- A.R.H. Fischer (1)
- K. Folkert Boersma (1)
- L.J. Frewer (1)
- J.H.G.M. Geffen van (1)
- François Hendrick (1)
- T.A.M. Hendrick (1)
- F. Hendrick (1)
- Jintai Lin (1)
- Mengyao Liu (1)
- E. Mahieu (1)
- B.G. Meerburg (1)
- Ruijing Ni (1)
- Gaia Pinardi (1)
- Michel Roozendael Van (1)
- M. Roozendael van (1)
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- M. Sneep (1)
- H. Tobi (1)
- J.P. Veefkind (1)
- Thomas Wagner (1)
- Pucai Wang (1)
- Ting Wang (1)
- Yang Wang (1)
- Pinhua Xie (1)
- Yingying Yan (1)
Improved aerosol correction for OMI tropospheric NO2 retrieval over East Asia : Constraint from CALIOP aerosol vertical profile
Liu, Mengyao ; Lin, Jintai ; Folkert Boersma, K. ; Pinardi, Gaia ; Wang, Yang ; Chimot, Julien ; Wagner, Thomas ; Xie, Pinhua ; Eskes, Henk ; Roozendael, Michel Van; Hendrick, François ; Wang, Pucai ; Wang, Ting ; Yan, Yingying ; Chen, Lulu ; Ni, Ruijing - \ 2019
Atmospheric Measurement Techniques 12 (2019)1. - ISSN 1867-1381 - p. 1 - 21.
Satellite retrieval of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) is critical for NOx pollution and impact evaluation. For regions with high aerosol loadings, the retrieval accuracy is greatly affected by whether aerosol optical effects are treated implicitly (as additional effective clouds) or explicitly, among other factors. Our previous POMINO algorithm explicitly accounts for aerosol effects to improve the retrieval, especially in polluted situations over China, by using aerosol information from GEOS-Chem simulations with further monthly constraints by MODIS/Aqua aerosol optical depth (AOD) data. Here we present a major algorithm update, POMINO v1.1, by constructing a monthly climatological dataset of aerosol extinction profiles, based on level 2 CALIOP/CALIPSO data over 2007-2015, to better constrain the modeled aerosol vertical profiles. We find that GEOS-Chem captures the month-to-month variation in CALIOP aerosol layer height (ALH) but with a systematic underestimate by about 300-600 m (season and location dependent), due to a too strong negative vertical gradient of extinction above 1 km. Correcting the model aerosol extinction profiles results in small changes in retrieved cloud fraction, increases in cloud-top pressure (within 2 %-6 % in most cases), and increases in tropospheric NO2 VCD by 4 %-16 % over China on a monthly basis in 2012. The improved NO2 VCDs (in POMINO v1.1) are more consistent with independent ground-based MAX-DOAS observations (R2=0.80, NMB =-3.4 %, for 162 pixels in 49 days) than POMINO (R2=0.80, NMB =-9.6 %), DOMINO v2 (R2=0.68, NMB =-2.1 %), and QA4ECV (R2=0.75, NMB =-22.0 %) are. Especially on haze days, R2 reaches 0.76 for POMINO v1.1, much higher than that for POMINO (0.68), DOMINO v2 (0.38), and QA4ECV (0.34). Furthermore, the increase in cloud pressure likely reveals a more realistic vertical relationship between cloud and aerosol layers, with aerosols situated above the clouds in certain months span id=page2 instead of always below the clouds. The POMINO v1.1 algorithm is a core step towards our next public release of the data product (POMINO v2), and it will also be applied to the recently launched S5P-TROPOMI sensor.
Improved spectral fitting of nitrogen dioxide from OMI in the 405–465 nm window
Geffen, J.H.G.M. van; Boersma, K.F. ; Roozendael, M. van; Hendrick, F. ; Mahieu, E. ; Smedt, I. de; Sneep, M. ; Veefkind, J.P. - \ 2015
Atmospheric Measurement Techniques 8 (2015). - ISSN 1867-1381 - p. 1685 - 1699.
An improved nitrogen dioxide (NO2) slant column density retrieval for the Ozone Monitoring Instrument (OMI) in the 405–465 nm spectral region is presented. Since the launch of OMI on board NASA's EOS-Aura satellite in 2004, differential optical absorption spectroscopy (DOAS) retrievals of NO2 slant column densities have been the starting point for the KNMI DOMINO and NASA SP NO2 vertical column data as well as the OMI NO2 data of some other institutes. However, recent intercomparisons between NO2 retrievals from OMI and other UV/Vis and limb spectrometers, as well as ground-based measurements, suggest that OMI stratospheric NO2 is biased high. This study revises and, for the first time, fully documents the OMI NO2 retrieval in detail. The representation of the OMI slit function to convolve high-resolution reference spectra onto the relevant spectral grid is improved. The window used for the wavelength calibration is optimised, leading to much-reduced fitting errors. Ozone and water vapour spectra used in the fit are updated, reflecting the recently improved knowledge of their absorption cross section in the literature. The improved spectral fit also accounts for absorption by the O2–O2 collision complex and by liquid water over clear-water areas. The main changes in the improved spectral fitting result from the updates related to the wavelength calibration: the RMS error of the fit is reduced by 23% and the NO2 slant column by 0.85 × 1015 molec cm-2, independent of latitude, solar zenith angle and NO2 value. Including O2–O2 and liquid water absorption and updating the O3 and water vapour cross-section spectra further reduces NO2 slant columns on average by 0.35 × 1015 molec cm-2, accompanied by a further 9% reduction in the RMS error of the fit. The improved OMI NO2 slant columns are consistent with independent NO2 retrievals from other instruments to within a range that can be explained by photochemically driven diurnal increases in stratospheric NO2 and by small differences in fitting window and approach. The revisions indicate that current OMI NO2 slant columns suffered mostly from an additive positive offset, which is removed by the improved wavelength calibration and representation of the OMI slit function. It is therefore anticipated that the improved NO2 slant columns are most important to retrievals of spatially homogeneous stratospheric NO2 rather than to heterogeneous tropospheric NO2.
Self-reported attitude scales: current practice in adequate assessment of reliability, validity, and dimensionality
Hendrick, T.A.M. ; Fischer, A.R.H. ; Tobi, H. ; Frewer, L.J. - \ 2013
Journal of Applied Social Psychology 43 (2013)7. - ISSN 0021-9029 - p. 1538 - 1552.
parametric statistics - resisting persuasion - implicit - model - strength - constructs - association - consistency
The development of methods to create self-reported attitude scales has lost momentum, in part because of increased research focused on implicit measures. This paper reviews 162 papers on methodological approaches applied to the validation and assessment of attitude scales. Assessment of methodological approaches applied indicates that neither reliability, validity, nor dimensionality assessments are consistently used according to standard operating procedures or in accordance with best practice.Within current practices in the field of attitude scale development, the full potential of self-report scales is not met, in part because of such methodological issues. The improvement of existing practices and adoption of promising new developments in attitude scale construction and evaluation are discussed, together with recommendations for best practice in scale validation.
Organic Agriculture and its Contribution to Zoonotic Pathogens
Meerburg, B.G. ; Borgsteede, F.H.M. - \ 2010
In: Zoonotic pathogens in the food chain / Krause, D.O., Hendrick, S., Wallingford, United Kingdom : CABI - ISBN 9781845936815 - p. 167 - 181.
This chapter discusses: the importance of safe food; risks of organic plant products (Listeria monocytogenes, Salmonella, Campylobacter and Escherichia coli O157); and risks of organic products of animal origin (Toxoplasma gondii, Salmonella and Campylobacter).