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Miniaturized Laser Heterodyne Radiometer (Mini-LHR) Ground Instrument


Laser heterodyne radiometry is a technique based on the radio receiver that has been in use since the 1970s for monitoring the concentrations of trace gases in the atmosphere. At GSFC, we have been developing passive, low-cost miniaturized versions of this technique since 2006 for both ground instruments and CubeSats using distributive feedback (DFB) lasers.



Field Measurements

MLO is the site of the longest running measurements of atmospheric CO2, begun in the late 1950s by Charles Keeling. MLO offers a unique testing environment for the Mini-LHR, as the altitude helps ensure the atmosphere sampled represents the “background” signal of the atmosphere.

In 2014, the mini-LHR participated in COW-GAS (PI. Ira Leifer) to monitor methane at the Cal Poly Research Dairy farm. Dairy farms are a significant source of methane in the atmosphere. 

In 2018, working with our partners at the University of Edinburgh, we deployed a mini-LHR at The Royal Observatory in Edinburgh, Scotland where we plan to make continuous column CH4 and CO2 measurements.

In 2017, we tested our new, compact version of the ground mini-LHR as part of the Hawai’i Space Exploration Analog and Simulation (Hi-SEAS) program which is a long duration Mars analog simulation program operated by the University of Hawai’i at Mānoa.

An early version of the mini-LHR was field tested at the NOAA WLEF tall tower site in Park Falls, Wisconsin in September 2012.

In 2014, we had the opportunity to test the mini-LHR alongside the TCCON (Total Column Carbon Observing Network) at Caltech in Pasadena, CA. 

The mini-LHR was ground tested from Castle airport in Central Valley, CA during the ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, & Seasons) DC-8 Field campaign in February 2013. Column measurements from the mini-LHR were compared with CO2 measurements from various instruments on the DC-8 during a spiral flight path centered at Castle airport.

This project, funded under NASA’s Interdisciplinary Science (IDS) Program, was to measure column CH4 and CO2 over thawing permafrost at the Bonanza Creek Research Forest near Fairbanks, Alaska.