The Applicability of Remote Sensing in the Field of Air Pollution

This report prepared by KNMI and JRC is the final result of a study on the applicability of remote sensing in the field of air pollution requested by the DG Environment. The objectives of this study were to: Have an assessment of presently available scientific information on the feasibility of utilising remote sensing techniques in the implementation of existing legislation, and describe opportunities for realistic streamlining of monitoring in air quality and emissions, based on greater use of remote sensing. Have recommendations for the next policy cycle on the use of remote sensing through development of appropriate provisions and new concepts, including, if appropriate, new environmental objectives, more suited to the use of remote sensing. Have guidance on how to effectively engage with GMES and other initiatives in the air policy field projects Satellite remote sensing of the troposphere is a rapidly developing field. Today several satellite sensors are in orbit that measure trace gases and aerosol properties relevant to air quality. Satellite remote sensing data have the following unique properties: Near-simultaneous view over a large area; Global coverage; Good spatial resolution. The properties of satellite data are highly complementary to ground-based in-situ networks, which provide detailed measurements at specific locations with a high temporal resolution. Although satellite data have distinct benefits, the interpretation is often less straightforward as compared to traditional in-situ measurements. Maps of air pollution measured from space are widespread in the scientific community as well as in the media, and have had a strong impact on the general public and the policy makers. The next step is to make use of satellite data in a quantitative way. Applications based solely on satellite data are foreseen, however an integrated approach using satellite data, ground-based data and models combined with data assimilation, will make the best use of the satellite remote-sensing potential, as well as of the synergy with ground-based observations.JRC.H.4-Transport and air qualit

High-Energy Aspects of Solar Flares: Overview of the Volume

In this introductory chapter, we provide a brief summary of the successes and remaining challenges in understanding the solar flare phenomenon and its attendant implications for particle acceleration mechanisms in astrophysical plasmas. We also provide a brief overview of the contents of the other chapters in this volume, with particular reference to the well-observed flare of 2002 July 23Comment: This is the introductory article for a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

Equatorial Kelvin wave signatures in ozone column measurements from the Global Ozone Monitoring Experiments (GOME)

This study investigates tropical Kelvin wave signatures in the total ozone column data from the Global Ozone Monitoring Experiment (GOME) instrument. A new approach for spectral analysis is introduced by generalizing an unequally spaced data technique from one to two dimensions. This enables the handling of satellite data containing gaps. The simple statistical behavior of the method furthermore allows an easy determinination of the statistical significance of any observed spectral features. Seven years of GOME data (1995–2002) have been analyzed in which we have identified three periods of high Kelvin wave activity in 1996, 1998, and 2000. The periods are in conjunction with westward equatorial zonal winds at 30 hPa and show eastward propagating waves 1–2 with periods of ~12–15 days. The induced Kelvin wave signatures in the ozone concentrations are around 2–4 DU peak-to-peak and can be attributed to "slow" Kelvin waves. The results are shown to be significant. Our study provides an important contribution to the study of Kelvin waves by introducing the bidimensional unequally spaced data spectral analysis and is the first to demonstrate the potential of the GOME ozone data set to contribute to a global description of equatorial Kelvin wave activity

Trends in large-scale VOC concentrations in the Southern Netherlands between 1991 and 1997

Results of C6-C12 hydrocarbon measurements at three sites in the southern part of The Netherlands, a polluted region in Western Europe, are presented. The measurements were carried out over the period March 1991-February 1997. The concentrations at the sites, with 100-150 km distance between them, are quite similar and they are predominantly determined by large-scale transport. The concentrations in this part of the country are substantially higher than those observed at a coastal site in the north of The Netherlands, but much lower compared to the concentrations in cities and near streets. A distinct difference between the trends of aromatics and aliphatics was observed. The concentrations of the aromatic components display trends that are systematically 4-5% yr-1 lower than the trends of the aliphatics, which is possibly related to the increased use of catalysts in cars and, partly, to an enhanced atmospheric chemical activity. For the chlorinated species the trends are highly significant. The trend of 1,1,1-trichloroethane is in the order of 8-12% yr-1 downward while for tetrachloromethane an annual downward trend of 4-6% is found. These downward trends suggest that measures have been taken to fulfil the requirements of the Montreal Protocol to ban the production of these species in a few years time from now

Determination of source contributions to ambient volatile organic compound concentrations in Berlin

