some debates about the general thought. Here, we report a significant temporal variation of the equatorial jet at high-altitude on Saturn. Long-term (2004-2009) observations by Cassini reveal that wind speed at the 60-mbar level increased from 270 m/s in 2004 to 290 m/s in 2008, while the wind speed has been mostly constant over time at the 500-mbar level in the southern equatorial region. The Cassini observations further reveal that the equatorial jet intensified approximately 60 m/s in the stratosphere (1-5 mbar) from 2005 to 2008. The fact that the wind acceleration is weaker at the 60-mbar level (approximately 20 m/s) than at the 1-mbar level (approximately 60 m/s) demonstrates that the equatorial oscillation is damped when it propagates downwards to the tropopause around 60 mbar. The direct measurement of the varying equatorial jet around the tropopause also serves as a key boundary condition when deriving the thermal wind fields in the stratosphere.

  9. The annual cycle in equatorial convection and sea surface temperature

    SciTech Connect

    Mitchell, T.P.; Wallace, J.M. NASA, Goddard Space Flight Center, Greenbelt, MD )

    1992-10-01

    The coupled atmosphere-ocean system in the equatorial eastern Pacific and Atlantic exhibits a distinct annual cycle that is reflected in contrasting conditions at the times of the two equinoxes. The contrasts are so strong that they dominate the annual march of zonally averaged outgoing long wave radiation for the equatorial belt. The March equinox corresponds to the warm season when the equatorial cold tongues in the eastern Pacific and Atlantic area absent. With the onset of summer monsoon convection over Colombia, Central America, and West Africa in May-June, northward surface winds strengthen over the eastern Pacific and Atlantic, the equatorial cold tongues reappear, and the marine convection shifts from the equatorial belt to the intertropical convergence zones (ITCZs) along 8 deg N. On the basis of observational evidence concerning the timing and year-to-year regularity of the surface wind changes during the development of the cold tongues, it is argued that (1) the increase in the northward surface winds in response to the onset of the northern summer monsoon may be instrumental in reestablishing the cold tongues, and (2) positive feedbacks involving both the zonal and meridional wind components contribute to the remarkable robustness of the cold tongue-ITCZs complexes in both oceans. 36 refs.

  10. Century scale climatic rhythms in the equatorial Indian Ocean during the late Quaternary: Faunal and geochemical proxies from the Maldivian Archipelago

    NASA Astrophysics Data System (ADS)

    Sarkar, S.; Gupta, A. K.

    2012-04-01

    The equatorial Indian Ocean is swept by the Indian Ocean equatorial westerlies (IEW) which are strong during monsoon transitions in April-May and October-November, driving Eastward Equatorial Current (EEC) in the upper ocean. This study is based on the biogenic sediments from Ocean Drilling Program (ODP) Hole 716A, recovered beneath the narrow equatorial track (7 Degree North to 7 Degree South) along which the IEW prevail. We analyzed 300 Kyr record of benthic and planktic foraminifera, pteropods combined with stable isotope values measured on planktic foraminifer Globigerinoides ruber from 451 core samples to understand paleoceanographic and paleoclimatic changes in the equatorial Indian Ocean during the late Quaternary (~450 - 150 Kyrs). Factor and cluster analyses of the 53 highest-ranked benthic foraminiferal species enabled to identify five biofacies, indicating varied nature of deep-sea environments during the late Quaternary, with a major shift across the middle Brunhes epoch (across Marine Isotope Stage 9 and 8). Biofacies Robulus nicobarensis - Trifarina reussi (Rn-Tr), Uvigerina porrecta - Reussella simplex (Upo-Rs) and Cymbaloporetta squammosa - Bolivinita sp. (Cs-Bsp) document high organic flux with low oxygen paleoenvironment dominating before the mid-Brunhes event, similar to Globigerina bulloides population, while benthic foraminiferal biofacies Hoeglundina elegans - Miliolinella subrotunda (He-Ms) and Uvigerina peregrina - Quinqueloculina seminulum (Upe-Qs) record high seasonality in food supply with well-oxygenated deep water after ~300 Kyr. These changes are also visible in planktic foraminifera and pteropod record. In the present day, the strength of the IEW is inversely related to the Indian Ocean Dipole (IOD). The IEW weakened across MIS 9/8 during which time the IOD strengthened, causing heavy rains and floods over the equatorial East Africa and deficient rainfall over Australasia. The proxy response changed from low to high frequency cycles

  11. The palaeobiology of high latitude birds from the early Eocene greenhouse of Ellesmere Island, Arctic Canada.

    PubMed

    Stidham, Thomas A; Eberle, Jaelyn J

    2016-02-12

    Fossils attributable to the extinct waterfowl clade Presbyornithidae and the large flightless Gastornithidae from the early Eocene (~52-53 Ma) of Ellesmere Island, in northernmost Canada are the oldest Cenozoic avian fossils from the Arctic. Except for its slightly larger size, the Arctic presbyornithid humerus is not distinguishable from fossils of Presbyornis pervetus from the western United States, and the Gastornis phalanx is within the known size range of mid-latitude individuals. The occurrence of Presbyornis above the Arctic Circle in the Eocene could be the result of annual migration like that of its living duck and geese relatives, or it may have been a year-round resident similar to some Eocene mammals on Ellesmere and some extant species of sea ducks. Gastornis, along with some of the mammalian and reptilian members of the Eocene Arctic fauna, likely over-wintered in the Arctic. Despite the milder (above freezing) Eocene climate on Ellesmere Island, prolonged periods of darkness occurred during the winter. Presence of these extinct birds at both mid and high latitudes on the northern continents provides evidence that future increases in climatic warming (closer to Eocene levels) could lead to the establishment of new migratory or resident populations within the Arctic Circle.

  12. A redescription of Lithornis vulturinus (Aves, Palaeognathae) from the Early Eocene Fur Formation of Denmark.

    PubMed

    Bourdon, Estelle; Lindow, Bent

    2015-10-20

    The extinct Lithornithidae include several genera and species of flying palaeognathous birds of controversial affinities known from the Early Paleogene of North America and Europe. An almost complete, articulated skeleton from the Early Eocene marine deposits of the Fur Formation (Denmark) was recently assigned to Lithornis vulturinus Owen, 1840. This study provides a detailed redescription and comparison of this three-dimensionally preserved specimen (MGUH 26770), which is one of the best preserved representatives of the Lithornithidae yet known. We suggest that some new features might be diagnostic of Lithornis vulturinus, including a pterygoid fossa shallower than in other species of Lithornis and the presence of a small caudal process on the os palatinum. We propose that Lithornis nasi (Harrison, 1984) is a junior synonym of Lithornis vulturinus and we interpret minor differences in size and shape among the specimens as intraspecific variation. To date, Lithornis vulturinus is known with certainty from the latest Paleocene-earliest Eocene to Early Eocene of the North Sea Basin (Ølst, Fur and London Clay Formations). Among the four species of the genus Lithornis, the possibility that Lithornis plebius Houde, 1988 (Early Eocene of Wyoming) is conspecific with either Lithornis vulturinus or Lithornis promiscuus Houde, 1988 (Early Eocene of Wyoming) is discussed. The presence of closely related species of Lithornis on either side of the North Atlantic in the Early Eocene reflects the existence of a high-latitude land connection between Europe and North America at that time.

  13. Cross section through the Toa Baja drillsite: Evidence for northward change in Late Eocene deformation intensity

    SciTech Connect

    Larue, D.K. ); Berrong, B. )

    1991-03-01

    A 55 km geologic cross section through the Toa Baja Drillsite, generated by integrating geologic mapping data from the foothills of the Central Mountains of Puerto Rico with onshore and offshore multichannel seismic reflection data, provides an opportunity to examine in profile from the arc interior northward to within 40 km of the current trench slope break. Three structural divisions are recognized. In the foothills of Puerto Rico, Cretaceous and Eocene rocks are separated by transpressional strike-slip faults. In the vicinity of the Toa Baja drillsite where both seismic reflection and borehole data are available, Eocene rocks, deformed by thrust faults, .ie above a lower unit, interpreted to be of Cretaceous age. Offshore, north of the drilling site, seismic reflections suggest Eocene rocks onlap structural basement, thought to be Cretaceous rocks, and both units appear only slightly deformed. All Eocene and Eocene ( ) rocks are overlain by little deformed Oligocene to Recent rocks. From south to north, or from the arc massif interior toward the present-day trench, there is an apparent decrease in amount of Late Eocene to Middle Oligocene strike-slip and shortening deformation. Deformation events occurred mostly in the arc-interior and were not directly associated with the plate boundary which was probably near the Puerto Rico Trench.

  14. The palaeobiology of high latitude birds from the early Eocene greenhouse of Ellesmere Island, Arctic Canada

    PubMed Central

    Stidham, Thomas A.; Eberle, Jaelyn J.

    2016-01-01

    Fossils attributable to the extinct waterfowl clade Presbyornithidae and the large flightless Gastornithidae from the early Eocene (~52–53 Ma) of Ellesmere Island, in northernmost Canada are the oldest Cenozoic avian fossils from the Arctic. Except for its slightly larger size, the Arctic presbyornithid humerus is not distinguishable from fossils of Presbyornis pervetus from the western United States, and the Gastornis phalanx is within the known size range of mid-latitude individuals. The occurrence of Presbyornis above the Arctic Circle in the Eocene could be the result of annual migration like that of its living duck and geese relatives, or it may have been a year-round resident similar to some Eocene mammals on Ellesmere and some extant species of sea ducks. Gastornis, along with some of the mammalian and reptilian members of the Eocene Arctic fauna, likely over-wintered in the Arctic. Despite the milder (above freezing) Eocene climate on Ellesmere Island, prolonged periods of darkness occurred during the winter. Presence of these extinct birds at both mid and high latitudes on the northern continents provides evidence that future increases in climatic warming (closer to Eocene levels) could lead to the establishment of new migratory or resident populations within the Arctic Circle. PMID:26867798

  15. The palaeobiology of high latitude birds from the early Eocene greenhouse of Ellesmere Island, Arctic Canada.

    PubMed

    Stidham, Thomas A; Eberle, Jaelyn J

    2016-01-01

    Fossils attributable to the extinct waterfowl clade Presbyornithidae and the large flightless Gastornithidae from the early Eocene (~52-53 Ma) of Ellesmere Island, in northernmost Canada are the oldest Cenozoic avian fossils from the Arctic. Except for its slightly larger size, the Arctic presbyornithid humerus is not distinguishable from fossils of Presbyornis pervetus from the western United States, and the Gastornis phalanx is within the known size range of mid-latitude individuals. The occurrence of Presbyornis above the Arctic Circle in the Eocene could be the result of annual migration like that of its living duck and geese relatives, or it may have been a year-round resident similar to some Eocene mammals on Ellesmere and some extant species of sea ducks. Gastornis, along with some of the mammalian and reptilian members of the Eocene Arctic fauna, likely over-wintered in the Arctic. Despite the milder (above freezing) Eocene climate on Ellesmere Island, prolonged periods of darkness occurred during the winter. Presence of these extinct birds at both mid and high latitudes on the northern continents provides evidence that future increases in climatic warming (closer to Eocene levels) could lead to the establishment of new migratory or resident populations within the Arctic Circle. PMID:26867798

