DOCSLIB.ORG

Decadal Scale Climate Variability During the Last Millennium As Recorded by the Bona Churchill and Quelccaya Ice Cores

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Decadal Scale Climate Variability During the Last Millennium As Recorded by the Bona Churchill and Quelccaya Ice Cores DECADAL SCALE CLIMATE VARIABILITY DURING THE LAST MILLENNIUM AS RECORDED BY THE BONA CHURCHILL AND QUELCCAYA ICE CORES DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By David Urmann, M.S. Geological Science Graduate Program * * * * * The Ohio State University 2009 Dissertation Committee: Professor Lonnie Thompson, Advisor Professor Gary McKenzie Professor Doug Alsdorf Professor Cornelis Vanderveen Professor Greg Wiles ABSTRACT This thesis outlines the development of the timescales, the calibration of the ice- climate relationships, and the possible linkages between the Quelccaya Summit Ice Core and the Bona Churchill Ice Core, with different modes of decadal and interannual climate variability during the last 1,000 years. The Bona Churchill Ice Core (BC1), drilled to bedrock in the spring of 2002 in the Wrangell-St. Elias Mountains of southeast Alaska (61o 24' N, 141o 42'W, 4420 meters), is one of the only annually dateable records of extended historical duration to ever be recovered from the northeastern side of the Pacific Basin. The Quelccaya Summit Ice Core (168.8m) was obtained during the most recent drilling project at Quelccaya (13º 56’S, 70º 50’W, 5670 meters), which took place in the summer of 2003 and is the longest of the three ice cores obtained. Dr. Thompson has led glacial studies in the region since 1976. These include a major drilling project in 1983; the mapping of the retreat of the Quelccaya Ice Cap using surface and aerial photos; documentary photography of the retreat of the Kori Qalis glacier; and setting up and recording data from automated weather stations. The timescale for BC1 is well constrained during the last 1,000 years by annual layering, the identification of the 1963 β- peak, the 1912 eruption of Katmai, and the 1783 eruption of Laki. Additionally, this study pinpoints the period A.D. 760 to 777 (according to the BC1 timeline) as the likely timing of the White River Ash, an important regional chronostratigraphic marker. It should be noted that the timeline before A.D. 1000 is only an approximation that is based entirely upon a simple time-depth model and the assumptions that are inherent to the model. The time-depth model suggests that the bottom of the ice core corresponds to A.D. 265. ii The timescale for the 2003 Quelccaya Summit Core is based upon multiple lines of evidence, including annual layer counting based on peaks in dust, a well-defined annual cycle in δ18O, the identification of ash layers in the ice core corresponding to historic volcanic eruptions, and comparisons of the Quelccaya core with other regional ice cores. Counting of annual layers was possible from A.D. 615 to 2003. By using a time-depth model, the timeline can be extended to A.D. 315, which corresponds with the end of the core. A comparison with the 2003 Coropuna Core (15° 31′S, 72 °39′W) that was obtained from the western cordillera of the Peruvian Andes shows that individual years can be identified and matched peak for peak for the last 200 years. This serves as a valid cross-check on the derived timeline and shows that the isotope profiles are not unique to either ice core, but are rather preserved systematically across this entire region of the Andes. Comparisons of the isotopic profiles from the 2003 to the 1983 Quelccaya ice cores over the last 500 years show that despite the differences in sampling methods, both records are nearly identical. This attests to the stability of the derived δ18O profiles through time and as a verification of the original 1983 timescale developed by Dr. Thompson. The records of δ18O and dust from BC1 can be related to long-term shifts in atmospheric circulation, which are expressed by the two primary modes of Northern Hemisphere circulation: the Aleutian Low (AL) and the Arctic Oscillation (AO). This thesis shows that the strongest climate signal in both δ18O and dust is that produced by the history of northerly flow (associated with weak AL and negative AO), versus southerly flow over the drill site. Comparisons with other regional records suggest that the longer-term trends in the records of both δ18O and dust, upon which the AO modulated peaks and troughs are superimposed, may reflect gradual changes in the strength or position of the AL through time. It is observed that large dust events and more negative values of δ18O occur when the AL is weak and the AO is negative as a result of an anomalous northerly flow over the drill site that likely results in the emplacement of a dustier, colder, and more continental air mass. In general, the AO acts to modulate the strength of the correlation between δ18O and dust with