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Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Articles 91 - 113 of 113

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Study Of Aerosols’ Characteristics And Dynamics Over The Kingdom Of Saudi Arabia Using A Multisensor Approach Combined With Ground Observations, Ashraf Farahat, Hesham El-Askary, Abdulaziz Al-Shaibani Jan 2015

Study Of Aerosols’ Characteristics And Dynamics Over The Kingdom Of Saudi Arabia Using A Multisensor Approach Combined With Ground Observations, Ashraf Farahat, Hesham El-Askary, Abdulaziz Al-Shaibani

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

This study covers various aspects of the aerosol distribution and characteristics, namely, optical depth climatology, absorption characteristics, and their microphysical properties over four regions in Saudi Arabia using satellite and ground observations including MODIS/Terra and Aqua, OMI, MISR/Terra, AERONET, and CALIPSO for the period April 2003–January 2013. The study includes cities in the North Western, Western, Eastern provinces of Saudi Arabia and in the Rub al Khali desert or Empty Quarter. Satellite and ground observations showed that the dust season extends from April to August with prominent peaks yet with high anthropogenic contribution late summer and early fall. Analysis shows …

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Studying Air Pollutants Origin And Associated Meteorological Parameters Over Seoul From 2000 To 2009, Sunmin Park, Hesham El-Askary, Ismail Sabbah, Hanbin Kwak, Anup K. Prasad, Woo-Kyun Lee, Menas Kafatos Jan 2015

Studying Air Pollutants Origin And Associated Meteorological Parameters Over Seoul From 2000 To 2009, Sunmin Park, Hesham El-Askary, Ismail Sabbah, Hanbin Kwak, Anup K. Prasad, Woo-Kyun Lee, Menas Kafatos

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We investigate the temporal characteristics of major air pollutants collected from 44 air quality stations over the city of Seoul, Korea, namely, nitrogen dioxide, carbon monoxide, particular matter at 10 microns, and sulfur dioxide (SO2) between 2000 and 2009. The corresponding satellite datasets, namely, aerosol optical depth (AODsat), Ångström exponent, and fine mode fraction, collected from moderate resolution imaging spectroradiometer (MODIS) as well as the Aeronet ground aerosol optical depth (AODaeronet), have been analyzed. Pollutants’ seasonal effect has been inferred from the precipitation and temperature. The four pollutants under study show varying temporal characteristics with different …

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Optical Characterization And Distribution Of Chromophoric Dissolved Organic Matter (Cdom) In Soil Porewater From A Salt Marsh Ecosystem, Catherine D. Clark, Paige Aiona, Jason K. Keller, Warren J. De Bruyn Dec 2014

Optical Characterization And Distribution Of Chromophoric Dissolved Organic Matter (Cdom) In Soil Porewater From A Salt Marsh Ecosystem, Catherine D. Clark, Paige Aiona, Jason K. Keller, Warren J. De Bruyn

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

To characterize chromophoric dissolved organic matter (CDOM) in marsh porewaters and its contribution as a carbon source, optical properties (absorbance, fluorescence indices, 3-dimensional excitation-emission matrices [EEMs]) of soil porewater and surface water were measured in a southern Californian salt marsh. Absorption coefficients and fluorescence intensities were higher in porewater than in overlying surface waters, consistent with higher CDOM concentration at depth. Humic-type peaks A and C were observed in EEMs in all samples, and peak M was observed in surface waters and shallow porewater to -5 cm depth. Fluorescence:absorbance (flu:abs) ratios and spectral slopes (S) decreased across the surface interface, …

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Public Interest In Climate Change Over The Past Decade And The Effects Of The ‘Climategate’ Media Event, William R. L. Anderegg, Gregory R. Goldsmith May 2014

Public Interest In Climate Change Over The Past Decade And The Effects Of The ‘Climategate’ Media Event, William R. L. Anderegg, Gregory R. Goldsmith

