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Articles 1981 - 2010 of 3306

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Interannual And Spatial Impacts Of Phenological Transitions, Growing Season Length, And Spring And Autumn Temperatures On Carbon Sequestration: A North America Flux Data Synthesis, Chaoyang Wu, Alemu Gonsamo, Jing Ming Chen, Werner A. Kurz, David T. Price, Peter M. Lafleur, Rachhpal S. Jassal, Danilo Dragoni, Gil Bohrer, Christopher M. Gough, Shashi B. Verma, Andrew E. Suyker, J. William Munger Jan 2012

Interannual And Spatial Impacts Of Phenological Transitions, Growing Season Length, And Spring And Autumn Temperatures On Carbon Sequestration: A North America Flux Data Synthesis, Chaoyang Wu, Alemu Gonsamo, Jing Ming Chen, Werner A. Kurz, David T. Price, Peter M. Lafleur, Rachhpal S. Jassal, Danilo Dragoni, Gil Bohrer, Christopher M. Gough, Shashi B. Verma, Andrew E. Suyker, J. William Munger

School of Natural Resources: Faculty Publications

Understanding feedbacks of ecosystem carbon sequestration to climate change is an urgent step in developing future ecosystem models. Using 187 site-years of flux data observed at 24 sites covering three plant functional types (i.e. evergreen forests (EF), deciduous forests (DF) and non-forest ecosystems (NF) (e.g., crop, grassland, wetland)) in North America, we present an analysis of both interannual and spatial relationships between annual net ecosystem production (NEP) and phenological indicators, including the flux-based carbon uptake period (CUP) and its transitions, degree-day-derived growing season length (GSL), and spring and autumn temperatures. Diverse responses were acquired between annul NEP and these indicators …


Ua94/6/10 Student / Alumni Personal Papers Wku Carl Ellis, Wku Archives Jan 2012

Ua94/6/10 Student / Alumni Personal Papers Wku Carl Ellis, Wku Archives

WKU Archives Collection Inventories

Scientific notebooks used by Carl Ellis during his years at WKU.


A Synoptic Perspective Of The Record 1-2 May 2010 Mid-South Heavy Precipitation Event, Joshua D. Durkee, Lee Campbell, Kyle Berry, Dustin Jordan, Gregory Goodrich, Rezaul Mahmood, Stuart Foster Jan 2012

A Synoptic Perspective Of The Record 1-2 May 2010 Mid-South Heavy Precipitation Event, Joshua D. Durkee, Lee Campbell, Kyle Berry, Dustin Jordan, Gregory Goodrich, Rezaul Mahmood, Stuart Foster

High Plains Regional Climate Center: Staff Publications

During 1–2 May 2010, a series of strong thunderstorms led to 41, 57, and 43 tornado, severe wind, and severe hail reports, respectively, across portions of the southern United States. In addition to severe weather, these storms also distributed recordsetting rainfall amounts across the mid-South region, which contributed to historic flooding across portions of central and western Kentucky and Tennessee (Fig. 1). This heavy precipitation event was sampled by multiple surface observational networks, including (but not limited to) 48 research-grade automated stations from the Kentucky Mesonet (www.kymesonet .org), first-order automated stations from the National Weather Service (NWS; www.ncdc.noaa.gov /oa/ncdc.html), and …


Sea-Level History Of Past Interglacial Periods From Uranium-Series Dating Of Corals, Curaçao, Leeward Antilles Islands, Daniel R. Muhs, John M. Pandolfi, Kathleen R. Simmons, R. Randall Schumann Jan 2012

Sea-Level History Of Past Interglacial Periods From Uranium-Series Dating Of Corals, Curaçao, Leeward Antilles Islands, Daniel R. Muhs, John M. Pandolfi, Kathleen R. Simmons, R. Randall Schumann

United States Geological Survey: Staff Publications

Curaçao has reef terraces with the potential to provide sea-level histories of interglacial periods. Ages of the Hato (upper) unit of the “Lower Terrace” indicate that this reef dates to the last interglacial period, Marine Isotope Stage (MIS) 5.5. On Curaçao, this high sea stand lasted at least 8000 yr (~126 to ~118 ka). Elevations and age of this reef show that late Quaternary uplift rates on Curaçao are low, 0.026–0.054 m/ka, consistent with its tectonic setting. Ages of ~200 ka for corals from the older Cortalein unit of the Lower Terrace correlate this reef to MIS 7, with paleo-sea …


