Preprints
https://doi.org/10.5194/amt-2020-521
https://doi.org/10.5194/amt-2020-521

  13 Apr 2021

13 Apr 2021

Review status: this preprint is currently under review for the journal AMT.

The “Ideal Spectrograph” for Atmospheric Observations

Ulrich Platt1,2, Thomas Wagner2, Jonas Kuhn1,2, and Thomas Leisner3 Ulrich Platt et al.
  • 1Institute of Environmental Physics (IUP), Heidelberg University, INF 229, D-69120 Heidelberg, Germany
  • 2Max Planck Institute for Chemistry, Mainz, Germany
  • 3Institute for Meteorology and Climate Research, KIT Karlsruhe

Abstract. Spectroscopy of scattered-sunlight in the near UV to near IR spectral ranges has proven to be an extremely useful tool for the analysis of atmospheric trace gas distributions. A central parameter for the achievable sensitivity and spatial resolution of spectroscopic instruments is the étendue (product of aperture angle and entrance area) of the spectrograph, which is at the heart of the instrument. The étendue of an instrument can be enhanced by (1) up-scaling all instrument dimensions or (2) by changing the instrument F-number, (3) by increasing the entrance area, or (4) by operating many instruments (of identical design) in parallel. The étendue can be enhanced by (in principle) arbitrary factors by options (1) and (4), the effect of options (2) and (3) is limited.

We present some new ideas and considerations how instruments for the spectroscopic determination of atmospheric gases could be optimized by using new possibilities in spectrograph design and manufacturing. Particular emphasis is on arrays of massively parallel instruments for observations using scattered-sunlight. Such arrays can reduce size and weight of instruments by orders of magnitude, while preserving spectral resolution and light throughput. We also discuss the optimal size of individual spectrographs in a spectrograph array and give examples of spectrograph systems for use on a (low Earth orbit) satellite including one with sub-km ground pixel size.

Ulrich Platt et al.

Status: open (until 08 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on amt-2020-521', Harry ten Brink, 19 Apr 2021 reply
  • RC1: 'Number of comments on amt-2020-521.', Anonymous Referee #2, 29 Apr 2021 reply
  • RC2: 'Comment on amt-2020-521', Anonymous Referee #1, 03 May 2021 reply

Ulrich Platt et al.

Ulrich Platt et al.

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Short summary
Absorption spectroscopy of scattered-sunlight is extremely useful for the analysis of atmospheric trace gas distributions. A central parameter for the achievable sensitivity of spectroscopic instruments is the light throughput, which can be enhanced in a number of ways. We present new ideas and considerations how instruments could be optimized. Particular emphasis is on arrays of massively parallel instruments. Such arrays can reduce size and weight of instruments by orders of magnitude.