the AL, so that when the AO is negative (positive), a stronger (weaker) correlation is observed with the AL. The record from BC1 provides an important record of past AO variability at a time when more iii investigators are just beginning to take an in-depth look at the effects of this feature on the climate in Alaska. The relationships identified between δ18O and dust with both the AO and AL suggests that the temperature response recorded by BC1 is indefinable, because more negative values of δ18O are associated with a weaker AL and/or a negative AO and more positive values of δ18O are associated with a stronger AL and/or a positive AO. Historical records show that a weaker (stronger) AL is associated with cooler (warmer) conditions and a negative (positive) AO is associated with warmer (cooler) conditions. This ambiguous relationship could explain why the record of BC1 δ18O shows no response to modern warming. During the last 25 years the AL has gotten stronger and the AO has been more positive, suggesting at least cooler temperatures in the upper atmosphere due to the influence of the AO and warmer temperatures at the surface due to the influence of a stronger AL. These results are consistent with the accumulation record from BC1 and with historical records, which show trends toward increasing precipitation and temperature. These trends might be expected given an overall increase in the regional lapse rate and increased moisture flux into the region, which is typically associated with a strong AL. The analysis of the 2003 Quelccaya core identifies a strong correlation between Quelccaya δ18O and NINO 4 Sea Surface Temperatures (SSTs) (r=0.646, p<0.001, 1856- 2003). The Pierson correlation coefficient between Jan-Dec NINO 4 SST and Quelccaya δ18O during the period 1856 to 1882 is 0.75 (as opposed to 0.65 for the modern period of record from 1882 to 2000), indicating that a strong relationship between δ18O and SST persisted even during the Little Ice Age (LIA) despite a substantially different background climate. Previous studies of the 1983 Quelccaya δ18O and of the record of NINO 4 SSTs show that decadal rather than interannual variability is dominant in both records. ENSO events can be observed in the 2003 Quelccaya δ18O superimposed on the lower-frequency decadal variability, but they are not the dominant feature. This occurs as Quelccaya δ18O is most strongly correlated with SST in the easternmost margin of the Pacific Warm Pool (PWP), and in general SST anomalies in this region are more persistent and evolve on slower timescales than those in the eastern Pacific. Previous studies indicate that increased convection in the eastern portion of the warm pool results iv in weaker trade winds in the Atlantic and warmer SST in the northern tropical Atlantic. Establishing a connection between decadal variability in the Pacific and Atlantic is of key importance, as the Atlantic is the primary moisture source area for Quelccaya. One of the primary purposes of this thesis was to reconstruct a multi-ice core history of El Niño events using the records from BC and Quelccaya, but the results of this analysis were of limited use because of the weak overall relationship between BC and ENSO events. The lack of connection between the ice core variables from Peru and Alaska during both the last 100 years and the last 1,000 years might result from the BC record of δ18O being more strongly related to fluctuations in the AO than in the AL. However, it might result from the fact that the Quelccaya δ18O record reflects decadal NINO 4 variability and seems for the most part disconnected from the lower-frequency regime shifts associated with the PDO, which primarily reflects North Pacific variability. Although it was not feasible to reconstruct a multi-ice core history of El Niño from the records from Quelccaya and Bona Churchill, the concept of constructing a history of El Niño events from the Quelccaya core is promising. As proof of concept, this thesis finds strong linkages between the time series of δ18O from Quelccaya with reconstructions of El Niño events based on historical records during the last 500 years and with a reconstruction of the Palmer Drought Severity Index (PDSI) for the southwestern U.S., a region with a strong and dependable ENSO teleconnection. Additionally, a strong relationship is noted between modern corals growing near Palmyra Island (162ºW, 6ºN) with Quelccaya δ18O. This is of particular interest, as the strongest correlations between Quelccaya 18O and Pacific SSTs occur in this same region. However, despite the fact that modern coral records exhibit a match with the Quelccaya, the relationship is not as clear when older fossil coral records from the same location are examined. The Quelccaya record offers a great deal of promise for future reconstructions of ENSO variability but needs to be paired with other proxy records that exhibit a strong ENSO signal.