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Despite overwhelming scientific consensus concerning anthropogenic climate change, many in the non-expert public perceive climate change as debated and contentious. There is concern that two recent high-profile media events—the hacking of the University of East Anglia emails and the Himalayan glacier melt rate presented in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change—may have altered public opinion of climate change. While survey data is valuable for tracking public perception and opinion over time, including in response to climate-related media events, emerging methods that facilitate rapid assessment of spatial and temporal patterns in public interest and opinion could …

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Regional Dust Storm Modeling For Health Services: The Case Of Valley Fever, William A. Sprigg, Slobodan Nickovic, John N. Galgiani, Goran Pejanovic, Slavo Petkovic, Mirjam Vujadinovic, Ana Vukovic, Milan Dacic, Scott Dibiase, Anup K. Prasad, Hesham El-Askary Jan 2014

Regional Dust Storm Modeling For Health Services: The Case Of Valley Fever, William A. Sprigg, Slobodan Nickovic, John N. Galgiani, Goran Pejanovic, Slavo Petkovic, Mirjam Vujadinovic, Ana Vukovic, Milan Dacic, Scott Dibiase, Anup K. Prasad, Hesham El-Askary

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

On 5 July 2011, a massive dust storm struck Phoenix, Arizona (USA), raising concerns for increased cases of valley fever (coccidioidomycosis, or, cocci). A quasi-operational experimental airborne dust forecast system predicted the event and provides model output for continuing analysis in collaboration with public health and air quality communities. An objective of this collaboration was to see if a signal in cases of valley fever in the region could be detected and traced to the storm - an American haboob. To better understand the atmospheric life cycle of cocci spores, the DREAM dust model (also herein, NMME-DREAM) was modified to …

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Weekly Gridded Aquarius L-Band Radiometer/Scatterometer Observations And Salinity Retrievals Over The Polar Regions - Part 1: Product Description, L. Brucker, Emmanuel P. Dinnat, L. S. Koenig Jan 2014

Weekly Gridded Aquarius L-Band Radiometer/Scatterometer Observations And Salinity Retrievals Over The Polar Regions - Part 1: Product Description, L. Brucker, Emmanuel P. Dinnat, L. S. Koenig

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Passive and active observations at L band (frequency similar to 1.4 GHz) from the Aquarius/SAC-D mission offer new capabilities to study the polar regions. Due to the lack of polar-gridded products, however, applications over the cryosphere have been limited. We present three weekly polar-gridded products of Aquarius data to improve our understanding of L-band observations of ice sheets, sea ice, permafrost, and the polar oceans. Additionally, these products intend to facilitate access to L-band data, and can be used to assist in algorithm developments. Aquarius data at latitudes higher than 50 degrees are averaged and gridded into weekly products of …

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Weekly Gridded Aquarius L-Band Radiometer/Scatterometer Observations And Salinity Retrievals Over The Polar Regions - Part 2: Initial Product Analysis, L. Brucker, Emmanuel P. Dinnat, L. S. Koenig Jan 2014

Weekly Gridded Aquarius L-Band Radiometer/Scatterometer Observations And Salinity Retrievals Over The Polar Regions - Part 2: Initial Product Analysis, L. Brucker, Emmanuel P. Dinnat, L. S. Koenig

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Following the development and availability of Aquarius weekly polar-gridded products, this study presents the spatial and temporal radiometer and scatterometer observations at L band (frequency similar to 1.4 GHz) over the cryosphere including the Greenland and Antarctic ice sheets, sea ice in both hemispheres, and over sub-Arctic land for monitoring the soil freeze/thaw state. We provide multiple examples of scientific applications for the L-band data over the cryosphere. For example, we show that over the Greenland Ice Sheet, the unusual 2012 melt event lead to an L-band brightness temperature (TB) sustained decrease of similar to 5K at horizontal polarization. Over …

