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A satellite algorithm able to identify Dust Aerosols (DA) is applied for a climatological investigation of Dust Aerosol Episodes (DAEs) over the greater Mediterranean Basin (MB), one of the most climatologically sensitive regions of the globe. The algorithm first distinguishes DA among other aerosol types (such as Sea Salt and Biomass Burning) by applying threshold values on key aerosol optical properties describing their loading, size and absorptivity, namely Aerosol Optical Depth (AOD), Aerosol Index (AI) and Ångström Exponent (α). The algorithm operates on a daily and 1° × 1° geographical cell basis over the 15-year period 2005–2019. Daily gridded spectral AOD data are taken from Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Collection 6.1, and are used to calculate the α data, which are then introduced into the algorithm, while AI data are obtained by the Ozone Monitoring Instrument (OMI) -Aura- Near-UV aerosol product OMAERUV dataset. The algorithm determines the occurrence of Dust Aerosol Episode Days (DAEDs), whenever high loads of DA (higher than their climatological mean value plus two/four standard deviations for strong/extreme DAEDs) exist over extended areas (more than 30 pixels or 300,000 km2). The identified DAEDs are finally grouped into Dust Aerosol Episode Cases (DAECs), consisting of at least one DAED. According to the algorithm results, 166 (116 strong and 50 extreme) DAEDs occurred over the MB during the study period. DAEDs are observed mostly in spring (47%) and summer (38%), with strong DAEDs occurring primarily in spring and summer and extreme ones in spring. Decreasing, but not statistically significant, trends of the frequency, spatial extent and intensity of DAECs are revealed. Moreover, a total number of 98 DAECs was found, primarily in spring (46 DAECs) and secondarily in summer (36 DAECs). The seasonal distribution of the frequency of DAECs varies geographically, being highest in early spring over the eastern Mediterranean, in late spring over the central Mediterranean and in summer over the western MB.
Maria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Christos Lolis; Nikolaos Mihalopoulos. A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data. Remote Sensing 2021, 13, 2895 .
AMA StyleMaria Gavrouzou, Nikolaos Hatzianastassiou, Antonis Gkikas, Christos Lolis, Nikolaos Mihalopoulos. A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data. Remote Sensing. 2021; 13 (15):2895.
Chicago/Turabian StyleMaria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Christos Lolis; Nikolaos Mihalopoulos. 2021. "A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data." Remote Sensing 13, no. 15: 2895.
Quantifying the dust optical depth (DOD) and its uncertainty across spatiotemporal scales is key to understanding and constraining the dust cycle and its interactions with the Earth System. This study quantifies the DOD along with its monthly and year-to-year variability between 2003 and 2017 at global and regional levels based on the MIDAS (ModIs Dust AeroSol) dataset, which combines MODIS-Aqua retrievals and MERRA-2 reanalysis products. We also describe the annual and seasonal geographical distributions of DOD across the main dust source regions and transport pathways. MIDAS provides columnar mid-visible (550 nm) DOD at fine spatial resolution (0.1° × 0.1°), expanding the current observational capabilities for monitoring the highly variable spatiotemporal features of the dust burden. We obtain a global DOD of 0.032 ± 0.003 – approximately a quarter (23.4 % ± 2.4 %) of the global AOD – with about one order of magnitude more DOD in the northern hemisphere (0.056 ± 0.004; 31.8 % ± 2.7 %) than in the southern hemisphere (0.008 ± 0.001; 8.2 % ± 1.1 %) and about 3.5 times more DOD over land (0.070 ± 0.005) than over ocean (0.019 ± 0.002). The northern hemisphere monthly DOD is highly correlated with the corresponding monthly AOD (R2 = 0.94) and contributes 20 % to 48 % of it, both indicating a dominant dust contribution. In contrast, the contribution of dust to the monthly AOD does not exceed 17 % in the southern hemisphere, although the uncertainty in this region is larger. Among the major dust sources of the planet, the maximum DODs (~1.2) are recorded in the Bodélé Depression of the northern Lake Chad Basin, whereas moderate-to-high intensities are encountered in the Western Sahara (boreal summer), along the eastern parts of the Middle East (boreal summer) and in the Taklamakan Desert (spring). Over oceans, major long-range dust transport is observed primarily along the Tropical Atlantic (intensified during boreal summer) and secondarily in the North Pacific (intensified during boreal spring). Our calculated global and regional averages and associated uncertainties are consistent with some but not all recent observationally based studies. Our work provides a simple, yet flexible method to estimate consistent uncertainties across spatiotemporal scales, which will enhance the use of the MIDAS dataset in future studies.
Antonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Eleni Marinou; Nikos Hatzianastassiou; Jasper F. Kok; Carlos Pérez García-Pando. Quantification of the dust optical depth across spatiotemporal scales with the MIDAS global dataset (2003–2017). 2021, 2021, 1 -51.
AMA StyleAntonis Gkikas, Emmanouil Proestakis, Vassilis Amiridis, Stelios Kazadzis, Enza Di Tomaso, Eleni Marinou, Nikos Hatzianastassiou, Jasper F. Kok, Carlos Pérez García-Pando. Quantification of the dust optical depth across spatiotemporal scales with the MIDAS global dataset (2003–2017). . 2021; 2021 ():1-51.