  16. A redescription of Lithornis vulturinus (Aves, Palaeognathae) from the Early Eocene Fur Formation of Denmark.

    PubMed

    Bourdon, Estelle; Lindow, Bent

    2015-01-01

    The extinct Lithornithidae include several genera and species of flying palaeognathous birds of controversial affinities known from the Early Paleogene of North America and Europe. An almost complete, articulated skeleton from the Early Eocene marine deposits of the Fur Formation (Denmark) was recently assigned to Lithornis vulturinus Owen, 1840. This study provides a detailed redescription and comparison of this three-dimensionally preserved specimen (MGUH 26770), which is one of the best preserved representatives of the Lithornithidae yet known. We suggest that some new features might be diagnostic of Lithornis vulturinus, including a pterygoid fossa shallower than in other species of Lithornis and the presence of a small caudal process on the os palatinum. We propose that Lithornis nasi (Harrison, 1984) is a junior synonym of Lithornis vulturinus and we interpret minor differences in size and shape among the specimens as intraspecific variation. To date, Lithornis vulturinus is known with certainty from the latest Paleocene-earliest Eocene to Early Eocene of the North Sea Basin (Ølst, Fur and London Clay Formations). Among the four species of the genus Lithornis, the possibility that Lithornis plebius Houde, 1988 (Early Eocene of Wyoming) is conspecific with either Lithornis vulturinus or Lithornis promiscuus Houde, 1988 (Early Eocene of Wyoming) is discussed. The presence of closely related species of Lithornis on either side of the North Atlantic in the Early Eocene reflects the existence of a high-latitude land connection between Europe and North America at that time. PMID:26624382

  17. Rain Barrels: A Catalyst for Change?

    ERIC Educational Resources Information Center

    Bakacs, Michele E.; Haberland, Mike; Mangiafico, Salvatore S.; Winquist, Aileen; Obropta, Christopher C.; Boyajian, Amy; Mellor, Sara

    2013-01-01

    Over the past 4 years, rain barrel programming for residents has been implemented in both Northern Virginia and New Jersey as a method for educating the public about stormwater management and water conservation. Program participants demonstrated a significant increase in knowledge of water resource issues. Follow-up surveys showed 58% of New…

  18. GPM Rain Rates in Tropical Cyclone Pam

    NASA Video Gallery

    NASA-JAXA's GPM Satellite Close-up of Cyclone Pam's Rainfall NASA-JAXA's GPM core satellite captured rain rates in Tropical Cyclone Pam at 03:51 UTC (2:51 p.m. local time) on March 14, 2015. Heavie...

  19. Acid Rain Analysis by Standard Addition Titration.

    ERIC Educational Resources Information Center

    Ophardt, Charles E.

    1985-01-01

    The standard addition titration is a precise and rapid method for the determination of the acidity in rain or snow samples. The method requires use of a standard buret, a pH meter, and Gran's plot to determine the equivalence point. Experimental procedures used and typical results obtained are presented. (JN)

  20. Remote sensing of rain over the ocean

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Computer models of the microwave emission from the earth's atmosphere were used to study the problem of retrieving meteorological information from the SMMR instrument that will be flown on NIMBUS-G. Methods for retrieving rain rate, wind speed, cloud height, and ocean temperature are described for the case when the satellite is over the ocean.

  1. Acid Rain: A Description of Bilingual Friesland.

    ERIC Educational Resources Information Center

    Zondag, Koen

    1984-01-01

    Using acid rain as a metaphor, discusses the status of the Frisian language and culture as one which, though apparently thriving, is really threatened. Examines the sources of this threat, i.e., the education system, the church, mass communication and transportation, and the demise of the Frisian village community. (SED)

  2. Acid Rain: Resource Materials for Schools.

    ERIC Educational Resources Information Center

    American Biology Teacher, 1983

    1983-01-01

    Provides listings of acid rain resource material groups under: (1) printed materials (pamphlets, books, articles); (2) audiovisuals (slide/tape presentations, tape, video-cassette); (3) miscellaneous (buttons, pocket lab, umbrella); (4) transparencies; (5) bibliographies; and (6) curriculum materials. Sources and prices (when applicable) are…

  3. Acid Rain Materials for Classroom Use.

    ERIC Educational Resources Information Center

    Factor, Lance; Kooser, Robert G.

    This booklet contains three separate papers suitable for use in an advanced high school or college chemistry course. The first paper provides background information on acids and bases. The second paper provides additional background information, focusing on certain aspects of atmospheric chemistry as it relates to the acid rain problem. An attempt…

  4. Acid Rain. Teacher's Guide. LHS GEMS.

    ERIC Educational Resources Information Center

    Hocking, Colin; Barber, Jacqueline; Coonrod, Jan

    This teacher's guide presents a unit on acid rain and introduces hands-on activities for sixth through eighth grade students. In each unit, students act as real scientists and gather evidence by using science process skills such as observing, measuring and recording data, classifying, role playing, problem solving, critical thinking, synthesizing…

  5. Acid Rain Program CEM audit program

    SciTech Connect

    Nguyen, K.O.T.; Alexander, T.H.; Dupree, J.C.

    1997-12-31

    This presentation will give an overview of the Acid Rain Program CEM Audit Program: electronic and field audits. The presentation will include the reasons for audits, field audit types and levels the steps used in develop in the audit program and the audit procedures.

  6. Acid Rain: A Student's First Sourcebook.

    ERIC Educational Resources Information Center

    Kyle, Beth Ann; And Others

    The purpose of this guide is to help students better understand the science, citizen action, and research issues that are part of the acid rain problem. The guide is designed for students in grades 4-8 and their teachers. Following an introduction, the first seven sections are informative in nature. They include: (1) "Observations about Acidity";…

  7. Disdrometer and Tipping Bucket Rain Gauge Handbook

    SciTech Connect

    Bartholomew. MJ

    2009-12-01

    The Distromet disdrometer model RD-80 and NovaLynx tipping bucket rain gauge model 260-2500E-12 are two devices deployed a few meters apart to measure the character and amount of liquid precipitation. The main purpose of the disdrometer is to measure drop size distribution, which it does over 20 size classes from 0.3 mm to 5.4 mm. The data from both instruments can be used to determine rain rate. The disdrometer results can also be used to infer several properties including drop number density, radar reflectivity, liquid water content, and energy flux. Two coefficients, N0 and Λ, from an exponential fit between drop diameter and drop number density, are routinely calculated. Data are collected once a minute. The instruments make completely different kinds of measurements. Rain that falls on the disdrometer sensor moves a plunger on a vertical axis. The disdrometer transforms the plunger motion into electrical impulses whose strength is proportional to drop diameter. The rain gauge is the conventional tipping bucket type. Each tip collects an amount equivalent to 0.01 in. of water, and each tip is counted by a data acquisition system anchored by a Campbell CR1000 data logger.

  8. Rain sensor for automatic systems on vehicles

    NASA Astrophysics Data System (ADS)

    Vasile, Alexandru; Vasile, Irina; Nistor, Adrian; Vladareanu, Luige; Pantazica, Mihaela; Caldararu, Florin; Bonea, Andreea; Drumea, Andrei; Plotog, Ioan

    2010-11-01

    Despite the fact that today vehicles are easier to drive and more reliable, the drivers' carefulness is diverted by a large number of factors (road conditions, traffic conditions, phone calls, navigation systems etc.). The automatic system of controlling the windscreen wipers meets exactly one of the carelessness factors. A rain sensor makes the activation of the system of windscreen wipers to become something that you turn on and forget about it. This completely automated system activated by rain measures the rain intensity and also the necessity to turn on the windscreen wipers and with what velocity. Using an advanced optical system, analogue signal processing and a control algorithm, this technology offers more safety and comfort on different weather conditions. The sensor beams an infrared light on the windshield at an angle carefully chosen. If the windshield is dry, the beam is reflected back in the sensor. If on the glass there are rain drops, they will reflect the light in different directions (the wetter the windshield is, the least of the beam ray is reflected back in the sensor).

  9. Air quality monitor and acid rain networks

    NASA Technical Reports Server (NTRS)

    Rudolph, H.

    1980-01-01

    The air quality monitor program which consists of two permanent air monitor stations (PAMS's) and four mobile shuttle pollutant air monitor stations (SPAMS's) is evaluated. The PAMS measures SO sub X, NO sub X particulates, CO, O3, and nonmethane hydrocarbons. The SPAMS measures O3, SO2, HCl, and particulates. The collection and analysis of data in the rain monitor program are discussed.

  10. TECHNOLOGICAL OPTIONS FOR ACID RAIN CONTROL

    EPA Science Inventory

    The paper discusses technological options for acid rain control. Compliance with Title IV of the Clean Air Act Amendments of 1990 will require careful scrutiny of a number of issues before selecting control options to reduce sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions...

  11. Promoting nitrate removal in rain gardens

    EPA Science Inventory

    Rain gardens are vegetated surface depressions, often located at low points in landscapes, designed to receive stormwater runoff from roads, roofs, and parking lots. The gardens’ sandy soils allow stormwater to drain quickly to the native soils below and eventually to groundwate...

  12. The crazy hollow formation (Eocene) of central Utah

    USGS Publications Warehouse

    Weiss, M.P.; Warner, K.N.

    2001-01-01

    The Late Eocene Crazy Hollow Formation is a fluviatile and lacustrine unit that was deposited locally in the southwest arm of Lake Uinta during and after the last stages of the lake the deposited the Green River Formation. Most exposures of the Crazy Hollow are located in Sanpete and Sevier Counties. The unit is characterized by a large variety of rock types, rapid facies changes within fairly short distances, and different lithofacies in the several areas where outcrops of the remnants of the formation are concentrated. Mudstone is dominant, volumetrically, but siltstone, shale, sandstone, conglomerate and several varieties of limestone are also present. The fine-grained rocks are mostly highly colored, especially in shades of yellow, orange and red. Sand grains, pebbles and small cobbles of well-rounded black chert are widespread, and "salt-and-pepper sandstone" is the conspicuous characteristic of the Crazy Hollow. The salt-and-pepper sandstone consists of grains of black chert, white chert, quartz and minor feldspar. The limestone beds and lenses are paludal and lacustrine in origin; some are fossiliferous, and contain the same fauna found in the Green River Formation. With trivial exceptions, the Crazy Hollow Formation lies on the upper, limestone member of the Green River Formation, and the beds of the two units are always accordant in attitude. The nature of the contact differs locally: at some sites there is gradation from the Green River to the Crazy Hollow; at others, rocks typical of the two units intertongue; elsewhere there is a disconformity between the two. A variety of bedrock units overlie the Crazy Hollow at different sites. In the southeasternmost districts it is overlain by the late Eocene formation of Aurora; in western Sevier County it is overlain by the Miocene-Pliocene Sevier River Formation; in northernmost Sanpete County it is overlain by the Oligocene volcanics of the Moroni Formation. At many sites bordering Sanpete and Sevier Valleys

  13. Inter- annual variability of water vapor over an equatorial coastal station using Microwave Radiometer observations.

    NASA Astrophysics Data System (ADS)

    Renju, Ramachandran Pillai; Uma, K. N.; Krishna Moorthy, K.; Mathew, Nizy; Raju C, Suresh

    The south-western region of the Indian peninsula is the gateway of Indian summer monsoon. This region experiences continuous monsoon rain for a longer period of about six months from June to November. The amount of water vapor variability is one of the important parameters to study the onset, active and break phases of the monsoon. Keeping this in view, a multi-frequency Microwave Radiometer Profiler (MRP) has been made operational for continuous measurements of water vapor over an equatorial coastal station Thiruvananthapuram (8.5(°) N, 76.9(°) E) since April 2010. The MRP estimated precipitable water vapor (PWV) for different seasons including monsoon periods have been evaluated by comparing with the collocated GPS derived water vapor and radiosonde measurements. The diurnal, seasonal and inter annual variation of water vapor has been studied for the last four years (2010-2013) over this station. The significant diurnal variability of water vapor is found only during the winter and pre-monsoon periods (Dec -April). The vertical distribution of water vapour is studied in order to understand its variability especially during the onset of monsoon. During the building up of south-west monsoon, the specific humidity increases to ˜ 10g/kg in the altitude range of 4-6 km and consistently maintained it throughout the active spells and reduces to below 2g/kg during break spells of monsoon. The instrument details and the results will be presented.

