1,721,016 research outputs found
Aircraft profiles of stable isotope ratios in atmospheric total and condensed water from the NASA ORACLES mission.
No full textAircraft in-situ measurements of water concentration and heavy water isotope ratios D/H and 18O/16O of cloud water and total water (water vapor plus condensed water) were collected during the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) project. Aircraft sampling took place in the southeast Atlantic marine boundary layer and lower troposphere (equator to 22 degrees south) over the months of Sept. 2016, Aug. 2017, and Oct. 2018. Isotope measurements were made using cavity ring-down spectroscopic analyzers integrated into the Water Isotope System for Precipitation and Entrainment Research (WISPER). The WISPER data are processed into mean latitude-altitude curtains and individual vertical profiles for each sampling period.
The WISPER data accompanied a suite of other variables including standard meteorological quantities (wind, temperature, moisture), trace gas and aerosol concentrations, radar, and lidar remote sensing, which can be accessed through the DOIs listed further down. The ORACLES campaigns are described by Redemann et al., (2021). The water isotope measurements are further described in Henze et al., (2021). The absolute error with respect to the SMOW-SLAP scale is explained in detail by Henze et al., (2021).
Total water concentration and isotope ratios were binned and averaged onto latitude-altitude grids using a kernel estimation approach, with weighting designed to estimate the mean during the approximate month-long duration of each sampling period. Standard deviations for each bin are also computed using kernel density estimation.
Time intervals during aircraft vertical profiling are isolated and averaged onto 50-meter vertical levels. The files include water concentration and isotope ratios for both total water and cloud water in addition to temperature, pressure, latitude, and longitude.
See included file README.txt for additional details.
References
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Henze, D., Noone, D., and Toohey, D.: Aircraft measurements of water vapor heavy isotope ratios in the marine boundary layer and lower troposphere during ORACLES, Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2021-238, in review, 2021.
Redemann, J., Wood, R., Zuidema, P., Doherty, S. J., Luna, B., LeBlanc, S. E., Diamond, M. S., Shinozuka, Y., Chang, I. Y., Ueyama, R., Pfister, L., Ryoo, J.-M., Dobracki, A. N., da Silva, A. M., Longo, K. M., Kacenelenbogen, M. S., Flynn, C. J., Pistone, K., Knox, N. M., Piketh, S. J., Haywood, J. M., Formenti, P., Mallet, M., Stier, P., Ackerman, A. S., Bauer, S. E., Fridlind, A. M., Carmichael, G. R., Saide, P. E., Ferrada, G. A., Howell, S. G., Freitag, S., Cairns, B., Holben, B. N., Knobelspiesse, K. D., Tanelli, S., L'Ecuyer, T. S., Dzambo, A. M., Sy, O. O., McFarquhar, G. M., Poellot, M. R., Gupta, S., O'Brien, J. R., Nenes, A., Kacarab, M., Wong, J. P. S., Small-Griswold, J. D., Thornhill, K. L., Noone, D., Podolske, J. R., Schmidt, K. S., Pilewskie, P., Chen, H., Cochrane, S. P., Sedlacek, A. J., Lang, T. J., Stith, E., Segal-Rozenhaimer, M., Ferrare, R. A., Burton, S. P., Hostetler, C. A., Diner, D. J., Seidel, F. C., Platnick, S. E., Myers, J. S., Meyer, K. G., Spangenberg, D. A., Maring, H., and Gao, L.: An overview of the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) project: aerosol–cloud–radiation interactions in the southeast Atlantic basin, Atmos. Chem. Phys., 21, 1507–1563, https://doi.org/10.5194/acp-21-1507-2021, 2021.
The complete archive of ORACLES data are accessible via the digital object identifiers (DOIs) provided under ORACLES Science Team references as follows:
ORACLES Science Team: Suite of Aerosol, Cloud, and Related Data Acquired Aboard P3 During ORACLES 2018, Version 3, NASA Ames Earth Science Project Office, https://doi.org/10.5067/Suborbital/ORACLES/P3/2018_V3, 2020a.
ORACLES Science Team: Suite of Aerosol, Cloud, and Related Data Acquired Aboard P3 During ORACLES 2017, Version 3, NASA Ames Earth Science Project Office, https://doi.org/10.5067/Suborbital/ORACLES/P3/2017_V3, 2020b.
ORACLES Science Team: Suite of Aerosol, Cloud, and Related Data Acquired Aboard P3 During ORACLES 2016, Version 3, NASA Ames Earth Science Project Office, https://doi.org/10.5067/Suborbital/ORACLES/P3/2016_V3, 2020c.