Saturated Thickness And Water In Storage In The High Plains Aquifer, 2009, And Water-Level Changes And Changes In Water In Storage In The High Plains Aquifer, 1980 To 1995, 1995 To 2000, 2000 To 2005, And 2005 To 2009, Virginia L. Mcguire, Kris D. Lund, Brenda K. Densmore Jan 2012

Saturated Thickness And Water In Storage In The High Plains Aquifer, 2009, And Water-Level Changes And Changes In Water In Storage In The High Plains Aquifer, 1980 To 1995, 1995 To 2000, 2000 To 2005, And 2005 To 2009, Virginia L. Mcguire, Kris D. Lund, Brenda K. Densmore

United States Geological Survey: Water Reports and Publications

The High Plains aquifer underlies about 112 million acres (about 175,000 square miles) in parts of eight States—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water levels declined in parts of the High Plains aquifer soon after the onset of substantial irrigation with groundwater (about 1950). This report presents the volume of saturated aquifer material and drainable water in storage in the High Plains aquifer in 2009; water-level changes in the High Plains aquifer from 1980 to 1995, 1995 to 2000, 2000 to 2005, and 2005 to 2009; and changes in the volume of drainable water in …


Hydrostratigraphic Interpretation Of Test-Hole And Surface Geophysical Data, Elkhorn And Loup River Basins, Nebraska, 2008 To 2011, Christopher M. Hobza, Paul A. Bedrosian, Benjamin R. Bloss Jan 2012

Hydrostratigraphic Interpretation Of Test-Hole And Surface Geophysical Data, Elkhorn And Loup River Basins, Nebraska, 2008 To 2011, Christopher M. Hobza, Paul A. Bedrosian, Benjamin R. Bloss

United States Geological Survey: Water Reports and Publications

The Elkhorn-Loup Model (ELM) was begun in 2006 to understand the effect of various groundwater-management scenarios on surface-water resources. During phase one of the ELM study, a lack of subsurface geological information was identified as a data gap. Test holes drilled to the base of the aquifer in the ELM study area are spaced as much as 25 miles apart, especially in areas of the western Sand Hills. Given the variable character of the hydrostratigraphic units that compose the High Plains aquifer system, substantial variation in aquifer thickness and characteristics can exist between test holes. To improve the hydrogeologic understanding …


A Brief History And Summary Of The Effects Of River Engineering And Dams On The Mississippi River System And Delta, Jason S. Alexander, Richard C. Wilson, W. Reed Green Jan 2012

A Brief History And Summary Of The Effects Of River Engineering And Dams On The Mississippi River System And Delta, Jason S. Alexander, Richard C. Wilson, W. Reed Green

United States Geological Survey: Water Reports and Publications

The United States Geological Survey Forecast Mekong project is providing technical assistance and information to aid management decisions and build science capacity of institutions in the Mekong River Basin. A component of this effort is to produce a synthesis of the effects of dams and other engineering structures on large-river hydrology, sediment transport, geomorphology, ecology, water quality, and deltaic systems. The Mississippi River Basin (MRB) of the United States was used as the backdrop and context for this synthesis because it is a continental scale river system with a total annual water discharge proportional to the Mekong River, has been …


Soil Genesis On The Island Of Bermuda In The Quaternary: The Importance Of African Dust Transport And Deposition, Daniel R. Muhs, James R. Budahn, Joseph M. Prospero, Gary Skipp, Stanley R. Herwitz Jan 2012

Soil Genesis On The Island Of Bermuda In The Quaternary: The Importance Of African Dust Transport And Deposition, Daniel R. Muhs, James R. Budahn, Joseph M. Prospero, Gary Skipp, Stanley R. Herwitz

United States Geological Survey: Staff Publications

The origin of terra rossa, red or reddish-brown, clay-rich soils overlying high-purity carbonate substrates, has intrigued geologists and pedologists for decades. Terra rossa soils can form from accumulation of insoluble residues during dissolution of the host limestones, addition of volcanic ash, or addition of externally derived, long-range-transported (LRT) aeolian particles. We studied soils and paleosols on high-purity, carbonate aeolianites of Quaternary age on Bermuda, where terra rossa origins have been debated for more than a century. Potential soil parent materials on this island include sand-sized fragments of local volcanic bedrock, the LRT, fine-grained (µm) component of distal loess from the …