  14. Acid rain: the impact of local sources

    SciTech Connect

    Spaite, P.; Esposito, M.P.; Szabo, M.F.; Devitt, T.W.

    1980-11-24

    It has been assumed that acid rain is predominantly a problem of long-range transport of pollutants from large fossil fuel combustion sources, namely coal-fired utilities. However, close examination of fuel use information and source emission characteristics in the Adirondacks, Florida, and California suggests that local oil burning and automotive sources may be major contributors to the occurrence of acid rain in these areas. This report describes the possible role of local combustion sources in the production of acid rain, discusses the implications of the findings, and their relevance to alternative control strategies for acid rain. Oil-fired boilers, especially the smaller commercial, industrial, and residential units, produce at least 3 to 10 times as much primary sulfate per unit of sulfur content as coal-fired units. Moreover, oil-fired units emit comparatively large quantities of catalytic compounds capable of rapidly converting still more sulfur oxide to sulfate in the atmosphere. Thus, in areas where large quantities of oil are burned, the direct impact from locally generated sulfates may equal or even exceed that produced by imported sulfates derived from distant coal-burning sources. Fuel consumption data show that large quantities of oil are being consumed in areas experiencing acid rain. Forty percent of the residual and 36 percent of the distillate oil burned in the United States is consumed in the eight-state area surrounding the Adirondacks. California is the next largest oil-consuming area and Florida is third. Nitric acid is responsible for about 30 percent of rainfall acidity in the Northeast and Florida, and for about 30 to 75 percent of the rainfall acidity in California.

  15. IMF polarity effects on the equatorial ionospheric F-region

    SciTech Connect

    Sastri, J.H.

    1985-01-01

    An exploratory study is made of the influence, during the equinoxes, of the interplanetary magnetic field (IMF) sector structure on the ionospheric F-region using ionosonde data from several equatorial stations for a 3-yr period around the 19th sunspot cycle maximum. It is found that, compared with days having positive IMF polarity, the post-sunset increase of h'F near the dip equator and the depth of the equatorial ionization anomaly (EIA) are reduced during the vernal equinox and enhanced during the autumnal equinox on days with negative IMF polarity. Similar trends are also noted in the data for the 20th sunspot cycle maximum, but with reduced amplitude. The systematic changes in the F-region characteristics suggest a modification of the equatorial zonal electric fields in association with the IMF polarity-related changes in the semi-annual variation of geomagnetic activity. 24 references.

  16. In situ observations of bifurcation of equatorial ionospheric plasma depletions

    SciTech Connect

    Aggson, T.L.; Pfaff, R.F.; Maynard, N.C.

    1996-03-01

    Vector electric field measurements from the San Marco D satellite are utilized to investigate the bifurcation of ionospheric plasma depletions (sometimes called {open_quotes}bubbles{close_quotes}) associated with nightside equatorial spread F. These depletions are identified by enhanced upward ExB convection in depleted plasma density channels in the nighttime equatorial ionosphere. The in situ determination of the bifurcation process is based on dc electric field measurements of the bipolar variation in the zonal flow, westward and eastward, as the eastbound satellite crosses isolated signatures of updrafting plasma depletion regions. The authors also present data in which more complicated regions of zonal velocity variations appear as the possible result of multiple bifurcations of updrafting equatorial plasma bubbles. 10 refs., 7 fig.

  17. Iron sources and pathways into the Pacific Equatorial Undercurrent

    NASA Astrophysics Data System (ADS)

    Qin, Xuerong; Menviel, Laurie; Sen Gupta, Alex; Sebille, Erik

    2016-09-01

    Using a novel observationally constrained Lagrangian iron model forced by outputs from an eddy-resolving biogeochemical ocean model, we examine the sensitivity of the Equatorial Undercurrent (EUC) iron distribution to EUC source region iron concentrations. We find that elevated iron concentrations derived from New Guinea Coastal Undercurrent (NGCU) alone is insufficient to explain the high concentrations observed in the EUC. In addition, due to the spread in transit times, interannual NGCU iron pulses are scavenged, diluted, or eroded, before reaching the eastern equatorial Pacific. With an additional iron source from the nearby New Ireland Coastal Undercurrent, EUC iron concentrations become consistent with observations. Furthermore, as both the New Guinea and New Ireland Coastal Undercurrents strengthen during El Niño, increased iron input into the EUC can enhance the iron supply into the eastern equatorial Pacific. Notably, during the 1997/1998 El Niño, this causes a simulated 30% iron increase at a 13 month lag.

  18. The effect of islands on low frequency equatorial motions

    NASA Technical Reports Server (NTRS)

    Cane, M. A.; Du Penhoat, Y.

    1982-01-01

    A complete analytic solution is presented for the influence of equatorial islands on steady low-frequency waves. If the island is small (the meridional extent is much less than the equatorial radius of deformation, R), the waves pass it almost undisturbed, with the mass flux incident on the upstream side flowing around it nearly equally to the north and to the south and continuing on downstream in the lee of the island. For large islands (comparable in extent with R or larger), the principal response is organized as it would be if the island barrier were meridionally infinite. An incident Kelvin wave is largely reflected as long Rossby waves; symmetric long Rossby waves are reflected as equatorial Kelvin waves, while antisymmetric ones stop at the island barrier. In all cases, a boundary current composed of short Rossby waves forms at the eastern side of the island and accomplishes the required meridional redistribution of the zonal mass flux.

  19. Response of Deep Ocean Carbon Cycling to Astronomical Forcing in the Non-Glaciated Eocene 'Greenhouse' World

    NASA Astrophysics Data System (ADS)

    Sexton, P. F.; Wilson, P. A.; Pälike, H.

    2007-12-01

    Atmospheric carbon dioxide concentrations predicted for 2100 may not have existed on Earth since the early part of the Eocene epoch when global conditions were much warmer and less glaciated than today. Yet our understanding of carbon cycling and climate stability within the Eocene is extremely rudimentary. Here we present the first high-resolution paleoceanographic records across the early to middle Eocene boundary. Our records reveal multiple prominent perturbations to Eocene climate and the carbon cycle. We also observe breakdown in the post-Eocene/Oligocene boundary spatial pattern of astronomical pacing of deep ocean sediment calcium carbonate content. We attribute this divergent response to astronomical forcing to the deglaciated early Eocene climate state.

  20. Was the Eocene Arctic a Source Area for Exotic Plants and Mammals? (Invited)

    NASA Astrophysics Data System (ADS)

    Eberle, J. J.; Harrington, G. J.; Fricke, H. C.; Humphrey, J.; Hackett, L.; Newbrey, M.; Hutchison, J. H.

    2010-12-01

    Today’s High Arctic is undergoing rapid warming, but the impact on its animal and plant communities is not clear. As a deep time analog to better understand and predict the impacts of global warming on the Arctic biota, early Eocene (52-53 Ma) rocks on Ellesmere Island, Nunavut in Canada’s High Arctic (~79°N latitude) preserve evidence of diverse terrestrial ecosystems that supported dense forests inhabited by turtles, alligators, snakes, primates, tapirs, brontotheres, and hippo-like Coryphodon. The fossil localities were just a few degrees further south and still well above the Arctic Circle during the early Eocene; consequently, the biota experienced months of continuous sunlight as well as darkness, the Arctic summer and winter, respectively. The flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, and recently published analyses of biogenic phosphate from fossil fish, turtle, and mammal estimate warm summers (19 - 20 C) and mild, above-freezing winters. In general, temperature estimates for the early Eocene Arctic can be compared to those found today in temperate rainforests in the Pacific Northwest of the United States. The early Eocene Arctic mammalian fauna shares most genera with coeval mid-latitude faunas thousands of kilometers to the south in the US Western Interior, and several genera also are shared with Europe and Asia. Recent analyses suggest that the large herbivores such as hippo-like Coryphodon were year-round inhabitants in the Eocene Arctic forests. Although several of the Eocene Arctic mammalian taxa are hypothesized to have originated in either mid-latitude North America or Asia, the earlier occurrence of certain clades (e.g., tapirs) in the Arctic raises the possibility of a northern high-latitude origin. Analysis of the early Eocene Arctic palynoflora indicates comparable richness to early Eocene plant communities in the US Western Interior, but nearly 50% of its species (mostly angiosperms) are

  1. A recent, equatorial, periglacial environment on Mars

    NASA Astrophysics Data System (ADS)

    Balme, M. R.; Gallagher, C.; Murray, J. B.; Muller, J.-P.

    2009-04-01

    During the Viking era, Mars' recent climatic history was held to be cold and dry with little evidence for long-lived liquid water near the surface; signs of a past wetter, warmer climate were confined to ancient Noachian or Hesperian-aged terrains. Recent missions have revealed contemporary near-surface water-ice to be abundant at high latitudes, and a population of mid-latitude fluvial-like gullies that appear to have formed by transient melting of ice or snow. Thus today's view of Mars' recent surface evolution is one of global permafrost existing within a framework of climate change, the timescales of which are governed by obliquity cycles with periods of tens to hundreds of thousands of years. However, in recent mapping work of the equatorial Elysium Planitia region using the latest very high resolution images of Mars (HiRISE; 25cm/pixel) we have found evidence for longer-lived, geologically recent liquid water at the martian surface. This suggests that there was a recent period when the climate was warmer than current obliquity cycle-based models predict. The Elysium Planitia region of Mars is both geologically young (late Amazonian period; <100 Ma) and hosts a variety of landforms that are morphologically similar to those of periglacial and permafrost environments on Earth. The region was exposed to massive flooding from deep underground sources during the late Amazonian, as demonstrated by the distinctive fluvial morphologies seen in the outflow channel Athabasca Vallis. These floods would have provided both the source of ice and particulate material required for a periglacial or permafrost landscape and there was probably a long-lived, but slowly freezing, lake or sea in the downstream Elysium basin. However, the provenance of the materials and landforms of this region is disputed: many authors still regard the Athabasca Vallis and Elysium basin as being flood lava provinces, with effusive volcanic materials reoccupying earlier flood landscapes (a classic

  2. Molecular characterization of Cryptosporidium isolates from humans in Equatorial Guinea.

    PubMed

    Blanco, María Alejandra; Iborra, Asunción; Vargas, Antonio; Nsie, Eugenia; Mbá, Luciano; Fuentes, Isabel

    2009-12-01

    The aim of the study was to perform a molecular characterization of clinical isolates of Cryptosporidium species from Equatorial Guinea. Standard laboratory methods were used to identify 35 cryptosporidiosis cases among 185 patients. PCR-RFLP successfully identified 34 Cryptosporidium species from these 35 cases, comprising C. parvum (52.9%), C. hominis (44.1%) and C. meleagridis (2.9%); over 90% of the species were isolated from HIV-positive patients. This is the first report of the molecular characterization of Cryptosporidium species isolated from humans in Equatorial Guinea and shows that zoonotic and anthroponotic transmission is present in this country.