ORACLES Science Team: Suite of Aerosol, Cloud, and Related Data Acquired Aboard ER2 During ORACLES 2016, Version 3, NASA Ames Earth Science Project Office, https://doi.org/10.5067/Suborbital/ORACLES/ER2/2016_V3, 2020d.See also mission information: https://espo.nasa.gov/ORACLES/content/ORACLES
Raw data archive: https://espoarchive.nasa.gov/archive/browse/oracle
A Sigh of Relief: Respiratory Illness In Areas Recently Affected By Hurricanes
Full text linkThis report investigates what physical, biological, and political mechanisms contribute to the observed increase in respiratory illness following the passage of a hurricane. No primary data was collected for this study, and all data presented in it
was previously published by accredited scientific sources. The data used for this study is representative of large geographic and temporal scales, but a significant amount of the data comes from the Gulf Coast of the Southeastern United States
during the 2005 hurricane season. Additionally, in this study, respiratory illness is generally classified in one of three ways, Acute Respiratory Infection (ARI), Upper Respiratory Symptoms (URS), and Lower Respiratory Symptoms (LRS). This report
first establishes a positive link between hurricanes and respiratory disease and then offers several potential ways to minimize the increase in respiratory disease following future storms
A Study of the Impact of Diesel Buses on Downtown Boulder
Full text linkThis research examined the major pollutants produced by diesel-powered engines within the city of Boulder, Colorado: particulate matter, black carbon, and nitrogen oxides. Ozone was studied due to its secondary formation from nitrogen oxides. Summer and Winter measurements were taken next to the Boulder Downtown Bus Station, for one week in each season. It was not possible to estimate bus emissions due to variability in the number of vehicles and buses traveling in the study corridor. Bicycle rides were carried out to capture fresh emissions on-road. Black carbon concentration peaked when chasing certain buses, while emissions from other buses were low. Passenger vehicle emissions were not reflected in the black carbon levels. With the use of MOVES and R-Line, the impact of buses on the concentration of pollutants was analyzed. Results showed the fraction of NOx and PM that could be attributable to buses was between 24-40% and 16-45%, respectively
Atmospheric Ethane-Methane Relationship and Implications for the Arctic
Full text linkThe purpose of this project is to evaluate hydrocarbon concentrations, their chemistry in the atmosphere, and the corresponding implications for arctic ecosystems. Recently, methane’s increasing threat as a greenhouse gas has warranted much research in the scientific field as global warming trends continue. A subject of significantly less research but perhaps of equal importance are ethane emissions, which are crucial to the understanding of methane’s growth. Though methane and ethane share anthropogenic sources, methane concentrations in the atmosphere vary due to biogenic sources specific to the chemical compound. Due to this constraint, co-measurement of methane and ethane is important because of the strong correlation between the two chemicals due to their shared anthropogenic sources. A significant upturn in methane growth without a corresponding increase in ethane may indicate releases of methane from biogenic sources such as melting permafrost. Recent studies have shown that ethane concentrations are decreasing worldwide, likely due to sequestration of anthropogenic fossil fuel emissions. However, methane concentrations are becoming a focus of concern for environmentalists
A Study of the Impact of Diesel Buses on Downtown Boulder
Full text linkThis research examined the major pollutants produced by diesel-powered engines within the city of Boulder, Colorado: particulate matter, black carbon, and nitrogen oxides. Ozone was studied due to its secondary formation from nitrogen oxides. Summer and Winter measurements were taken next to the Boulder Downtown Bus Station, for one week in each season. It was not possible to estimate bus emissions due to variability in the number of vehicles and buses traveling in the study corridor. Bicycle rides were carried out to capture fresh emissions on-road. Black carbon concentration peaked when chasing certain buses, while emissions from other buses were low. Passenger vehicle emissions were not reflected in the black carbon levels. With the use of MOVES and R-Line, the impact of buses on the concentration of pollutants was analyzed. Results showed the fraction of NOx and PM that could be attributable to buses was between 24-40% and 16-45%, respectively
Characteristics of Atmospheric Humidity Derived From Reanalyses and Stable Isotopic Measurements From Space