East Versus West: Organic Contaminant Differences In Brown Pelican (Pelecanus Occidentalis) Eggs From South Carolina, Usa And The Gulf Of California, Mexico, Stacy S. Vander Pol, Daniel W. Anderson, Patrick G.R. Jodice, Joyce E. Stuckey Jan 2012

East Versus West: Organic Contaminant Differences In Brown Pelican (Pelecanus Occidentalis) Eggs From South Carolina, Usa And The Gulf Of California, Mexico, Stacy S. Vander Pol, Daniel W. Anderson, Patrick G.R. Jodice, Joyce E. Stuckey

United States Geological Survey: Staff Publications

Brown pelicans (Pelecanus occidentalis) were listed as endangered in the United States in 1970, largely due to reproductive failure and mortality caused by organochlorine contaminants, such as DDT. The southeast population, P.o. carolinensis, was delisted in 1985, while the west coast population, P.o. californicus, was not delisted until 2009. As fish-eating coastal seabirds, brown pelicans may serve as a biomonitors. Organic contaminants were examined in brown pelican eggs collected from the Gulf of California in 2004 and South Carolina in 2005 using gas chromatography/mass spectrometry (GC/MS). Contaminants were compared using all individual data as well as …


Strontium Isotope Systematics Of Mixing Groundwater And Oil-Field Brine At Goose Lake In Northeastern Montana, Usa, Zell E. Peterman, Joanna N. Thamke, Kiyoto Futa, Todd M. Preston Jan 2012

Strontium Isotope Systematics Of Mixing Groundwater And Oil-Field Brine At Goose Lake In Northeastern Montana, Usa, Zell E. Peterman, Joanna N. Thamke, Kiyoto Futa, Todd M. Preston

United States Geological Survey: Staff Publications

Groundwater, surface water, and soil in the Goose Lake oil field in northeastern Montana have been affected by Cl- rich oil-field brines during long-term petroleum production. Ongoing multidisciplinary geochemical and geophysical studies have identified the degree and local extent of interaction between brine and groundwater. Fourteen samples representing groundwater, surface water, and brine were collected for Sr isotope analyses to evaluate the usefulness of 87Sr/86Sr in detecting small amounts of brine. Differences in Sr concentrations and 87Sr/86Sr are optimal at this site for the experiment. Strontium concentrations range from 0.13 to 36.9 mg/L, …


Critique On The Use Of The Standardized Avian Acute Oral Toxicity Test For First Generation Anticoagulant Rodenticides, Nimish B. Vyas, Barnett A. Rattner Jan 2012

Critique On The Use Of The Standardized Avian Acute Oral Toxicity Test For First Generation Anticoagulant Rodenticides, Nimish B. Vyas, Barnett A. Rattner

United States Geological Survey: Staff Publications

Avian risk assessments for rodenticides are often driven by the results of standardized acute oral toxicity tests without regards to a toxicant’s mode of action and time course of adverse effects. First generation anticoagulant rodenticides (FGARs) generally require multiple feedings over several days to achieve a threshold concentration in tissue and cause adverse effects. This exposure regimen is much different than that used in the standardized acute oral toxicity test methodology. Median lethal dose values derived from standardized acute oral toxicity tests underestimate the environmental hazard and risk of FGARs. Caution is warranted when FGAR toxicity, physiological effects, and pharmacokinetics …


Climate Change And Infectious Disease Dynamics, Raina K. Plowright, Paul C. Cross, Gary M. Tabor, Emily Almberg, Leslie Bienen, Peter J. Hudson Jan 2012

Climate Change And Infectious Disease Dynamics, Raina K. Plowright, Paul C. Cross, Gary M. Tabor, Emily Almberg, Leslie Bienen, Peter J. Hudson

United States Geological Survey: Staff Publications

The International Panel on Climate Change has made an unequivocal case that the earth's climate is changing in profound ways, and that human activities are contributing significantly to climate disruption (IPCC 2007). The weight of evidence demonstrates warming global temperatures, changing patterns of precipitation, and increasing climate variability, with more extreme events. Thus, the physical underpinnings of ecology are changing, with pervasive effects on disease dynamics. Interactions among environment, hosts, and pathogens drive disease processes, and climate change will influence every interaction in this triad, directly and indirectly.