Load more

Recommended publications
  • Multiple Sources for Tephra from AD 1259 Volcanic Signal in Antarctic Ice
    Multiple sources for tephra from AD 1259 volcanic signal in Antarctic ice cores Biancamaria Narcisi, Jean Robert Petit, Barbara Delmonte, Valentina Batanova, Joel Savarino To cite this version: Biancamaria Narcisi, Jean Robert Petit, Barbara Delmonte, Valentina Batanova, Joel Savarino. Mul- tiple sources for tephra from AD 1259 volcanic signal in Antarctic ice cores. Quaternary Science Reviews, Elsevier, 2019, 210, pp.164-174. 10.1016/j.quascirev.2019.03.005. hal-02350371 HAL Id: hal-02350371 https://hal.archives-ouvertes.fr/hal-02350371 Submitted on 25 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Manuscript Details Manuscript number JQSR_2019_21 Title MULTIPLE SOURCES FOR TEPHRA FROM AD 1259 VOLCANIC SIGNAL IN ANTARCTIC ICE CORES Abstract Strong volcanic signals simultaneously recorded in polar ice sheets are commonly assigned to major low-latitude eruptions that dispersed large quantities of aerosols in the global atmosphere with the potential of inducing climate perturbations. Parent eruptions responsible for specific events are typically deduced from matching to a known volcanic eruption having coincidental date. However, more robust source linkage can be achieved only through geochemical characterisation of the airborne volcanic glass products (tephra) sometimes preserved in the polar strata.
    [Show full text]
  • Review of Local and Global Impacts of Volcanic Eruptions and Disaster Management Practices: the Indonesian Example
    geosciences Review Review of Local and Global Impacts of Volcanic Eruptions and Disaster Management Practices: The Indonesian Example Mukhamad N. Malawani 1,2, Franck Lavigne 1,3,* , Christopher Gomez 2,4 , Bachtiar W. Mutaqin 2 and Danang S. Hadmoko 2 1 Laboratoire de Géographie Physique, Université Paris 1 Panthéon-Sorbonne, UMR 8591, 92195 Meudon, France; [email protected] 2 Disaster and Risk Management Research Group, Faculty of Geography, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia; [email protected] (C.G.); [email protected] (B.W.M.); [email protected] (D.S.H.) 3 Institut Universitaire de France, 75005 Paris, France 4 Laboratory of Sediment Hazards and Disaster Risk, Kobe University, Kobe City 658-0022, Japan * Correspondence: [email protected] Abstract: This paper discusses the relations between the impacts of volcanic eruptions at multiple- scales and the related-issues of disaster-risk reduction (DRR). The review is structured around local and global impacts of volcanic eruptions, which have not been widely discussed in the literature, in terms of DRR issues. We classify the impacts at local scale on four different geographical features: impacts on the drainage system, on the structural morphology, on the water bodies, and the impact Citation: Malawani, M.N.; on societies and the environment. It has been demonstrated that information on local impacts can Lavigne, F.; Gomez, C.; be integrated into four phases of the DRR, i.e., monitoring, mapping, emergency, and recovery. In Mutaqin, B.W.; Hadmoko, D.S. contrast, information on the global impacts (e.g., global disruption on climate and air traffic) only fits Review of Local and Global Impacts the first DRR phase.
    [Show full text]
  • Aleutian Islands
    Ecosystem Status Report 2018 Aleutian Islands Edited by: Stephani Zador1 and Ivonne Ortiz2 1Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA 7600 Sand Point Way NE, Seattle, WA 98115 2 JISAO, University of Washington, Seattle, WA With contributions from: Sonia Batten, Jennifer Boldt, Nick Bond, Anne Marie Eich, Ben Fissel, Shannon Fitzgerald, Sarah Gaichas, Jerry Hoff, Steve Kasperski, Carol Ladd, Ned Laman, Geoffrey Lang, Jean Lee, Jennifer Mondragon, John Olson,Ivonne Ortiz, Wayne Palsson, Heather Renner, Nora Rojek, Chris Rooper, Kim Sparks, Michelle St Martin, Jordan Watson, George A. Whitehouse, Sarah Wise, and Stephani Zador Reviewed by: The Plan Teams for the Groundfish Fisheries of the Bering Sea, Aleutian Islands, and Gulf of Alaska November 13, 2018 North Pacific Fishery Management Council 605 W. 4th Avenue, Suite 306 Anchorage, AK 99301 Aleutian Islands 2018 Report Card Region-wide The North Pacific Index (NPI) was strongly positive from fall 2017 into 2018 due to the relatively high sea level pressure in the region of the Aleutian Low, which was displaced to the northwest, over Siberia, and caused persistent warm winds from the southwest. Positive NPI is expected during La Ni~na,but its magnitude was greater than expected. The Aleutians Islands region experienced suppressed storminess through fall and winter 2017/2018 across the region. The Alaska Stream appears to have been relatively diffuse on the south side of the eastern Aleutian Islands. Although the sea surface temperatures cooled in 2018, relative to the 2014{2017 warm period, the overall temperature was still warm due to heat retention throughout the water column.
