| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | July 19, 2016 |
| Latest Amendment Date: | September 13, 2019 |
| Award Number: | 1638402 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Roberto Delgado
robdelga@nsf.gov (703)292-2397 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | August 1, 2016 |
| End Date: | July 31, 2021 (Estimated) |
| Total Intended Award Amount: | $176,383.00 |
| Total Awarded Amount to Date: | $176,383.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1850 RESEARCH PARK DR STE 300 DAVIS CA US 95618-6153 (530)754-7700 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
One Shields Ave Davis CA US 95616-5270 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | AON-Arctic Observing Network |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
Fine particles directly scatter and absorb sunlight, and depending on their size and composition can either heat or cool the Earth. They come from both natural sources like volcanoes, dust storms, and forest fires, and from man-made sources like industry, power plants and vehicles. Since a signature of their origin is imbedded in their composition, they can be tracked back to sources even thousands of miles away using meteorological models. Understanding the composition and sources of these fine particles is critical to developing better models of global climate change, but requires many years of observation. One of the best places to measure these fine particles in the atmosphere is at the Greenland Summit research station because the site is not near populated areas or the ocean which are sources of these particles. This renewal of an Arctic Observing Network project will extend sampling of these fine particles at the Greenland Summit site another 5 years. The results will be of value to molders of global climate change and to atmospheric scientists. Undergraduate students will be involved in sample analysis.
This program is unique in that the Greenland Summit site is the only high elevation Arctic site and thus responds to aerosols in the free troposphere, the region of the atmosphere that dominates long range transport. Since 2003, aerosols have been collected continuously in 8 size modes, 15 µm to 0.09 µm, on slowly rotating drums that allow for 12 hr. time resolution and an excellent match to the various transport patterns that bring aerosols into the Arctic. Since there is very little mass to analyze, the large synchrotron x-ray source at the Lawrence Berkeley Laboratory Advanced Light Source has been used to make the compositional analyses, yielding the lowest values of many aerosol species ever measured in the ambient atmosphere. The new program has several enhancements. Optical back scattering will allow measurement of the global albedo, important since aerosols are roughly 2/3 of the total uncertainty in global climate models. A new method has been added for measuring aerosol organic matter that will allow mass closure. In this protocol, the sum of all species equals the total mass present in each of the 8 size modes so that all aerosol mass can be accounted for in determination of the optical properties The higher energy beams at the Stanford Synchrotron Radiation Light Source will now also be included, allowing the program to access heavier elements to better identify industrial sources. These data will be compared with other high elevation sites like the Mauna Loa Observatory in Hawaii to better track long-range transport of aerosols in the Northern hemisphere. A further benefit of these data is that they allow a measurement of how airborne particles get imbedded in the snow pack and eventually the ice cores collected at the Summit site. Thus, these measurements help explain the dust present over the past millennia, during both warm periods and ice ages.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The DELTA Group/Air Quality Research Center of the University of California, Davis (AQRC) conducted a multi-year monitoring campaign at the National Science Foundation Greenland Summit Station to aid in understanding the impact of a long-transport aerosols on the Arctic environment.
The overarching goal of this monitoring study was to develop methods for monitoring long-transport aerosols in the challenging Arctic environment. The study design leveraged the unique capabilities of UC Davis cascading impactor technology keyed to national laboratory energy beam analyses. The previous monitoring campaign from 2003 to 2013 was the foundation from which we attempted to improve from.
Particulate matter (PM) samples were collected using a DRUM-style cascading impactor (Davis Rotating Unit for Monitoring). Collected samples were analyzed using several non-destructive techniques to determine optical attenuation and elemental concentrations. These included:
- Broadband transmission/reflectance spectrometry
- Synchrotron-induced X-Ray Fluorescence
- Proton-Induced X-ray Emission
- Proton Elastic Scattering Analysis
Consistent with previous deployments from 2003 to 2013, elemental and optical measurements were conducted on daily samples collected from 2015 to 2021. Over the years, modifications were made to the sampling equipment and to the laboratory analyses to improve data quality and consistency. While not all changes were fully successful, the following provides a summary of improvements and challenges:
- Development of beamline 2-2 at the Stanford Synchrotron Radiation Lightsource
- Development of beamline 1B at the UC Davis Crocker Nuclear Laboratory
- Calibration of the optical transmission method
- Development of an optical reflectance method
- Experimentation with microprocessor-driven sampling equipment
The monitoring of elemental species fills an important niche in the international effort to study Arctic environments. Mineral species are an important contributor to particle optical properties and mass balance. Anthropogenic metals are useful tracers for identifying sources of pollution into the region. The new proton beamline developed for this project offers the possibility of quantifying bound hydrogen as well as carbon, oxygen, and nitrogen as a function of particle size. To our knowledge, this capability is not currently available at any Arctic observatories.
This project collected a large amount of optical information. We plan to continue investigations of both methods employed along with the measurement results to better understand what information DRUM sample optical properties may provide to the scientific community. As validated data is produced, we will upload to the Arctic data center and update our metadata files for public use.
Last Modified: 11/29/2021
Modified by: Nicholas J Spada
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