skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Model representations of aerosol layers transported from North America over the Atlantic Ocean during the Two-Column Aerosol Project

Abstract

The ability of the Weather Research and Forecasting model with chemistry (WRF-Chem) version 3.7 and the Community Atmosphere Model version 5.3 (CAM5) in simulating profiles of aerosol properties is quantified using extensive in situ and remote sensing measurements from the Two Column Aerosol Project (TCAP) conducted during July of 2012. TCAP was supported by the U.S. Department of Energy’s Atmospheric Radiation Measurement program and was designed to obtain observations within two atmospheric columns; one fixed over Cape Cod, Massachusetts and the other several hundred kilometers over the ocean. The performance is quantified using most of the available aircraft and surface measurements during July, and two days are examined in more detail to identify the processes responsible for the observed aerosol layers. The higher resolution WRF-Chem model produced more aerosol mass in the free troposphere than the coarser resolution CAM5 model so that the fraction of aerosol optical thickness above the residual layer from WRF-Chem was more consistent with lidar measurements. We found that the free troposphere layers are likely due to mean vertical motions associated with synoptic-scale convergence that lifts aerosols from the boundary layer. The vertical displacement and the time period associated with upward transport in the troposphere dependmore » on the strength of the synoptic system and whether relatively high boundary layer aerosol concentrations are present where convergence occurs. While a parameterization of subgrid scale convective clouds applied in WRF-Chem modulated the concentrations of aerosols aloft, it did not significantly change the overall altitude and depth of the layers.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [2];  [2];  [1];  [3];  [4];  [1];  [1];  [4];  [1];  [3];  [1];  [1];  [1]
  1. Pacific Northwest National Laboratory, Richland Washington USA
  2. NASA Langley Research Center, Hampton Virginia USA
  3. Department of Chemistry, Colorado University, Boulder Colorado USA
  4. Brookhaven National Laboratory, Upton New York USA
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1340781
Report Number(s):
PNNL-SA-119932
Journal ID: ISSN 2169-897X; 49096; KP1701000
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Geophysical Research: Atmospheres; Journal Volume: 121; Journal Issue: 16
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Fast, Jerome D., Berg, Larry K., Zhang, Kai, Easter, Richard C., Ferrare, Richard A., Hair, Johnathan W., Hostetler, Chris A., Liu, Ying, Ortega, Ivan, Sedlacek, Arthur, Shilling, John E., Shrivastava, Manish, Springston, Stephen R., Tomlinson, Jason M., Volkamer, Rainer, Wilson, Jacqueline, Zaveri, Rahul A., and Zelenyuk, Alla. Model representations of aerosol layers transported from North America over the Atlantic Ocean during the Two-Column Aerosol Project. United States: N. p., 2016. Web. doi:10.1002/2016JD025248.
Fast, Jerome D., Berg, Larry K., Zhang, Kai, Easter, Richard C., Ferrare, Richard A., Hair, Johnathan W., Hostetler, Chris A., Liu, Ying, Ortega, Ivan, Sedlacek, Arthur, Shilling, John E., Shrivastava, Manish, Springston, Stephen R., Tomlinson, Jason M., Volkamer, Rainer, Wilson, Jacqueline, Zaveri, Rahul A., & Zelenyuk, Alla. Model representations of aerosol layers transported from North America over the Atlantic Ocean during the Two-Column Aerosol Project. United States. doi:10.1002/2016JD025248.
Fast, Jerome D., Berg, Larry K., Zhang, Kai, Easter, Richard C., Ferrare, Richard A., Hair, Johnathan W., Hostetler, Chris A., Liu, Ying, Ortega, Ivan, Sedlacek, Arthur, Shilling, John E., Shrivastava, Manish, Springston, Stephen R., Tomlinson, Jason M., Volkamer, Rainer, Wilson, Jacqueline, Zaveri, Rahul A., and Zelenyuk, Alla. 2016. "Model representations of aerosol layers transported from North America over the Atlantic Ocean during the Two-Column Aerosol Project". United States. doi:10.1002/2016JD025248.