Chicago/Turabian StyleAntonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Eleni Marinou; Nikos Hatzianastassiou; Jasper F. Kok; Carlos Pérez García-Pando. 2021. "Quantification of the dust optical depth across spatiotemporal scales with the MIDAS global dataset (2003–2017)." 2021, no. : 1-51.
Stavros-Andreas Logothetis; Vasileios Salamalikis; Antonis Gkikas; Stelios Kazadzis; Vassilis Amiridis; Andreas Kazantzidis. Supplementary material to "15-year variability of desert dust optical depth on global and regional scales". 2021, 1 .
AMA StyleStavros-Andreas Logothetis, Vasileios Salamalikis, Antonis Gkikas, Stelios Kazadzis, Vassilis Amiridis, Andreas Kazantzidis. Supplementary material to "15-year variability of desert dust optical depth on global and regional scales". . 2021; ():1.
Chicago/Turabian StyleStavros-Andreas Logothetis; Vasileios Salamalikis; Antonis Gkikas; Stelios Kazadzis; Vassilis Amiridis; Andreas Kazantzidis. 2021. "Supplementary material to "15-year variability of desert dust optical depth on global and regional scales"." , no. : 1.
This study aims to investigate the global, regional and seasonal temporal dust changes as well as the effect of dust particles on total aerosol loading, using the MIDAS fine resolution dataset. MIDAS delivers dust optical depth (DOD) at fine spatial resolution (0.1° × 0.1°) spanning from 2003 to 2017. Within this study period, the dust burden has been increased across Central Sahara (up to 0.023 yr−1) and Arabian Peninsula (up to 0.024 yr−1). Both regions observed their highest seasonal trends in summer (up to 0.031 yr−1). On the other side, declining DOD trends are encountered in Western (down to −0.015 yr−1) and Eastern (down to −0.023 yr−1) Sahara, Bodélé Depression (down to −0.021 yr−1), Thar (down to −0.017 yr−1) and Gobi (down to −0.011 yr−1) Deserts and Mediterranean Basin (down to −0.009 yr−1). At spring, the most negative seasonal trends are recorded in Bodélé Depression (down to −0.038 yr−1) and Gobi Desert (down to −0.023 yr−1) whereas in West (down to −0.028 yr−1) and East Sahara (down to −0.020 yr−1), and Thar Desert (down to −0.047 yr−1) at summer. Over western and eastern sector of Mediterranean Basin, the most negative seasonal trends are computed at summer (down to −0.010 yr−1) and spring (down to −0.006 yr−1), respectively. The effect of DOD to the total aerosol optical depth (AOD) changes is determined calculating the DOD to AOD ratio. Over Sahara Desert the median ratio values range from 0.83 to 0.95 whereas in other dust affected areas (Arabian Peninsula, South Mediterranean, Thar and Gobi Deserts) is recorded approximately around 0.6. In addition, a comprehensive analysis of the factors effecting the sign, the magnitude and the statistical significance of the calculated trends is conducted. Firstly, the implications between the implementation of geometric mean instead of arithmetic mean to trend calculations are discussed revealing that the arithmetic-based trends tend to overestimate compared with the geometric-based trends both over land and ocean. Secondly, an analysis interpreting the differences in trend calculations under different spatial resolutions (fine and coarse) and time intervals is conducted, which sounds a critical aspect when satellite-based measurements are utilized.
Stavros-Andreas Logothetis; Vasileios Salamalikis; Antonis Gkikas; Stelios Kazadzis; Vassilis Amiridis; Andreas Kazantzidis. 15-year variability of desert dust optical depth on global and regional scales. 2021, 2021, 1 -40.
AMA StyleStavros-Andreas Logothetis, Vasileios Salamalikis, Antonis Gkikas, Stelios Kazadzis, Vassilis Amiridis, Andreas Kazantzidis. 15-year variability of desert dust optical depth on global and regional scales. . 2021; 2021 ():1-40.
Chicago/Turabian StyleStavros-Andreas Logothetis; Vasileios Salamalikis; Antonis Gkikas; Stelios Kazadzis; Vassilis Amiridis; Andreas Kazantzidis. 2021. "15-year variability of desert dust optical depth on global and regional scales." 2021, no. : 1-40.
Cyprus focuses on increasing the share of its renewable energy resources from 13.9% in 2020 to 22.9% in 2030, with solar energy exploitation systems to be one of the main pillars of this effort, due to the high solar potential of the island. In this study, we investigated the effect of clouds as well as aerosols, and especially dust, on the downwelling surface solar irradiation in terms of Global Horizontal Irradiation (GHI) and Direct Normal Irradiation (DNI). In order to quantify the effects of clouds, aerosols and dust on different surface solar radiation components, we used the synergy of satellite derived products for clouds, high quality and fine resolution satellite retrievals of aerosols and dust from the newly developed MIDAS dataset, and radiative transfer modeling (RTM). GHI and DNI climatologies have been also developed based on the above information. According to our findings, clouds attenuate ~25 – 30% of annual GHI and 35 – 50% of annual DNI, aerosols attenuate 5 – 10% and 15 – 35% respectively, with dust being responsible for 30 – 50% of the overall attenuation by aerosols. The outcomes of this study are useful for installation planning and for estimating the PV and CSP performance on a short-term future basis, helping towards improved penetration of solar energy exploitation systems in the electric grid of Cyprus. Furthermore, they are strongly linked to Affordable and Clean Energy (SDG 7) which has a central role in national climate plans and requires services in energy meteorology, climate applications of satellite data, and providing high quality wind and radiation data.
