The high-resolution solar reference spectrum between 250 and 550 nm and its application to measurements with the ozone monitoring instrument

We have constructed a new high resolution solar reference spectrum in the spectral range between 250 and 550 nm. The primary use of this spectrum is for the calibration of the Dutch¿-¿Finnish Ozone Monitoring Instrument (OMI), but other applications are mentioned. The incentive for deriving a new high resolution solar reference spectrum is that available spectra do not meet our requirements on radiometric accuracy or spectral resolution. In this paper we explain the steps involved in constructing the new spectrum, based on available low and high resolution spectra and discuss the main sources of uncertainty. We compare the result with solar measurements obtained with the OMI as well as with other UV-VIS space-borne spectrometers with a similar spectral resolution. We obtain excellent agreement with the OMI measurements, which indicates that both the newly derived solar reference spectrum and our characterization of the OMI instrument are well understood. We also find good agreement with previously published low resolution spectra. The absolute intensity scale, wavelength calibration and representation of the strength of the Fraunhofer lines have been investigated and optimized to obtain the resulting high resolution solar reference spectrum. © 2008 Springer Science+Business Media B.V. U7 - Export Date: 2 August 2010 U7 - Source: Scopu

Accurate satellite-derived estimates of the tropospheric ozone impact on the global radiation budget

Estimates of the radiative forcing due to anthropogenically-produced tropospheric O3 are derived primarily from models. Here, we use tropospheric ozone and cloud data from several instruments in the A-train constellation of satellites as well as information from the GEOS-5 Data Assimilation System to accurately estimate the radiative effect of tropospheric O3 for January and July 2005. Since we cannot distinguish between natural and anthropogenic sources with the satellite data, our derived radiative effect reflects the unadjusted (instantaneous) effect of the total tropospheric O3 rather than the anthropogenic component. We improve upon previous estimates of tropospheric ozone mixing ratios from a residual approach using the NASA Earth Observing System (EOS) Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) by incorporating cloud pressure information from OMI. We focus specifically on the magnitude and spatial structure of the cloud effect on both the short- and long-wave radiative budget. The estimates presented here can be used to evaluate the various aspects of model-generated radiative forcing. For example, our derived cloud impact is to reduce the radiative effect of tropospheric ozone by ~16%. This is centered within the published range of model-produced cloud effect on unadjusted ozone radiative forcing

Oog voor klimaat en luchtkwaliteit

Geoscience and Remote SensingCivil Engineering and Geoscience

XUV-LASER SPECTROSCOPY ON THE C'4 SIGMA-U+, UPSILON=0 AND C3 1-PI-U, UPSILON=0 RYDBERG STATES OF N2

The c

XUV-LASER SPECTROSCOPY ON CO - ISOTOPE-SELECTIVE PREDISSOCIATION RATES

The K (4p-sigma) (1)SIGMA+, upsilon = 0 and W (3s-sigma) 1II, upsilon = 2 states in (CO)-C-12-O-16 and (CO)-C-13-O-16 have been studied in high resolution with extreme ultraviolet laser radiation in the wavelength range 94 - 97 nm. Accurate spectroscopic constants for both isotopes and states have been derived from absolute rotational line positions. From linewidths of individual rotational transitions predissociation rates for (CO)-C-12-O-16 and (CO)-C-13-O-16 in the W 1II upsilon = 2 state have been deduced: k(p) (CO)-C-12 = 1.15 (15) x 10(11) s-1 and k(p) (CO)-C-13 = 0.58 (13) x 10(11) s-1. The rate of photodissociation of K (1)SIGMA+, upsilon = 0 was found to be smaller: k(p) = 2.6 (1.3) x 10(10) s-1 for both isotopes