@article{osti_1340781,
title = {Model representations of aerosol layers transported from North America over the Atlantic Ocean during the Two-Column Aerosol Project},
author = {Fast, Jerome D. and Berg, Larry K. and Zhang, Kai and Easter, Richard C. and Ferrare, Richard A. and Hair, Johnathan W. and Hostetler, Chris A. and Liu, Ying and Ortega, Ivan and Sedlacek, Arthur and Shilling, John E. and Shrivastava, Manish and Springston, Stephen R. and Tomlinson, Jason M. and Volkamer, Rainer and Wilson, Jacqueline and Zaveri, Rahul A. and Zelenyuk, Alla},
abstractNote = {The ability of the Weather Research and Forecasting model with chemistry (WRF-Chem) version 3.7 and the Community Atmosphere Model version 5.3 (CAM5) in simulating profiles of aerosol properties is quantified using extensive in situ and remote sensing measurements from the Two Column Aerosol Project (TCAP) conducted during July of 2012. TCAP was supported by the U.S. Department of Energy’s Atmospheric Radiation Measurement program and was designed to obtain observations within two atmospheric columns; one fixed over Cape Cod, Massachusetts and the other several hundred kilometers over the ocean. The performance is quantified using most of the available aircraft and surface measurements during July, and two days are examined in more detail to identify the processes responsible for the observed aerosol layers. The higher resolution WRF-Chem model produced more aerosol mass in the free troposphere than the coarser resolution CAM5 model so that the fraction of aerosol optical thickness above the residual layer from WRF-Chem was more consistent with lidar measurements. We found that the free troposphere layers are likely due to mean vertical motions associated with synoptic-scale convergence that lifts aerosols from the boundary layer. The vertical displacement and the time period associated with upward transport in the troposphere depend on the strength of the synoptic system and whether relatively high boundary layer aerosol concentrations are present where convergence occurs. While a parameterization of subgrid scale convective clouds applied in WRF-Chem modulated the concentrations of aerosols aloft, it did not significantly change the overall altitude and depth of the layers.},
doi = {10.1002/2016JD025248},
journal = {Journal of Geophysical Research: Atmospheres},
number = 16,
volume = 121,
place = {United States},
year = 2016,
month = 8
}
  • The ability of the Weather Research and Forecasting model with chemistry (WRF-Chem) version 3.7 and the Community Atmosphere Model version 5.3 (CAM5) in simulating profiles of aerosol properties is quantified using extensive in situ and remote sensing measurements from the Two-Column Aerosol Project (TCAP) conducted during July of 2012. TCAP was supported by the U.S. Department of Energy's Atmospheric Radiation Measurement program and was designed to obtain observations within two atmospheric columns; one fixed over Cape Cod, Massachusetts, and the other several hundred kilometers over the ocean. The performance is quantified using most of the available aircraft and surface measurementsmore » during July, and 2 days are examined in more detail to identify the processes responsible for the observed aerosol layers. The higher-resolution WRF-Chem model produced more aerosol mass in the free troposphere than the coarser-resolution CAM5 model so that the fraction of aerosol optical thickness above the residual layer from WRF-Chem was more consistent with lidar measurements. We found that the free troposphere layers are likely due to mean vertical motions associated with synoptic-scale convergence that lifts aerosols from the boundary layer. The vertical displacement and the time period associated with upward transport in the troposphere depend on the strength of the synoptic system and whether relatively high boundary layer aerosol concentrations are present where convergence occurs. In conclusion, while a parameterization of subgrid scale convective clouds applied in WRF-Chem modulated the concentrations of aerosols aloft, it did not significantly change the overall altitude and depth of the layers.« less