Full text linkThis study identifies the large-scale processes that balance regional relative humidity (H), and utilizes satellite measurements of HDO/H2O to characterize moisture processes that influence large-scale humidity. Using the MERRA reanalysis, dynamical and thermodynamical processes that balance zonal mean H are presented. The controls on H vary regionally, with eddy heat and moisture divergence being most influential in the extratropics. Condensation and eddy moisture convergence in midlatitudes, and subsidence and heat divergence in the NH subtropics, have increased from 1979-2004. While H has remained in balance, the strength of the compensating regional controls are changing in response to large-scale circulation shifts. The distribution of HDO/H2O in water vapor, measured from the Tropospheric Emission Spectrometer, is analyzed to quantify influences from advection, convection, condensation, vapor recycling, and evapotranspiration. The analysis focuses on monsoonal regions, where strong hydrological coupling between the land surface and atmosphere provides an ideal test bed for the new dataset. Wet-minus-dry season differences in δD values over the Asian, South American, and North Australian regions are near-zero, negative, and positive, respectively, due to seasonal variations in the characteristics and strength of convection and subsidence. A global Lagrangian mass budget model, constrained by H2O and HDO/H2O measurements, was constructed to give estimates of mixing and loss rates of moisture, fractional increases in humidity due to local moistening, the humidity and isotopic composition of regional source waters, and post-condensational exchange. The source water results are compared to expectations from simple mixing and dehydration models in order to gain new insight into the nature of the exchange processes (e.g., convective detrainment or direct mixing). Further insight is given by the sensitivity of the effective isotopic fractionation in the Lagrangian model to the conditions during condensation. Reversible moist adiabatic processes (i.e., cloud evaporation) are shown to moisten the dry subtropics, while rainfall evaporation is found to provide local moistening in the tropics and summertime subtropics. This study shows that compensating processes may preclude proper interpretation of small changes in mean humidity. Enhanced characterization of the processes that underlie the humidity budget is required for accounting for changes in atmospheric hydrology with climate shifts
Atmospheric Ethane-Methane Relationship and Implications for the Arctic
Full text linkThe purpose of this project is to evaluate hydrocarbon concentrations, their chemistry in the atmosphere, and the corresponding implications for arctic ecosystems. Recently, methane’s increasing threat as a greenhouse gas has warranted much research in the scientific field as global warming trends continue. A subject of significantly less research but perhaps of equal importance are ethane emissions, which are crucial to the understanding of methane’s growth. Though methane and ethane share anthropogenic sources, methane concentrations in the atmosphere vary due to biogenic sources specific to the chemical compound. Due to this constraint, co-measurement of methane and ethane is important because of the strong correlation between the two chemicals due to their shared anthropogenic sources. A significant upturn in methane growth without a corresponding increase in ethane may indicate releases of methane from biogenic sources such as melting permafrost. Recent studies have shown that ethane concentrations are decreasing worldwide, likely due to sequestration of anthropogenic fossil fuel emissions. However, methane concentrations are becoming a focus of concern for environmentalists
The Impact of Hydrological and Climatic Variations on the Oxygen-18 Content of Atmospheric CO2
Full text linkThe 18O composition of atmospheric CO2 is a potentially valuable tracer of global interactions between the hydrologic and carbon cycles. The observed 18O composition of atmospheric CO2 (hereafter δCa, where δ=(R/Rstandard-1) ~ 1000 and R is the molar ratio of heavy to light isotopes) does not show a clear long-term trend, though almost all monitoring stations observed an impressive decrease in δCa from 1992 to 1998. The cause(s) of this and other interannual δCa variations are still relatively unknown, and this work aims to better understand the driving mechanisms that caused the observed interannual δCa variations.
Observed interannual δCa anomalies from Mauna Loa were correlated with anomalies of certain meteorological variables that could potentially affect δCa. Negative correlation existed between δCa and both relative humidity and precipitation amount within parts of the tropics. Positive correlations existed between δCa variations and the 18O content of precipitation for the same tropical regions. Rough estimates suggest that about 20% of the decrease in δCa during the 1990s was due to increases in relative humidity and about 80% of the decrease was due to decreases in the δ18O value of precipitation (and likely a consequence of increases in the amount of precipitation).