Acknowledgements
This study was funded by the EuroGEO e-shape (grant agreement No 820852) and EXCELSIOR (grant agreement No 857510)
Kyriakoula Papachristopoulou; Ilias Fountoulakis; Panagiotis Kosmopoulos; Panagiotis Ι. Raptis; Rodanthi-Elisavet Mamouri; Argyro Nisantzi; Jonas Witthuhn; Johannes Bühl; Antonis Gkikas; Diofantos G. Hadjimitsis; Charalampos Kontoes; Stelios Kazadzis. Clouds and aerosol effects on solar energy in Cyprus. 2021, 1 .
AMA StyleKyriakoula Papachristopoulou, Ilias Fountoulakis, Panagiotis Kosmopoulos, Panagiotis Ι. Raptis, Rodanthi-Elisavet Mamouri, Argyro Nisantzi, Jonas Witthuhn, Johannes Bühl, Antonis Gkikas, Diofantos G. Hadjimitsis, Charalampos Kontoes, Stelios Kazadzis. Clouds and aerosol effects on solar energy in Cyprus. . 2021; ():1.
Chicago/Turabian StyleKyriakoula Papachristopoulou; Ilias Fountoulakis; Panagiotis Kosmopoulos; Panagiotis Ι. Raptis; Rodanthi-Elisavet Mamouri; Argyro Nisantzi; Jonas Witthuhn; Johannes Bühl; Antonis Gkikas; Diofantos G. Hadjimitsis; Charalampos Kontoes; Stelios Kazadzis. 2021. "Clouds and aerosol effects on solar energy in Cyprus." , no. : 1.
Cyprus plans to drastically increase the share of renewable energy sources from 13.9% in 2020 to 22.9% in 2030. Solar energy can play a key role in the effort to fulfil this goal. The potential for production of solar energy over the island is much higher than most of European territory because of the low latitude of the island and the nearly cloudless summers. In this study, high quality and fine resolution satellite retrievals of aerosols and dust, from the newly developed MIDAS climatology, and information for clouds from CM SAF are used in order to quantify the effects of aerosols, dust, and clouds on the levels of surface solar radiation for 2004–2017 and the corresponding financial loss for different types of installations for the production of solar energy. Surface solar radiation climatology has also been developed based on the above information. Ground-based measurements were also incorporated to study the contribution of different species to the aerosol mixture and the effects of day-to-day variability of aerosols on SSR. Aerosols attenuate 5–10% of the annual global horizontal irradiation and 15–35% of the annual direct normal irradiation, while clouds attenuate 25–30% and 35–50% respectively. Dust is responsible for 30–50% of the overall attenuation by aerosols and is the main regulator of the variability of total aerosol. All-sky annual global horizontal irradiation increased significantly in the period of study by 2%, which was mainly attributed to changes in cloudiness.
Ilias Fountoulakis; Panagiotis Kosmopoulos; Kyriakoula Papachristopoulou; Ioannis-Panagiotis Raptis; Rodanthi-Elisavet Mamouri; Argyro Nisantzi; Antonis Gkikas; Jonas Witthuhn; Sebastian Bley; Anna Moustaka; Johannes Buehl; Patric Seifert; Diofantos Hadjimitsis; Charalampos Kontoes; Stelios Kazadzis. Effects of Aerosols and Clouds on the Levels of Surface Solar Radiation and Solar Energy in Cyprus. Remote Sensing 2021, 13, 2319 .
AMA StyleIlias Fountoulakis, Panagiotis Kosmopoulos, Kyriakoula Papachristopoulou, Ioannis-Panagiotis Raptis, Rodanthi-Elisavet Mamouri, Argyro Nisantzi, Antonis Gkikas, Jonas Witthuhn, Sebastian Bley, Anna Moustaka, Johannes Buehl, Patric Seifert, Diofantos Hadjimitsis, Charalampos Kontoes, Stelios Kazadzis. Effects of Aerosols and Clouds on the Levels of Surface Solar Radiation and Solar Energy in Cyprus. Remote Sensing. 2021; 13 (12):2319.
Chicago/Turabian StyleIlias Fountoulakis; Panagiotis Kosmopoulos; Kyriakoula Papachristopoulou; Ioannis-Panagiotis Raptis; Rodanthi-Elisavet Mamouri; Argyro Nisantzi; Antonis Gkikas; Jonas Witthuhn; Sebastian Bley; Anna Moustaka; Johannes Buehl; Patric Seifert; Diofantos Hadjimitsis; Charalampos Kontoes; Stelios Kazadzis. 2021. "Effects of Aerosols and Clouds on the Levels of Surface Solar Radiation and Solar Energy in Cyprus." Remote Sensing 13, no. 12: 2319.
Cyprus plans to drastically increase the share of renewable energy sources from 13.9% in 2020 to 22.9% in 2030. Solar energy can play a key role in the effort to fulfil this goal. The potential for production of solar energy over the island is much higher than most of European territory because of the low latitude of the island and the nearly cloudless summers. In this study, high quality and fine resolution satellite retrievals of aerosols and dust, from the newly developed MIDAS climatology, as well as information for clouds from CMSAF are used in order to quantify the effects of aerosols, dust, and clouds on the levels of surface solar radiation (SSR) and the corresponding financial loss for different types of installations for production of solar energy. An SSR climatology has been also developed based on the above information. Ground-based measurements were also incorporated to study the contribution of different species to the aerosol mixture and the effects of day-to-day variability of aerosols on SSR. Aerosols attenuate 5 – 10% of annual GHI and 15 – 35% of annual DNI, while clouds attenuate ~25 – 30% and 35 – 50% respectively. Dust is responsible for 30 – 50% of the overall attenuation by aerosols.