  • The particulate heavy metal concentrations of Cr, Fe, Ni, Cu, Zn, Cd, Tl, and Pb were determined in the atmosphere over the Atlantic Ocean from 60{degree}S to 54{degree}N with the definitive method of isotope dilution mass spectrometry. Fe was used as a reference element for the influence of crustal material calculating the corresponding enrichment factors EF(Fe) for the other metal traces. Tl showed the lowest abundance of all heavy metals with concentrations of less than 20 pg m{sup {minus}3} for all samples except those from the area around the English Channel. The concentration ranges for the other elements were Crmore » = <0.08-9 ng m{sup {minus}3}, Fe = <2.6-7,500 ng m{sup {minus}3}, Ni = <0.05-10 ng m{sup {minus}3}, Cu = <0.02-20 ng m{sup {minus}3}, Zn = <0.09-450 ng m{sup {minus}3}, Cd = <0.003-3.5 ng m{sup {minus}3}, and Pb = <0.05-200 ng m{sup {minus}3}. The lowest element concentrations were usually measured in the remote areas of the South Atlantic, whereas the highest ones were detected around the English Channel. Due to high Fe concentrations, a substantial influence of crustal material was observed in the atmosphere southeast of the South American continent, in the South Atlantic area of the southeast trades, and over the North Atlantic west of North Africa. EF(Fe) values for the most part less than 10 for Cr and Ni and less than 50 for Cu indicate that the influence of crustal material for these metals is much higher than for Zn, Cd, and Pb where EF(Fe) values between 500 and 5,000 had often been determined. This is due to anthropogenic and biological influences.« less
  • Aerosol properties above clouds have been retrieved over the South East Atlantic Ocean during the fire season 2006 using satellite observations from POLDER (Polarization and Directionality of Earth Reflectances). From June to October, POLDER has observed a mean Above-Cloud Aerosol Optical Thickness (ACAOT) of 0.28 and a mean Above-Clouds Single Scattering Albedo (ACSSA) of 0.87 at 550nm. These results have been used to evaluate the simulation of aerosols above clouds in 5 AeroCom (Aerosol Comparisons between Observations and Models) models (GOCART, HadGEM3, ECHAM5-HAM2, OsloCTM2 and SPRINTARS). Most models do not reproduce the observed large aerosol load episodes. The comparison highlightsmore » the importance of the injection height and the vertical transport parameterizations to simulate the large ACAOT observed by POLDER. Furthermore, some models overestimate the ACSSA. In accordance with recent recommendations of the black carbon refractive index, a higher prescription of the imaginary part allows a better comparison with POLDER’s ACSSA.« less
  • The low-frequency variability of the surface climate over the North Atlantic during winter is described, using 90 years of weather observations from the Comprehensive Ocean-Atmosphere Data Set. Results are based on four components of the climate system: sea surface temperature (SST), air temperature, wind, and sea level pressure. Variability of the wintertime surface climate over the North Atlantic during this century is characterized by a dipole pattern in SSTs and surface air southeast coast of the United States. Wind fluctuations occur locally over the regions of large surface temperature anomalies, with stronger-than-normal winds overlying cooler-than-normal SSTs. The decadal fluctuations aremore » irregular in length, averaging [approximately] 9 years before 1945 and [approximately] 12 years afterward. There does not appear to be any difference between the wind-SST relationships on the different time scales. The decadal fluctuations in SSTs east of Newfoundland are closely linked to decadal variations in sea ice the Labrador Sea, with periods of greater than normal sea ice extent preceding by [approximately] 2 years periods of colder-than-normal SSTs east of Newfoundland. Another dominant mode of variability is associated with the global surface warming trend during the 1920s and 1930s. The patterns of SST and air temperature change between 1900-29 and 1939-68 indicate that the warming was concentrated along the Gulf Stream east of Cape Hatteras. Warming also occurred over the Greenland Sea and the eastern subtropical Atlantic. The warming trend was accompanied by a decrease in the strength of the basin-scale atmospheric circulation (negative phase of the North Atlantic Oscillation). In marked contrast to the dipole pattern, the wind changes occurred downstream of the largest SST anomalies; hence, the gradual surface warming along the Gulf Stream may have been a result of altered ocean currents rather than local wind forcing. 43 refs., 25 figs.« less