Title
TROPOMI and TROPI: UV/VIS/NIR/SWIR instruments
Author
TNO Industrie en Techniek
Levelt, P.F.
van den Oord, G.H.J.
Dobber, M.R.
Eskes, H.
van Weele, M.
Veefkind, J.P.
van Oss, R.
Aben, I.
Jongma, R.T.
Landgraf, J.
de Vries, J.
Visser, H.
Publication year
2006
Abstract
TROPOMI (Tropospheric Ozone-Monitoring Instrument) is a five-channel UV-VIS-NIR-SWIR non-scanning nadir viewing imaging spectrometer that combines a wide swath (114°) with high spatial resolution (10 × 10 km 2). The instrument heritage consists of GOME on ERS-2, SCIAMACHY on Envisat and, especially, OMI on EOS-Aura. TROPOMI has even smaller ground pixels than OMI-Aura but still exceeds OMI's signal-to-noise performance. These improvements optimize the possibility to retrieve tropospheric trace gases. In addition, the SWIR capabilities of TROPOMI are far better than SCIAMACHY's both in terms of spatial resolution and signal to noise performance. TROPOMI is part of the TRAQ payload, a mission proposed in response to ESA's EOEP call. The TRAQ mission will fly in a non-sun synchronous drifting orbit at about 720 km altitude providing nearly global coverage. TROPOMI measures in the UV-visible wavelength region (270-490 nm), in a near-infrared channel (NIR) in the 710-775 nm range and has a shortwave infrared channel (SWIR) near 2.3 um. The wide swath angle, in combination with the drifting orbit, allows measuring a location up to 5 times a day at 1.5-hour intervals. The spectral resolution is about 0.45 nm for UV-VIS-NIR and 0.25 nm for SWIR. Radiometric calibration will be maintained via solar irradiance measurements using various diffusers. The instrument will carry on-board calibration sources like LEDs and a white light source. Innovative aspects include the use of improved detectors in order to improve the radiation hardness and the spatial sampling capabilities. Column densities of trace gases (NO2, O3, SO2 and HCHO) will be derived using primarily the Differential Optical Absorption Spectroscopy (DOAS) method. The NIR channel serves to obtain information on clouds and the aerosol height distribution that is needed for tropospheric retrievals. A trade-off study will be conducted whether the SWIR channel, included to determine column densities of CO and CH4, will be incorporated in TROPOMI or in the Fourier Transform Spectrometer SIFTI on TRAQ. The TROPI instrument is similar to the complete TROPOMI instrument (UV-VIS-NIR-SWIR) and is proposed for the CAMEO initiative, as described for the U.S. NRC Decadal Study on Earth Science and Applications from Space. CAMEO also uses a non-synchronous drifting orbit, but at a higher altitude (around 1500 km). The TROPI instrument design is a modification of the TROPOMI design to achieve identical coverage and ground pixel sizes from a higher altitude. In this paper capabilities of TROPOMI and TROPI are discussed with emphasis on the UV-VIS-NIR channels as the TROPOMI SWIR channel is described in a separate contribution [5].
Subject
Remote sensing
Troposphere
Ultraviolet
Imaging systems
Information retrieval
Optimization
Ozone
Spectrometers
Troposphere
Differential Optical Absorption Spectroscopy (DOAS)
Near infrared
Shortwave infrared channel (SWIR)
Spacecraft instruments
To reference this document use:
http://resolver.tudelft.nl/uuid:864b313d-381c-41c0-9e02-88e3d5042375
TNO identifier
239591
Publisher
SPIE
ISBN
9780819463753
ISSN
0277-786X
Source
Earth Observing Systems XI, 14-16 August 2006, San Diego, CA, USA. Conference code: 68432, 6296 (6296)
Series
Proceedings of SPIE - The International Society for Optical Engineering
Document type
conference paper