Wildlife Toxicology: Environmental Contaminants And Their National And International Regulation, K. Christiana Grim, Anne Fairbrother, Barnett A. Rattner Jan 2012

Wildlife Toxicology: Environmental Contaminants And Their National And International Regulation, K. Christiana Grim, Anne Fairbrother, Barnett A. Rattner

United States Geological Survey: Staff Publications

Wildlife toxicology is the study of potentially harmful effects of toxic agents in wild animals, focusing on amphibians, reptiles, birds, and mammals. Fish and aquatic invertebrates are not usually included as part of wildlife toxicology since they fall within the field of aquatic toxicology, but collectively both disciplines often provide inSight into one another and both are integral parts of ecotoxicology (Hoffman et al. 2003). It entails monitoring, hypothesis testing, forensics, and risk assessment; encompasses molecular through ecosystem responses and various research venues (laboratory, mesocosm, field); and has been shaped by chemical use and misuse, ecological mishaps, and biomedical research. …


Sorta Situ: The New Reality Of Management Conditions For Wildlife Populations In The Absence Of "Wild" Spaces, Barbara A. Wolfe, Roberto F. Aguilar, A. Alonso Aguirre, Glenn H. Olsen, Evan S. Blumer Jan 2012

Sorta Situ: The New Reality Of Management Conditions For Wildlife Populations In The Absence Of "Wild" Spaces, Barbara A. Wolfe, Roberto F. Aguilar, A. Alonso Aguirre, Glenn H. Olsen, Evan S. Blumer

United States Geological Survey: Staff Publications

The rate of species loss today is approaching catastrophic levels. Scientists project that over the next two decades, more than 1 million species of plants and animals will become extinct. E.O. Wilson has estimated that "the rate ofloss may exceed 50,000 a year, 137 a day ... this rate, while horrendous, is actually the minimal estimate, based on the species/area relationship alone" (Kellert and Wilson 1993, p. 16; Aguirre 2009). Ever-expanding communities, strained natural resources, changes in land use, and other anthropogenic drivers are compromising ecosystems and rapidly changing the landscape and the availability of "wild" spaces.


Agricultural Drought Monitoring In Kenya Using Evapotranspiration Derived From Remote Sensing And Reanalysis Data, Michael T. Marshall, Christopher Funk, Joel Michaelsen Jan 2012

Agricultural Drought Monitoring In Kenya Using Evapotranspiration Derived From Remote Sensing And Reanalysis Data, Michael T. Marshall, Christopher Funk, Joel Michaelsen

United States Geological Survey: Staff Publications

More than half of the people in sub-Saharan Africa live on less than US$ 1.25 per day, and nearly 30% do not receive sufficient nourishment to maintain daily health (UN, 2009a). These figures are expected to rise as a result of the recent global financial crisis that has led to an increase in food prices. Food for Peace (FFP), the program that administers more than 85% of U.S. international food aid, recently reported that the seven largest recipient countries of food aid worldwide are in sub-Saharan Africa (FFP, 2010). In Kenya, the fifth largest recipient of food aid from FFP …


Thermal-Based Evaporative Stress Index For Monitoring Surface Moisture Depletion, Martha C. Anderson, Christopher R. Hain, Brian D. Wardlow, Agustin Pimstein, John R. Mecikalski, William P. Kustas Jan 2012

Thermal-Based Evaporative Stress Index For Monitoring Surface Moisture Depletion, Martha C. Anderson, Christopher R. Hain, Brian D. Wardlow, Agustin Pimstein, John R. Mecikalski, William P. Kustas

National Drought Mitigation Center: Faculty Publications

The standard suite of indicators currently used in operational drought monitoring reflects anomalous conditions in several major components of the hydrologic budget—representing deficits in precipitation, soil moisture content, runoff, surface and groundwater storage, snowpack, and streamflow. In principle, it is useful to have a diversity of indices because drought can assume many forms (meteorological, agricultural, hydrological, and socioeconomic), over broad ranges in timescale (weeks to years), and with varied impacts of interest to different stakeholder groups. Farmers, for example, may be principally interested in soil moisture deficits, river forecasters will focus on streamflow fluctuations, and water managers will be concerned …


Where Is The Rain-On-Snow Zone In The West-Central Washington Cascades?: Monte Carlo Simulation Of Large Storms In The Northwest, Matthew John Brunengo Jan 2012

Where Is The Rain-On-Snow Zone In The West-Central Washington Cascades?: Monte Carlo Simulation Of Large Storms In The Northwest, Matthew John Brunengo

