Abstract

Abstract. Ground-based high spectral resolution Fourier-transform infrared (FTIR) solar absorption spectroscopy is a powerful remote sensing technique to obtain information on the total column abundances and on the vertical distribution of various constituents in the atmosphere. This work presents results from two FTIR measurement campaigns in 2002 and 2004, held at Ile de La Réunion (21° S, 55° E). These campaigns represent the first FTIR observations carried out at a southern (sub)tropical site. They serve the initiation of regular, long-term FTIR monitoring at this site in the near future. To demonstrate the capabilities of the FTIR measurements at this location for tropospheric and stratospheric monitoring, a detailed report is given on the retrieval strategy, information content and corresponding full error budget evaluation for ozone (O3), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), ethane (C2H6), hydrogen chloride (HCl), hydrogen fluoride (HF) and nitric acid (HNO3) total and partial column retrievals. Moreover, we have made a thorough comparison of the capabilities at sea level altitude (St.-Denis) and at 2200 m a.s.l. (Maïdo). It is proved that the performances of the technique are such that the atmospheric variability can be observed, at both locations and in distinct altitude layers. Comparisons with literature and with correlative data from ozone sonde and satellite (i.e., ACE-FTS, HALOE and MOPITT) measurements are given to confirm the results. Despite the short time series available at present, we have been able to detect the seasonal variation of CO in the biomass burning season, as well as the impact of particular biomass burning events in Africa and Madagascar on the atmospheric composition above Ile de La Réunion. We also show that differential measurements between St.-Denis and Maïdo provide useful information about the concentrations in the boundary layer.

Highlights

  • The Network for the Detection of Atmospheric Composition Change1 (NDACC, http://www.ndacc.org/) is a worldwide network of observatories, for which primary objectives are to monitor the evolution of the atmospheric composition and structure, and to provide independent data for the validation of numerical models of the atmosphere and of satellite data

  • We present results from the first two Fourier transform infrared (FTIR) campaigns that we performed at Ile de La Reunion, in 2002 and 2004, to verify the feasibility of FTIR measurements at a tropical site and to start the long-term monitoring

  • We have focused on the retrieval of ozone (O3), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), ethane (C2H6), hydrogen chloride (HCl), hydrogen fluoride (HF) and nitric acid (HNO3)

Read more

Summary

Introduction

The Network for the Detection of Atmospheric Composition Change (NDACC, http://www.ndacc.org/) is a worldwide network of observatories, for which primary objectives are to monitor the evolution of the atmospheric composition and structure, and to provide independent data for the validation of numerical models of the atmosphere and of satellite data. The only tropical NDACC stations at which FTIR measurements are performed are Mauna Loa (19.54◦ N, 155.6◦ W) and Paramaribo (5.8◦ N, 55.2◦ W), both in the Northern Hemisphere The former one is at high altitude (3459 m a.s.l.), and at the latter one, the measurements are performed on a campaign basis, since September 2004 only (Petersen et al, 2008). The OPAR is located at 21◦ S, 55◦ E, in the Indian Ocean, East of Madagascar, at the edge between the southern tropics and subtropics. It is a measurement station led by the Laboratoire de l’Atmosphere et des Cyclones (LACy) of the Universitede La Reunion, that performs radio sonde observations since 1992, SAOZ measurements since 1993 and lidar measurements since 1994 (Baray et al, 2006). The implementation of FTIR solar absorption measurements at this site, providing information about the total column abundances and vertical distributions of a large number of atmospheric constituents (e.g., Brown et al, 1992), will be a useful complement to the station’s observations, and will fill the gap in the Southern Hemisphere tropical region

Methods
Findings
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call