  3. Longitudinal Variation and Waves in Jupiter's South Equatorial Wind Jet

    NASA Technical Reports Server (NTRS)

    Simon-Miller, A. A.; Rogers, John H.; Gierasch, Peter J.; Choi, David; Allison, Michael; Adamoli, Gianluigi; Mettig, Hans-Joerg

    2012-01-01

    We have conducted a detailed study of the cloud features in the strong southern equatorial wind jet near 7.5 S planetographic latitude. To understand the apparent variations in average zonal wind jet velocity at this latitude [e.g.. 1,2,3], we have searched for variations iIi both feature latitude and velocity with longitude and time. In particular, we focused on the repetitive chevron-shaped dark spots visible on most dates and the more transient large anticyclonic system known as the South Equatorial Disturbance (SED). These small dark spots are interpreted as cloud holes, and are often used as material tracers of the wind field.

  4. Observations of ELF electromagnetic waves associated with equatorial spread F

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.; Holtet, J. A.; Tsurutani, B. T.

    1979-01-01

    Extreme low frequency electromagnetic waves have been observed below the F peak in the equatorial ionosphere by instruments onboard OGO-6. Electrostatic wave observations indicate that the steep gradient was unstable to the process which causes equatorial spread F above the region where the electromagnetic waves were observed. The data are very similar to observations near the polar cusp and give further evidence that ELF waves are excluded from regions of rapid and irregular density increases. Low level electromagnetic waves with similar properties were occasionally observed on the nightside by the OVI-17 electric field sensor and may be plasmaspheric hiss which has propagated to low altitude.

  5. 40 CFR 76.3 - General Acid Rain Program provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false General Acid Rain Program provisions. 76.3 Section 76.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.3 General Acid Rain Program...

  6. 40 CFR 76.3 - General Acid Rain Program provisions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 17 2014-07-01 2014-07-01 false General Acid Rain Program provisions. 76.3 Section 76.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.3 General Acid Rain Program...

  7. 40 CFR 76.3 - General Acid Rain Program provisions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 17 2012-07-01 2012-07-01 false General Acid Rain Program provisions. 76.3 Section 76.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.3 General Acid Rain Program...

  8. 40 CFR 76.3 - General Acid Rain Program provisions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 17 2013-07-01 2013-07-01 false General Acid Rain Program provisions. 76.3 Section 76.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.3 General Acid Rain Program...

  9. 40 CFR 76.3 - General Acid Rain Program provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 16 2011-07-01 2011-07-01 false General Acid Rain Program provisions. 76.3 Section 76.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.3 General Acid Rain Program...

  10. Effects of acid rain on crops and trees

    SciTech Connect

    Cowling, E.B.; Dochinger, L.S.

    1984-01-01

    A general treatment of the subject of acid rain and its effets are discussed along with sources of acid rain and its near-term (the last couple of decades). The effects of acid rain on terrestrial ecosystems are treated in some detail. Some treatment is given of the ecosystem-level effects of acid precipitation.

  11. 14 CFR 33.78 - Rain and hail ingestion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Rain and hail ingestion. 33.78 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.78 Rain and... rain and hail, as defined in appendix B to this part. Acceptable engine operation precludes...

  12. 14 CFR 33.78 - Rain and hail ingestion.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Rain and hail ingestion. 33.78 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.78 Rain and... rain and hail, as defined in appendix B to this part. Acceptable engine operation precludes...

  13. 14 CFR 33.78 - Rain and hail ingestion.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Rain and hail ingestion. 33.78 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.78 Rain and... rain and hail, as defined in appendix B to this part. Acceptable engine operation precludes...

  14. 14 CFR 33.78 - Rain and hail ingestion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rain and hail ingestion. 33.78 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.78 Rain and... rain and hail, as defined in appendix B to this part. Acceptable engine operation precludes...

  15. 14 CFR 33.78 - Rain and hail ingestion.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Rain and hail ingestion. 33.78 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.78 Rain and... rain and hail, as defined in appendix B to this part. Acceptable engine operation precludes...

  16. The Effects of Rain Garden Size on Performance

    EPA Science Inventory

    The presentation discusses the effect of rain garden size on the hydrologic and pollutant removal performance of rain garden systems. The slides will summarize data from both the full-scale rain garden project associated with the permeable pavement parking lot as well as the pilo...

  17. Anthropoid humeri from the late Eocene of Egypt

    PubMed Central

    Seiffert, Erik R.; Simons, Elwyn L.; Fleagle, John G.

    2000-01-01

    A number of recent studies have, by necessity, placed a great deal of emphasis on the dental evidence for Paleogene anthropoid interrelationships, but cladistic analyses of these data have led to the erection of phylogenetic hypotheses that appear to be at odds with biogeographic and stratigraphic considerations. Additional morphological data from the cranium and postcranium of certain poorly understood Paleogene primates are clearly needed to help test whether such hypotheses are tenable. Here we describe humeri attributable to Proteopithecus sylviae and Catopithecus browni, two anthropoids from late Eocene sediments of the Fayum Depression in Egypt. Qualitative and morphometric analyses of these elements indicate that humeri of the oligopithecine Catopithecus are more similar to early Oligocene propliopithecines than they are to any other Paleogene anthropoid taxon, and that Proteopithecus exhibits humeral similarities to parapithecids that may be symplesiomorphies of extant (or “crown”) Anthropoidea. The humeral morphology of Catopithecus is consistent with certain narrowly distributed dental apomorphies—such as the loss of the upper and lower second premolar and the development of a honing blade for the upper canine on the lower third premolar—which suggest that oligopithecines constitute the sister group of a clade containing propliopithecines and Miocene-Recent catarrhines and are not most closely related to Proteopithecus as has recently been proposed. PMID:10963669

  18. Primate postcrania from the late middle Eocene of Myanmar

    PubMed Central

    Ciochon, Russell L.; Gingerich, Philip D.; Gunnell, Gregg F.; Simons, Elwyn L.

    2001-01-01

    Fossil primates have been known from the late middle to late Eocene Pondaung Formation of Myanmar since the description of Pondaungia cotteri in 1927. Three additional primate taxa, Amphipithecus mogaungensis, Bahinia pondaungensis and Myanmarpithecus yarshensis, were subsequently described. These primates are represented mostly by fragmentary dental and cranial remains. Here we describe the first primate postcrania from Myanmar, including a complete left humerus, a fragmentary right humerus, parts of left and right ulnae, and the distal half of a left calcaneum, all representing one individual. We assign this specimen to a large species of Pondaungia based on body size and the known geographic distribution and diversity of Myanmar primates. Body weight estimates of Pondaungia range from 4,000 to 9,000 g, based on humeral length, humeral midshaft diameter, and tooth area by using extant primate regressions. The humerus and ulna indicate that Pondaungia was capable of a wide variety of forelimb movements, with great mobility at the shoulder joint. Morphology of the distal calcaneus indicates that the hind feet were mobile at the transverse tarsal joint. Postcrania of Pondaungia present a mosaic of features, some shared in common with notharctine and adapine adapiforms, some shared with extant lorises and cebids, some shared with fossil anthropoids, and some unique. Overall, Pondaungia humeral and calcaneal morphology is most consistent with that of other known adapiforms. It does not support the inclusion of Pondaungia in Anthropoidea. PMID:11438722

  19. Continental warming preceding the Palaeocene-Eocene thermal maximum.

    PubMed

    Secord, Ross; Gingerich, Philip D; Lohmann, Kyger C; Macleod, Kenneth G

    2010-10-21

    Marine and continental records show an abrupt negative shift in carbon isotope values at ∼55.8 Myr ago. This carbon isotope excursion (CIE) is consistent with the release of a massive amount of isotopically light carbon into the atmosphere and was associated with a dramatic rise in global temperatures termed the Palaeocene-Eocene thermal maximum (PETM). Greenhouse gases released during the CIE, probably including methane, have often been considered the main cause of PETM warming. However, some evidence from the marine record suggests that warming directly preceded the CIE, raising the possibility that the CIE and PETM may have been linked to earlier warming with different origins. Yet pre-CIE warming is still uncertain. Disentangling the sequence of events before and during the CIE and PETM is important for understanding the causes of, and Earth system responses to, abrupt climate change. Here we show that continental warming of about 5 °C preceded the CIE in the Bighorn Basin, Wyoming. Our evidence, based on oxygen isotopes in mammal teeth (which reflect temperature-sensitive fractionation processes) and other proxies, reveals a marked temperature increase directly below the CIE, and again in the CIE. Pre-CIE warming is also supported by a negative amplification of δ(13)C values in soil carbonates below the CIE. Our results suggest that at least two sources of warming-the earlier of which is unlikely to have been methane-contributed to the PETM.

  20. Seawater calcium isotope ratios across the Eocene-Oligocene transition

    USGS Publications Warehouse

    Griffith, E.M.; Paytan, A.; Eisenhauer, A.; Bullen, T.D.; Thomas, E.

    2011-01-01

    During the Eocene-Oligocene transition (EOT, ca. 34 Ma), Earth's climate cooled significantly from a greenhouse to an icehouse climate, while the calcite (CaCO3) compensation depth (CCD) in the Pacific Ocean increased rapidly. Fluctuations in the CCD could result from various processes that create an imbalance between calcium (Ca) sources to, and sinks from, the ocean (e.g., weathering and CaCO3 deposition), with different effects on the isotopic composition of dissolved Ca in the oceans due to differences in the Ca isotopic composition of various inputs and outputs. We used Ca isotope ratios (??44/40Ca) of coeval pelagic marine barite and bulk carbonate to evaluate changes in the marine Ca cycle across the EOT. We show that the permanent deepening of the CCD was not accompanied by a pronounced change in seawater ??44/40Ca, whereas time intervals in the Neogene with smaller carbonate depositional changes are characterized by seawater ??44/40Ca shifts. This suggests that the response of seawater ??44/40Ca to changes in weathering fluxes and to imbalances in the oceanic alkalinity budget depends on the chemical composition of seawater. A minor and transient fluctuation in the Ca isotope ratio of bulk carbonate may reflect a change in isotopic fractionation associated with CaCO3 precipitation from seawater due to a combination of factors, including changes in temperature and/or in the assemblages of calcifying organisms. ?? 2011 Geological Society of America.

  1. Paleoecology of Early eocene strata near Buffalo, Wyoming

    SciTech Connect

    Durkin, T.V.; Rich, F.J.

    1986-08-01

    Palynological investigation has helped illustrate the paleoecology of a vertical section of strata from the Wasatch Formation between the Healy and Walters coal burns near Buffalo, Wyoming. Numerous silicified logs and stumps of cypress and sequoia have been preserved at the site and drew initial attention to it. Flood-basin deposits enclose the trees and include sandstones, siltstones, shale, and coal beds that accumulated as channel, levee, crevasse-splay, and swamp/marsh sediments. Detrital sediments were probably derived from the Bighorn Mountains and accumulated as they were carried into the Powder River basin fluvial system. One hundred five polynomorph taxa have been distinguished, as well as 10 types of fungal spores. Platycarya, Tilia, Sparganium, and Platanus pollen indicate an early Eocene age for the strata. Other pollen, as well as the genera of trees and megafossil remains from a clinker bed several miles from the study area, reinforce the interpretation of a warm-temperature or subtropical climate at the time of deposition. The megafossil assemblage includes pinnae of the aquatic fern Marsilea, never before described from the fossil record. Variations in the species composition of the polynomorph assemblages show that several plant communities existed in succession at the site. These varied from pond or marsh types to mature forests.

