Thilo Erbertseder

Satellite Monitoring of Volcanic Sulfur Dioxide Emissions for Early Warning of Volcanic Hazards

Satellite-based remote sensing measurements of volcanic sulfur dioxide (SO2) provide critical information for reducing volcanic hazards. This paper describes the use of SO2 measurements from the thermal infrared sounder IASI and the UV-VIS instrument GOME-2 in services related to aviation hazard and early warning of volcanic unrest. The high sensitivity of both instruments to SO2 allows the detection and global tracking of volcanic eruption plumes and makes them a valuable tool for volcanic aviation hazard mitigation. The GOME-2 and IASI SO2 data are produced in near-real time and distributed to the Volcanic Ash Advisory Centers (VAACS) to assist them in issuing alerts to airlines and air traffic control organizations. Examples of recent eruptions affecting air traffic are presented including Jebel al Tair (Yemen, September 2007), Mount Okmok (Alaska, July 2008), and Mount Kasatochi (Alaska, August 2008). In addition, GOME-2 can detect changes in the SO2 emissions from passively degassing volcanoes and, therefore, provide critical information for hazard assessment. The monitoring of pre-eruptive degassing by GOME-2 is used in early warning of volcanic activity by a mobile volcano fast response system in combination with numerous other parameters, such as seismicity, deformation, and thermal anomalies.

Sensitivity of UV erythemally effective irradiance and daily dose to spatial variability in total ozone.

The total ozone column (TOC) is the most significant quantity for estimating the erythemally effective UV radiation under clear sky conditions. Uncertainties in TOC measurements and a limited spatial and temporal resolution therefore influence the quality of calculated erythemally effective radiation. The UV Index, the internationally accepted measure of the erythemally effective radiation, is used in public and the media to inform about current levels of UV radiation and builds the base for sun protection. Thus, the accuracy of the promoted values is essential. While in a preceding study we estimated the influence of measurement uncertainties, in this study we analyze the influence of spatial gaps and variability of TOC to the erythemally effective irradiance at noon and to the daily dose. The results allow defining the necessary spatial resolution of TOC values when a certain accuracy for the UV Index or for the purpose of sun protection is required. In case of the erythemally effective irradiance this study reveals that spatial gaps in TOC or the assumption of spatial invariability causes similar uncertainties independent of the geographic location. At higher latitudes the higher spatial variability of TOC counteracts the lower level of irradiance. For the daily dose gaps in TOC have an even higher impact at higher latitudes.

Monitoring of volcanic SO 2 emissions using the GOME-2 satellite instrument

Atmospheric sulfur dioxide is an important indicator of volcanic activity. Space based atmospheric sensors like GOME-2 on MetOp and OMI on EOS-Aura make it possible to detect the emissions of volcanic SO2 and monitor volcanic activity and eruptions on a global scale. With GOME-2, it is possible to detect and track volcanic eruption plumes and SO2 from passive degassing in near-real time (NRT). This is particularly important for early warning services, as increases in SO2 fluxes are an indicator for new episodes of volcanic unrest. The SO2 daily measurements from space are used for several early warning services related volcanic risk (Exupery, GlobVolcano) and for aviation warning purposes (GSE-PROMOTE).

Sensitivity of Erythemally Effective UV Irradiance and Daily Exposure to Temporal Variability in Total Ozone

The provision of information to the public about current levels of the erythemally effective UV radiation is an important issue in health care. The quality of promoted values is therefore of special importance. The atmospheric parameter which affects the erythemally effective UV radiation under clear sky most is the total ozone content of the atmosphere. In this paper we examined the sensitivity of the erythemally effective irradiance and daily radiant exposure to the temporal variability of total ozone on time scales from 1 to 15 days. The results show that the sensitivity is highest for the first 24 h. Larger time scales do not exhibit a similar influence. Total ozone measurements of the previous day may already cause uncertainties higher than 0.5 UV index (UVI) independent of the geolocation. For comparison, a temporal persistence of 15 days may cause uncertainties of 1.2 UVI at 50°N, 1 UVI at 30°S and less than 1 UVI at the equator. The results of this study allow finding the necessary temporal resolution of total ozone values when a certain accuracy for the UVI or for the purpose of sun protection is required. The results are compared with those of two preceding studies where we quantified the influence of measurement uncertainties and spatial total ozone variability to the erythemally effective irradiance at noon and to the daily dose. We conclude that temporal variability of total ozone is the most critical issue, but also measurement uncertainties do have a noticeable influence on the erythemally effective radiation.

The STREAMER Project: An overview

In recent years it has become evident that the distribution of ozone is strongly characterized by small scale structures both in time and space. This extraordinary variability is mostly due to the formation of finger-like structures (streamers) reaching out from equatorial regions, towards higher latitudes and obviously carrying ozone-low air towards densely populated areas such as Europe. As a consequence, strong modulations in the intensity of ground-level UV-B radiation is observed. Today, there is broad agreement that high UV dosages can cause considerable biological damage, to man, crops and animals. The objective of STREAMER (Small Scale Structure Early Warning and Monitoring in Atmospheric Ozone and Related Exposure to UV-B Radiation) is the development, installation and validation of an operational information and early warning system for providing daily nowcast and forecast of ozone vertical profiles, total column ozone and UV ground level intensity. Focus is on smaller scale structures such as streamers and mini-holes approaching Europe. STREAMER uses the end-to-end philosophy: it starts with the processing of the satellites bits and bytes, continues with their interpretation into meaningful information and finally ends up with the provision of a comfortable on-line information system that allows customers easy access to exactly that kind of information they require. For the realization of the projects objectives a consortium was established within the 4th Framework Programme of the European Commission: German Aerospace Center (coordination), German Weather Service, Federal Environment Agency Austria, German Federal Environment Agency, Aristotle University Thessaloniki (Greece), Instituto Nacional de Technica Aerospatial (Spain), Federal Office for Radiation Protection (Germany).