Ilias Fountoulakis; Panagiotis Kosmopoulos; Kyriakoula Papachristopoulou; Panagiotis-Ioannis Raptis; Rodanthi-Elisavet Mamouri; Argyro Nisantzi; Antonis Gkikas; Jonas Witthuhn; Sebastian Bley; Anna Moustaka; Johannes Buehl; Patric Seifert; Diofantos G. Hadjimitsis; Charalampos Kontoes; And Stelios Kazadzis. Effects of Aerosols and Clouds on the Levels of Surface Solar Radiation and Solar Energy in Cyprus. 2021, 1 .
AMA StyleIlias Fountoulakis, Panagiotis Kosmopoulos, Kyriakoula Papachristopoulou, Panagiotis-Ioannis Raptis, Rodanthi-Elisavet Mamouri, Argyro Nisantzi, Antonis Gkikas, Jonas Witthuhn, Sebastian Bley, Anna Moustaka, Johannes Buehl, Patric Seifert, Diofantos G. Hadjimitsis, Charalampos Kontoes, And Stelios Kazadzis. Effects of Aerosols and Clouds on the Levels of Surface Solar Radiation and Solar Energy in Cyprus. . 2021; ():1.
Chicago/Turabian StyleIlias Fountoulakis; Panagiotis Kosmopoulos; Kyriakoula Papachristopoulou; Panagiotis-Ioannis Raptis; Rodanthi-Elisavet Mamouri; Argyro Nisantzi; Antonis Gkikas; Jonas Witthuhn; Sebastian Bley; Anna Moustaka; Johannes Buehl; Patric Seifert; Diofantos G. Hadjimitsis; Charalampos Kontoes; And Stelios Kazadzis. 2021. "Effects of Aerosols and Clouds on the Levels of Surface Solar Radiation and Solar Energy in Cyprus." , no. : 1.
Mineral dust is an important component of the climate system, affecting radiation, cloud formation, biogeochemical cycles, as well as having negative effects on solar energy budget and human health. All these processes are affected from the size of the particles which is significantly underestimated by the Earth System Models. Here, we present results from a first attempt to modify the size distribution parameterizations in the GOCART-AFWA dust scheme of WRF - Chem, by including the large dust particles with diameters greater than 20 µm to describe the mineral dust cycle. The parameterization is based on Saharan dust observational datasets from FENNEC and SAMUM campaigns. We investigate the impact of the extended size distribution on the overall transported dust load and also the impact of particle settling considerations in deposition rates. The model results are compared with airborne dust measurements from AER-D campaign. In order to achieve the best agreement with the observations, an artificial force that counteracts gravity approximately by 80% for the large particles is needed, indicating the presence of one or more under-represented physical processes in the model.
Acknowledgment: This research was supported by D-TECT (Grant Agreement 725698) funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme.
Eleni Drakaki; Alexandra Tsekeri; Vasillis Amiridis; Stavros Solomos; Antonis Gkikas; Emmanouil Proestakis; Christos Spyrou; Sotirios Mallios; Eleni Marinou; Claire L. Ryder; Petros Katsafados. A modeling insight into the transport of large dust particles. 2021, 1 .
AMA StyleEleni Drakaki, Alexandra Tsekeri, Vasillis Amiridis, Stavros Solomos, Antonis Gkikas, Emmanouil Proestakis, Christos Spyrou, Sotirios Mallios, Eleni Marinou, Claire L. Ryder, Petros Katsafados. A modeling insight into the transport of large dust particles. . 2021; ():1.
Chicago/Turabian StyleEleni Drakaki; Alexandra Tsekeri; Vasillis Amiridis; Stavros Solomos; Antonis Gkikas; Emmanouil Proestakis; Christos Spyrou; Sotirios Mallios; Eleni Marinou; Claire L. Ryder; Petros Katsafados. 2021. "A modeling insight into the transport of large dust particles." , no. : 1.
Aerosols play a key role in radiative transfer processes at the Earth’s atmosphere. The complex interactions between aerosols and solar radiation cannot be easily modeled, and thus, aerosols constitute a major uncertainty factor in radiative transfer simulations. Radiative effects of aerosols depend not only on their physical and chemical properties, but also on their distribution in the atmosphere. Despite the important role of the vertical distribution of aerosols in the atmosphere, default climatological profiles are commonly used in modeling studies. Uncertainties related with the use of default profiles have been roughly analyzed and discussed in the existing bibliography.
In the context of the present study we simulated the downwelling and upwelling irradiance, heating rates, and the actinic flux at different altitudes, from 0 to 8 km, in the atmosphere. Simulations were performed for four different European sites – where aerosol mixtures constitute from quite different aerosol species – using a default climatological aerosol extinction profile, and the seasonally and annually averaged extinction profiles for each site from the LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies (LIVAS). By comparing the results, the effect of using a more representative profile of the aerosol extinction coefficient for each of the sites, instead of a default climatological profile, was estimated. In addition to the aerosol profiles, climatological values of aerosol optical properties and water vapor from the AErosol RObotic NETwork (AERONET), the version 2 Max-Planck-Institute Aerosol Climatologyand (MACv2), the Modis Dust AeroSol (MIDAS) climatology, and atmospheric and land-surface variables from the Copernicus Atmospheric Monitoring System (CAMS), were used as inputs to the libRadtran radiative transfer model. Spectra in the range 280 – 3000 nm were simulated for different solar zenith angles, and the integrals of the spectra, as well as the integrals in the ultraviolet and visible spectral regions were analyzed.