  2. Middle Eocene seagrass facies from Apennine carbonate platforms (Italy)

    NASA Astrophysics Data System (ADS)

    Tomassetti, Laura; Benedetti, Andrea; Brandano, Marco

    2016-04-01

    Two stratigraphic sections located in the Latium-Abruzzi (Monte Porchio, Central Apennines, Central Italy) and in the Apulian carbonate platform (S. Cesarea-Torre Tiggiano, Salento, Southern Italy) were measured and sampled to document the sedimentological characteristic and the faunistic assemblages of Middle Eocene seagrass deposits. The faunistic assemblages are dominated by porcellaneous foraminifera Orbitolites, Alveolina, Idalina, Spiroloculina, Quinqueloculina, Triloculina and abundant hooked-shaped gypsinids, associated with hooked red algae and green algae Halimeda. Fabiania, rotaliids and textulariids as well as nummulitids are subordinated. The samples were assigned to Lutetian (SBZ13-16) according to the occurrence of Nummulites cf. lehneri, Alveolina ex. gr. elliptica, Idalina berthelini, Orbitolites complanatus, Slovenites decastroi and Medocia blayensis. At Santa Cesarea reticulate nummulites occur in association with Alveolina spp. and Halkyardia minima marking the lower Bartonian (SBZ17). Three main facies associations have been recognised: I) larger porcellaneous foraminiferal grainstones with orbitolitids and alveolinids deposited into high-energy shallow-water settings influenced by wave processes that reworked the sediments associated with a seagrass; II) grainstone to packstone with small porcellaneous foraminifera and abundant permanently-attached gypsinids deposited in a more protected (e.g., small embayment) in situ vegetated environment; III) bioclastic packstone with parautochthonous material reworked from the seagrass by rip currents and accumulated into rip channels in a slightly deeper environment. The biotic assemblages suggest that the depositional environment is consistent with tropical to subtropical vegetated environments within oligotrophic conditions.

  3. Late Eocene stable isotope stratigraphy of North Atlantic IODP Site U1411: Orbitally paced climatic heartbeat at the close of the Eocene greenhouse

    NASA Astrophysics Data System (ADS)

    Coxall, Helen; Bohaty, Steve; Wilson, Paul; Liebrand, Diederik; Nyberg, Anna; Holmström, Max

    2016-04-01

    Integrated Ocean Drilling Program (IODP) Expedition 342 drilled sediment drifts on the Newfoundland margin to recover high-resolution records of North Atlantic ocean-climate history and track the evolution of the modern climate system through the Late Cretaceous and Early Cenozoic. An early Paleogene deep-sea benthic stable isotope composite record from multiple Exp. 342 sites is currently in development and will provide a key reference section for investigations of Atlantic and global climate dynamics. This study presents initial results for the late Eocene slice of the composite from Site U1411, located at mid depth (˜2850m Eocene paleodepth) on the Southeast Newfoundland Ridge. Stable oxygen (δ18O) and carbon (δ13C) isotope ratios were measured on 640 samples hosting exceptionally well-preserved epifaunal benthic foraminifera obtained from the microfossil-rich uppermost Eocene clays at 4cm spacing. Sedimentation rates average 2-3 cm/kyr through the late Eocene, such that our sampling resolution is sufficient to capture the dominant Milankovitch frequencies. Late Eocene Site U1411 benthic δ18O values (1.4 to 0.5‰ VPDB) are comparable to the Pacific and elsewhere in the Atlantic at similar depths; however, δ13C is lower by ˜0.5 ‰ with values intermediate between those of the Southern Labrador Sea to the north (-1 to 0) and mid latitude/South Atlantic (0.5 to 1.5) to the south, suggesting poorly ventilated bottom waters in the late Eocene North Atlantic and limited production of North Atlantic deep water. Applying the initial shipboard magneto-biostratigraphic age framework, the Site U1411 benthic δ13C and δ18O records display clear cyclicity on orbital timescales. Spectral analysis of the raw unfiltered datasets identifies eccentricity (400 and 100 kyr), obliquity (40 kyr) and precession (˜20 kyr) signals imprinted on our time series, revealing distinct climatic heart beats in the late Eocene prior to the transition into the 'ice house'.

  4. State acid rain permitting programs: A report from EPA

    SciTech Connect

    Miller, R.L.

    1995-12-31

    States and EPA are laying the groundwork for state acid rain permitting in Phase 2 of the Acid Rain Program. Early indications suggest a high degree of state compliance with the acid rain permitting requirements of the Acid Rain Program. Phase 2 acid rain permitting forms have been revised and are available on EPA`s Technology Transfer Network. EPA has developed a policy and rationale concerning submission of Phase 2 permit applications, as well as suggested state timing and methodology regarding adoption of 40 CFR Part 76, the NO{sub x} regulation.

  5. The Acid Rain Program: Monitoring the future

    SciTech Connect

    Bloomer, B.J.

    1995-12-31

    This paper presents a summary of the development of the Acid Rain Program`s approach to Continuous Emissions Monitoring Systems (CEMS) and their use in the market based pollution control program of Title IV of the Clean Air Act Amendments of 1990. The roles of the regulatory agencies are discussed and projections are put forward as to how the roles will evolve over time. In addition a discussion of the activities the regulated community is expected to focus on is presented. Finally, a discussion occurs about the requirements that new technologies and instrument providers and purchasers should keep in mind about the Acid Rain Program`s monitoring requirements as they attempt to bring new products into this market.

  6. Is acid rain impacting the Sudetic lakes?

    PubMed

    Sienkiewicz, Elwira; Gasiorowski, Michał; Hercman, Helena

    2006-10-01

    The diatoms and Cladocera (Crustacea) remains from two lakes in the Sudets Mountains were analyzed to indicate an influence of acidification induced by anthropogenic factors during the last 150 years. The border area of the Czech Republic, Germany and Poland, the so-called "Black Triangle", has been strongly impacted by developed industry for several decades. The most visible effect of this process is the destruction of mountain forests in the region by acid rains. The diatom communities of Mały Staw and Wielki Staw show that acid rain has strongly affected water biota. Diatom-inferred pH reconstruction suggests major acidification during the last two decades. This process was controlled mainly by anthropogenic factors. Cladoceran records also presented changes of dominant taxa in this period and point to significant changes in living conditions. The discovery of a pH decrease during the last decade is contradictory to emissions data that suggest decrease in industrial pollution.

  7. Fraud in the acid rain debate

    SciTech Connect

    Bagge, C.

    1984-06-01

    Electric utility executives, according to the author, and millions of other Americans are the victims of a gigantic fraud being carried on in the name of controlling acid rain. This fraud, states the author, involves the distorted, dire image of acidity in nature being created by environmental groups, politicians and others - to gain public sympathy for their legislative goals. The alleged fraud involves the very nature of the legislation being promoted as a low-cost cure for acid rain. On the basis of scientific evidence to date there is no assurance it will reduce acidity by any appreciable amount, but on the other hand it most certainly will cost users of electricity hundreds of billions of dollars in new costs. What has already happened to the nuclear industry is also meant for coal.

  8. Acid rain erodes business profits, too

    SciTech Connect

    Not Available

    1980-11-01

    Evidence is mounting that acid rain may be more expensive, in the long run, than even the most sophisticated, costly pollution control. Unabated, the pollution will have increasingly devastating economic effects. It is difficult to quantify acid rain's economically damaging effects, since they vary considerably with soil quality. Well-buffered soils can tolerate greater quantities of acidic precipitation than can those not well-buffered. Unfortunately, some of the most susceptible areas of the country are also most dependent on agricultural ore recreational business for economic survival. Economically damaging effects vary: they can be either short- or long-term; reversible or irreversible. A partial list might include crop damage, long-term effects on forest growth, fisheries losses, long-term declines in property values on acidified lakes, effects on recreational industries in acid-sensitive areas, and costs incurred by having to treat chemically altered groundwater.

  9. Federal report on acid rain draws criticism

    SciTech Connect

    Roberts, L.

    1987-09-18

    Congress established a 10-year interagency research program in 1980 to examine the causes and effects of acid rain and recommend actions to limit or reduce its harmful effects. On September 17, the National Acid Precipitation Assessment Program (NAPAP) is scheduled to release its interim assessment. The impression that emerges from the summary is that there is not much to worry about. Acid rain has negligible or no effects on crops and forests, though tropospheric ozone may be a serious problem. Only a small number of lakes have been acidified, and no further significant acidification is likely in the northeast. No abrupt increase in damage to crops, forests, and lakes is likely at current emissions.

  10. ARMAR: An airborne rain-mapping radar

    NASA Technical Reports Server (NTRS)

    Durden, S. L.; Im, E.; Li, F. K.; Ricketts, W.; Tanner, A.; Wilson, W.

    1994-01-01

    A new airborne rain-mapping radar (ARMAR) has been developed by NASA and the Jet Propulsion Laboratory for operation on the NASA Ames DC-8 aircraft. The radar operates at 13.8 GHz, the frequency to be used by the radar on the Tropical Rainfall Measuring Mission (TRMM). ARMAR simulates the TRMM radar geometry by looking downward and scanning its antenna in the cross-track direction. This basic compatibility between ARMAR and TRMM allows ARMAR to provide information useful for the TRMM radar design, for rain retrieval algorithm development, and for postlaunch calibration. ARMAR has additional capabilities, including multiple polarization, Doppler velocity measurement, and a radiometer channel for brightness temperature measurement. The system has been tested in both ground-based and airborne configurations. This paper describes the design of the system and shows results of field tests.

  11. Marine and terrestrial environmental changes in NW Europe preceding carbon release at the Paleocene-Eocene transition

    NASA Astrophysics Data System (ADS)

    Kender, Sev; Stephenson, Michael H.; Riding, James B.; Leng, Melanie J.; Knox, Robert W. O.'B.; Peck, Victoria L.; Kendrick, Christopher P.; Ellis, Michael A.; Vane, Christopher H.; Jamieson, Rachel

    2012-11-01

    Environmental changes associated with the Paleocene-Eocene thermal maximum (PETM, ∼56 Ma) have not yet been documented in detail from the North Sea Basin. Located within proximity to the North Atlantic igneous province (NAIP), the Kilda Basin, and the northern rain belt (paleolatitude 54 °N) during the PETM, this is a critical region for testing proposed triggers of atmospheric carbon release that may have caused the global negative carbon isotope excursion (CIE) in marine and terrestrial environments. The CIE onset is identified from organic matter δ13C in exceptional detail within a highly expanded sedimentary sequence. Pollen and spore assemblages analysed in the same samples for the first time allow a reconstruction of possible changes to vegetation on the surrounding landmass. Multiproxy palynological, geochemical, and sedimentologic records demonstrate enhanced halocline stratification and terrigenous deposition well before (103 yrs) the CIE, interpreted as due to either tectonic uplift possibly from a nearby magmatic intrusion, or increased precipitation and fluvial runoff possibly from an enhanced hydrologic cycle. Stratification and terrigenous deposition increased further at the onset and within the earliest CIE which, coupled with evidence for sea level rise, may be interpreted as resulting from an increase in precipitation over NW Europe consistent with an enhanced hydrologic cycle in response to global warming during the PETM. Palynological evidence indicates a flora dominated by pollen from coastal swamp conifers before the CIE was abruptly replaced with a more diverse assemblage of generalist species including pollen similar to modern alder, fern, and fungal spores. This may have resulted from flooding of coastal areas due to relative sea level rise, and/or ecologic changes forced by climate. A shift towards more diverse angiosperm and pteridophyte vegetation within the early CIE, including pollen similar to modern hickory, documents a long term

  12. Materials degradation caused by acid rain

    SciTech Connect

    Baboian, R.

