| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | August 13, 2012 |
| Latest Amendment Date: | November 21, 2016 |
| Award Number: | 1229738 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Sylvia Edgerton
sedgerto@nsf.gov (703)292-8522 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | August 15, 2012 |
| End Date: | December 31, 2017 (Estimated) |
| Total Intended Award Amount: | $274,866.00 |
| Total Awarded Amount to Date: | $274,866.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1000 E UNIVERSITY AVE LARAMIE WY US 82071-2000 (307)766-5320 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1000 E. University Ave. Laramie WY US 82071-2000 |
| 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): | Major Research Instrumentation |
| 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): | 47.050 |
ABSTRACT
This project is focused on developing an in situ particle size spectrometer for particles with radii ranging from 0.1 to 10 micrometers, and suitable for short- and long-term autonomous deployments at remote sites, or on balloon platforms. Immediate applications of the instrument would be to: 1) Replace current instrumentation for stratospheric aerosol profile measurements from Laramie, Wyoming, and 2) Add particle size measurements to equatorial Lagrangian balloons planned for missions in 2016 to 2018. Such measurements are important since aerosol play fundamental roles in the chemistry of mid-latitude stratospheric ozone, and provide one pathway for water to enter the lower stratosphere through penetrating convection, mainly in the tropics.
There are important societal broader impacts from the scientific measurements possible with new autonomous aerosol spectrometers. Consistent records of stratospheric size distributions are important to refine past estimates of climate and to anticipate future variations, due to unpredictable volcanic eruptions, or possible geo-engineering options. Improving understanding of the flux of species across the tropical tropopause is important to understand and predict the global distribution of stratospheric trace gases and particles, both essential ingredients to climate and chemistry models, which are the primary tools to anticipate long term anthropogenic impacts on the atmosphere in which we live. Such knowledge is needed to inform policy decisions related to a variety of air quality and climate issues. Development of the new instrument and results from it will be published through the peer reviewed literature. Instrumentation developed through the proposal will be available to the department and others for future measurements, in particular the Lagrangian balloon platforms. Participants in the project will gain valuable instrumental, experimental, and scientific experience. While one graduate student is included specifically, all graduate students in the principal investigator's group will participate to some extent in instrument development and testing. The group's activities will be extended to the larger community through public presentations, and participation in the University of Wyoming's Engineering Summer Program for promising high school students.
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.
All global climate and climate-chemistry models have to consider the impact of stratospheric aerosol on the Earth’s radiation balance. This balance is influenced by stratospheric aerosol through direct scattering of sunlight back to space, and through providing surfaces for heterogeneous chemical reactions involving ozone. The information required, aerosol cross section and aerosol surface area can be derived from the aerosol size distribution. Unfortunately there are almost no instruments which measure the stratospheric aerosol size distribution. All satellite instruments measure an optical moment such as extinction or scattering, from which the geophysical quantities of interest must be retrieved. Only in situ instruments, carried on aircraft or balloons, measure aerosol size distribution directly, and only balloons reach altitudes above 22 km.
The goal of this National Science Foundation (NSF) Major Research Infrastructure (MRI) award was to develop a replacement optical particle counter (OPC) for the current third generation instrument which has been deployed on balloons from Laramie, Wyoming, and elsewhere, since 2006. The measurements at Laramie began in 1971. Since then the instrumentation has gone through three major transitions, while maintaining a consistent continuous record of in situ stratospheric aerosol measurements. This record is unique in the world for its length and its ability, since the 1990s, to measure the large particle tail of the aerosol size distribution. Even though these measurements are made at only a few locations in the world, and only a few times per year, they provide, in addition to the direct measurements of aerosol cross section and surface area, essential information for validation of the inversion algorithms used by satellites, and other remote aerosol measurements, to derive the geophysical quantities needed by the models.
Unfortunately the elliptical mirror OPC initially designed under support from this NSF MRI award was not successful. The design, concentrated the instrument response too heavily on scattering in the forward direction. This design produced too much stray light and was a fatal flaw, which could not be overcome with the resources remaining. That led to considering the possibility of commercial optical blocks, around which an autonomous instrument could be built, with the characteristics desired for atmospheric aerosol size distribution measurements. Fortuitously, instruments designed for clean rooms have an aerosol measurement range similar to the relatively clean stratosphere. Thus several manufacturers of these instruments have developed optical blocks which can be applied to stratospheric measurements. Identifying the appropriate optical blocks and testing them in the laboratory and in flight was the avenue pursued for the last few years of this NSF award. This laid the ground work to adapt optical blocks from the company Met One to two autonomous balloon-borne instruments, one to measure aerosol between 0.15 and 10.0 µm, and the second the total aerosol population. Under this MRI award, and support from an additional NSF award, these instruments have been built and flown on three validation flights in comparison with the third generation Wyoming instrument. These new instruments formed the basis for two NSF proposals which were successful. The first is focused on extending the mid latitude in situ aerosol measurement record, the second on new aerosol measurements from drifting balloons in the tropical tropopause layer, the region encompassing the pathway of material into the stratosphere. These instruments were also the basis for a successful NASA proposal to contribute to the validation of the SAGE III satellite instrument deployed on the international space station in 2017.
In summary while the initial instrument designed under this award failed, ideas developed during that process, and after the failure, helped with the development of the new instruments which are now replacing the third generation Wyoming instruments. The new instruments are lighter, cheaper, and more capable, due to advances in clean room technology, electronics, and microprocessors. Thus they will both extend the previous suite of measurements and open the door to new measurements, which were not previously feasible.
Last Modified: 04/11/2018
Modified by: Terry L Deshler
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