Twenty years of ground-based NDACC FTIR spectrometry at Izaña Observatory – overview and long-term comparison to other techniques

Abstract

Abstract. High-resolution Fourier Transform InfraRed (FTIR) solar observations are particularly relevant for climate studies, as they allow atmospheric gaseous composition and multiple climate processes to be monitored in detail. In this context, the present paper provides an overview of 20 years of FTIR measurements taken in the framework of the NDACC (Network for the Detection of Atmospheric Composition Change) from 1999 to 2018 at the subtropical Izaña Observatory (IZO, Spain). Firstly, long-term instrumental performance is comprehensively assessed, corroborating the temporal stability and reliable instrumental characterisation of the two FTIR spectrometers installed at IZO since 1999. Then, the time series of all trace gases contributing to NDACC at IZO are presented (i.e. C2H6, CH4, ClONO2, CO, HCl, HCN, H2CO, HF, HNO3, N2O, NO2, NO, O3, OCS, and water vapour isotopologues H216O, H218O, and HD16O), reviewing the major accomplishments drawn from these observations. In order to examine the quality and long-term consistency of the IZO FTIR observations, a comparison of those NDACC products for which other high-quality measurement techniques are available at IZO has been performed (i.e. CH4, CO, H2O, NO2, N2O, and O3). This quality assessment was carried out on different timescales to examine what temporal signals, and to what extent, are captured by the FTIR records. After 20 years of operation, the IZO NDACC FTIR observations have been found to be very consistent and reliable over time, demonstrating great potential for climate research. Long-term NDACC FTIR data sets, such as IZO, are indispensable tools for the investigation of atmospheric composition trends, multi-year phenomena and complex climate feedback processes, as well as for the validation of past and present space-based missions and chemistry climate models.

Evaluation of the N2O Rate of Change to Understand the Stratospheric Brewer‐Dobson Circulation in a Chemistry‐Climate Model

“…However, García et al. (2021) showed good agreement above Izaña for tropospheric N 2 O abundances and total N 2 O columns obtained from independent measurements. The difference between the stratospheric N 2 O columns measured by FTIR and ACE‐FTS could be explained by the poor coverage of ACE‐FTS over the tropical and subtropical regions.…”

“…This high‐altitude station is characterized by excellent conditions for FTIR spectroscopy, with clear sky conditions for most of the year. Observations started using a Bruker 120M spectrometer and continued, since 2005, with a Bruker 125HR (García et al., 2021). The retrieval code for the N 2 O profiles is the SFIT‐v4 (v0.9.4.4) for the Jungfraujoch, Lauder and Wollongong stations, and PROFITT9 for the Izaña station (Zhou et al., 2019).…”

Impact of instrumental line shape characterization on ozone monitoring by FTIR spectrometry

“…For this study, the 20-year O 3 measurements taken from 1999 to 2018 have been used. Refer to García et al (2021) for a detailed description of the FTIR spectrometry activities at IZO.…”

“…By analysing the measured solar absorption spectra, this technique can provide atmospheric concentrations of many different gases simultaneously and with high precision (e.g. Rinsland et al, 1982;Hase et al, 2004;Schneider et al, 2008a;García et al, 2012;Sepúlveda et al, 2014;Barthlott et al, 2015;Vigouroux et al, 2015;Barthlott et al, 2017;De Mazière et al, 2018;García et al, 2022García et al, , 2021.…”

“…In the third approach, ILS is monitored through independent, regular, and calibrated low-pressure gas cell measurements (Hase et al, 1999;Hase, 2012;Fig. 5 of García et al, 2021), whereby both the independence of FTIR gas retrievals and the instrumental characterization are ensured.…”