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Air-Sea Dimethylsulfide (Dms) Gas Transfer In The North Atlantic: Evidence For Limited Interfacial Gas Exchange At High Wind Speed, T. G. Bell, Warren J. De Bruyn, S. D. Miller, B. Ward, K. Christensen, E. S. Saltzman Jan 2013

Air-Sea Dimethylsulfide (Dms) Gas Transfer In The North Atlantic: Evidence For Limited Interfacial Gas Exchange At High Wind Speed, T. G. Bell, Warren J. De Bruyn, S. D. Miller, B. Ward, K. Christensen, E. S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Shipboard measurements of eddy covariance dimethylsulfide (DMS) air-sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k(660)) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s(-1). At higher wind speeds the relationship between k(660) and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent …

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Toward A Framework For Systematic Error Modeling Of Spaceborne Precipitation Radar With Noaa/Nssl Ground Radar Based National Mosaic Qpe, Pierre-Emmanuel Kirstetter, Y. Hong, J. J. Gourley, S. Chen, Z. Flamig, J. Zhang, M. Schwaller, W. Peterson, Eyal Amitai Jan 2012

Toward A Framework For Systematic Error Modeling Of Spaceborne Precipitation Radar With Noaa/Nssl Ground Radar Based National Mosaic Qpe, Pierre-Emmanuel Kirstetter, Y. Hong, J. J. Gourley, S. Chen, Z. Flamig, J. Zhang, M. Schwaller, W. Peterson, Eyal Amitai

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Characterization of the error associated with satellite rainfall estimates is a necessary component of deterministic and probabilistic frameworks involving spaceborne passive and active microwave measurements for applications ranging from water budget studies to forecasting natural hazards related to extreme rainfall events. The authors focus here on the error structure of NASA's Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) quantitative precipitation estimation (QPE) at ground. The problem is addressed by comparison of PR QPEs with reference values derived from ground-based measurements using NOAA/NSSL ground radar based National Mosaic and QPE system (NMQ/Q2). A preliminary investigation of this subject has been …

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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 …

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Evaluation Of Satellite-Retrieved Extreme Precipitation Rates Across The Central United States, A. Aghakoucak, A. Behrangi, S. Sorooshian, K. Hsu, Eyal Amitai Jan 2011

Evaluation Of Satellite-Retrieved Extreme Precipitation Rates Across The Central United States, A. Aghakoucak, A. Behrangi, S. Sorooshian, K. Hsu, Eyal Amitai

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Water resources management, forecasting, and decision making require reliable estimates of precipitation. Extreme precipitation events are of particular importance because of their severe impact on the economy, the environment, and the society. In recent years, the emergence of various satellite-retrieved precipitation products with high spatial resolutions and global coverage have resulted in new sources of uninterrupted precipitation estimates. However, satellite-based estimates are not well integrated into operational and decision-making applications because of a lack of information regarding the associated uncertainties and reliability of these products. In this study, four satellite-derived precipitation products (CMORPH, PERSIANN, TMPA-RT, and TMPA-V6) are evaluated with …

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Post-Coring Entrapment Of Modern Air In Some Shallow Ice Cores Collected Near The Firn-Ice Transition: Evidence From Cfc-12 Measurements In Antarctic Firn Air And Ice Cores, Murat Aydin, S. A. Montzka, M. O. Battle, M. B. Williams, Warren J. De Bruyn, J. H. Butler, K. R. Verhulst, C. Tatum, B. K. Gun, D. A. Plotkin, B. D. Hall, Eric S. Saltzman Jan 2010

Post-Coring Entrapment Of Modern Air In Some Shallow Ice Cores Collected Near The Firn-Ice Transition: Evidence From Cfc-12 Measurements In Antarctic Firn Air And Ice Cores, Murat Aydin, S. A. Montzka, M. O. Battle, M. B. Williams, Warren J. De Bruyn, J. H. Butler, K. R. Verhulst, C. Tatum, B. K. Gun, D. A. Plotkin, B. D. Hall, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

In this study, we report measurements of CFC-12 (CCl2F2) in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores …

