| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | July 25, 2022 |
| Latest Amendment Date: | July 25, 2022 |
| Award Number: | 2233136 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Eric DeWeaver
edeweave@nsf.gov (703)292-8527 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | August 15, 2022 |
| End Date: | July 31, 2024 (Estimated) |
| Total Intended Award Amount: | $189,543.00 |
| Total Awarded Amount to Date: | $189,543.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3100 MARINE ST Boulder CO US 80309-0001 (303)492-6221 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
3100 MARINE ST STE 481 572 UCB BOULDER CO US 80309-0584 |
| 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): | Climate & Large-Scale Dynamics |
| 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 award supports development of a hygrometer, or water vapor sensor, for use in the tropical tropopause layer (TTL), the transition zone between the troposphere (the domain of clouds and precipitation) and the stratosphere (the cold and dry region above it which contains the ozone layer). TTL water vapor is of interest for several reasons including its role in the formation of cirrus clouds, which have a strong effect on earth's radiative energy balance, and the fact that much of the water vapor in the stratosphere enters through the TTL. The hygrometer developed under this award is intended for use in an instrument package previously developed under AGS-1643022 called RACHuTS, for Reel-down Aerosol Cloud Humidity and Temperature Sensor. RACHuTS is a shoebox-size package weighing less than 2kg which is raised and lowered on a 2km nylon cable attached to the gondola of a research balloon. RACHuTS is intended to study the formation of cirrus clouds, collecting the temperature, humidity, and cloud particle observations needed to observe the formation of cirrus clouds due to the supersaturation of ambient air. The hygrometer replaces the FLASH-B hygrometer originally used for RACHuTS, which is no longer available.
The requirements for the hygrometer are quite challenging as it has to measure water vapor over a range of 2 to 500 parts per million with a resolution less than 5% over the whole range and a response time of one second. It also has to operate unattended in the TTL environment for 2-3 months. In order to fit the RACHuTS package it has to weigh less than 700 grams and have an average power consumption less than 3 watts. The hygrometer developed in this project uses wavelength modulation spectroscopy to meet these challenges, taking advantage of a distributed feedback infrared laser developed for telecommunications, an open multi-pass Herriott cell, and low-cost microcontrollers marketed to hobbiests. The hygrometer can be developed quickly because it is similar to existing hygrometers including the University of Colorado Second Generation Laser Hygrometer (CLH-2). The project includes a test flight on a balloon launched in 2023, and the hygrometer should be available in time for use in the 2024 deployment of the Strateole-2 long-duration ballooning campaign.
The work has scientific broader impacts due to the value of RACHuTS observations for addressing a variety of questions regarding TTL processes. In addition, work under this award fosters the development of a new class of low-cost, lightweight instruments that can be used in a variety of configurations and applications. Potential applications include specialized "dropsondes" released from "hurricane hunter" aircraft and smaller, lower sensitivity versions for use in citizen science.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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.
Intellectual Merit: This project was the development of a lightweight, economical instrument specifically aimed at high-accuracy measurements of water vapor for the Strateole II campaign. The instrument uses tunable diode lasers in the infrared region of the spectrum, with an open-path optical cell extending approximately 1 meter from the electronics package, to sample water vapor without contaminating the measurements with water off-gassing from surfaces of the payload. The instrument was designed based on previous instruments used by the principal investigator on NASA and NSF research aircraft over the past 20 years. Miniaturization of commercal electronics, such as the Arduino family of microprocessors, allows for significant reductions in size, weight, power consumption, and cost. Test flights were carried out in October 2023, and March, May, and June of 2024, each addressing a particular aspect of the design and operation of the instrument that allowed for step-wise improvement in the design and operation leading up to a final version, which will be flown in the tropics on the Strateole II long-duration balloons. The new hygrometer performed nearly flawlessly on all flights. The method was demonstrated to be robust and ready for the hostile conditions expected on long-duration flights in the tropical UTLS.
Broader Impacts: This instrument could ultimately replace the industry "standard" frostpoint hygrometer used for many decades, thus eliminating the need for release of potent greenhouse gases used as cryogens and simplifying logistics for deploying from remote locations. In addition to providing high-accuracy, reliable measurements of water vapor in the tropical lower stratosphere, the new design will enable a new class of instruments that may significantly alter the way balloon-borne measurements of water vapor and other trace gases are carried out in the future. This could include modifications for measurements of emissions of methane from welands, landfills, and leaks from deep wells and connecting pipelines.
Last Modified: 12/03/2024
Modified by: Darin W Toohey
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