Results of the analyses are presented and discussed in order to study the sensitivity of the radiometric quantities simulated by the model to the used aerosol extinction profile, for each of the four sites. Differences between the products of the simulations when the used aerosol optical depth (AOD) comes from different sources (LIVAS, AERONET, MIDAS, CAMS) have been also investigated.
Acknowledgements
This study was funded by the EuroGEO e-shape (grant agreement No 820852).
Ilias Fountoulakis; Kyriakoula Papachristopoulou; Emmanouil Proestakis; Antonis Gkikas; Panagiotis Ioannis Raptis; Nikolaos Siomos; Charalampos Kontoes; Stelios Kazadzis. Effect of aerosol vertical distribution on the transfer of solar radiation through the atmosphere. 2021, 1 .
AMA StyleIlias Fountoulakis, Kyriakoula Papachristopoulou, Emmanouil Proestakis, Antonis Gkikas, Panagiotis Ioannis Raptis, Nikolaos Siomos, Charalampos Kontoes, Stelios Kazadzis. Effect of aerosol vertical distribution on the transfer of solar radiation through the atmosphere. . 2021; ():1.
Chicago/Turabian StyleIlias Fountoulakis; Kyriakoula Papachristopoulou; Emmanouil Proestakis; Antonis Gkikas; Panagiotis Ioannis Raptis; Nikolaos Siomos; Charalampos Kontoes; Stelios Kazadzis. 2021. "Effect of aerosol vertical distribution on the transfer of solar radiation through the atmosphere." , no. : 1.
Mediterranean Basin (MB), due to its position near to the greatest world deserts (the Sahara Desert in North Africa and the deserts of Middle East), is frequently affected by dust transport. This results in dust episodes, associated with high Dust Aerosol (DA) loads reaching the northern parts of MB, taking place every year with different intensity, but with specific seasonal and spatial characteristics. The seasonal and spatial characteristics of Dust Aerosol Episodes (DAEs) in the region are connected to specific atmospheric conditions that favor the injection of DA into the region’s atmosphere, as well as to specific atmospheric circulation characteristics favoring the transport to the MB.
DA not only are affected by, but they also can affect the atmospheric conditions and thus the regional weather and climate regime. Specifically, due to their ability to absorb the shortwave, but also the longwave, radiation, DA can modify the temperature structure of the atmosphere as well as the radiative budget. In addition, DA are effective Ice Nuclei (IN), and also, under mature stages, Cloud Condensation Nuclei (CCN), thus affecting cloud properties. These effects of DA become more important, but also complicated, when high dust loads are associated with other aerosol types, e.g. sea-salt (SS) and biomass burning (BB) over a region with high solar radiation, diverse topography and cloud regimes such as the MB.
In the present study, the atmospheric circulation (geopotential height and mean sea level pressure), as well as the meteorological conditions (cloud fraction, cloud optical thickness, cloud phase, temperature and humidity profiles and vertical velocity) before, during and after an extreme Dust Aerosol Episode Case (DAEC) that took place over the western MB on June 16, 2016 are examined. The studied DAEC is identified using a satellite algorithm, which uses MODIS C6.1 and OMI OMAERUV derived aerosol optical properties. Emphasis is given to the understanding of the 3-D structure of the episode and its possible effects on the atmospheric temperature and humidity regime, as well as on cloud properties. For this reason, different reanalyses and satellite data, namely from the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis Project), MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, Version 2) and MODIS databases, are analyzed. In addition, the vertical aerosol profile is obtained from MERRA-2 data.
Maria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Christos Lolis; Nikos Mihalopoulos. Atmospheric circulation and meteorological conditions during dust aerosol episodes over the broader Mediterranean Basin. The case of 16 June 2016. 2021, 1 .
AMA StyleMaria Gavrouzou, Nikos Hatzianastassiou, Antonis Gkikas, Marios-Bruno Korras-Carraca, Christos Lolis, Nikos Mihalopoulos. Atmospheric circulation and meteorological conditions during dust aerosol episodes over the broader Mediterranean Basin. The case of 16 June 2016. . 2021; ():1.
Chicago/Turabian StyleMaria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Christos Lolis; Nikos Mihalopoulos. 2021. "Atmospheric circulation and meteorological conditions during dust aerosol episodes over the broader Mediterranean Basin. The case of 16 June 2016." , no. : 1.