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A Chemical Ionization Mass Spectrometer For Continuous Underway Shipboard Analysis Of Dimethylsulfide In Near-Surface Seawater, Eric S. Saltzman, Warren J. De Bruyn, M. J. Lawler, Christa Marandino, C. A. Mccormick Jan 2009

A Chemical Ionization Mass Spectrometer For Continuous Underway Shipboard Analysis Of Dimethylsulfide In Near-Surface Seawater, Eric S. Saltzman, Warren J. De Bruyn, M. J. Lawler, Christa Marandino, C. A. Mccormick

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

A compact, low-cost atmospheric pressure, chemical ionization mass spectrometer ('mini-CIMS') has been developed for continuous underway shipboard measurements of dimethylsulfide (DMS) in seawater. The instrument was used to analyze DMS in air equilibrated with flowing seawater across a porous Teflon membrane equilibrator. The equilibrated gas stream was diluted with air containing an isotopically-labeled internal standard. DMS is ionized at atmospheric pressure via proton transfer from water vapor, then declustered, mass filtered via quadrupole mass spectrometry, and detected with an electron multiplier. The instrument described here is based on a low-cost residual gas analyzer (Stanford Research Systems), which has been modified …

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Air-Sea Gas Exchange Of Co2 And Dms In The North Atlantic By Eddy Covariance, Scott Miller, Christa Marandino, Warren J. De Bruyn, Eric S. Saltzman Jan 2009

Air-Sea Gas Exchange Of Co2 And Dms In The North Atlantic By Eddy Covariance, Scott Miller, Christa Marandino, Warren J. De Bruyn, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report the first simultaneous eddy covariance flux measurements of CO2 and dimethylsulfide (DMS) over the open ocean for two North Atlantic cruises. After normalization for Schmidt number, the two gases give essentially identical gas transfer coefficients and wind speed dependences for the wind speed range 2-10 ms(-1). The data indicate a linear relationship between the gas transfer coefficient and mean wind speed, with measured gas transfer coefficients slightly above the Wanninkhof (1992) parameterization, particularly at low wind speeds. Citation: Miller, S., C. Marandino, W. de Bruyn, and E. S. Saltzman (2009), Air-sea gas exchange of CO2 and DMS in …

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Open Ocean Dms Air/Sea Fluxes Over The Eastern South Pacific Ocean, C. A. Marandino, Warren J. De Bruyn, S. D. Miller, E. S. Saltzman Jan 2009

Open Ocean Dms Air/Sea Fluxes Over The Eastern South Pacific Ocean, C. A. Marandino, Warren J. De Bruyn, S. D. Miller, E. S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Air/sea fluxes of dimethylsulfide (DMS) were measured by eddy correlation over the Eastern South Pacific Ocean during January 2006. The cruise track extended from Manzanillo, Mexico, along 110 degrees W, to Punta Arenas, Chile. Bulk air and surface ocean DMS levels were also measured and gas transfer coefficients (k(DMS)) were computed. Air and seawater DMS measurements were made using chemical ionization mass spectrometry (API-CIMS) and a gas/liquid membrane equilibrator. Mean surface seawater DMS concentrations were 3.8 +/- 2.2 nM and atmospheric mixing ratios were 340 +/- 370 ppt. The air/sea flux of DMS was uniformly out of the ocean, with …

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Dms Air/Sea Flux And Gas Transfer Coefficients From The North Atlantic Summertime Coccolithophore Bloom, Christa Marandino, Warren J. De Bruyn, Scott Miller, Eric S. Saltzman Jan 2008

