The arctic seasonal cycle of total column CO 2 and CH 4 from ground-based solar and lunar FTIR absorption spectrometry

Solar absorption spectroscopy in the near infrared has been performed in Ny-Ålesund (78.9° N, 11.9° E) since 2002; however, due to the high latitude of the site, the sun is below the horizon from October to March (polar night) and no solar absorption measurements are possible. Here we present a nove...

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Bibliographic Details
Published in:Atmospheric Measurement Techniques
Main Authors: M. Buschmann, N. M. Deutscher, M. Palm, T. Warneke, C. Weinzierl, J. Notholt
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2017
Subjects:
Environmental engineering
TA170-171
Earthwork. Foundations
TA715-787
Arctic
Ny-Ålesund
Ny Ålesund
polar night
Online Access:https://doi.org/10.5194/amt-10-2397-2017
https://doaj.org/article/1f9a1ffa9d924fa3a14be93754114165
Description
Summary:Solar absorption spectroscopy in the near infrared has been performed in Ny-Ålesund (78.9° N, 11.9° E) since 2002; however, due to the high latitude of the site, the sun is below the horizon from October to March (polar night) and no solar absorption measurements are possible. Here we present a novel method of retrieving the total column dry-air mole fractions (DMFs) of CO 2 and CH 4 using moonlight in winter. Measurements have been taken during the polar nights from 2012 to 2016 and are validated with TCCON (Total Carbon Column Observing Network) measurements by solar and lunar absorption measurements on consecutive days and nights during spring and autumn. The complete seasonal cycle of the DMFs of CO 2 and CH 4 is presented and a precision of up to 0.5 % is achieved. A comparison of solar and lunar measurements on consecutive days during day and night in March 2013 yields non-significant biases of 0. 66 ± 4. 56 ppm for xCO 2 and −1. 94 ± 20. 63 ppb for xCH 4 . Additionally a model comparison has been performed with data from various reanalysis models.

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