    [Show full text]
  • Review of the Draft Climate Science Special Report
    THE NATIONAL ACADEMIES PRESS This PDF is available at http://www.nap.edu/24712 SHARE Review of the Draft Climate Science Special Report DETAILS 132 pages | 8.5 x 11 | PAPERBACK ISBN 978-0-309-45664-7 | DOI: 10.17226/24712 CONTRIBUTORS GET THIS BOOK Committee to Review the Draft Climate Science Special Report; Board on Atmospheric Sciences and Climate; Division on Earth and Life Studies; National Academies of Sciences, Engineering, and FIND RELATED TITLES Medicine Visit the National Academies Press at NAP.edu and login or register to get: – Access to free PDF downloads of thousands of scientific reports – 10% off the price of print titles – Email or social media notifications of new titles related to your interests – Special offers and discounts Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the National Academies Press. (Request Permission) Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved. Review of the Draft Climate Science Special Report Committee to Review the Draft Climatee Science Special Report Board on Atmospheric Sciences and Climate Division on Earth and Life Studies A Report of Copyright © National Academy of Sciences. All rights reserved. Review of the Draft Climate Science Special Report THE NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001 This study was supported by the National Aeronautics and Space Administration under award numbers NNH14CK78B and NNH14CK79D. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.
    [Show full text]
  • North American Notes
    268 NORTH AMERICAN NOTES NORTH AMERICAN NOTES BY KENNETH A. HENDERSON HE year I 967 marked the Centennial celebration of the purchase of Alaska from Russia by the United States and the Centenary of the Articles of Confederation which formed the Canadian provinces into the Dominion of Canada. Thus both Alaska and Canada were in a mood to celebrate, and a part of this celebration was expressed · in an extremely active climbing season both in Alaska and the Yukon, where some of the highest mountains on the continent are located. While much of the officially sponsored mountaineering activity was concentrated in the border mountains between Alaska and the Yukon, there was intense activity all over Alaska as well. More information is now available on the first winter ascent of Mount McKinley mentioned in A.J. 72. 329. The team of eight was inter­ national in scope, a Frenchman, Swiss, German, Japanese, and New Zealander, the rest Americans. The successful group of three reached the summit on February 28 in typical Alaskan weather, -62° F. and winds of 35-40 knots. On their return they were stormbound at Denali Pass camp, I7,3oo ft. for seven days. For the forty days they were on the mountain temperatures averaged -35° to -40° F. (A.A.J. I6. 2I.) One of the most important attacks on McKinley in the summer of I967 was probably the three-pronged assault on the South face by the three parties under the general direction of Boyd Everett (A.A.J. I6. IO). The fourteen men flew in to the South east fork of the Kahiltna glacier on June 22 and split into three groups for the climbs.