Sensitivity of erythemally effective UV irradiance and daily exposure to uncertainties in measured total ozone

In this study the sensitivity of the erythemally effective radiation to uncertainties in operationally measured total ozone content of the atmosphere (TOC) was estimated. For this, daily operational TOC measurements from different instruments were applied covering the period from 1997 to 1999. Measurements were gained from space by Earth Probe Satellite, Earth Remote Sensing satellite/Global Ozone Monitoring Experiment and Operational Vertical Sounder and from the ground by Dobson and Brewer spectrophotometers for the locations of Hradec Kralove (Czech Republic, 50°N), Nairobi (Kenya, 1°S) and Springbok (Republic of South Africa, 30°S). The values were used as input parameter to model calculations of erythemally effective irradiance and daily radiant exposure.

WISENT: e-Science for Energy Meteorology

Our energy production increasingly depends on renewable energy sources, which impose new challenges for distributed and decentralized systems. One problem is that the availability of renewable energy sources such as wind and solar is not continuous as it is affected by meteorological factors. The challenge is to develop forecast methods capable of determining the level of power generation in near real-time in order to control power plants for optimal energy production. Another scenario is the identification of optimal locations for such power plants. In our collaborative project, these tasks are investigated in the domain of energy meteorology. For that purpose large data sources from many different sensors (e.g., satellites and ground stations) are the base for complex computations. The idea is to parallelize these computations in order to obtain significant speedup. This paper reports on an ongoing project employing Grid technologies in that context. Our approach to processing large data sets from a variety of heterogeneous data sources as well as ideas for parallel and distributed computing in energy meteorology are presented. Preliminary experience with several Grid middleware systems in our application scenario is discussed.

Possible contribution of satellite measurements to monitoring of air pollution in European cities and their surrounding areas for health services

Today there is broad agreement that populations health is significantly affected by influences from the polluted environment. Among the most tremendous consequences are allergies, skin cancer, and deseases of the respiratory tract. As a result of increasing frequence of such health problems health services started to initiate so-called environmental ambulances where patients get proper advice and treatment, especially in densely populated areas with severe air pollution problems. It turned out that the work of such ambulances can be strongly supported by delivering information on environmental conditions such as tropospheric ozone smog, aerosol particles and UV irradiance in near-real time. In such a way the medical staff is supplied with proper knowledge on the occurence of pollution events and their spatial distribution and detailed nature. The German Remote Sensing Data Center (DFD) receives data of different sensors on various satellite platforms and processes them into products of tropospheric ozone, the optical thickness and type of aerosol particles and UV intensity on 1-40 km grids. Satellite retrieved information itself can thus be a tool to monitor air quality and will directly be used by the environmental ambulance and other public health services. Furthermore, DFD extracts information about land use/land cover from its operational processing chains allowing the characterisation of ground pixels in terms of emissions of biogenic volatile organic compounds (BVOC) into the air. Air Pollution VIII, C.A. Brebbia, H. Power & J.W.S Longhurst (Editors)

Towards an operational atmospheric correction for AVHRR land surface products

The German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) has been operating a ground segment for high resolution picture transmission (HRPT) data acquisition, archiving, and distribution since the early 1980s. Since 1994 daily normalized difference vegetation index (NDVI) synthesis maps for all of Europe have been derived from Advanced Very High Resolution Radiometer (AVHRR) measurements in near real-time with a horizontal resolution of about 1 km. In 1998 the processing chain has been expanded to European land surface temperatures (LST). Due to the presence and high variability of atmospheric ozone, water vapour and aerosols in time and space, the atmosphere significantly impacts the solar channels and results in erroneous NDVI data and noisy time series. A robust operational near real-time atmospheric correction scheme is presented. Until ENVISAT data is available, total ozone data derived from ERS-2 GOME and water vapour from NOAA-TOVS are considered for correction. An aerosol retrieval scheme based on GOME and ATSR data is currently being developed. For the determination of LST from the AVHRR brightness temperature measurements also an explicit correction of the atmospheric influence, mainly caused by water vapour absorption, is necessary. Therefore a simple split window technique is applied instead of a single channel method in terms of operational processing. The results have been validated over different sites in Germany, Egypt and Jordan.

Der Wochenrhythmus der Städte – Erfassung anthropogener Aktivitätsmuster aus dem All

Luftschadstoffe aus Verbrennungsprozessen sind Spiegel menschlicher Aktivitat und Mobilitat. In diesem Beitrag werden globale Satellitendaten des Luftschadstoffs Stickstoffdioxid (NO2) analysiert, um die raum-zeitliche Variabilitat von anthropogenen Aktivitatsmustern abzuleiten. NO2-Wochengange ausgewahlter Stadte lassen dabei eindeutig auf ihre kultur- und wirtschaftsraumliche Identitat schliesen. Stadte mit christlicher, islamischer oder judischer Weltanschauung zeigen ebenso ein charakteristisches Verhalten wie Stadte des Globalen Sudens und Chinas mit einem ganzlich fehlendem Wochenrhythmus. Mit diesem Verfahren wird der Versuch einer globalen Klassifikation von Kultur- und Wirtschaftsraumen aller Stadte mit mehr als 2 Mio. Einwohnern unternommen. Die Methode wird abschliesend eingesetzt, um die uberregionale Bedeutung von Stadten zu quantifizieren.