Dissertations and Theses

Rain-on-snow (ROS) occurs when warm, wet air moves into latitudes and/or elevations having vulnerable snowpacks, where it can alter water inputs to infiltration, runoff and erosion. The Pacific Northwest is particularly susceptible: winter storms off the Pacific cause locally heavy rain plus snowmelt almost annually, and disastrous flooding and landsliding intermittently. In maritime mountainous terrain, the effects seem more likely and hydrologically important where warm rains and seasonal snowpacks are liable to coincide, in middle elevations. Several questions arise: (1) In the PNW, does ROS affect the long-term frequency and magnitude of water delivery to the ground, versus total precipitation …


Diatom Evidence For The Onset Of Pliocene Cooling From And-1b, Mcmurdo Sound, Antarctica, Christina R. Riesselman, Robert B. Dunbar Jan 2012

Diatom Evidence For The Onset Of Pliocene Cooling From And-1b, Mcmurdo Sound, Antarctica, Christina R. Riesselman, Robert B. Dunbar

ANDRILL Research and Publications

The late Pliocene, ~3.3–3.0 Ma, is the most recent interval of sustained global warmth in the geologic past. This window is the focus of climate reconstruction efforts by the U.S. Geological Survey’s Pliocene Research, Interpretation, and Synoptic Mapping (PRISM) Data/Model Cooperative, and may provide a useful climate analog for the coming century. Reconstructions of past surface ocean conditions proximal to the Antarctic continent are essential to understanding the sensitivity of the cryosphere to this key interval in Earth’s climate evolution. An exceptional marine sediment core collected from the southwestern Ross Sea (78° S), Antarctica, during ANDRILL’s McMurdo Ice Shelf Project …


A Diatom Record Of Late Pliocene Cooling From The Ross Sea Continental Shelf, And-1b, Antarctica, Charlotte Sjunneskog, Diane Winter Jan 2012

A Diatom Record Of Late Pliocene Cooling From The Ross Sea Continental Shelf, And-1b, Antarctica, Charlotte Sjunneskog, Diane Winter

ANDRILL Research and Publications

A late Pliocene – early Pleistocene, 2.9–2.0Ma, diatom record from the Antarctic Geological Drilling Program (ANDRILL) MIS drillcore AND-1B is presented. This core, recovered from beneath the Ross Ice Shelf south of Ross Island, comprises multiple diatomaceous-sediment units deposited during interglacial periods with open water over the core site. These represent interglacial phases of orbitally paced climate cycles and are punctuated by glacial advances. Extant diatom assemblages have limited presence in the late Pliocene record, which makes environmental interpretation less straight forward. We employ modern ecological data in combination with late Pliocene to present variation in diatom assemblages across the …


Fragilariopsis Tigris Sp. Nov., A New Late Pliocene Antarctic Continental Shelf Diatom With Biostratigraphic Promise, Christina R. Riesselman Jan 2012

Fragilariopsis Tigris Sp. Nov., A New Late Pliocene Antarctic Continental Shelf Diatom With Biostratigraphic Promise, Christina R. Riesselman

ANDRILL Research and Publications

Anew species within the genus Fragilariopsis, F. tigris, is described and illustrated using light microscopy and scanning electron microscopy. This species is restricted to a single 8-meter-thick diatom unit within the 585-meter-long section of alternating diatomites and diamictites recovered in the upper portion of the ANtarctic geological DRILLing (ANDRILL) McMurdo Ice Shelf Project (MIS) AND-1B marine sediment core. This new taxon from a diverse, well-preserved diatom assemblage is inferred to be the youngest member of the well-documented, biostratigraphically useful F. praeinterfrigidaria – F. interfrigidaria – F. weaveri lineage and may represent a near-shore corollary to the open-ocean species …


Droughtscape, Winter 2012, National Drought Mitigation Center Jan 2012

Droughtscape, Winter 2012, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

Drought Planning for Kansas Ranchers Jan. 21

South Hoping La Niña Dryness Stays Away

2011 Brought Record-Breaking Extent of D4

Reported Impacts Ease as Growing Season Ends

Disaster Planning in Nanjing at Hohai U

Ag, Fire and Water Supply Topped 2011 Impacts


Hurricane Disturbance And Recovery Of Energy Balance, Co2 Fluxes And Canopy Structure In A Mangrove Forest Of The Florida Everglades, Jordan G. Barr, Vic Engel, Thomas J. Smith, José D. Fuentes Jan 2012