    [Show full text]
  • COV4 Meeting Schedule Monday, 23 January, 2006
    COV4 Meeting Schedule Monday, 23 January, 2006 Sala 1 (large)† 8H15 Welcoming Statements 8H30 Invited Speaker M. Hall: LIVING WITH VOLCANOES 9H00 - 9H30 Invited Speaker A. Lavell: SOCIETY AND RISK: RISK MANAGEMENT AND VOLCANIC HAZARDS 9H30 - 10H00 Plenary Symposium IV-B: Monitoring Volcanoes J. EWERT: ASSESSING VOLCANIC THREAT AND PRIORITIZING VOLCANO MONITORING IN THE UNITED STATES 10H00 - Plenary Symposium II: Ash Falls and Aerosols 10H30 W. Rose: ASH-FALL AND AEROSOLS, AN OVERVIEW 10H30 - 11H00 Coffee Break Sala 1 (large) Sala 2 (medium) IV-B: Monitoring Volcanoes II: Ash Falls and Aerosols Chairs: J. Ewert, A. García, H. Kumagai & J. Chairs: J.-L. Le Pennec, C. Connor, T. Johnson Casadevall, D. Johnston & D. Schneider 11H00 - S. Carn: MONITORING GLOBAL VOLCANIC A. Neri: ASSESSING ASH FALL HAZARD 11H20 DEGASSING WITH OMI FROM WEAK EXPLOSIVE PLUMES 11H20 - C. Oppenheimer: NEW DEVELOPMENTS IN C. Bonadonna: PROBABILISTIC MODELLING 11H40 VOLCANIC GAS SURVEILLANCE OF TEPHRA DISPERSON 11H40 - B. Galle: DEVELOPMENT OF OPTICAL B. Houghton: PROXIMAL TEPHRA HAZARDS: 12H00 REMOTE SENSING INSTRUMENTS FOR RECENT ERUPTION STUDIES APPLIED TO VOLCANOLOGICAL APPLICATIONS VOLCANIC RISK IN THE AUCKLAND VOLCANIC FIELD, NEW ZEALAND 12H00-12H20 F. Donnadieu: ERUPTION DYNAMICS OF P. Baxter: GRAIN SIZE ANALYSIS OF ARENAL VOLCANO, COSTA RICA: INSIGHTS VOLCANIC ASH FOR THE ASSESSMENT OF FROM DOPPLER RADAR AND SEISMIC HEALTH HAZARD MEASUREMENTS 12H20 - 14H00 Lunch in the Centro Cultural Metropolitano- Plaza Grande IV-B: Monitoring-Cont. II: Ash- Cont. 14H00- A. Gerst: REAL-TIME 4D MONITORING OF D. Andronico: ASH EMISSIONS AT THE 14H20 ERUPTIVE PROCESSES WITH DOPPLER SUMMIT OF ETNA DURING THE 2004-05 RADARS- A NEW TOOL FOR HAZARDS FLANK ERUPTION MITIGATION AND VOLCANO SCIENCE 14H20-14H40 M.
    [Show full text]
  • Resedimentation of the Late Holocene White River Tephra, Yukon Territory and Alaska
    Resedimentation of the late Holocene White River tephra, Yukon Territory and Alaska K.D. West1 and J.A. Donaldson2 Carleton University3 West, K.D. and Donaldson, J.A. 2002. Resedimentation of the late Holocene White River tephra, Yukon Territory and Alaska. In: Yukon Exploration and Geology 2002, D.S. Emond, L.H. Weston and L.L. Lewis (eds.), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, p. 239-247. ABSTRACT The Wrangell region of eastern Alaska represents a zone of extensive volcanism marked by intermittent pyroclastic activity during the late Holocene. The most recent and widely dispersed pyroclastic deposit in this area is the White River tephra, a distinct tephra-fall deposit covering 540 000 km2 in Alaska, Yukon, and the Northwest Territories. This deposit is the product of two Plinian eruptions from Mount Churchill, preserved in two distinct lobes, created ca. 1887 years B.P. (northern lobe) and 1147 years B.P. (eastern lobe). The tephra consists of distal primary air-fall deposits and proximal, locally resedimented volcaniclastic deposits. Distinctive layers such as the White River tephra provide important chronostratigraphic control and can be used to interpret the cultural and environmental impact of ancient large magnitude eruptions. The resedimentation of White River tephra has resulted in large-scale terraces, which fl ank the margins of Klutlan Glacier. Preliminary analysis of resedimented deposits demonstrates that the volcanic stratigraphy within individual terraces is complex and unique. RÉSUMÉ Au cours de l’Holocène tardif, des matériaux pyroclastiques ont été projetés lors d’importantes et nombreuses éruptions volcaniques, dans la région de Wrangell de l’est de l’Alaska.