    1986-01-01

    Materials Degradation Caused by Acid Rain, based on a symposium sponsored by the American Chemical Society, presents a detailed analysis of the types of materials damages that may result from acid deposition, as well as techniques for evaluating the economic impact of these damages. The 29 chapters are organized into five sections. These sections include: Measurement and Monitoring of Atmospheric Deposition; Metallic Corrosion; Degradation of Organics; and Economic Effects.

  13. NASA's DC-8 With Rain Mapping Radar

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In a joint venture between NASA and Japan's NASDA, scientists have been using satellites, airplanes, and boats to measure rain physics in and under thunderstorms over open water. This Quick Time movie shows the ER-2, a high altitude reconnaissance aircraft equipped with 8 lightening detectors and other instruments used to study hurricanes and thunderstorms. Earth science and weather studies are an important ongoing function of NASA and its affiliates.

  14. Response of the Pacific inter-tropical convergence zone to global cooling and initiation of Antarctic glaciation across the Eocene Oligocene Transition

    PubMed Central

    Hyeong, Kiseong; Kuroda, Junichiro; Seo, Inah; Wilson, Paul A.

    2016-01-01

    Approximately 34 million years ago across the Eocene–Oligocene transition (EOT), Earth’s climate tipped from a largely unglaciated state into one that sustained large ice sheets on Antarctica. Antarctic glaciation is attributed to a threshold response to slow decline in atmospheric CO2 but our understanding of the feedback processes triggered and of climate change on the other contents is limited. Here we present new geochemical records of terrigenous dust accumulating on the sea floor across the EOT from a site in the central equatorial Pacific. We report a change in dust chemistry from an Asian affinity to a Central-South American provenance that occurs geologically synchronously with the initiation of stepwise global cooling, glaciation of Antarctica and aridification on the northern continents. We infer that the inter-tropical convergence zone of intense precipitation extended to our site during late Eocene, at least four degrees latitude further south than today, but that it migrated northwards in step with global cooling and initiation of Antarctic glaciation. Our findings point to an atmospheric teleconnection between extratropical cooling and rainfall climate in the tropics and the mid-latitude belt of the westerlies operating across the most pivotal transition in climate state of the Cenozoic Era. PMID:27507793

  15. Response of the Pacific inter-tropical convergence zone to global cooling and initiation of Antarctic glaciation across the Eocene Oligocene Transition

    NASA Astrophysics Data System (ADS)

    Hyeong, Kiseong; Kuroda, Junichiro; Seo, Inah; Wilson, Paul A.

    2016-08-01

    Approximately 34 million years ago across the Eocene–Oligocene transition (EOT), Earth’s climate tipped from a largely unglaciated state into one that sustained large ice sheets on Antarctica. Antarctic glaciation is attributed to a threshold response to slow decline in atmospheric CO2 but our understanding of the feedback processes triggered and of climate change on the other contents is limited. Here we present new geochemical records of terrigenous dust accumulating on the sea floor across the EOT from a site in the central equatorial Pacific. We report a change in dust chemistry from an Asian affinity to a Central-South American provenance that occurs geologically synchronously with the initiation of stepwise global cooling, glaciation of Antarctica and aridification on the northern continents. We infer that the inter-tropical convergence zone of intense precipitation extended to our site during late Eocene, at least four degrees latitude further south than today, but that it migrated northwards in step with global cooling and initiation of Antarctic glaciation. Our findings point to an atmospheric teleconnection between extratropical cooling and rainfall climate in the tropics and the mid-latitude belt of the westerlies operating across the most pivotal transition in climate state of the Cenozoic Era.

  16. Observations of ULF wave related equatorial electrojet and density fluctuations

    NASA Astrophysics Data System (ADS)

    Yizengaw, E.; Zesta, E.; Biouele, C. M.; Moldwin, M. B.; Boudouridis, A.; Damtie, B.; Mebrahtu, A.; Anad, F.; Pfaff, R. F.; Hartinger, M.

    2013-10-01

    We report on Pc5 wave related electric field and vertical drift velocity oscillations at the equator as observed by ground magnetometers for an extended period on 9 August 2008. We show that the magnetometer-estimated equatorial E×B drift oscillates with the same frequency as ULF Pc5 waves, creating significant ionospheric density fluctuations. We also show ionospheric density fluctuations during the period when we observed ULF wave activity. At the same time, we detect the ULF activity on the ground using ground-based magnetometer data from the African Meridian B-field Education and Research (AMBER) and the South American Meridional B-field Array (SAMBA). From space, we use magnetic field observations from the GOES 12 and the Communication/Navigation Outage and Forecast System (C/NOFS) satellites. Upstream solar wind conditions are provided by the ACE spacecraft. We find that the wave power observed on the ground also occurs in the upstream solar wind and in the magnetosphere. All these observations demonstrate that Pc5 waves with a likely driver in the solar wind can penetrate to the equatorial ionosphere and modulate the equatorial electrodynamics. While no direct drift measurements from equatorial radars exist for the 9 August 2008 event, we used JULIA 150 km radar drift velocities observed on 2 May 2010 and found similar fluctuations with the period of 5-8 min, as a means of an independent confirmation of our magnetometer derived drift dynamics.

  17. Signatures of strong geomagnetic storms in the equatorial latitude

    NASA Astrophysics Data System (ADS)

    Olawepo, A. O.; Adeniyi, J. O.

    2014-04-01

    Ionosonde data from two equatorial stations in the African sector have been used to study the signatures of four strong geomagnetic storms on the height - electron density profiles of the equatorial ionosphere with the objective of investigating the effects and extent of the effects on the three layers of the equatorial ionosphere. The results showed that strong geomagnetic storms produced effects of varying degrees on the three layers of the ionosphere. Effect of strong geomagnetic storms on the lower layers of the equatorial ionosphere can be significant when compared with effect at the F2-layer. Fluctuations in the height of ionization within the E-layer were as much as 0% to +20.7% compared to -12.5% to +8.3% for the F2-layer. The 2007 version of the International Reference Ionosphere, IRI-07 storm-time model reproduced responses at the E-layer but overestimated the observed storm profiles for the F1- and F2-layers.

  18. Exact Nonlinear Internal Equatorial Waves in the f-plane

    NASA Astrophysics Data System (ADS)

    Hsu, Hung-Chu

    2016-07-01

    We present an explicit exact solution of the nonlinear governing equations for internal geophysical water waves propagating westward above the thermocline in the f-plane approximation near the equator. Moreover, the mass transport velocity induced by this internal equatorial wave is eastward and a westward current occurs in the transition zone between the great depth where the water is still and the thermocline.

  19. Timing and significance of maximum and minimum equatorial insolation

    NASA Astrophysics Data System (ADS)

    Ashkenazy, Yosef; Gildor, Hezi

    2008-01-01

    Variations in summer insolation at high northern latitudes on a timescale of 100 ka are very small. Thus a common belief is that the pronounced ~100 ka glacial cycles are not directly linked to the very weak 100 ka insolation periodicity. Here we show, analytically and numerically, that the annual maximum (and minimum) of daily equatorial insolation has pronounced eccentricity periodicities, with timescales of ~400 ka and ~100 ka, as well as a pronounced half-precession periodicity with timescale of ~11 ka. The timing of the maximum (and minimum) annual equatorial insolation may change around the equinoxes (solstices), alternating between the vernal and autumnal equinoxes (summer and winter solstices) where the time of the maximum (minimum) equatorial insolation may occur up to more than 1 month from the equinoxes (solstices). We also show that when considering the mean insolation of periods larger than 1 d, the ~11 ka periodicity becomes less dominant, and it vanishes when the averaging period is half a year; for the later case the maximum (minimum) may occur for any day in the annual cycle. The maximum equatorial insolation may alter the timing and amplitude of the maximum surface temperature of the summer hemisphere and in this way may drastically affect the Hadley circulation. Changes in Hadley circulation affect the heat and moisture transport from low to high latitudes, affecting the buildup of the high-latitude Northern Hemisphere ice sheets.

  20. Evolution of Ion Clouds in the Equatorial Ionosphere

    NASA Astrophysics Data System (ADS)

    Petrochuk, Yevgeny; Blaunstein, Nathan; Mishin, Evgeny; Pedersen, Todd; Caton, Ron; Viggiano, Al; Schuman, Nick

    2015-11-01

    We report on the results of 2- and 3-dimentional numerical investigations of the evolution of samarium ion clouds injected in the equatorial ionosphere, alike the recent MOSC experiments. The ambient conditions are described by a standard model of the quiet-time equatorial ionosphere from 90 to 350 km. The altitudinal distribution of the transport processes and ambient electric and magnetic fields is taken into account. The fast process of stratification of ion clouds and breaking into small plasmoids occur only during the late stage of the cloud evolution. The role of the background plasma and its depletion zones formed due to the short-circuiting currents is not as evident as in mid latitudes. It is also revealed that the altitudinal dependence of the diffusion and drift plays a minor role in the cloud evolution at the equator. Likewise, the cloud remains stable with respect to the Raleigh-Taylor and gradient-drift instabilities. These two features are defined by the equatorial near-horizontal magnetic field which leads to a strongly-elongated ellipsoid-like plasma cloud. The critical dip angle separating the stable (equatorial) and unstable (mid-latitude) cloud regimes will be defined in future simulation studies, as well as the dependence on the ambient electric field and neutral wind. 2Space Vehicles Directorate, Air Force Research Laboratory

  1. Upwelling: a unit of disturbance in equatorial spread F

    NASA Astrophysics Data System (ADS)

    Tsunoda, Roland T.

    2015-12-01

    Plasma structure in the nighttime equatorial F layer, often referred to as equatorial spread F (ESF), is not uniformly distributed, either in time or in space. Observations indicate that ESF in the bottomside F layer takes the form of patches; plasma structure within the F layer takes the form of localized plasma depletions, called equatorial plasma bubbles (EPBs), which tend to occur in clusters. Another observed feature is an upwelling, which has been described as a localized, upward modulation of isodensity contours in the bottomside F layer. Interestingly, zonal widths of ESF patches, EPB clusters, and upwellings are similar. Moreover, all display an east-west asymmetry. The objective of this paper is to show, for the first time, that an ESF patch is the bottomside counterpart of an EPB cluster, and that both are products of the electrodynamical process that takes place within an upwelling. The process can be described as having three phases: (1) amplification of upwelling amplitude during the post-sunset rise of the F layer, (2) launching of the first EPB of the evening, from crest of the upwelling, and (3) structuring of plasma within the upwelling. Hence, an upwelling, whose presence is responsible for the formation of ESF patches and EPB clusters, can be envisioned as a unit of disturbance that occurs in the nighttime equatorial ionosphere.

  2. History of the Italian San Marco equatorial mobile range

    NASA Technical Reports Server (NTRS)

    Nesbitt, H. N.

    1971-01-01

    Events leading to the development of the San Marco Equatorial Range are presented. Included are background information leading to the cooperative space program between the United States and Italy, conceptual planning, training activities, equipment design and fabrication, and range utilization. The technical support provided the San Marco Program by Scout Project Office, and other NASA installations is described.

  3. Spatial and diurnal features of the Jovian equatorial anomaly

    NASA Astrophysics Data System (ADS)

    Tan, A.

