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Crustal And Upper Mantle Structure Beneath The Northeastern Tibetan Plateau From Joint Analysis Of Receiver Functions And Rayleigh Wave Dispersions, Dan Zheng, Hongyi Li, Yang Shen, Jing Tan, Longbin Ouyang, Xinfu Lu
Crustal And Upper Mantle Structure Beneath The Northeastern Tibetan Plateau From Joint Analysis Of Receiver Functions And Rayleigh Wave Dispersions, Dan Zheng, Hongyi Li, Yang Shen, Jing Tan, Longbin Ouyang, Xinfu Lu
Graduate School of Oceanography Faculty Publications
The crustal and upper mantle velocity structure in the northeastern Tibetan Plateau is obtained from joint analysis of receiver functions and Rayleigh wave dispersions. The resulting velocity model reveals a close correlation between the thick (>60 km) crust and the presence of an intracrustal low-velocity zone beneath the Qiangtang and Songpan-Ganzi terranes as well as the northwestern Qilian orogen. However, the high Vp/Vs ratio of the crust is found only beneath the Qiangtang and Songpan-Ganzi terranes. The crustal low velocity zone does not appear in the west Qinling and southeastern Qilian orogens, which have a …
Upper Tropospheric Ozone Production From Lightning NoX‐ Impacted Convection: Smoke Ingestion Case Study From The Dc3 Campaign, E. C. Apel, R. S. Hornbrook, A. J. Hills, N. J. Blake, M. C. Barth, A. Weinheimer, C. Cantrell, S. A. Rutledge, B. Basarab, J. Crawford, G. Diskin, C. R. Homeyer, T. Campos, F. Flocke, A. Fried, D. R. Blake, W. Brune, I. Pollack, J. Peischl, T. Ryerson, P. O. Crounse, A. Wisthaler, T. Mikoviny, G. Huey, Brian G. Heikes, D. O'Sullivan, D. D. Riemer
Upper Tropospheric Ozone Production From Lightning NoX‐ Impacted Convection: Smoke Ingestion Case Study From The Dc3 Campaign, E. C. Apel, R. S. Hornbrook, A. J. Hills, N. J. Blake, M. C. Barth, A. Weinheimer, C. Cantrell, S. A. Rutledge, B. Basarab, J. Crawford, G. Diskin, C. R. Homeyer, T. Campos, F. Flocke, A. Fried, D. R. Blake, W. Brune, I. Pollack, J. Peischl, T. Ryerson, P. O. Crounse, A. Wisthaler, T. Mikoviny, G. Huey, Brian G. Heikes, D. O'Sullivan, D. D. Riemer
Graduate School of Oceanography Faculty Publications
As part of the Deep Convective Cloud and Chemistry (DC3) experiment, the National Science Foundation/National Center for Atmospheric Research (NCAR) Gulfstream‐V (GV) and NASA DC‐8 research aircraft probed the chemical composition of the inflow and outflow of two convective storms (north storm, NS, south storm, SS) originating in the Colorado region on 22 June 2012, a time when the High Park wildfire was active in the area. A wide range of trace species were measured on board both aircraft including biomass burning (BB) tracers hydrogen cyanide (HCN) and acetonitrile (ACN). Acrolein, a much shorter lived tracer for BB, was also …
Formaldehyde Over North America And The North Atlantic During The Summer 2004 Intex Campaign: Methods, Observed Distributions, And Measurement‐Model Comparisons, Alan Fried, James G. Walega, Jennifer R. Olson, Jim H. Crawford, Gao Chen, Petter Weibring, Dirk Richter, Chad Roller, Frank K. Tittel, Brian G. Heikes, Julie A. Snow, Haiwei Shen, Daniel W. O'Sullivan, Michael Porter, Henry Fuelberg, Jeremy Halland, Dylan B. Millet
Formaldehyde Over North America And The North Atlantic During The Summer 2004 Intex Campaign: Methods, Observed Distributions, And Measurement‐Model Comparisons, Alan Fried, James G. Walega, Jennifer R. Olson, Jim H. Crawford, Gao Chen, Petter Weibring, Dirk Richter, Chad Roller, Frank K. Tittel, Brian G. Heikes, Julie A. Snow, Haiwei Shen, Daniel W. O'Sullivan, Michael Porter, Henry Fuelberg, Jeremy Halland, Dylan B. Millet
Graduate School of Oceanography Faculty Publications
A tunable diode laser absorption spectrometer (TDLAS) was operated on the NASA DC‐8 aircraft during the summer INTEX‐NA study to acquire ambient formaldehyde (CH2O) measurements over North America and the North Atlantic Ocean from ∼0.2 km to ∼12.5 km altitude spanning 17 science flights. Measurements of CH2O in the boundary layer and upper troposphere over the southeastern United States were anomalously low compared to studies in other years, and this was attributed to the record low temperatures over this region during the summer of 2004. Formaldehyde is primarily formed over the southeast from isoprene, and isoprene …
