A fast SWIR imager for observations of transient features in OH airglow

Patrick Hannawald,Michael Bittner,Sabine Wüst,Carsten Schmidt

doi:10.5194/amt-9-1461-2016

Patrick Hannawald, Michael Bittner + Show 2 more

Open Access

https://doi.org/10.5194/amt-9-1461-2016

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Abstract

Abstract. Since December 2013 the new imaging system FAIM (Fast Airglow IMager) for the study of smaller-scale features (both in space and time) is in routine operation at the NDMC (Network for the Detection of Mesospheric Change) station at DLR (German Aerospace Center) in Oberpfaffenhofen (48.1° N, 11.3° E).Covering the brightest OH vibrational bands between 1 and 1.7 µm, this imaging system can acquire two frames per second. The field of view is approximately 55 km times 60 km at the mesopause heights. A mean spatial resolution of 200 m at a zenith angle of 45° and up to 120 m for zenith conditions are achieved. The observations show a large variety of atmospheric waves.This paper introduces the instrument and compares the FAIM data with spectrally resolved GRIPS (GRound-based Infrared P-branch Spectrometer) data. In addition, a case study of a breaking gravity wave event, which we assume to be associated with Kelvin–Helmholtz instabilities, is discussed.

Highlights

The OH airglow layer is located at a height of about 87 km with a half-width of approximately 4 km (e.g. Baker and Stair, 1988)
This paper introduces the instrument and compares the FAIM data with spectrally resolved GRIPS (GRound-based Infrared P-branch Spectrometer) data
It is widely accepted that propagating atmospheric gravity waves are important for the understanding of atmospheric dynamics and the energy budget of the atmosphere, as they provide the majority of the momentum forcing that drives the circulation in the mesosphere and lower thermosphere region (MLT) (Smith, 2012)

Summary

Introduction

The OH airglow layer is located at a height of about 87 km with a half-width of approximately 4 km (e.g. Baker and Stair, 1988). Sato, 1994; Chu et al, 2005; Dunker et al, 2015) Besides these active instruments, passive spectrometers and imagers are frequently used to observe airglow emissions, which originate in the MLT region and are modulated by gravity waves. The temporal resolution typically varies from one image every few seconds to one every few minutes (see e.g. Hecht et al, 2002 or Taguchi et al, 2004) Another type of instrument related to both spectrometers and imagers are the MTM (Mesospheric Temperature Mapper; Taylor et al, 1999) and the AMTM (Advanced Mesospheric Temperature Mapper; Pautet et al, 2014), both of which use very narrowband filters to isolate individual emission lines, allowing the determination of airglow temperature during later processing.

Instrumentation and operation

Data analysis

Results and discussion

Summary and conclusions