In this study, we present a comparison of the AEOLUS satellite L2A product with the retrievals of the ground-based lidar systems of EARLINET (European Aerosol Research Lidar Network), part the European Research Infrastructure for the observation of Aerosol, Clouds and Trace Gases (ACTRIS). Dedicated ground‐based measurements during AEOLUS overpasses have been performed among the 29 member stations since the beginning of the mission, however, we have included only the stations that have gathered a significant number of collocations in the analysis. The satellite timeseries we deployed covers the period 2019-2020 that correspond to the best available version of the satellite processing algorithms. We harvest the collocations using the following spacio-temporal criteria. Only overpasses that fall within a radius less than 100km around the station are included. Using this criterion, the AEOLUS L2A climatology is generated per station independently of the ground-based measurements. To isolate collocated data we reject all AEOLUS data with a time interval between the overpass and the central time of the ground-based measurement that is greater than 3 hours. The ground based lidar climatology is also computed per station. AEOLUS L2A products include aerosol extinction coefficient profiles and aerosol co-polar backscatter coefficient profiles from circularly polarized light emission. While the extinction profiles are directly comparable with the ground-based lidars, this is not the case for the backscatter profiles since AEOLUS cannot measure the cross polar component of the aerosol backscatter. The co-polar backscatter is close to the total backscatter only in the absence of depolarizing scatterers such as dust, pollen, volcanic ash, and cirrus ice crystals. Ground-based measurements are divided in two categories for the evaluation depending on whether aerosol depolarization measurements have been performed. If the particle linear depolarization ratio (PLDR) is available, it can be applied to convert the lidar total backscatter to an AOLUS-like co-polar backscatter coefficient. This category is applied for the direct evaluation of the satellite product. Cases that lack PLDR information assist to quantify the uncertainties introduced by using the AEOLUS co-polar backscatter as a substitute for the total backscatter. The analysis includes both an indirect climatological comparison and a direct collocation comparison between the ground based and satellite datasets. Via the collocation comparison, random and systematic uncertainties in the satellite product are identified and quantified. A climatological comparison can show the potential of AEOLUS to capture annual cycles despite its intrinsic random errors. In the future, the analysis will be further supported with auxiliary data such as sunphotometer measurements, aerosol classification flags, modeled backward trajectories, and satellite cloud fraction data.
Nikolaos Siomos; Antonis Gkikas; Holger Baars; Ulla Wandinger; Vasilis Amiridis; Peristera Paschou; EARLINET consortium. Investigating the performance of AEOLUS L2A products over Europe with EARLINET ground-based lidars. 2021, 1 .
AMA StyleNikolaos Siomos, Antonis Gkikas, Holger Baars, Ulla Wandinger, Vasilis Amiridis, Peristera Paschou, EARLINET consortium. Investigating the performance of AEOLUS L2A products over Europe with EARLINET ground-based lidars. . 2021; ():1.
Chicago/Turabian StyleNikolaos Siomos; Antonis Gkikas; Holger Baars; Ulla Wandinger; Vasilis Amiridis; Peristera Paschou; EARLINET consortium. 2021. "Investigating the performance of AEOLUS L2A products over Europe with EARLINET ground-based lidars." , no. : 1.
A satellite-based algorithm is developed and used to determine the presence of dust aerosols on a global scale. The algorithm uses as input aerosol optical properties from the MOderate Resolution Imaging Spectroradiometer (MODIS)-Aqua Collection 6.1 and Ozone Monitoring Instrument (OMI)-Aura version v003 (OMAER-UV) datasets and identifies the existence of dust aerosols in the atmosphere by applying specific thresholds, which ensure the coarse size and the absorptivity of dust aerosols, on the input optical properties. The utilized aerosol optical properties are the multiwavelength aerosol optical depth (AOD), the Aerosol Absorption Index (AI) and the Ångström Exponent (a). The algorithm operates on a daily basis and at 1° × 1° latitude-longitude spatial resolution for the period 2005–2019 and computes the absolute and relative frequency of the occurrence of dust. The monthly and annual mean frequencies are calculated on a pixel level for each year of the study period, enabling the study of the seasonal as well as the inter-annual variation of dust aerosols’ occurrence all over the globe. Temporal averaging is also applied to the annual values in order to estimate the 15-year climatological mean values. Apart from temporal, a spatial averaging is also applied for the entire globe as well as for specific regions of interest, namely great global deserts and areas of desert dust export. According to the algorithm results, the highest frequencies of dust occurrence (up to 160 days/year) are primarily observed over the western part of North Africa (Sahara), and over the broader area of Bodélé, and secondarily over the Asian Taklamakan desert (140 days/year). For most of the study regions, the maximum frequencies appear in boreal spring and/or summer and the minimum ones in winter or autumn. A clear seasonality of global dust is revealed, with the lowest frequencies in November–December and the highest ones in June. Finally, an increasing trend of global dust frequency of occurrence from 2005 to 2019, equal to 56.2%, is also found. Such an increasing trend is observed over all study regions except for North Middle East, where a slight decreasing trend (−2.4%) is found.
Maria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Nikolaos Mihalopoulos. A Global Climatology of Dust Aerosols Based on Satellite Data: Spatial, Seasonal and Inter-Annual Patterns over the Period 2005–2019. Remote Sensing 2021, 13, 359 .
AMA StyleMaria Gavrouzou, Nikolaos Hatzianastassiou, Antonis Gkikas, Marios-Bruno Korras-Carraca, Nikolaos Mihalopoulos. A Global Climatology of Dust Aerosols Based on Satellite Data: Spatial, Seasonal and Inter-Annual Patterns over the Period 2005–2019. Remote Sensing. 2021; 13 (3):359.
Chicago/Turabian StyleMaria Gavrouzou; Nikolaos Hatzianastassiou; Antonis Gkikas; Marios-Bruno Korras-Carraca; Nikolaos Mihalopoulos. 2021. "A Global Climatology of Dust Aerosols Based on Satellite Data: Spatial, Seasonal and Inter-Annual Patterns over the Period 2005–2019." Remote Sensing 13, no. 3: 359.