Hurricane Disturbance And Recovery Of Energy Balance, Co2 Fluxes And Canopy Structure In A Mangrove Forest Of The Florida Everglades, Jordan G. Barr, Vic Engel, Thomas J. Smith, José D. Fuentes

United States Geological Survey: Staff Publications

Eddy covariance (EC) estimates of carbon dioxide (CO2) fluxes and energy balance are examined to investigate the functional responses of a mature mangrove forest to a disturbance generated by Hurricane Wilma on October 24, 2005 in the Florida Everglades. At the EC site, high winds from the hurricane caused nearly 100% defoliation in the upper canopy and widespread tree mortality. Soil temperatures down to −50 cm increased, and air temperature lapse rates within the forest canopy switched from statically stable to statically unstable conditions following the disturbance. Unstable conditions allowed more efficient transport of water vapor and CO2 from …


A New Phase Speciation Leaching Procedure For The Determination Of Metals In Oxic And Anoxic Sediments, Brandon R. Gipson Jan 2012

A New Phase Speciation Leaching Procedure For The Determination Of Metals In Oxic And Anoxic Sediments, Brandon R. Gipson

OES Theses and Dissertations

Toxic trace elements such as cadmium, lead, chromium, and arsenic released by human activities can accumulate in marine and estuarine sediments, where these metals are often sequestered until local environmental changes (e.g., redox, salinity, and/or pH) allow these elements to be reintroduced into the food web. In order to assess the extent of toxic trace element contamination in sediment, numerous leaching schemes have been developed that separate sediment-bound trace metals into operationally defined geochemical phases. These "phase speciation" leaching schemes are typically designed with the purpose of being used on either oxic or anoxic sediments. However, natural sediments often contain …


Rapid And Noncontaminating Sampling System For Trace Elements In Global Ocean Surveys, Gregory A. Cutter, Kenneth W. Bruland Jan 2012

Rapid And Noncontaminating Sampling System For Trace Elements In Global Ocean Surveys, Gregory A. Cutter, Kenneth W. Bruland

OES Faculty Publications

A system for the rapid and noncontaminating sampling of trace elements with volumes of up to 36 L per depth and including the dissolved and particulate phases has been developed for ocean sections that are a crucial part of programs such as International GEOTRACES. The system uses commercially available components, including an aluminum Seabird Carousel with all titanium pressure housings for electronics and sensors to eliminate zinc sacrificial anodes and holding twenty-four 12 L GO-FLO bottles, and a 7500 m, 14 mm Vectran conducting cable (passing over an A-frame with nonmetallic sheave) spooled onto a traction winch. The GO-FLO bottles …


Diversity, Distribution, And Expression Of Diazotroph Nifh Genes In Oxygen-Deficient Waters Of The Arabian Sea, Amal Jayakumar, Mamoon M. D. Al-Rshadat, Bess B. Ward, Margaret R. Mulholland Jan 2012

Diversity, Distribution, And Expression Of Diazotroph Nifh Genes In Oxygen-Deficient Waters Of The Arabian Sea, Amal Jayakumar, Mamoon M. D. Al-Rshadat, Bess B. Ward, Margaret R. Mulholland

OES Faculty Publications

The Arabian Sea oxygen minimum zone (OMZ), the largest suboxic region in the world's oceans, is responsible for up to half of the global mesopelagic fixed nitrogen ( N ) loss from the ocean via denitrification and anammox. Dinitrogen (N2) fixation is usually attributed to cyanobacteria in the surface ocean. Model prediction and physiological inhibition of N2 fixation by oxygen, however, suggest that N2 fixation should be enhanced near the oxygen-deficient zone (ODZ) of the Arabian Sea. N2 fixation and cyanobacterial nifH genes (the gene encoding dinitrogenase reductase) have been reported in surface waters overlying …


Impact Of Abrupt Deglacial Climate Change On Tropical Atlantic Subsurface Temperatures, Matthew W. Schmidt, Ping Chang, Jennifer E. Hertzberg, Theodore R. Them Ii, Link Li, Bette L. Otto-Bliesner Jan 2012

Impact Of Abrupt Deglacial Climate Change On Tropical Atlantic Subsurface Temperatures, Matthew W. Schmidt, Ping Chang, Jennifer E. Hertzberg, Theodore R. Them Ii, Link Li, Bette L. Otto-Bliesner

OES Faculty Publications

Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and sub-thermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. …


