# Autonomous field measurements of CO2 in the atmospheric column with the miniaturized laser heterodyne radiometer (Mini-LHR)

## TL;DR

A miniaturized sensor called Mini-LHR was used to autonomously measure CO2 in the atmosphere, showing potential for global deployment and improved climate monitoring.

## Contribution

The Mini-LHR introduces a low-cost, portable, and autonomous CO2 measurement system for atmospheric monitoring.

## Key findings

- The Mini-LHR successfully measured CO2 column concentrations at Mauna Loa Observatory in 2013.
- The instrument demonstrated high sensitivity to changes in atmospheric absorption.
- The Mini-LHR can complement existing networks and satellite missions for better global coverage.

## Abstract

We present column CO2 measurements taken by the passive miniaturized laser heterodyne radiometer (Mini-LHR) at 1611.51 nm at the Mauna Loa Observatory in Hawaii. The Mini-LHR was operated autonomously, during the month of May 2013 at this site, working in tandem with an AERONET sun photometer that measures aerosol optical depth at 15-min intervals during daylight hours. Laser heterodyne radiometry has been used since the 1970s to measure atmospheric gases such as ozone, water vapor, methane, ammonia, chlorine monoxide, and nitrous oxide. This iteration of the technology utilizes distributed feedback lasers to produce a low-cost, small, portable sensor that has potential for global deployment. Applications of this instrument include supplementation of existing monitoring networks to provide denser global coverage, providing validation for larger satellite missions, and targeting regions of carbon flux uncertainty. Also presented here are preliminary retrieval analysis and the performance analysis that demonstrate that the Mini-LHR responds extremely well to changes in the atmospheric absorption.