A global model was constructed to simulate atmospheric CO2 and CO18O (and thus δCa). This model employed an isotopic land model (ISOLSM) and the Community Atmosphere Model (CAM). The model is used for a series of sensitivity experiments to better understand how both steady-state and interannual varying δCa respond to changes in relative humidity, δ18O values of precipitation and water vapor, temperature, and light levels. δCa responded the most to changes in the δ18O values of precipitation and water vapor, with moderate responses to relative humidity changes. Model results suggest that the decrease in δCa during the 1990s was due primarily to decreases in the 18O composition of precipitation with a smaller a contribution from increased relative humidity. Thus, observations of δCa may become a powerful integrative tool in the coming decades for monitoring large scale changes in the hydrological cycle should it accelerate under a warming climate, as predicted.</p
The Impact of Hydrological and Climatic Variations on the Oxygen-18 Content of Atmospheric CO2
Full text linkThe 18O composition of atmospheric CO2 is a potentially valuable tracer of global interactions between the hydrologic and carbon cycles. The observed 18O composition of atmospheric CO2 (hereafter δCa, where δ=(R/Rstandard-1) ~ 1000 and R is the molar ratio of heavy to light isotopes) does not show a clear long-term trend, though almost all monitoring stations observed an impressive decrease in δCa from 1992 to 1998. The cause(s) of this and other interannual δCa variations are still relatively unknown, and this work aims to better understand the driving mechanisms that caused the observed interannual δCa variations.
Observed interannual δCa anomalies from Mauna Loa were correlated with anomalies of certain meteorological variables that could potentially affect δCa. Negative correlation existed between δCa and both relative humidity and precipitation amount within parts of the tropics. Positive correlations existed between δCa variations and the 18O content of precipitation for the same tropical regions. Rough estimates suggest that about 20% of the decrease in δCa during the 1990s was due to increases in relative humidity and about 80% of the decrease was due to decreases in the δ18O value of precipitation (and likely a consequence of increases in the amount of precipitation).
A global model was constructed to simulate atmospheric CO2 and CO18O (and thus δCa). This model employed an isotopic land model (ISOLSM) and the Community Atmosphere Model (CAM). The model is used for a series of sensitivity experiments to better understand how both steady-state and interannual varying δCa respond to changes in relative humidity, δ18O values of precipitation and water vapor, temperature, and light levels. δCa responded the most to changes in the δ18O values of precipitation and water vapor, with moderate responses to relative humidity changes. Model results suggest that the decrease in δCa during the 1990s was due primarily to decreases in the 18O composition of precipitation with a smaller a contribution from increased relative humidity. Thus, observations of δCa may become a powerful integrative tool in the coming decades for monitoring large scale changes in the hydrological cycle should it accelerate under a warming climate, as predicted.</p
Characteristics of Atmospheric Humidity Derived From Reanalyses and Stable Isotopic Measurements From Space
Full text linkThis study identifies the large-scale processes that balance regional relative humidity (H), and utilizes satellite measurements of HDO/H2O to characterize moisture processes that influence large-scale humidity. Using the MERRA reanalysis, dynamical and thermodynamical processes that balance zonal mean H are presented. The controls on H vary regionally, with eddy heat and moisture divergence being most influential in the extratropics. Condensation and eddy moisture convergence in midlatitudes, and subsidence and heat divergence in the NH subtropics, have increased from 1979-2004. While H has remained in balance, the strength of the compensating regional controls are changing in response to large-scale circulation shifts. The distribution of HDO/H2O in water vapor, measured from the Tropospheric Emission Spectrometer, is analyzed to quantify influences from advection, convection, condensation, vapor recycling, and evapotranspiration. The analysis focuses on monsoonal regions, where strong hydrological coupling between the land surface and atmosphere provides an ideal test bed for the new dataset. Wet-minus-dry season differences in δD values over the Asian, South American, and North Australian regions are near-zero, negative, and positive, respectively, due to seasonal variations in the characteristics and strength of convection and subsidence. A global Lagrangian mass budget model, constrained by H2O and HDO/H2O measurements, was constructed to give estimates of mixing and loss rates of moisture, fractional increases in humidity due to local moistening, the humidity and isotopic composition of regional source waters, and post-condensational exchange. The source water results are compared to expectations from simple mixing and dehydration models in order to gain new insight into the nature of the exchange processes (e.g., convective detrainment or direct mixing). Further insight is given by the sensitivity of the effective isotopic fractionation in the Lagrangian model to the conditions during condensation. Reversible moist adiabatic processes (i.e., cloud evaporation) are shown to moisten the dry subtropics, while rainfall evaporation is found to provide local moistening in the tropics and summertime subtropics. This study shows that compensating processes may preclude proper interpretation of small changes in mean humidity. Enhanced characterization of the processes that underlie the humidity budget is required for accounting for changes in atmospheric hydrology with climate shifts
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