Deglacial Variability Of Antarctic Intermediate Water Penetration Into The North Atlantic From Authigenic Neodymium Isotope Ratios, Ruifang C. Xie, Franco Marcantonio, Matthew W. Schmidt Jan 2012

Deglacial Variability Of Antarctic Intermediate Water Penetration Into The North Atlantic From Authigenic Neodymium Isotope Ratios, Ruifang C. Xie, Franco Marcantonio, Matthew W. Schmidt

OES Faculty Publications

Understanding intermediate water circulation across the last deglacial is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation variability across abrupt climate events. However, the links between intermediate water circulation and abrupt climate events such as the Younger Dryas (YD) and Heinrich Event 1 (H1) are still poorly constrained. Here, we reconstruct changes in Antarctic Intermediate Water (AAIW) circulation in the subtropical North Atlantic over the past 25 kyr by measuring authigenic neodymium isotope ratios in sediments from two sites in the Florida Straits. Our authigenic Nd isotope records suggest that there was little …


Solar Forcing Of Florida Straits Surface Salinity During The Early Holocene, Matthew W. Schmidt, William A. Weinlein, Franco Marcantonio, Jean Lynch-Stieglitz Jan 2012

Solar Forcing Of Florida Straits Surface Salinity During The Early Holocene, Matthew W. Schmidt, William A. Weinlein, Franco Marcantonio, Jean Lynch-Stieglitz

OES Faculty Publications

Previous studies showed that sea surface salinity (SSS) in the Florida Straits as well as Florida Current transport covaried with changes in North Atlantic climate over the past two millennia. However, little is known about earlier Holocene hydrographic variability in the Florida Straits. Here, we combine Mg/Ca-paleothermometry and stable oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC 51 (24° 24.70' N, 83° 13.14' W, 198 m deep) to reconstruct a high-resolution (~25 yr/sample) early to mid Holocene record of sea surface temperature and δ18OSW)(a …


Controls On Dissolved Cobalt In Surface Waters Of The Sargasso Sea: Comparisons With Iron And Aluminum, R. U. Shelley, Peter N. Sedwick, T. S. Bibby, P. Cabedo-Sanz, T. M. Church, R. J. Johnson, A. I. Macey, C. M. Marsay, E. R. Sholkovitz, S. J. Ussher, P. J. Worsfold, M. C. Lohan Jan 2012

Controls On Dissolved Cobalt In Surface Waters Of The Sargasso Sea: Comparisons With Iron And Aluminum, R. U. Shelley, Peter N. Sedwick, T. S. Bibby, P. Cabedo-Sanz, T. M. Church, R. J. Johnson, A. I. Macey, C. M. Marsay, E. R. Sholkovitz, S. J. Ussher, P. J. Worsfold, M. C. Lohan

OES Faculty Publications

Dissolved cobalt (dCo), iron (dFe) and aluminum (dAl) were determined in water column samples along a meridional transect (∼31°N to 24°N) south of Bermuda in June 2008. A general north-to-south increase in surface concentrations of dFe (0.3-1.6 nM) and dAl (14-42 nM) was observed, suggesting that aerosol deposition is a significant source of dFe and dAl, whereas no clear trend was observed. for near-surface dCo concentrations. Shipboard aerosol samples indicate fractional solubility values of 8-100% for aerosol Co, which are significantly higher than corresponding estimates of the solubility of aerosol Fe (0.44-45%). Hydrographic observations and analysis of time series rain …


Assessing Satellite-Based Rainfall Estimates In Semiarid Watersheds Using The Usda-Ars Walnut Gulch Gauge Network And Trmm Pr, Eyal Amitai, Carl L. Unkrich, David C. Goodrich, Emad Habib, Bryson Thill Jan 2012

Assessing Satellite-Based Rainfall Estimates In Semiarid Watersheds Using The Usda-Ars Walnut Gulch Gauge Network And Trmm Pr, Eyal Amitai, Carl L. Unkrich, David C. Goodrich, Emad Habib, Bryson Thill

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The rain gauge network associated with the Walnut Gulch Experimental Watershed (WGEW) in southeastern Arizona provides a unique opportunity for direct comparisons of in situ measurements and satellite-based instantaneous rain rate estimates like those from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR). The WGEW network is the densest rain gauge network in the PR coverage area for watersheds greater than 10 km(2). It consists of 88 weighing rain gauges within a 149-km(2) area. On average, approximately 10 gauges can be found in each PR field of view (similar to 5-km diameter). All gauges are very well synchronized with …