Analysis Of The Atmospheric Distribution, Sources, And Sinks Of Oxygenated Volatile Organic Chemicals Based On Measurements Over The Pacific During Trace‐P, H. B. Singh, L. J. Salas, R. B. Chatfield, E. Czech, A. Fried, J. Walega, M. J. Evans, B. S. Field, D. J. Jacob, D. Blake, Brian G. Heikes, R. Talbot, G. Sachse, J. H. Crawford, M. A. Avery, S. Sandholm, H. Fuelberg
Analysis Of The Atmospheric Distribution, Sources, And Sinks Of Oxygenated Volatile Organic Chemicals Based On Measurements Over The Pacific During Trace‐P, H. B. Singh, L. J. Salas, R. B. Chatfield, E. Czech, A. Fried, J. Walega, M. J. Evans, B. S. Field, D. J. Jacob, D. Blake, Brian G. Heikes, R. Talbot, G. Sachse, J. H. Crawford, M. A. Avery, S. Sandholm, H. Fuelberg
Graduate School of Oceanography Faculty Publications
Airborne measurements of a large number of oxygenated volatile organic chemicals (OVOC) were carried out in the Pacific troposphere (0.1–12 km) in winter/spring of 2001 (24 February to 10 April). Specifically, these measurements included acetone (CH3COCH3), methylethyl ketone (CH3COC2H5, MEK), methanol (CH3OH), ethanol (C2H5OH), acetaldehyde (CH3CHO), propionaldehyde (C2H5CHO), peroxyacylnitrates (PANs) (CnH2n+1COO2NO2), and organic nitrates (CnH2n+1ONO2). Complementary measurements of formaldehyde (HCHO), …
Sources Of Upper Tropospheric HoX Over The South Pacific Convergence Zone: A Case Study, Céline Mari, Carine Saüt, Daniel J. Jacob, François Ravetta, Bruce Anderson, Melody A. Avery, Donald R. Blake, William H. Brune, Ian Faloona, G. L. Gregory, Brian G. Heikes, Glen W. Sachse, Scott T. Sandholm, Hanwant B. Singh, Robert W. Talbot, David Tan, Stephanie Vay
Sources Of Upper Tropospheric HoX Over The South Pacific Convergence Zone: A Case Study, Céline Mari, Carine Saüt, Daniel J. Jacob, François Ravetta, Bruce Anderson, Melody A. Avery, Donald R. Blake, William H. Brune, Ian Faloona, G. L. Gregory, Brian G. Heikes, Glen W. Sachse, Scott T. Sandholm, Hanwant B. Singh, Robert W. Talbot, David Tan, Stephanie Vay
Graduate School of Oceanography Faculty Publications
A zero‐dimensional (0‐D) model has been applied to study the sources of hydrogen oxide radicals (HOx = HO2 + OH) in the tropical upper troposphere during the Pacific Exploratory Mission in the tropics (PEM‐Tropics B) aircraft mission over the South Pacific in March–April 1999. Observations made across the Southern Pacific Convergence Zone (SPCZ) and the southern branch of the Intertropical Convergence Zone (ITCZ) provided the opportunity to contrast the relative contributions of different sources of HOx, in a nitrogen oxide radical (NOx)‐limited regime, in relatively pristine tropical air. The primary sources of HOx …
On The Relative Role Of Convection, Chemistry, And Transport Over The South Pacific Convergence Zone During Pem-Tropics B: A Case Study, Céline Mari, Carine Saüt, Daniel J. Jacob, Amanda Staudt, Melody A. Avery, William H. Brune, Ian Faloona, Brian G. Heikes, Glen W. Sachse, Scott T. Sandholm, Hanwant B. Singh, David Tan
On The Relative Role Of Convection, Chemistry, And Transport Over The South Pacific Convergence Zone During Pem-Tropics B: A Case Study, Céline Mari, Carine Saüt, Daniel J. Jacob, Amanda Staudt, Melody A. Avery, William H. Brune, Ian Faloona, Brian G. Heikes, Glen W. Sachse, Scott T. Sandholm, Hanwant B. Singh, David Tan
Graduate School of Oceanography Faculty Publications
A mesoscale 3D model (Meso‐NH) is used to assess the relative importance of convection (transport and scavenging), chemistry, and advection in the vertical redistribution of HOx and their precursors in the upper tropical troposphere. The study is focused on marine deep convection over the South Pacific Convergence Zone (SPCZ) during the PEM‐Tropics B Flight 10 aircraft mission. The model reproduces well the HOx mixing ratios. Vertical variations and the contrast between north and south of the SPCZ for O3 are captured. Convection uplifted O3‐poor air at higher altitude, creating a minimum in the 9–12 km …
