RIVM Stratosferisch Ozon Lidar voor NDSC Station Lauder, Nieuw Zeeland

Dit rapport beschrijft de ontwikkeling van een lidarsysteem voor het meten van stratosferisch ozon, en de implementatie daarvan in Lauder, Nieuw Zeeland. Als een onderdeel van het Nationaal Onderzoeksprogramma voor Mondiale Luchtverontreiniging en Klimaatverandering (NOP-MLK) werd bij het RIVM in Bilthoven een lidarsysteem ontwikkeld. Het instrument is ontworpen voor het meten van ozonconcentraties in de stratosfeer in het hoogtebereik van 15 tot 45 kilometer. Het systeem is naar Nieuw Zeeland getransporteerd en geinstalleerd op een van de vijf hoofd-meetstations van het International Network for the Detection of Stratospheric Change (NDSC). Routinemetingen vingen aan in november 1994.This report describes the development of a lidar system for stratospheric ozone measurements and its implementation in Lauder, New Zealand. As a part of the Dutch National Research program on Global Air Pollution and Climate Change, a lidar system has been developed in Bilthoven, the Netherlands. The instrument is designed to measure vertical profiles of stratospheric ozone concentrations in the altitude range of 15 to 45 kilometers. The system was shipped to New Zealand and installed at one of the five Primary Charter Sites of the International Network for the Detection of Stratospheric Change (NDSC). The routine operation started in November 1994.NOP/MLKRIV

Near-real time retrieval of tropospheric NO₂ from OMI

We present a new algorithm for the near-real time retrieval – within 3 h of the actual satellite measurement – of tropospheric NO2 columns from the Ozone Monitoring Instrument (OMI). The retrieval is based on the combined retrieval-assimilation-modelling approach developed at KNMI for off-line tropospheric NO2 from the GOME and SCIAMACHY satellite instruments. We have adapted the off-line system such that the required a priori information – profile shapes and stratospheric background NO2 – is now immediately available upon arrival (within 80 min of observation) of the OMI NO2 slant columns and cloud data at KNMI. Slant columns for NO2 are retrieved using differential optical absorption spectroscopy (DOAS) in the 405–465 nm range. Cloud fraction and cloud pressure are provided by a new cloud retrieval algorithm that uses the absorption of the O2-O2 collision complex near 477 nm. On-line availability of stratospheric slant columns and NO2 profiles is achieved by running the TM4 chemistry transport model (CTM) forward in time based on forecast ECMWF meteo and assimilated NO2 information from all previously observed orbits. OMI NO2 slant columns, after correction for spurious across-track variability, show a random error for individual pixels of approximately 0.7×10¹5 molec cm¿². Cloud parameters from OMI's O2-O2 algorithm have similar frequency distributions as retrieved from SCIAMACHY's Fast Retrieval Scheme for Cloud Observables (FRESCO) for August 2006. On average, OMI cloud fractions are higher by 0.011, and OMI cloud pressures exceed FRESCO cloud pressures by 60 hPa. A sequence of OMI observations over Europe in October 2005 shows OMI's capability to track changeable NOx air pollution from day to day in cloud-free situations

The 2005 and 2006 DANDELIONS NO2 and aerosol intercomparison campaigns

Dutch Aerosol and Nitrogen Dioxide Experiments for Validation of OMI and SCIAMACHY (DANDELIONS) is a project that encompasses validation of spaceborne measurements of NO\u3csub\u3e2\u3c/sub\u3e by the Ozone Monitoring Instrument (OMI) and Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), and of aerosol by OMI and Advanced Along-Track Scanning Radiometer (AATSR), using an extensive set of ground-based and balloon measurements over the polluted area of the Netherlands. We present an extensive data set of ground-based, balloon, and satellite data on NO\u3csub\u3e2\u3c/sub\u3e, aerosols, and ozone obtained from two campaigns within the project, held during May-June 2005 and September 2006. We have used these data for first validation of OMI NO\u3csub\u3e2\u3c/sub\u3e, and the data are available through the Aura Validation Data Center website for use in other validation efforts. In this paper we describe the available data, and the methods and instruments used, including the National Institute of Public Health and the Environment (RIVM) NO\u3csub\u3e2\u3c/sub\u3e lidar. We show that NO\u3csub\u3e2\u3c/sub\u3e from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) compares well with in situ measurements. We show that different MAX-DOAS instruments, operating simultaneously during the campaign, give very similar results. We also provide unique information on the spatial homogeneity and the vertical and temporal variability of NO\u3csub\u3e2\u3c/sub\u3e, showing that during a number of days, the NO\u3csub\u3e2\u3c/sub\u3e columns derived from measurements in different directions varied significantly, which implies that, under polluted conditions, measurements in one single azimuth direction are not always representative for the averaged field that the satellite observes. In addition, we show that there is good agreement between tropospheric NO\u3csub\u3e2\u3c/sub\u3e from OMI and MAX-DOAS, and also between total NO\u3csub\u3e2\u3c/sub\u3e from OMI and direct-sun observations. Observations of the aerosol optical thickness (AOT) show that values derived with three ground-based instruments correspond well with each other, and with aerosol optical thicknesses observed by OMI. Copyright 2008 by the American Geophysical Union. U7 - Export Date: 2 August 2010 U7 - Source: Scopus U7 - Art. No.: D16S4

Effects of local meteorology and aerosols on ozone and nitrogen dioxide retrievals from OMI and pandora spectrometers in Maryland, USA during DISCOVER-AQ 2011

An analysis is presented for both ground- and satellite-based retrievals of total column ozone and nitrogen dioxide levels from the Washington, D.C., and Baltimore, Maryland, metropolitan area during the NASA-sponsored July 2011 campaign of Deriving Information on Surface COnditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ). Satellite retrievals of total column ozone and nitrogen dioxide from the Ozone Monitoring Instrument (OMI) on the Aura satellite are used, while Pandora spectrometers provide total column ozone and nitrogen dioxide amounts from the ground. We found that OMI and Pandora agree well (residuals within ±25 % for nitrogen dioxide, and ±4.5 % for ozone) for a majority of coincident observations during July 2011. Comparisons with surface nitrogen dioxide from a Teledyne API 200 EU NOx Analyzer showed nitrogen dioxide diurnal variability that was consistent with measurements by Pandora. However, the wide OMI field of view, clouds, and aerosols affected retrievals on certain days, resulting in differences between Pandora and OMI of up to ±65 % for total column nitrogen dioxide, and ±23 % for total column ozone. As expected, significant cloud cover (cloud fraction \u3e0.2) was the most important parameter affecting comparisons of ozone retrievals; however, small, passing cumulus clouds that do not coincide with a high (\u3e0.2) cloud fraction, or low aerosol layers which cause significant backscatter near the ground affected the comparisons of total column nitrogen dioxide retrievals. Our results will impact post-processing satellite retrieval algorithms and quality control procedures