    1986-01-01

    This paper outlines a time-dependent model of the Jovian ionosphere with electrodynamic drift to study the spatial and temporal features of the Jovian equatorial anomaly. Two sinusoidal drift velocity models are considered, model 1, akin to that in the terrestrial ionosphere and model 2, having opposite phase. The drift velocity amplitude is taken to be 100 m/s. In either model, an equatorial anomaly which persists throughout the day unlike its terrestrial counterpart, and disappears after midnight is obtained. The crest of ionization is centered around 7-8 degrees latitude in either model as compared with about 15 degrees for the terrestrial anomaly. The Rm index attains a maximum value of 2.6 in the afternoon in model 2. The peak electron density at the equator minimizes before midnight in model 1, but after sunrise in model 2. There is no 'noon biteout' like that found in the terrestrial equatorial ionosphere. The height of the peak electron density roughly follows the drift velocity pattern. Comparison with experimental data indicates that drift velocity amplitudes far exceeding 100 m/s would be required to produce the observed Jovian equatorial anomaly.

  4. The equatorial electrojet current modelling from SWARM satellite data

    NASA Astrophysics Data System (ADS)

    Benaissa, Mahfoud

    2016-07-01

    Equatorial ElectroJet (EEJ) is an intense eastward electric current circulating in the ionospheric magnetic equator band between 100 and 130 km of altitude in E region. These currents vary by day, by season, by solar activity, and also with the main magnetic field of internal origin. The irregularity of the ionosphere has a major impact on the performance of communication systems and navigation (GPS), industry.... Then it becomes necessary study the characteristics of EEJ. In this paper, we present a study of the equatorial electrojet (EEJ) phenomenon along one year (2014) period. In addition, the satellite data used in this study are obtained with SWARM satellite scalar magnetometer data respecting magnetically quiet days with KP < 2. In this paper, we process to separate and extract the electrojet intensity signal from other recorded signal-sources interfering with the main signal and reduce considerably the signal to noise ratio during the SWARM measurements. This pre-processing step allows removing all external contributions in regard to EEJ intensity value. Key words: Ionosphere (Equatorial ionosphere; Electric fields and currents; Equatorial electrojet (EEJ)); SWARM.

  5. Acid Rain in Shenandoah National Park, Virginia

    USGS Publications Warehouse

    Rice, Karen C.; Deviney, Frank A.; Olson, Gordon

    2007-01-01

    Visitors to Shenandoah National Park (SNP) enjoy the animal and plant life and the scenery but may not realize how vulnerable these features are to various threats, such as invasion of exotic plants and insects, improper use of park resources by humans, and air and water pollution. The National Park Service strives to protect natural resources from such threats to ensure that the resources will be available for enjoyment now and in the future. Because SNP has limited influence over the air pollution that envelops the region, acidic deposition--commonly known as acid rain--is one of the more challenging threats facing park managers. With the help of U.S. Geological Survey (USGS) scientists, park managers can understand how acid rain interacts with ground- and surface-water resources, which enables them to explain why reductions in air pollution can help preserve park resources. Such understanding also provides essential insight into ecosystem processes, as managers strive to unravel and resolve other environmental problems that are interrelated to acid rain.

  6. Court date for EPA acid rain rule

    SciTech Connect

    Lobsenz, G.

    1994-03-04

    In an acid rain rulemaking that appears headed straight for the courtroom, the Environmental Protection Agency this week announced new limits on emissions of nitrogen oxides from coal-fired power plants. The regulations, announced March 1, are expected to achieve a 1.8 million ton per year reduction in power plant NOx emissions, which are considered a major contributor to acid rain. The agency issued companion regulations last year to cut power plant discharges of sulfur dioxide, the other major acid rain pollutant. The NOx rulemaking elicited contradictory responses from utility industry officials. One point of contention involves the agency's definition of low-NOx burner technology, a key regulatory determination. If a utility installs EPA-defined low-NOx burner technology and still cannot meet the new NOx limits, it can apply for a less stringent [open quotes]alternative emission limit.[close quotes] The other issue likely to be raised by industry officials involves the January 1995 compliance deadline for utilities included in Phase I of the NOx program. While EPA will allow individual utilities to seek a deadline extension until April 1996 in the event of operational difficulties, the agency rejected the industry's request for an across-the-board extension.

  7. Energetic photoelectrons and the polar rain

    NASA Technical Reports Server (NTRS)

    Decker, Dwight T.; Jasperse, J. R.; Winningham, J. D.

    1990-01-01

    In the daytime midlatitudes, the Low Altitude Plasma Instrument (LAPI) on board the Dynamics Explorer 2 satellite has observed photoelectrons with energies as high as 850 eV. These energetic photoelectrons are an extension of the 'classical' photoelectrons (less than 60 eV) and result from photoionization of neutrals by soft solar X-rays. Since these photoelectrons are produced wherever the solar flux is incident on the earth's atmosphere, they should be present in sunlit polar cap. But in the polar cap, over these same energies, there is a well-known electron population: the polar rain, a low intensity electron flux of magnetospheric origin. Thus, in the sunlit polar cap, an energetic population of electrons should consist of both an ionospheric (photoelectron) and a magnetospheric (polar rain) component. Using numerical solutions of an electron transport equation with appropriate boundary conditions and sunlit polar cap LAPI data, it is shown that the two populations (photoelectron and polar rain) are indeed present and are both needed to explain polar cap observations.

  8. Influence of acid rain upon water plumbosolvency.

    PubMed Central

    Moore, M R

    1985-01-01

    The West of Scotland has had particular problems in the past associated with soft acidic water supplies and uptake of lead from domestic plumbing systems by such water. As a consequence of this, health problems related to overexposure to lead have been identified. The current debate on acidification of ground waters by acid rain is therefore particularly pertinent to this area. Studies have shown that even a modest decrease in pH will result in very substantial increase in plumbosolvency. This was found to be of particular importance in the city of Glasgow and town of Ayr, where prior to water treatment, pH values were 6.3 and 5.4, respectively, and where, consequentially, large numbers of homes did not comply with lead in water standards. Closed-loop lime-dosing systems were introduced in both Glasgow and Ayr to increase the pH with immediate decrease in the lead content of the water and, subsequently, blood lead concentrations of the subjects living in these areas. Such closed-loop systems will compensate for any acidity in water supplies, whether of natural origin or originating from acid rain precipitation. However, when such treatment has not been applied, any increase in water acidity due to acid rain which is, in many cases, already unacceptable. which is, in many cases, already unacceptable. PMID:4076078

  9. Influence of acid rain upon water plumbosolvency.

    PubMed

    Moore, M R

    1985-11-01

    The West of Scotland has had particular problems in the past associated with soft acidic water supplies and uptake of lead from domestic plumbing systems by such water. As a consequence of this, health problems related to overexposure to lead have been identified. The current debate on acidification of ground waters by acid rain is therefore particularly pertinent to this area. Studies have shown that even a modest decrease in pH will result in very substantial increase in plumbosolvency. This was found to be of particular importance in the city of Glasgow and town of Ayr, where prior to water treatment, pH values were 6.3 and 5.4, respectively, and where, consequentially, large numbers of homes did not comply with lead in water standards. Closed-loop lime-dosing systems were introduced in both Glasgow and Ayr to increase the pH with immediate decrease in the lead content of the water and, subsequently, blood lead concentrations of the subjects living in these areas. Such closed-loop systems will compensate for any acidity in water supplies, whether of natural origin or originating from acid rain precipitation. However, when such treatment has not been applied, any increase in water acidity due to acid rain which is, in many cases, already unacceptable. which is, in many cases, already unacceptable.

  10. Late paleogene (eocene to oligocene) paleoceanography of the northern North Atlantic. Doctoral thesis

    SciTech Connect

    Miller, K.G.

    1982-11-01

    Seismic stratigraphic evidence indicates that a major change in abyssal circulation occurred in the latest Eocene-earliest Oligocene of the North Atlantic. Reflector R4 reflects a change from weakly (Eocene) to vigorously circulating bottom water (early Oligocene). Sediment distribution studies indicate a northern source for this bottom water, probably from the Arctic via the Norwegian-Greenland Sea/Faeroe-Shetland Channel. Current-controlled sedimentation and erosion continued through the Oligocene; however, above reflector R3 (upper Oligocene), the general intensity of abyssal currents decreased. Above reflector R2 (lower Miocene) a further reduction in abyssal currents resulted in more coherent current-controlled sedimentation and a major phase of sediment drift development. Major deep-sea benthic foraminiferal changes occurred between the middle Eocene and earliest Oligocene: an agglutinated assemblage was replaced by a calcareous assemblage (abyssal Labrador Sea), and an indigenous Eocene calcareious fauna became extinct (abyssal Bay of Biscay). In shallower Atlantic sites (< 3km paleodepth), a Nuttallides truempyi assemblage was replaced by an assemblage of long- and wide-ranging taxa in the early late Eocene.

  11. The oldest African bat from the early Eocene of El Kohol (Algeria)

    NASA Astrophysics Data System (ADS)

    Ravel, Anthony; Marivaux, Laurent; Tabuce, Rodolphe; Adaci, Mohammed; Mahboubi, Mohammed; Mebrouk, Fateh; Bensalah, Mustapha

    2011-05-01

    The Afro-Arabian Paleogene fossil record of Chiroptera is very poor. In North Africa and Arabia, this record is limited, thus far, to a few localities mainly in Tunisia (Chambi, late early Eocene), Egypt (Fayum, late Eocene to early Oligocene), and Sultanate of Oman (Taqah, early Oligocene). It consists primarily of isolated teeth or mandible fragments. Interestingly, these African fossil bats document two modern groups (Vespertilionoidea and Rhinolophoidea) from the early Eocene, while the bat fossil record of the same epoch of North America, Eurasia, and Australia principally includes members of the "Eochiroptera." This paraphyletic group contains all primitive microbats excluding modern families. In Algeria, the region of Brezina, southeast of the Atlas Mountains, is famous for the early Eocene El Kohol Formation, which has yielded one of the earliest mammalian faunas of the African landmass. Recent fieldwork in the same area has led to the discovery of a new vertebrate locality, including isolated teeth of Chiroptera. These fossils represent the oldest occurrence of Chiroptera in Africa, thus extending back the record of the group to the middle early Eocene (Ypresian) on that continent. The material consists of an upper molar and two fragments of lower molars. The dental character association matches that of "Eochiroptera." As such, although very fragmentary, the material testifies to the first occurrence of "Eochiroptera" in Algeria, and by extension in Africa. This discovery demonstrates that this basal group of Chiroptera had a worldwide distribution during the early Paleogene.

  12. Multiple microtektite horizons in upper Eocene marine sediments: No evidence for mass extinctions

    USGS Publications Warehouse

    Keller, G.; D'Hondt, S.; Vallier, T.L.

    1983-01-01

    Microtektites have been recovered from three horizons in eight middle Eocene to middle Oligocene marine sediment sequences. Five of these occurrences are coeval and of latest Eocene age (37.5 to 38.0 million years ago); three are coeval and of early late Eocene age (38.5 to 39.5 million years ago); and three are of middle Oligocene age (31 to 32 million years ago). In addition, rare probable microtektites have been found in sediments with ages of about 36.0 to 36.5 million years. The microtektite horizon at 37.5 to 38.0 million years can be correlated with the North American tektite-strewn field, which has a fission track age (minimum) of 34 to 35 million years and a paleomagnetic age of 37.5 to 38.0 million years. There is no evidence for mass faunal extinctions at any of the microtektite horizons. Many of the distinct faunal changes that occurred in the middle Eocene to middle Oligocene can be related to the formation of the Antarctic ice sheet and the associated cooling phenomena and intensification of bottom currents that led to large-scale dissolution of calcium carbonate and erosion, which created areally extensive hiatuses in the deep-sea sediment records. The occurrence of microtektite horizons of several ages and the lack of evidence for faunal extinctions suggest that the effects of extraterrestrial bolide impacts may be unimportant in the biologic realm during middle Eocene to middle Oligocene time.