During three measuring campaigns in June, July, and August 1996, volatile organic compound (VOC) concentrations were measured at a rural background site, a city residential site, and a street site in Berlin. In addition, samples were taken near relevant sources of VOCs. The measurements covered the volatile hydrocarbons in the range C1-C14 and included aldehydes and ketones. Samples were taken at four characteristic periods of 2 hr/day: during the night, during the early morning rush hour, at midday, and during the evening rush hour. An assessment of the contribution of emission categories to the observed concentrations was made with the chemical mass balance (CMB) modelling technique. The VOC concentrations at the residential area and at the street site in the inner city were, respectively, a factor of 3 and 7 above the background concentration. Traffic exhaust contributed approximately 80-90% of the non-methane hydrocarbon (NMHC) concentration in the inner city and approximately 60% at the background area. Evaporative losses of motor fuel are estimated to account for approximately 7% at all sites. Natural gas leakage also contributed significantly to the observed VOC concentrations: in the inner city approximately 510% and at the background area approximately 30%. The measurements also showed a contribution of smaller sources, such as dry cleaning, use of solvents, and biogenic emissions. However, the contribution of these sources to the total observed concentrations at the sites is estimated to be very small

Kelvin wave signatures in ECMWF meteo fields and Global Ozone Monitoring Experiment (GOME) ozone columns

[1] This study investigates the vertical structure of the Kelvin wave signals previously found in total ozone column measurements from the Global Ozone Monitoring Experiment (GOME) instrument. For this, zonal wind and temperature measurements from the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis data set are analyzed by using the same bidimensional spectral method as was used to analyze the GOME total ozone columns. These fields are available on 60 levels from the surface to 0.1 hPa. For the three high Kelvin wave activity periods identified in the GOME data we found spectral features in the ECMWF fields associated with Kelvin waves with zonal wave numbers 1 or 2 and periods around 15-20 days. These characteristics correspond to the characteristics of the Kelvin waves detected in GOME. The signals are significant throughout the lower stratosphere between ?100 and 10 hPa and, depending on the period, are largest around 15, 45, or 65 hPa. There is a good correlation between the Kelvin wave signals in the ECMWF zonal wind and temperature and the GOME total ozone column. The induced fluctuations in zonal wind and temperature are, respectively, up to 8 m/s and 2 K. From these induced zonal wind fluctuations, expected total ozone column fluctuations of around 1 DU are calculated, corresponding to the ozone fluctuations found in the GOME data. The results indicate that the analyzed total ozone column fluctuations are mainly caused by transport effects in the lower stratosphere. This study shows that combined use of ECMWF Re-Analysis data and GOME ozone columns provides a possibility to study the three-dimensional structure of Kelvin wave activity. Copyright 2005 by the American Geophysical Unio

Equatorial Kelvin wave signatures in ozone profile measurements from Global Ozone Monitoring Experiment (GOME)

This study investigates the ability to derive height-resolved information on equatorial Kelvin wave activity from three different Global Ozone Monitoring Experiment (GOME) ozone profile data sets. The ozone profiles derived using the Ozone Profile Retrieval Algorithm (OPERA) based on optimal estimation and the Neural Network Ozone Retrieval System (NNORSY) both show Kelvin wave signals in agreement with previously identified signals in the GOME total ozone columns. However, because of the inadequate vertical resolution, these two data sets are not able to resolve the vertical structure of the Kelvin wave activity. The third data set, consisting of assimilated OPERA ozone profiles, does provide height-resolved information on Kelvin wave activity that is consistent with results from the analysis of GOME total ozone columns and ECMWF Re-Analysis (ERA-40) temperature data. Largest Kelvin-wave-induced perturbations of up to 0.69 DU/km coincide with the maximum vertical gradient in ozone around 35 hPa and show an in-phase relationship with temperature perturbations in ERA-40 as expected from theoretical considerations. These results indicate that the ozone perturbations in the lower stratosphere and in the total column of ozone are transport related. Between 10 and 1 hPa, large Kelvin-wave-induced fluctuations in ozone mixing ratio are present that, however, because of their small contribution to the total column, do not constitute a large contribution to the total ozone column perturbations. The ozone perturbations between 10 and 1 hPa show an out-of-phase relationship with temperature perturbations in ERA-40, indicating that the perturbations can either be caused by transport effects or photochemical influences