Magdy Abdel Wahab

Assessing surface solar irradiance and its long-term variations in the northern Africa desert climate using Meteosat images

Two databases of solar surface irradiance (SSI) derived from satellites were compared to ground measurements in Algeria, Egypt, Libya and Tunisia. We found that it was possible to accurately derive the SSI from geostationary meteorological satellites, even with a coarse spatial resolution. The two databases HelioClim-1 (HC1) and SSE exhibited similar and good performances. The bias was generally lower for SSE than for HC1; however, HC1 exhibited a smaller scattering of data compared to ground measurements (smaller standard deviation) than the SSE, allowing better performance when mapping the long-term variations in SSI. The long-term variations in SSI from 1985 to 2005 show that these four countries as a whole experienced dimming. Detailed analyses of the range of dimming at sites with long-term records and of its spatial distribution were performed. We found that the analysis of SSI from HC1 supports the findings for the individual sites. Dimming may be explained by: (1) transportation of sand dust northwards from the Sahel, (2) an increase in urbanization, and (3) an increase in cloud cover and aerosol loading.

Validation of the Surface Downwelling Solar Irradiance Estimates of the HelioClim-3 Database in Egypt

HelioClim-3 (HC3) is a database providing time series of the surface downwelling solar irradiance that are computed from images of the Meteosat satellites. This paper presents the validation results of the hourly global horizontal irradiance (GHI) and direct normal irradiance (DNI), i.e., beam irradiance at normal incidence, of versions four and five of HC3 at seven Egyptian sites. The validation is performed for all-sky conditions, as well as cloud-free conditions. Both versions of HC3 provide similar performances whatever the conditions. Another comparison is made with the estimates provided by the McClear database that is restricted to cloud-free conditions. All databases capture well the temporal variability of the GHI in all conditions, McClear being superior for cloud-free cases. In cloud-free conditions for the GHI, the relative root mean square error (RMSE) are fairly similar, ranging from 6% to 15%; both HC3 databases exhibit a smaller bias than McClear. McClear offers an overall better performance for the cloud-free DNI estimates. For all-sky conditions, the relative RMSE for GHI ranges from 10% to 22%, except one station, while, for the DNI, the results are not so good for the two stations with DNI measurements.

Extreme Variability of Aerosol Optical Properties: The Cairo Aerosol Characterization Experiment Case Study

Because they scatter and absorb solar and terrestrial radiation, aerosol plumes can easily be detected on satellite images. Thus, the time-dependent spatial extension of the aerosol clouds can be derived from space-borne observations. However, using remote observations for estimating particle concentrations, let alone for apportioning aerosol loads between all the potential sources of particulate matter, is less straightforward. Indeed, this apportionment would require perfect knowledge of the scattering and absorbing potential of particles of different origins as well as the spectral dependence of these potentials. Contrary to what can be done with most atmospheric gases, it is usually impossible to reproduce in the laboratory the complexity of natural atmospheric aerosols. As a consequence, measuring their wavelength-dependent optical properties can only be done during specially designed experiments performed in natural conditions. This is the case of the Cairo Aerosol CHaracterization Experiment (CACHE) that was performed in the Egyptian capital from the end of October 2004 to mid April 2005. During this period a wide variety of aerosol conditions have been sampled, but this work is focused on the spring intensive observation period during which several occurrences of mineral dust transport to Cairo were observed. We detail the modifications of optical properties resulting from these inputs of mineral particles into the background ‘urban aerosol’ and show that scattering and absorption, as well as their spectral dependence are extremely sensitive to the proportions of the “urban pollution/mineral dust” mixtures that form over Cairo during the dust events. Unfortunately, this precludes the use of predefined aerosol models supposed to represent particularly simple aerosol types (e.g., urban pollution, mineral dust,...) for inverting satellite observations over areas where aerosol mixing is known to be the rule rather than the exception (e.g., over the eastern Mediterranean in spring, over or downwind of continental China during the dust season, over west Africa during the biomass burning period, ...). In these cases, sophisticated parameterizations of the optical properties must be used for assessing the impact of aerosol mixtures on radiative transfer.