Monitoring and describing the spatiotemporal variability in dust aerosols is crucial for understanding their multiple effects, related feedbacks, and impacts within the Earth system. This study describes the development of the ModIs Dust AeroSol (MIDAS) data set. MIDAS provides columnar daily dust optical depth (DOD) at 550 nm at a global scale and fine spatial resolution (0.1∘ × 0.1∘) over a 15-year period (2003–2017). This new data set combines quality filtered satellite aerosol optical depth (AOD) retrievals from MODIS-Aqua at swath level (Collection 6.1; Level 2), along with DOD-to-AOD ratios provided by the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) reanalysis to derive DOD on the MODIS native grid. The uncertainties of the MODIS AOD and MERRA-2 dust fraction, with respect to the AEronet RObotic NETwork (AERONET) and LIdar climatology of vertical Aerosol Structure for space-based lidar simulation (LIVAS), respectively, are taken into account for the estimation of the total DOD uncertainty. MERRA-2 dust fractions are in very good agreement with those of LIVAS across the dust belt in the tropical Atlantic Ocean and the Arabian Sea; the agreement degrades in North America and the Southern Hemisphere, where dust sources are smaller. MIDAS, MERRA-2, and LIVAS DODs strongly agree when it comes to annual and seasonal spatial patterns, with colocated global DOD averages of 0.033, 0.031, and 0.029, respectively; however, deviations in dust loading are evident and regionally dependent. Overall, MIDAS is well correlated with AERONET-derived DODs (R=0.89) and only shows a small positive bias (0.004 or 2.7 %). Among the major dust areas of the planet, the highest R values (>0.9) are found at sites of North Africa, the Middle East, and Asia. MIDAS expands, complements, and upgrades the existing observational capabilities of dust aerosols, and it is suitable for dust climatological studies, model evaluation, and data assimilation.
Antonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Alexandra Tsekeri; Eleni Marinou; Nikos Hatzianastassiou; Carlos Pérez García-Pando. ModIs Dust AeroSol (MIDAS): a global fine-resolution dust optical depth data set. Atmospheric Measurement Techniques 2021, 14, 309 -334.
AMA StyleAntonis Gkikas, Emmanouil Proestakis, Vassilis Amiridis, Stelios Kazadzis, Enza Di Tomaso, Alexandra Tsekeri, Eleni Marinou, Nikos Hatzianastassiou, Carlos Pérez García-Pando. ModIs Dust AeroSol (MIDAS): a global fine-resolution dust optical depth data set. Atmospheric Measurement Techniques. 2021; 14 (1):309-334.
Chicago/Turabian StyleAntonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Alexandra Tsekeri; Eleni Marinou; Nikos Hatzianastassiou; Carlos Pérez García-Pando. 2021. "ModIs Dust AeroSol (MIDAS): a global fine-resolution dust optical depth data set." Atmospheric Measurement Techniques 14, no. 1: 309-334.
We examine the capability of near-spherical-shaped particles to reproduce the triple-wavelength particle linear depolarization ratio (PLDR) and lidar ratio (LR) values measured over Europe for stratospheric smoke originating from Canadian wildfires. The smoke layers were detected both in the troposphere and the stratosphere, though in the latter case the particles presented PLDR values of almost 18 % at 532 nm as well as a strong spectral dependence from the UV to the near-IR wavelength. Although recent simulation studies of rather complicated smoke particle morphologies have shown that heavily coated smoke aggregates can produce large PLDR, herein we propose a much simpler model of compact near-spherical smoke particles. This assumption allows for the reproduction of the observed intensive optical properties of stratospheric smoke, as well as their spectral dependence. We further examine whether an extension of the current Aerosol Robotic Network (AERONET) scattering model to include the near-spherical shapes could be of benefit to the AERONET retrieval for stratospheric smoke cases associated with enhanced PLDR. Results of our study illustrate the fact that triple-wavelength PLDR and LR lidar measurements can provide us with additional insight when it comes to particle characterization.
Anna Gialitaki; Alexandra Tsekeri; Vassilis Amiridis; Romain Ceolato; Lucas Paulien; Anna Kampouri; Antonis Gkikas; Stavros Solomos; Eleni Marinou; Moritz Haarig; Holger Baars; Albert Ansmann; Tatyana Lapyonok; Anton Lopatin; Oleg Dubovik; Silke Groß; Martin Wirth; Maria Tsichla; Ioanna Tsikoudi; Dimitris Balis. Is the near-spherical shape the “new black” for smoke? Atmospheric Chemistry and Physics 2020, 20, 14005 -14021.
AMA StyleAnna Gialitaki, Alexandra Tsekeri, Vassilis Amiridis, Romain Ceolato, Lucas Paulien, Anna Kampouri, Antonis Gkikas, Stavros Solomos, Eleni Marinou, Moritz Haarig, Holger Baars, Albert Ansmann, Tatyana Lapyonok, Anton Lopatin, Oleg Dubovik, Silke Groß, Martin Wirth, Maria Tsichla, Ioanna Tsikoudi, Dimitris Balis. Is the near-spherical shape the “new black” for smoke? Atmospheric Chemistry and Physics. 2020; 20 (22):14005-14021.