    [Show full text]
  • Water Chemistry of Lake Quilotoa (Ecuador) and Assessment of Natural Hazards
    Journal of Volcanology and Geothermal Research 97 (2000) 271–285 www.elsevier.nl/locate/volgeores Water chemistry of Lake Quilotoa (Ecuador) and assessment of natural hazards E. Aguileraa, G. Chiodinib, R. Cionic,*, M. Guidic, L. Marinid, B. Racoe aEscuela Politecnica del Ejercito, Sangolquı´, Apartado 231-D, Ecuador bOsservatorio Vesuviano, via Manzoni 249, 80122 Napoli, Italy cIst. Geocronologia e Geochimica Isotopica, CNR, Via Alfieri 1, I-56010 Ghezzano (Piza), Italy dDip. Te. Ris., Univ. di Genova, Corso Europa 26, I-16132 Genova, Italy eDip. Scienze della Terra, Univ. di Pisa, Via Santa Maria 53, 56126 Pisa, Italy Abstract A geochemical survey carried out in November 1993 revealed that Lake Quilotoa was composed by a thin (,14 m) oxic epilimnion overlying a ,200 m-thick anoxic hypolimnion. Dissolved CO2 concentrations reached 1000 mg/kg in the lower stratum. Loss of CO2 from epilimnetic waters, followed by calcite precipitation and a consequent lowering in density, was the apparent cause of the stratification. The Cl, SO4 and HCO3 contents of Lake Quilotoa are intermediate between those of acid–SO4–Cl Crater lakes and those of neutral-HCO3 Crater lakes, indicating that Lake Quilotoa has a ‘memory’ of the inflow and absorption of HC1- and S-bearing volcanic (magmatic) gases. The Mg/Ca ratios of the lake waters are governed by dissolution of local volcanic rocks or magmas, but K/Na ratios were likely modified by precipitation of alunite, a typical mineral in acid–SO4–Cl Crater lakes. The constant concentrations of several conservative chemical species from lake surface to lake bottom suggest that physical, chemical and biological processes did not have enough time, after the last overturn, to cause significant changes in the contents of these chemical species.
    [Show full text]
  • Calidad Microbiológica Del Agua Del Lago Volcánico Quilotoa. Coto- Paxi-Ecuador
    REVISTA CON-CIENCIA Nº1/VOL. 9, JULIO 2021, ISSN: 2310-0265, ISSN ELECTRÓNICO: 2710-3609 Calidad microbiológica del agua del lago volcánico quilotoa. coto- paxi-ecuador Microbiological quality of water of the quilotoa volcanic lake. cotopaxi-ecuador GONZÁLEZ, MARCO1 ESCOBAR, SANDRA2 ACUÑA, JESSICA1 ARAQUE, JUDITH1,3 ESCOBAR, JESSICA1 ANDUEZA, FELIX1,3 FECHA DE RECEPCIÓN: 26 ABRIL 2021 FECHA DE ACEPTACIÓN: 6 JUNIO DE 2021 Resumen Abstract Introducción. El agua de los lagos volcánicos Introduction. The water of volcanic lakes is no es estéril, en ella se ha adaptado a través de not sterile, native microbiota shows different met- milenios una microbiota con diversas capacida- abolic capabilities established over millennia. The des metabólicas. La diversidad microbiana de microbial diversity of volcanic lakes in Ecuador los lagos volcánicos en Ecuador ha sido poco have been little studied and their abundance and estudiada y aún se desconoce su abundancia y richness are still unknown. riqueza. Objetivo: Determinar la dinámica es- Objective. The objective of this study was to tructural entre las conformaciones abierta y know the microbiological quality of water of Lake cerrada del canal KATP en células pancreáticas. Quilotoa, located in the Province of Cotopaxi-Ec- Objetivo. El objetivo del presente es- uador. tudio fue conocer la calidad microbio- Materials and methods. Two samplings were lógica del agua del lago Quilotoa, situa- carried out during 2019, collecting a total of 32 do en la Provincia de Cotopaxi-Ecuador. samples. Microbiological quality was quantified Materiales y Metodos. Se realizaron dos using the membrane filtration technique on R2A muestreos durante el año 2019, recolectando agar for heterotrophic bacteria, eosin blue meth- un total 32 muestras.
