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MAX-DOAS measurements in Merida
Introduction Instrument Data References Links Contact
Introduction:
An
atmospheric measurement station (MARS) was established
in cooperation with the University of Mérida, Physics Department in the
vicinity of the city Mérida,
Venezuela (8°N,
71°W).
This station takes advantages of the high altitude site Pico Espejo (4765 m) for
measurements with a
DOAS
instrument and a microwave
sensor.
Pico Espejo is accessible with the
world's highest cable car. The DOAS instrument at this station
was operated from March 2004 to November 2008 when it had to be removed due to
interruption of cable car services. As a result of extended periods of power
outage, only a partial time series is available.
The Pico Espejo station is characterized by its high altitude, facilitating stratospheric measurements in a tropical region that is unperturbed by tropospheric pollution and the large tropospheric water vapour burden usually found at these latitudes. Therefore it is an ideal site for both stratospheric research and the validation of satellite instruments such as GOME, SCIAMACHY and MIPAS. Using the off-axis measurements of the DOAS instrument it is also possible to investigate trace gases in the free troposphere, and to quantify the effects of local pollution from Mérida and additionally long range transport from the fires in Southern America.
Instrument:
The DOAS instrument in Mérida was located inside the MARS station building. It comprised a temperature stabilized grating spectrometer equipped with a cooled CCD detector. The instrument was connected to a telescope, which was located outside the building, with a quartz fibre bundle and a number of electrical and control connections. The telescope had two viewing ports: One in zenith direction, the other one towards the horizon (off-axis). In the off-axis direction, up to 4 angles could be observed sequentially in the range of -5° to 25° elevation by means of a motorized mirror. Both line-lamp and white light calibration lamp were integrated in the telescope box and are used for daily calibration measurements. More on the instrument and measurement principle can be found on our MAXDOAS page.
The instrument was fully automated and controlled remotely through an internet connection to Bremen. To ensure continuous operation during power black outs, it was connected to an UPS shared with the microwave instrument.
Data:
If you have any requests, please contact Folkard Wittrock.
References:
- SCIAMACHY validation with ground-based DOAS observations final report (in German)
- A scientific, technical, and organizational summary in pdf-format for the new atmospheric research station MARS can be found here.
Links:
- Our local partners in Mérida are at the Universidad de los Andes
- The Microwave instrument at the station is operated by the Forschungszentrum Karlsruhe.
- The instruments on Pico Espejo is used for the validation of SCIAMACHY.
Contact:
If you are interested in more information or would like to have access to our data, please contact Folkard Wittrock.