EM27/SUN Series FTIR Remote Sensing analyzer

Importance of the Topic

Monitoring atmospheric concentrations of key greenhouse gases such as carbon dioxide and methane is essential to understand climate dynamics, inform environmental policy, and assess anthropogenic and natural emissions.

Objectives and Study Overview

This whitepaper introduces the EM27/SUN Series, portable Fourier Transform Infrared (FTIR) spectrometers designed for remote atmospheric gas measurements. These instruments aim to quantify total column abundances of CO2 and CH4 by analyzing solar infrared absorption spectra using an innovative CAMTracker solar tracking system. The overview covers design features, performance benchmarks, and field applicability.

Methodology and Instrumentation

The EM27/SUN spectrometers leverage a compact FTIR design with permanently aligned RockSolidTM interferometers. Two spectral configurations are offered:

• NIR version: 5000–14500 cm^-1 at 0.5 cm^-1 resolution
• MIR version: 750–5200 cm^-1 at 0.5 cm^-1 (0.2 cm^-1 high-resolution option)

A camera-based CAMTracker system provides automatic sun tracking with <0.006 mrad accuracy, ensuring stable solar alignment even under partial cloud cover. Data acquisition and device control are managed via TCP/IP.

Main Results and Discussion

Field comparisons demonstrate excellent agreement between CO2 column concentrations retrieved by EM27/SUN and those measured by the high-resolution Bruker IFS 125HR in TCCON campaigns. The portable EM27/SUN offers robust performance in remote environments, capturing total column data comparable to larger stationary instruments. Example spectra from both NIR and MIR configurations illustrate clear absorption features for target gases, confirming instrument sensitivity and precision.

Benefits and Practical Applications

• Direct total column measurements of greenhouse gases
• Compact, lightweight design ideal for mobile and remote deployments
• Low maintenance, rapid setup without special optical elements
• Insensitive to inhomogeneous illumination and minor obstructions
• Applicable in urban, remote, and harsh field environments

Future Trends and Opportunities

Future developments may integrate EM27/SUN units with unmanned aerial platforms, expand spectral coverage, and automate data processing pipelines. Deploying dense networks can enhance spatial resolution of greenhouse gas monitoring, support satellite validation, and contribute to real-time atmospheric modeling.

Conclusion

The EM27/SUN Series balances portability, accuracy, and ease of use for atmospheric greenhouse gas monitoring. Its proven agreement with high-resolution benchmarks validates its role in both research and operational networks, enabling flexible deployment across diverse environments.

Reference

1. Hase F., Frey M., Blumenstock T., Groß J., Kiel M., Kohlhepp R., Mengistu Tsidu G., Schäfer K., Sha M.K., Orphal J. Atmos. Meas. Tech. 8, 3059–3068 (2015)
2. Gisi M., Hase F., Dohe S., Blumenstock T., Simon A., Keens A. Atmos. Meas. Tech. 5, 2969–2980 (2012)