Distribution And Fate Of Selected Oxygenated Organic Species In The Troposphere And Lower Stratosphere Over The Atlantic, H. Singh, Y. Chen, A. Tabazadeh, Y. Fukui, I. Bey, R. Yantosca, D. Jacob, F. Arnold, K. Wohlfrom, E. Atlas, F. Flocke, D. Blake, N. Blake, Brian G. Heikes, J. Snow, R. Talbot, G. Gregory, G. Sachse, S. Vay, Y. Kondo
Distribution And Fate Of Selected Oxygenated Organic Species In The Troposphere And Lower Stratosphere Over The Atlantic, H. Singh, Y. Chen, A. Tabazadeh, Y. Fukui, I. Bey, R. Yantosca, D. Jacob, F. Arnold, K. Wohlfrom, E. Atlas, F. Flocke, D. Blake, N. Blake, Brian G. Heikes, J. Snow, R. Talbot, G. Gregory, G. Sachse, S. Vay, Y. Kondo
Graduate School of Oceanography Faculty Publications
A large number of oxygenated organic chemicals (peroxyacyl nitrates, alkyl nitrates, acetone, formaldehyde, methanol, methylhydroperoxide, acetic acid and formic acid) were measured during the 1997 Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) airborne field campaign over the Atlantic. In this paper, we present a first picture of the distribution of these oxygenated organic chemicals (Ox‐organic) in the troposphere and the lower stratosphere, and assess their source and sink relationships. In both the troposphere and the lower stratosphere, the total atmospheric abundance of these oxygenated species (ΣOx‐organic) nearly equals that of total nonmethane hydrocarbons (ΣNMHC), which have been traditionally …
A Case Study Of Transport Of Tropical Marine Boundary Layer And Lower Tropospheric Air Masses To The Northern Midlatitude Upper Troposphere, William B. Grant, Edward V. Browell, Carolyn F. Butler, Marta A. Fenn, Marian B. Clayton, John R. Hannan, Henry E. Fuelberg, Donald R. Blake, Nicola J. Blake, Gerald L. Gregory, Brian G. Heikes, Glen W. Sachse, Hanwant B. Singh, Julie Snow, Robert W. Talbot
A Case Study Of Transport Of Tropical Marine Boundary Layer And Lower Tropospheric Air Masses To The Northern Midlatitude Upper Troposphere, William B. Grant, Edward V. Browell, Carolyn F. Butler, Marta A. Fenn, Marian B. Clayton, John R. Hannan, Henry E. Fuelberg, Donald R. Blake, Nicola J. Blake, Gerald L. Gregory, Brian G. Heikes, Glen W. Sachse, Hanwant B. Singh, Julie Snow, Robert W. Talbot
Graduate School of Oceanography Faculty Publications
Low‐ozone (ppbv) air masses were observed in the upper troposphere in northern midlatitudes over the eastern United States and the North Atlantic Ocean on several occasions in October 1997 during the NASA Subsonic Assessment, Ozone and Nitrogen Oxide Experiment (SONEX) mission. Three cases of low‐ozone air masses were shown to have originated in the tropical Pacific marine boundary layer or lower troposphere and advected poleward along a warm conveyor belt during a synoptic‐scale disturbance. The tropopause was elevated in the region with the low‐ozone air mass. Stratospheric intrusions accompanied the disturbances. On the basis of storm track and stratospheric intrusion …
Ozone Production Efficiencies Of Acetone And Peroxides In The Upper Troposphere, Ian Folkins, R. Chatfield, H. Singh, Y. Chen, Brian G. Heikes
Ozone Production Efficiencies Of Acetone And Peroxides In The Upper Troposphere, Ian Folkins, R. Chatfield, H. Singh, Y. Chen, Brian G. Heikes
Graduate School of Oceanography Faculty Publications
HOx concentrations in the upper tropical troposphere can be enhanced by the presence of acetone and the convective injection of peroxides. These enhancements in HOx might be expected to increase ozone production by increasing the rate of the HO2+NO reaction. We show however that the convective enhancements of hydrogen peroxide (H2O2) and methyl hydroperoxide (CH3OOH) above steady state during the PEM West B campaign were largely restricted to air parcels of marine boundary layer origin in which the mean NO concentration was 8 pptv. The ozone production efficiencies of the …
Comparisons Of Trace Constituents From Ground Stations And The Dc‐8 Aircraft During Pem‐West B, R. Arimoto, R. A. Duce, J. M. Prospero, D. L. Savoie, R. W. Talbot, J. E. Dibb, Brian G. Heikes, Barbara J. Ray, N. F. Lewis, U. Tomza
Comparisons Of Trace Constituents From Ground Stations And The Dc‐8 Aircraft During Pem‐West B, R. Arimoto, R. A. Duce, J. M. Prospero, D. L. Savoie, R. W. Talbot, J. E. Dibb, Brian G. Heikes, Barbara J. Ray, N. F. Lewis, U. Tomza