Tackling the mortality from long-term exposure to outdoor air pollution in megacities: Lessons from the Greater Cairo case study

Objective The poor outdoor air quality in megacities of the developing world and its impact on health is a matter of concern for both the local populations and the decision‐makers. The objective of this work is to quantify the mortality attributable to long‐term exposure to PM2.5, NO2, and O3 in Greater Cairo (Egypt). Methods We analyze the temporal and spatial variability of the three pollutants concentrations measured at 18 stations of the area. Then, we apply the method recommended by the WHO to estimate the excess mortality. In this assessment, three different shapes (log‐linear, linear, and log‐log) of the concentration‐response functions (CRF) are used. Results With PM2.5 concentrations varying from 50 to more than 100 &mgr;g/m3 in the different sectors of the megacity, the spatial variability of this pollutant is found to be one important cause of uncertainty on the excess mortality associated with it. Also important is the choice of the CRF. With the average (75 &mgr;g/m3) PM2.5 concentration and the most favorable log‐log shape of the CRF, 11% (CI, 9–14%) of the non‐accidental mortality in the population older than 30 years can still be attributed to PM2.5, which corresponds to 12520 (CI, 10240–15930) yearly premature deaths. Should the Egyptian legal 70 &mgr;g/m3 PM10 limit (corresponding to approximately 37.5 &mgr;g/m3 for PM2.5) be met, this number would be reduced to 7970, meaning that 4550 premature deaths could be avoided each year. Except around some industrial or traffic hot spots, NO2 concentration is found to be below the 40 &mgr;g/m3 air quality guideline of the WHO. However, the average concentration (34 &mgr;g/m3) of this gas exceeds the stricter 10 &mgr;g/m3 recommendation of the HRAPIE project and it is thus estimated that from 7850 to 10470 yearly deaths can be attributed to NO2. Finally, with the ozone concentration measured at one station only, it is found that, depending on the choice of the CRF, between 2.4% and 8.8% of the mortality due to respiratory diseases can be attributed to this gas. Conclusion In Greater Cairo, PM2.5 and NO2 constitute major health risks. The best estimate is that in the population older than 30 years, 11% and 8% of the non‐accidental mortality can be attributed to these two pollutants, respectively. HighlightsMortality due to long‐term exposure to air pollution in Greater Cairo is estimated.Air‐suspended matter (PM2.5) is the most severe problem.At least from 10240 to 15930 people die each year of exposure to PM2.5.From 7850 to 10470 die of exposure to NO2.

Overcoming Bandwidth and Satellite Communications Limitations to Accelerate Applications of Remote Sensing and High Performance Computing for Sustainable African Development: Contributions from Egypt, Nigeria and South Africa

Sixty-two years after the first photos of earth taken by a camera aboard a V-2 rocket in October, 1946, and forty-eight years since the first CORONA satellite images were captured, the status of remote sensing research and applications within the African continent has made dramatic progress. Many African countries now have remote sensing research centers, within government agencies, research institutes and universities. Some countries in Africa currently have earth observing and/or telecommunications satellites in orbit and/or have such assets in various planning stages. The authors document such progress, in addition to the constraints to further applications of remote sensing for sustainable development in Africa, with special reference to data distribution constraints. Moreover, the authors address the urgency for bandwidth improvements within the African continent, so as to enable sustainable development initiatives to benefit from advances in high performance computing, required for ab initio near-real-time analysis of satellite-data. Such capabilities, it is argued, are propaedeutic for time-critical initiatives, such as vulnerability assessment, disaster preparedness and mitigation, emergency response, humanitarian assistance and post-calamity reconstruction, associated with a wide array of biogenic and anthropogenic disasters. Case studies of advances in infrastructure for satellite remote sensing and high performance computing, with implications for sustainable development in Africa, are provided from Egypt, Nigeria and South Africa.