Dms Air/Sea Flux And Gas Transfer Coefficients From The North Atlantic Summertime Coccolithophore Bloom, Christa Marandino, Warren J. De Bruyn, Scott Miller, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Dimethylsulfide (DMS) atmospheric and oceanic concentrations and eddy covariance air/sea fluxes were measured over the N. Atlantic Ocean during July 2007 from Iceland to Woods Hole, MA, USA. Seawater DMS levels north of 55 degrees N ranged from 3 to 17 nM, with variability related to the satellite-derived distributions of coccoliths and to a lesser extent, chlorophyll. For the most intense bloom region southwest of Iceland, DMS air/sea fluxes were as high as 300 mu mol m(-2) d(-1), larger than current model estimates. The observations imply that gas exchange coefficients in this region are significantly greater than those estimated using …

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Salt Marshes As A Source Of Chromophoric Dissolved Organic Matter (Cdom) To Southern California Coastal Waters, Catherine D. Clark, Liannea P. Litz, Stanley B. Grant Jan 2008

Salt Marshes As A Source Of Chromophoric Dissolved Organic Matter (Cdom) To Southern California Coastal Waters, Catherine D. Clark, Liannea P. Litz, Stanley B. Grant

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

To determine chromophoric dissolved organic matter (CDOM) sources in Southern California coastal waters, optical properties of a river outlet and adjacent tidally flushed salt marshes were monitored (dry season; June July 2001). Average absorption coefficients doubled at ebb vs. flood tides (4.8 +/- 1.5 vs. 2.1 +/- 0.9 m(-1); 300 nm), suggesting significant salt marsh CDOM inputs into coastal waters. Average spectral slopes were not statistically different for any sites or tides (0.010 +/- 0.002 nm(-1)), consistent with salt marsh CDOM dominating coastal waters. Three-dimensional fluorescence excitation-emission matrices (EEMs) at ebb tide showed contributions from terrestrial, protein, and marine humic-like …

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Eddy Correlation Measurements Of The Air/Sea Flux Of Dimethylsulfide Over The North Pacific Ocean, Christa A. Marandino, Warren J. De Bruyn, Scott D. Miller, Eric S. Saltzman Jan 2007

Eddy Correlation Measurements Of The Air/Sea Flux Of Dimethylsulfide Over The North Pacific Ocean, Christa A. Marandino, Warren J. De Bruyn, Scott D. Miller, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Shipboard measurements of air/sea fluxes and sea surface concentrations of dimethylsulfide (DMS) were made over the tropical and midlatitude North Pacific Ocean. Atmospheric pressure chemical ionization mass spectrometry was used to measure DMS levels in ambient air and in air equilibrated with surface seawater drawn from a depth of 5 m. Air/sea fluxes were obtained using eddy covariance. Corrections and uncertainties involved in the calculation of fluxes from shipboard data are discussed. The surface ocean DMS concentrations measured during this study ranged from 1 to 10 nM, and atmospheric mixing ratios ranged from 20 to 1000 ppt. Air/sea fluxes ranged …

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Oceanic Uptake And The Global Atmospheric Acetone Budget, Christa Marandino, Warren J. De Bruyn, Scott Miller, M. J. Prather, Eric S. Saltzman Jan 2005

Oceanic Uptake And The Global Atmospheric Acetone Budget, Christa Marandino, Warren J. De Bruyn, Scott Miller, M. J. Prather, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

In this study, direct measurements of the air/ sea flux of acetone were made over the North Pacific Ocean. The results demonstrate that the net flux of acetone is into, rather than out of the oceans. The extrapolated global ocean uptake of 48 Tg yr(-1) requires a major revision of the atmospheric acetone budget. This result is consistent with a recent reevaluation of acetone photodissociation quantum yields.