Graduate School of Oceanography Faculty Publications
Chemical data from ground stations in Asia and the North Pacific are compared with data from the DC‐8 aircraft collected during the Pacific Exploratory Measurements in the Western Pacific Ocean (PEM‐West B) mission. Ground station sampling took place on Hong Kong, Taiwan, Okinawa, and Cheju; and at three Pacific islands, Shemya, Midway, and Oahu. Aircraft samples were collected during 19 flights, most over the western North Pacific. Aluminum was used as an indicator of mineral aerosol, and even though the aircraft did sample Asian dust, strong dust storms were not encountered. The frequency distribution for non‐sea‐salt sulfate (nss SO4 …
Chemical Characteristics Of Continental Outflow Over The Tropical South Atlantic Ocean From Brazil And Africa, R. W. Talbot, J. D. Bradshaw, S. T. Sandholm, S. Smyth, D. R. Blake, N. R. Blake, G. W. Sachse, J. E. Collins, Brian G. Heikes, B. E. Anderson, G. L. Gregory, H. B. Singh, B. L. Lefer, A. S. Bachmeier
Chemical Characteristics Of Continental Outflow Over The Tropical South Atlantic Ocean From Brazil And Africa, R. W. Talbot, J. D. Bradshaw, S. T. Sandholm, S. Smyth, D. R. Blake, N. R. Blake, G. W. Sachse, J. E. Collins, Brian G. Heikes, B. E. Anderson, G. L. Gregory, H. B. Singh, B. L. Lefer, A. S. Bachmeier
Graduate School of Oceanography Faculty Publications
The chemical characteristics of air parcels over the tropical South Atlantic during September – October 1992 are summarized by analysis of aged marine and continental outflow classifications. Positive correlations between CO and CH3Cl and minimal enhancements of C2Cl4 and various chlorofluorocarbon (CFC) species in air parcels recently advected over the South Atlantic basin strongly suggest an impact on tropospheric chemistry from biomass burning on adjacent continental areas of Brazil and Africa. Comparison of the composition of aged Pacific air with aged marine air over the South Atlantic basin from 0.3 to 12.5 km altitude indicates …
Formaldehyde, Glyoxal, And Methylglyoxal In Air And Cloudwater At A Rural Mountain Site In Central Virginia, J. William Munger, D. J. Jacob, B. C. Daube, L. W. Horowitz, W. C. Keene, Brian G. Heikes
Formaldehyde, Glyoxal, And Methylglyoxal In Air And Cloudwater At A Rural Mountain Site In Central Virginia, J. William Munger, D. J. Jacob, B. C. Daube, L. W. Horowitz, W. C. Keene, Brian G. Heikes
Graduate School of Oceanography Faculty Publications
As part of the Shenandoah Cloud and Photochemistry Experiment (SCAPE), we measured formaldehyde (HCHO), glyoxal (CHOCHO), and methylglyoxal (CH3C(O)CHO) concentrations in air and cloudwater at Pinnacles (elevation 1037 m) in Shenandoah National Park during September 1990. Mean gas‐phase concentrations of HCHO and CHOCHO were 980 and 44 pptv, respectively. The concentration of CH3C(O)CHO rarely exceeded the detection limit of 50 pptv. Mean cloudwater concentrations of HCHO and CHOCHO were 9 and 2 μM, respectively; the mean CH3C(O)CHO concentration was below its detection limit of 0.3 μM. The maximum carbonyl concentrations …
Measurements Of Tropospheric Nitric Acid Over The Western United States And Northeastern Pacific Ocean, P. J. Lebel, B. J. Huebert, H. I. Schiff, S. A. Vay, S. E. Vanbramer, D. R. Hastie
Measurements Of Tropospheric Nitric Acid Over The Western United States And Northeastern Pacific Ocean, P. J. Lebel, B. J. Huebert, H. I. Schiff, S. A. Vay, S. E. Vanbramer, D. R. Hastie
Graduate School of Oceanography Faculty Publications
During the August–September 1986 GTE/CITE 2 aircraft mission, more than 240 measurements of nitric acid (HNO3) were made in the free troposphere as well as in the boundary layer over the northeastern Pacific Ocean and western continental United States. Marine HNO3 measurement results were strikingly similar to results from GAMETAG and other past atmospheric field experiments. The marine boundary layer HNO3 average, 62 parts per trillion by volume (pptv), was one third lower than the marine free tropospheric average, 108 pptv, suggesting that the boundary layer is a sink for tropospheric nitric acid, probably by dry …