The Kamal Ewida Earth Observatory: A NATO supported real-time remote sensing receiving station being established in Egypt with HPC-enabled near-real-time data products for mitigation of environmental & public health disasters

Establishment of the Kamal Ewida Earth Observatory (KEEO) has been funded by the North Atlantic Treaty Organization (NATO) Science for Peace Program. KEEO is a joint initiative of two of Egypts largest and most venerable institutions of higher learning, Cairo University and Al Azhar University, both based in Cairo, Egypt, in collaboration with established environmental observatories in two NATO countries, Turkey and the USA. Specifically, the Egyptian partners, based in their Departments of Meteorology and Astronomy, Faculty of Science, at the two Egyptian Universities, are engaging in applications development, research and instructional collaboration with partnering resources from Bogaziçi Universitys Kandilli Observatory and Earthquake Research Institute (Istanbul, Turkey), with expertise in disaster mitigation, and Purdue Universitys Rosen Center for Advanced Computings Purdue Terrestrial Observatory (West Lafayette, Indiana, USA), with expertise in real-time remote sensing and multi-disciplinary applications of satellite data. The KEEO project provides an interdisciplinary approach to effective disaster management and facilitates collaborative research and decision support, within the Egyptian context, for disaster mitigation.

Deployment of real-time satellite remote sensing infrastructure to support disaster mitigation: A NATO Science for Peace collaboration project with Research Universities in Turkey, Egypt and the USA

The authors delineate the specific roles of the research partner institutions from Turkey, Egypt and the USA, in planning and implementing the North Atlantic Treaty Organization (NATO) Science for Peace sponsored Kamal Ewida Earth Observatory (KEEO), a network of real-time satellite remote sensing ground stations, being established over the next three years in Egypt, with a tracking station for polar orbiting satellites at Cairo University, and a networked geostationary receiving station for the European Space Agencys Meteosat being deployed at Al Azhar University. The primary objective of the project is to facilitate early warning and mitigation of a wide range of biogenic and anthropogenic disasters. The project will also address mitigation of epidemics and epizootics, through identification and monitoring of infectious disease vector and reservoir habitat. Some examples of common concern among participating countries are climate change and its impacts, the land use problems in agriculture, air pollution problems in major cities such as Cairo and Istanbul, recent epidemics such as the bird flu, swine flu and oil spills along the seashores. Archival and real-time remote sensing and generation of near-real-time spatial data products, utilizing high performance computing clusters, are planned throughout the life cycle of disaster management, including vulnerability assessment, infrastructure safeguards, early warning, emergency response, humanitarian relief, as well as post-disaster damage assessment, reconstruction and societal recovery.

Acquisition, analysis and distribution of real-time multi-sensor satellite data, in a high performance computing environment, for disaster mitigation applications: Case studies from the NATO science for peace funded Kamal Ewida Earth Observatory in Egypt, the Electronic Geophysical Year (eGY)-Africa and the US Geological Survey supported AmericaView

The paper presents an implementation of the current state-of-the-art, with respect to acquisition, analysis and distribution of real-time remotely sensed data from multiple polar orbiting and geostationary earth observing satellite sensors, deploying high performance computing for time-critical disaster mitigation applications. The authors also describe the prototype Kamal Ewida Earth Observatory (KEEO), now under development at Cairo University and at Al Azhar University in Egypt, as a technological exemplar of indigenous expertise, real-time remote sensing, near-real-time spatial data products, supercomputer access from Egypts space agency-NARSS, partnerships with multi-lateral agencies (e.g. UN WHO, Electronic Geophysical Year (eGY)-Africa), sensor data archives from the United States Geological Survey (USGS)-supported AmericaView, funding from NATOs Science for Peace Program and collaborative research with Bogaziçi Universitys Kandilli Observatory and Earthquake Research Institute (KOERI) in Istanbul, Turkey and with Purdue Universitys Rosen Center for Advanced Computings Purdue Terrestrial Observatory (PTO) in West Lafayette, Indiana, USA.