    [Show full text]
  • Surface Flux Variability Over the North Pacific and North Atlantic Oceans
    NOVEMBER 1997 ALEXANDER AND SCOTT 2963 Surface Flux Variability over the North Paci®c and North Atlantic Oceans MICHAEL A. ALEXANDER AND JAMES D. SCOTT CIRES, University of Colorado, Boulder, Colorado (Manuscript received 22 January 1996, in ®nal form 9 May 1997) ABSTRACT Daily ®elds obtained from a 17-yr atmospheric GCM simulation are used to study the surface sensible and latent heat ¯ux variability and its relationship to the sea level pressure (SLP) ®eld. The ¯uxes are analyzed over the North Paci®c and Atlantic Oceans during winter. The leading mode of interannual SLP variability consists of a single center associated with the Aleutian low in the Paci®c, and a dipole pattern associated with the Icelandic low and Azores high in the Atlantic. The surface ¯ux anomalies are organized by the low-level atmospheric circulation associated with these modes in agreement with previous observational studies. The surface ¯ux variability on all of the timescales examined, including intraseasonal, interannual, 3±10 day, and 10±30 day, is maximized along the north and west edges of both oceans and between Japan and the date line at ;358N in the Paci®c. The intraseasonal variability is approximately 3±5 times larger than the interannual variability, with more than half of the total surface ¯ux variability occuring on timescales of less than 1 month. Surface ¯ux variability in the 3±10-day band is clearly associated with midlatitude synoptic storms. Composites indicate upward (downward) ¯ux anomalies that exceed |30 W m22| occur to the west (east) of storms, which move eastward across the oceans at 108±158 per day.
    [Show full text]
  • Conduit and Eruption Dynamics of the 1912 Vulcanian Explosions at Novarupta, Alaska
    CONDUIT AND ERUPTION DYNAMICS OF THE 1912 VULCANIAN EXPLOSIONS AT NOVARUPTA, ALASKA A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I AT MĀNOA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN GEOLOGY AND GEOPHYSICS December 2017 By Samantha Jo Isgett Dissertation Committee: Bruce F. Houghton, Chairperson Helge M. Gonnermann Christina Neal Thomas Shea John Allen © 2017, Samantha Jo Isgett ii Acknowledgements I probably would not be “standing here today” if my advisor Bruce Houghton had not introduced me to the wonderful world of volcanology. I entered his 300 level volcanology class as a naïve sophomore who had no ambitions of going to graduate school and left knowing that I wanted to be volcanologist and the steps that I needed to take to get there. Bruce has a passion not only for solving the big science question, but also in passing on his knowledge and skill-sets to his students. I cannot thank Bruce enough for seeing in me the potential makings of a scientist and guiding me there. It was, and always will be, a privilege to work with you. I would like to thank my committee — Helge Gonnermann, Thomas Shea, Christina Neal, and John Allen — for pushing me to take every problem and interpretation just a little (or a lot) further. I am especially grateful to Tom and John for stepping in at the last hour. Thank you all for your time and patience. Alain Burgisser, Laurent Arbaret, and Sarah Fagents also brought outside perspectives and skill-sets that were crucial for this project.
    [Show full text]
  • Defining and Sizing-Up Mountains
    Defining and Sizing-up Mountains By Steven Fry What are the ten highest mountains in the world? ridge-level, before it is considered an individual Is Mount Everest larger than Mount McKinley? Does mountain. Mount Rainier rise higher above its base than In 1981, following 12 years of academic, profes- Everest? Unbelievably, these questions have never sional and recreational mountain study, I decided to been answered with any certainty, for the simple rea- make a serious attempt to establish a workable defi- son that mountains have remained essentially nition for mountains. I studied thousands of moun- undefined. tains and hills before I arrived at the conclusion There are some who may say defining mountains presented in this article. My research mainly focused is irnposstbte. However, the word "impossible" on Washington's Cascade Range, but I also studied should be used with great caution, especially within other sections of the Cascade Range, the Rockies, the climbing community. Furthermore, classifica- Sierra Nevada, Appalachians, Himalayas, Andes, tion systems are ubiquitous for such things as trees, Alps, British Isles, Alaska Range and numerous animals, rocks and clouds-and although not other geographic localities. perfect - these systems do help people better de- Mountain Definitions scribe and eventually understand the world around A mountain can be defined based upon the follow- us. ing three geographic parameters: A. Local Relief; B. Various geographers and geologists have stated Elevation; and C. Prominence. These three that a mountain must have: 1. 1,000 or 2,000 feet parameters are utilized in the mountain definitions of local relief; 2. Relatively steep slopes; and 3.
    [Show full text]