Facility Description
Fourier Transform InfraRed Spectrometer
The ABB Bomem DA8 Fourier Transform Spectrometer (FTS) has a maximum optical path difference of 250 cm resulting in a maximum resolution of 0.004 cm-1. The FTS is equipped with KBr (700-4300 cm-1) and CaF2 (1200-8500 cm-1) beam splitters. Attached to the front of the instrument are two detectors, which are cooled with liquid nitrogen to reduce detector self-emission of infrared radiation at room temperature. The InSb detector is responsive from 1800-8500 cm-1 region and the HgCdTe (MCT) detector is responsive in the 500-5000 cm-1. Before solar radiation enters the spectrometer, it passes through one of the 6 NDACC standard filters. The filters only allow a specific region of the infrared spectrum to enter the spectrometer.
| NDACC Filter | Wavenumber
(cm-1) |
Wavelength
(μm) |
Chemical Species |
|---|---|---|---|
| 1 | 4020-4290 | 2.33-2.49 | HF |
| 2 | 3000-3820 | 2.62-3.33 | C2H2, HCN, H2O & isotopes |
| 3 | 2420-3080 | 3.25-4.13 | CO2, H2O, HDO, HCl, O3, N2O, CH4, NO2, C2H6 |
| 4 | 2020-2570 | 3.89-4.95 | OCS CO N2 |
| 5 | 1590-2150 | 4.65-6.29 | NO COF2 |
| 6 | 670-1351 | 7.40-15 | C2H2, C2H4, ClONO2, O3, N2O, HNO3, NH3, CCl2F2, CHF2Cl |
Heliostat
The heliostat (Suntracker) captures the solar radiation for the primary DA8 FTS and some guest instruments. It is mounted on the roof and follows the Sun during the day, reflecting solar radiation into the lab through an opening in the roof. Once the radiation enters the lab, a series of mirrors are used to focus, split, and direct the radiation beam into the instruments.
UV-Visible Grating Spectrometer (UT-GBS)
The University of Toronto UV-visible grating spectrometer was assembled in 1998, and has been deployed on the MANTRA balloon campaigns at Vanscoy, SK, and on Arctic springtime campaigns at Eureka, NU since 1999. When it is not in the field, this instrument is installed at TAO. The instrument consists of an ISA/JY Triax 180 triple-grating spectrometer with diffraction gratings of 400, 600 and 1800 grooves/mm, providing spectral resolutions of 2.0, 0.9, and 0.5 nm (FWHM). The detector is a thermoelectrically cooled CCD array. The instrument is automated and records UV-visible absorption spectra of the light scattered from the zenith sky. These are analyzed using the technique of differential optical absorption spectroscopy (DOAS) to retrieve vertical columns of O3, NO2, and BrO. Vertical profiles of NO2 can also be derived from the measurements of NO2 slant column variation with solar zenith angle.
Brewer MKIV Spectrophotometer
A Brewer spectrophotometer is on loan from the Meteorological Service of Canada (MSC) and was installed at TAO in March 2005. It is an automated UV-visible spectrometer that makes daily measurements of total ozone columns using direct solar observations. Over 80 Brewer spectrophotometers are used worldwide to monitor stratospheric ozone: the TAO Brewer is number 083.
Alan Brewer was a faculty member of the University of Toronto Physics Department from 1962 to 1977. Among his many accomplishments was the development of the Brewer spectrophotometer.
Weather Station
A Davis Vantage Pro weather station is used to record basic weather parameters, such as temperature, humidity, wind speed and direction, precipitation, and solar irradiance.
Systeme d'Analyse par Observation Zenithales (SAOZ)
The Systeme d'Analyse par Observations Zenithales (SAOZ) instrument was developed in the late 1980s at the Service d'Aeronomie of the Centre Nationale de la Recherche Scientifique in France. SAOZ instruments are now deployed in a global network for measurements of stratospheric concentrations of trace gases important to ozone loss. SAOZ is a grating spectrometer with an uncooled 1024-pixel linear diode array. It records zenith-sky spectra with a 10-degree field-of-view between 270 and 620 nm, with a resolution of 1.0 nm. Throughout the day, spectra are recorded every thirty minutes, and are continuously obtained when the Solar Zenith Angle (SZA) is between 80 and 95 degrees. A SAOZ instrument has been deployed at TAO on an intermittent basis for several years, generally alternating with deployment at Eureka, Nunavut on springtime Arctic campaigns.
VLF Lightning Detector
The newly installed VLF (Very Long Frequency) lightning detector at the TAO is part of a global effort to detect lightning across the Earth with high accuracy and efficiency and minimal cost. The detector calculates the arrival time of a lightning pulse in the VLF range using the Time Of Group Arrival (TOGA) method. When a lightning pulse is detected at more than three detectors, the location and time of the lightning is found by using the TOGA from each detector. Each detector is capable of detecting lightning from thousands of kilometers away.
Custom-Built Suntracker
The University of Toronto (UT) Suntracker was developed at the University of Toronto and is installed in the TAO for testing purposes. Additional development is being done at Dalhousie University. The UT Suntracker is made from off-the-shelf parts using open-source software, and, once fully tested, the design and control software will be made publicly available. Currently, another version of the UT Suntracker is installed at the Polar Environment Atmospheric Research Laboratory at Eureka, Nunavut for UV-visible direct-Sun measurements.
Lab Computers
The computers used for instrument control and data acquisition are located in room MP1606 of the TAO facility, in close proximity to the DA8 FTS and those instruments located outdoors.