  13. Multiple microtektite horizons in upper eocene marine sediments: no evidence for mass extinctions.

    PubMed

    Keller, G; D'Hondt, S; Vallier, T L

    1983-07-01

    Microtektites have been recovered from three horizons in eight middle Eocene to middle Oligocene marine sediment sequences. Five of these occurrences are coeval and of latest Eocene age (37.5 to 38.0 million years ago); three are coeval and of early late Eocene age (38.5 to 39.5 million years ago); and three are of middle Oligocene age (31 to 32 million years ago). In addition, rare probable microtektites have been found in sediments with ages of about 36.0 to 36.5 million years. The microtektite horizon at 37.5 to 38.0 million years can be correlated with the North American tektite-strewn field, which has a fission track age (minimum) of 34 to 35 million years and a paleomagnetic age of 37.5 to 38.0 million years. There is no evidence for mass faunal extinctions at any of the microtektite horizons. Many of the distinct faunal changes that occurred in the middle Eocene to middle Oligocene can be related to the formation of the Antarctic ice sheet and the associated cooling phenomena and intensification of bottom currents that led to large-scale dissolution of calcium carbonate and erosion, which created areally extensive hiatuses in the deep-sea sediment records. The occurrence of microtektite horizons of several ages and the lack of evidence for faunal extinctions suggest that the effects of extraterrestrial bolide impacts may be unimportant in the biologic realm during middle Eocene to middle Oligocene time.

  14. Larger benthic foraminiferal turnover across the Eocene-Oligocene transition at Siwa Oasis, Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Orabi, H.; El Beshtawy, M.; Osman, R.; Gadallah, M.

    2015-05-01

    In the Eocene part of the Siwa Oasis, the larger foraminifera are represented by the genera Nummulites, Arxina, Operculina, Sphaerogypsina, Asterocyclina, Grzybowskia, Silvestriella, Gaziryina and Discocyclina in order of abundance. Operculina continues up to the early Oligocene as modern representatives in tropical regions, while the other genera became extinct. Nevertheless, the most common larger foraminiferal genus Lepidocyclina (Nephrolepidina) appears only in the lowermost Oligocene. In spite of the Eocene-Oligocene (E/O) transition is thought to have been attended by major continental cooling at northern middle and high latitudes, we discover that at the Siwa Oasis, there is a clear warming trend from the late Eocene (extinction level of Nummulites, Sphaerogypsina, Asterocyclina, Grzybowskia, Silvestriella and Discocyclina) to the early Oligocene is observed due to the high abundance of Operculina and occurrence of kaolinite and gypsiferous shale deposits in both Qatrani and El Qara formations (Oligocene) at this transition. The El Qara Formation is a new rock unit proposed herein for the Oligocene (Rupelian age) in the first time. Several episodes of volcanic activity occurred in Egypt during the Cenozoic. Mid Tertiary volcanicity was widespread and a number of successive volcanic pulses are starting in the late Eocene. The release of mantle CO2 from this very active volcanic episode may have in fact directly caused the warm Eocene-Oligocene greenhouse climate effect.

  15. Fossil plant stomata indicate decreasing atmospheric CO2 prior to the Eocene-Oligocene boundary

    NASA Astrophysics Data System (ADS)

    Steinthorsdottir, Margret; Porter, Amanda S.; Holohan, Aidan; Kunzmann, Lutz; Collinson, Margaret; McElwain, Jennifer C.

    2016-02-01

    A unique stratigraphic sequence of fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany has been used to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the inverse relationship between the density of stomata and pCO2, we show that pCO2 decreased continuously from the late middle to late Eocene, reaching a relatively stable low value before the end of the Eocene. Based on the subsequent records, pCO2 in parts of the Oligocene was similar to latest Eocene values. These results suggest that a decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene-Oligocene transition and that when a certain threshold of pCO2 change was crossed, the cumulative effects of this and other factors resulted in rapid temperature decline, ice build up on Antarctica and hence a change of climate mode.

  16. Fossil plant stomata indicate decreasing atmospheric CO2 prior to the Eocene-Oligocene boundary

    NASA Astrophysics Data System (ADS)

    Steinthorsdottir, M.; Porter, A. S.; Holohan, A.; Kunzmann, L.; Collinson, M.; McElwain, J. C.

    2015-10-01

    A unique stratigraphic sequence of fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany has been used to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the inverse relationship between the density of stomata and pCO2, we show that pCO2 decreased continuously from the late middle to late Eocene, reaching a relatively stable low value before the end of the Eocene. Based on the subsequent records, pCO2 in parts of the Oligocene was similar to latest Eocene values. These results show that a decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene-Oliogocene transition. This may be related to the "hysteresis effect" previously proposed - where a certain threshold of pCO2 change was crossed before the cumulative effects of this and other factors resulted in rapid temperature decline, ice build up on Antarctica and hence a change of climate mode.

  17. The oldest African bat from the early Eocene of El Kohol (Algeria).

    PubMed

    Ravel, Anthony; Marivaux, Laurent; Tabuce, Rodolphe; Adaci, Mohammed; Mahboubi, Mohammed; Mebrouk, Fateh; Bensalah, Mustapha

    2011-05-01

    The Afro-Arabian Paleogene fossil record of Chiroptera is very poor. In North Africa and Arabia, this record is limited, thus far, to a few localities mainly in Tunisia (Chambi, late early Eocene), Egypt (Fayum, late Eocene to early Oligocene), and Sultanate of Oman (Taqah, early Oligocene). It consists primarily of isolated teeth or mandible fragments. Interestingly, these African fossil bats document two modern groups (Vespertilionoidea and Rhinolophoidea) from the early Eocene, while the bat fossil record of the same epoch of North America, Eurasia, and Australia principally includes members of the "Eochiroptera." This paraphyletic group contains all primitive microbats excluding modern families. In Algeria, the region of Brezina, southeast of the Atlas Mountains, is famous for the early Eocene El Kohol Formation, which has yielded one of the earliest mammalian faunas of the African landmass. Recent fieldwork in the same area has led to the discovery of a new vertebrate locality, including isolated teeth of Chiroptera. These fossils represent the oldest occurrence of Chiroptera in Africa, thus extending back the record of the group to the middle early Eocene (Ypresian) on that continent. The material consists of an upper molar and two fragments of lower molars. The dental character association matches that of "Eochiroptera." As such, although very fragmentary, the material testifies to the first occurrence of "Eochiroptera" in Algeria, and by extension in Africa. This discovery demonstrates that this basal group of Chiroptera had a worldwide distribution during the early Paleogene. PMID:21442243

  18. Sonora, Mexico, source for the Eocene Poway Conglomerate of southern California

    NASA Astrophysics Data System (ADS)

    Abbott, Patrick L.; Smith, T. E.

    1989-04-01

    Alluvial-fan conglomerates of the Eocene Poway Group are composed largely of exotic rhyolite and dacite clasts derived from far to the east of their Eocene depositional site. Remnants of the Upper Jurassic bedrock source of the Poway rhyolite clasts may yet be exposed in hills in Sonora, Mexico. For this study, pieces of bedrock were taken from hills 13 km west of El Plomo in Sonora. Clasts texturally and mineralogically similar to the Sonoran bedrock were collected from the apex of the Eocene alluvial fan in San Diego County, California Nine couplets of bedrock and conglomerate clast samples (textural twins) were analyzed for 16 trace elements selected for their wide range of behaviors during magmatic and alteration processes. Statistical comparisons of the trace-element data, by using the standard error-of-the-difference method, show that there are no significant differences between the two populations. These data strongly suggest that the rhyolitic bedrock hills west of El Plomo were part of the source terrane for the Eocene conglomerate in San Diego. The latitudinal separation between bedrock source and the site of deposition is only the 2° created by the opening of the Gulf of California This implies that any boundary separating a paleomagnetically efined, Baja-Borderland terrane from the craton since Eocene time was at least 100 km east of the Gulf of California in northernmost Sonora.

  19. Geochronology of upper Paleocene and lower Eocene strata, eastern Gulf Coastal Plain

    SciTech Connect

    Mancini, E.A.; Tew, B.H. Geological Survey of Alabama, Tuscaloosa, AL )

    1994-03-01

    Four samples of glauconitic sand from upper Paleocene and lower Eocene strata of the eastern Gulf Coastal Plain were analyzed for conventional potassium-argon (K-Ar) age determination. Results from these analyses are as follows: Coal Bluff Marl Member of the Naheola Formation of the Midway Group (58.2 [+-] 1.5 MA), Ostrea thirsae beds of the Nanafalia Formation of the Wilcox Group (56.3 [+-] 1.5 MA), upper Tuscahoma Sand of the Wilcox Group (54.5 [+-] 1.4 MA), and Bashi Marl Member of the Hatchetigbee Formation of the Wilcox Group (53.4 [+-] 1.4 MA). The Nanafalia Formation (Wilcox Group) disconformably overlies the Naheola Formation (Midway Group), and based on the data presented here, the age of this unconformity is bracketed between 59.7 and 54.8 MA. The Paleocene-Eocene Epoch boundary occurs in the Wilcox Group and coincides with the lithostratigraphic contact of the upper Paleocene Tuscahoma Sand with the lower eocene Hatchetigbee Formation. The age of this boundary, which is also an unconformity, can be placed between 55.9 and 52.0 MA. The K-Ar age dates for this boundary in the Gulf Coastal Plain compare favorably with the numerical limits placed on the Paleocene-Eocene boundary in the published literature. Generally, the Paleocene-Eocene Epoch boundary is reported as approximately 54 to 55 MA.

  20. Astronomical calibration of the middle Eocene Contessa Highway section (Gubbio, Italy)

    NASA Astrophysics Data System (ADS)

    Coccioni, R.; Florindo, F.; Jovane, L.; Marsili, A.; Sprovieri, M.

    2008-12-01

    The Earth's Eocene to early Oligocene climatic system experienced an important transition with a long-term cooling trend from warm greenhouse to icehouse conditions. Today, it is a priority to understand the causes and consequences that drove this major climatic change. In this context, a multidisciplinary study has been carried out on the middle Eocene sedimentary succession of the Contessa Highway (Gubbio, Italy). Spectral analysis and CWT technique of seven multidisciplinary high-resolution records demonstrate that climatic changes, in the western Neo-Tethys (Umbria-Marche basin) during the middle Eocene, are sensitive to eccentricity, obliquity and precession astronomical variations. In the Contessa Highway section, the lithology shows high-frequency cyclicity, which is strongly modulated by insolation. The lithologic cyclostratigraphy combined with the ~7 My-long astronomically driven climate proxy records, provide a first astronomical calibration of the middle Eocene. Here, we present astronomical age for the bio-magnetostratigraphic events along the middle Eocene Contessa Highway section. These astronomically calibrated ages mark significant improvements for the dating of biostratigraphic events and minimal correction to chronostratigraphy. Based on the available high-resolution bio-, isotope- and magnetostratigraphy and the precise multi-proxy astronomical tuning of the sedimentary record we retain that the Contessa Highway section represents an excellent candidate as GSSP for the Lutetian/Bartonian boundary.