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Atmospheric Variability Of Methyl Chloride During The Last 300 Years From An Antarctic Ice Core And Firn Air, M. Aydin, Eric S. Saltzman, Warren J. De Bruyn, S. A. Montzka, J. H. Butler, M. Battle Jan 2004

Atmospheric Variability Of Methyl Chloride During The Last 300 Years From An Antarctic Ice Core And Firn Air, M. Aydin, Eric S. Saltzman, Warren J. De Bruyn, S. A. Montzka, J. H. Butler, M. Battle

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Measurements of methyl chloride (CH3Cl) in Antarctic polar ice and firn air are used to describe the variability of atmospheric CH3Cl during the past 300 years. Firn air results from South Pole and Siple Dome suggest that the atmospheric abundance of CH3Cl increased by about 10% in the 50 years prior to 1990. Ice core measurements from Siple Dome provide evidence for a cyclic natural variability on the order of 10%, with a period of about 110 years in phase with the 20th century rise inferred from firn air. Thus, the CH3Cl increase measured in firn air may largely be …

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Diurnal Variation In The Basal Emission Rate Of Isoprene, Jennifer L. Funk, Clive G. Jones, Christine J. Baker, Heather M. Fuller, Christian P. Giardina, Manuel T. Lerdau Jan 2003

Diurnal Variation In The Basal Emission Rate Of Isoprene, Jennifer L. Funk, Clive G. Jones, Christine J. Baker, Heather M. Fuller, Christian P. Giardina, Manuel T. Lerdau

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Isoprene is emitted from numerous plant species and profoundly influences tropospheric chemistry. Due to the short lifetime of isoprene in the atmosphere, developing an understanding of emission patterns at small time scales is essential for modeling regional atmospheric chemistry processes. Previous studies suggest that diurnal fluctuations in isoprene emission may be substantial, leading to inaccuracies in emission estimates at larger scales. We examined diurnal patterns in the basal emission rate of isoprene in red oak (Quercus rubra), eastern cottonwood (Populus deltoides), and eucalyptus (Eucalyptus saligna) and the influence of light and temperature on the magnitude of these diurnal patterns. Maximum …

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Near-Real-Time Measurement Of Sea-Salt Aerosol During The Seas Campaign: Comparison Of Emission-Based Sodium Detection With An Aerosol Volatility Technique, P. Campuzano-Jost, Catherine D. Clark, H. Maring, D. S. Covert, S. Howell, V. Kapustin, K. A. Clarke, E. S. Saltzman, A. J. Hynes Jan 2003

Near-Real-Time Measurement Of Sea-Salt Aerosol During The Seas Campaign: Comparison Of Emission-Based Sodium Detection With An Aerosol Volatility Technique, P. Campuzano-Jost, Catherine D. Clark, H. Maring, D. S. Covert, S. Howell, V. Kapustin, K. A. Clarke, E. S. Saltzman, A. J. Hynes

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The first deployment of an emission-based aerosol sodium detector (ASD), designed to chemically characterize marine aerosols on a near-real-time basis, is reported. Deployment occurred as part of the Shoreline Environment Aerosol Study ( SEAS) from 16 April to 1 May 2000 at Bellows Air Force Base on the east side of Oahu, where the University of Hawaii's Department of Oceanography maintains a tower for aerosol measurements. The instrument was operated in size-unsegregated mode and measurements were made that included two extended continuous sampling periods, each of which lasted for 24 h. During this time, the ASD was compared with measurements …

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The Aqueous Phase Yield Of Alkyl Nitrates From Roo+No: Implications For Photochemical Production In Seawater, Elizabeth E. Dahl, Eric S. Saltzman, Warren J. De Bruyn Jan 2003

The Aqueous Phase Yield Of Alkyl Nitrates From Roo+No: Implications For Photochemical Production In Seawater, Elizabeth E. Dahl, Eric S. Saltzman, Warren J. De Bruyn

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Alkyl nitrates have been observed in remote oceanic regions of the troposphere and in the surface ocean. The mechanism for their production in the oceans is not known. A likely source is the reaction of ROO + NO (where R is an alkyl group). Steady-state laboratory experiments show that alkyl nitrates are produced in the aqueous phase via this reaction, with branching ratios of 0.23 +/- 0.04, 0.67 +/- 0.03, and 0.71 +/- 0.04 for methyl, ethyl, and propyl nitrate respectively. The branching ratios in aqueous solution are significantly higher than in the gas phase. Irradiation of surface seawaters yield …

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