User Tools

Site Tools


Atmospheric Emitted Radiance Interferometer (AERI)

AERI at JOYCE ©B. Pospichal
AERI installed at Jülich


The AERI is an operational infrared spectrometer that measures the downwelling infrared radiance from 3.3-19 µm at 1 cm-1 resolution. Like the microwave spectrum, the infrared spectrum also contains information on the vertical profile of temperature and humidity. Spectral observations from 612-713 cm-1 and 2223-2260 cm-1 (i.e., measurements from the 15 µm and 4.3 µm CO2 bands, respectively) are used for temperature profiling, and observations from 538-588 cm-1 and 1250-1350 cm-1 (i.e., measurements from the wings of the rotational and 6.3 µm water vapor bands, respectively) for water vapor profiling. Additionally, selected window channels provide information on low-LWP (< 50 gm-2) liquid water cloud effective radius and cloud optical depth as well as ice clouds and aerosol. Currently, our AERI is also used for columnar trace gas retrieval (CO2, CH4, N2O).

Measurement modes

  • Vertically pointing observations of downwelling spectral radiance in two spectral bands
  • Band 1: 520-1800 cm-1 (5.6-19.2 µm)
  • Band 2: 1800-3020 cm-1 (3.3-5.6 µm)

JOYCE-CF Standard Operation Procedures

  • Radiances in both spectral bands with a temporal resolution of 20 seconds and a spectral resolution of 1 cm-1
  • AERI-OE profiles using an optimal estimation framework to derive cloud and thermodynamic (temperature, water vapor) profiles using AERI radiances and additional inputs. More information can be found in Turner and Löhnert 2014

Data availability

Data are available on request, please fill the data request sheet and send it to

Dataset Temporal resolution File size Filename Remarks
Downwelling radiances Channel 1 20 seconds 1 file per day (~39 MB) jueaerich1C1.b1.YYYYMMDD.HHMMSS.cdf NetCDF format
Downwelling radiances Channel 2 20 seconds 1 file per day (~37 MB) jueaerich1C1.b1.YYYYMMDD.HHMMSS.cdf NetCDF format
AERI-OE profiles (temperature, water vapor, cloud properties) 10 minutes 1 file per day (20-25 MB) jueaerioe1turnC1.b1.YYYYMMDD.HHMMSS.cdf

Data quicklooks can be found in the JOYCE quicklook browser.

AERI on webmads link: This link shows the current observation of AERI instruments around the world

Measurement examples

Current observations:

AERI History

Period Place Project
May 13, 2011 - today Forschungszentrum Jülich JOYCE

Technical Specifications

Parameter Specification Remark
Spectral range receiver 1 5.6-19 µm corresponds to 1800 to 520 cm-1
Spectral range receiver 2 3.3-5.6 µm corresponds to 3020 to 1800 cm-1
Spectral resolution 1 cm-1
Number of channels ~2500 per receiver
Front end gold-coated mirror, optical paths redirect radiation into back end
Calibration targets 2 black bodies (ambient and hot load) 3rd target optional
Back end FT-IR (Fourier Transform Infrared) spectrometer (ABB)
Temporal resolution ~1 min for one spectrum 142 interferometer sweeps / min.
Manufacturer ABB Analytical Business, Québec, CANADA
aeri.txt · Last modified: 2021/03/01 10:57 by bpospich