UV-visible spectrometers deployed around the world
The NDACC UV-VIS Working Group (UVVIS-WG) consists of about 15 research institutes and University labs specialized in UV-Visible spectroscopy and atmospheric gas retrieval.
They operate more than 30 UV-visible spectrometers deployed around the world, from pole to pole. Launched in the early 90s to study the long-term evolution of the ozone layer, NDACC's UV-VIS zenith-sky monitoring has produced long series of measurements of O3 and NO2 columns, sometimes spanning more than three decades, supplemented in the polar regions by observations of OClO and BrO.
Multi-AXis DOAS (MAX-DOAS) technique
More recently the focus of the UVVIS-WG has been enlarged to also encompass the monitoring of several key tropospheric gases by means of the Multi-AXis DOAS (MAX-DOAS) technique.
This technique, which utilizes different viewing directions in addition to zenith, has been developed for detecting absorbers in the lowest few kilometers of the atmosphere. Based on multiple-scattering radiative transfer modelling the inversion of MAX-DOAS measurements allows retrieving the vertical distribution of several tropospheric species like NO2, HCHO, BrO, CHOCHO, as well as aerosols.
The number of NDACC stations equipped with MAX-DOAS instruments has increased in recent years. To ensure that consistent, traceable and quality controlled data products are generated from these instruments, a centralised data processing system has been developed as part of the ESA FRM4DOAS project. This service feeds the NDACC RD repository with total ozone and tropospheric NO2 products with a latency of one day. It also assists PIs in generating consolidated MAX-DOAS data sets.
Ensuring long-term quality and consistency of data
Data evaluation and quality assessment procedures are under the responsibility of the NDACC UVVIS-WG. These are essential for ensuring the long-term quality and consistency of the data sets. Within this objective, field instruments and algorithms intercomparison campaigns are organized on a regular basis since 1992.
The NDACC UVVIS-WG also provides recommendations and data analysis tools to foster the harmonization of the network data series.
Contacts
Representatives of the UV/VIS Working Group in the NDACC Steering Committee:
- Dr Michel Van Roozendael
michelv at aeronomie.be
Royal Belgian Institute for Space Aeronomy (BIRA-IASB)
3, Avenue Circulaire
1180 Brussels
Belgium - Dr Karin Kreher
karin.kreher at bkscientific.eu
Bodeker Scientific
42 Young Lane RD1
Alexandra 9391
Central Otago
New Zealand