Chicago/Turabian StyleAnna Gialitaki; Alexandra Tsekeri; Vassilis Amiridis; Romain Ceolato; Lucas Paulien; Anna Kampouri; Antonis Gkikas; Stavros Solomos; Eleni Marinou; Moritz Haarig; Holger Baars; Albert Ansmann; Tatyana Lapyonok; Anton Lopatin; Oleg Dubovik; Silke Groß; Martin Wirth; Maria Tsichla; Ioanna Tsikoudi; Dimitris Balis. 2020. "Is the near-spherical shape the “new black” for smoke?" Atmospheric Chemistry and Physics 20, no. 22: 14005-14021.
The overarching goal of the current study is to quantify the aerosol-induced clear-sky direct radiative effects (DREs) within the Earth-atmosphere system at the global scale and for the 40-year period 1980–2019. To this aim, the MERRA-2 aerosol radiative properties, along with meteorological fields and surface albedo, are used as inputs to the Foundation for Research and Technology-Hellas (FORTH) radiative transfer model (RTM). Our preliminary results, representative for the year 2015, reveal strong surface radiative cooling (down to −45 Wm−2) over areas where high aerosol loadings and absorbing particles (i.e., dust and biomass burning) dominate. This reduction of the incoming solar radiation in the aforementioned regions is largely attributed to its absorption by the overlying suspended particles resulting in atmospheric warming reaching up to 40 Wm−2. At the top of the atmosphere (TOA), negative DREs (planetary cooling) are computed worldwide (down to −20 Wm−2) with few exceptions over bright surfaces (warming up to 5 Wm−2). Finally, the strong variations between the obtained DREs of different aerosol species (dust, sea salt, sulfate, and organic/black carbon) as well as between hemispheres and surface types (i.e., land vs. ocean) are also discussed.
Marios-Bruno Korras-Carraca; Antonis Gkikas; Arlindo M. Da Silva; Christos Matsoukas; Nikolaos Hatzianastassiou; Ilias Vardavas. Optical Properties and Direct Radiative Effects of Aerosol Species at the Global Scale Based on the Synergistic Use of MERRA-2 Optical Properties and the FORTH Radiative Transfer Model. Environmental Sciences Proceedings 2020, 4, 4 .
AMA StyleMarios-Bruno Korras-Carraca, Antonis Gkikas, Arlindo M. Da Silva, Christos Matsoukas, Nikolaos Hatzianastassiou, Ilias Vardavas. Optical Properties and Direct Radiative Effects of Aerosol Species at the Global Scale Based on the Synergistic Use of MERRA-2 Optical Properties and the FORTH Radiative Transfer Model. Environmental Sciences Proceedings. 2020; 4 (1):4.
Chicago/Turabian StyleMarios-Bruno Korras-Carraca; Antonis Gkikas; Arlindo M. Da Silva; Christos Matsoukas; Nikolaos Hatzianastassiou; Ilias Vardavas. 2020. "Optical Properties and Direct Radiative Effects of Aerosol Species at the Global Scale Based on the Synergistic Use of MERRA-2 Optical Properties and the FORTH Radiative Transfer Model." Environmental Sciences Proceedings 4, no. 1: 4.
In the present study, dust aerosol episodes (DAEs) in the broader Mediterranean Basin (MB) are investigated over a 15-year (2005–2019) period using contemporary MODIS Collection 6.1 and OMI OMAERUV satellite data and a satellite algorithm applying a thresholding technique on selected aerosol optical properties. The algorithm operates on a daily and 1° × 1° pixel level basis, first identifying the presence of dust, and consequently requiring the presence of unusually high dust loads, i.e., dust episodes. Apart from the presence of pixel-level DAEs, an extended spatial coverage of dust is also required. Thus, a specific day is characterized as a Dust Aerosol Episode Day (DAED), when at least 30 episodic pixels exist over Mediterranean Basin (MB). According to the algorithm results, 166 DAEDs (116 strong and 50 extreme) took place in the MB from 2005 to 2019. Most DAEDs occurred in spring (47%) and summer (38%), while a different seasonality is observed for strong and extreme episodes. The interannual variability of DAEDs reveal a decreasing trend, which is however not statistically significant.
Maria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Nikos Mihalopoulos. A 15-Year Climatology of Desert Dust Episodes in the Broader Mediterranean Basin. Environmental Sciences Proceedings 2020, 4, 1 .
AMA StyleMaria Gavrouzou, Nikos Hatzianastassiou, Antonis Gkikas, Nikos Mihalopoulos. A 15-Year Climatology of Desert Dust Episodes in the Broader Mediterranean Basin. Environmental Sciences Proceedings. 2020; 4 (1):1.
Chicago/Turabian StyleMaria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Nikos Mihalopoulos. 2020. "A 15-Year Climatology of Desert Dust Episodes in the Broader Mediterranean Basin." Environmental Sciences Proceedings 4, no. 1: 1.
Antonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Alexandra Tsekeri; Eleni Marinou; Nikos Hatzianastassiou; Carlos Pérez García-Pando. Supplementary material to "ModIs Dust AeroSol (MIDAS): A global fine resolution dust optical depth dataset". 2020, 1 .
AMA StyleAntonis Gkikas, Emmanouil Proestakis, Vassilis Amiridis, Stelios Kazadzis, Enza Di Tomaso, Alexandra Tsekeri, Eleni Marinou, Nikos Hatzianastassiou, Carlos Pérez García-Pando. Supplementary material to "ModIs Dust AeroSol (MIDAS): A global fine resolution dust optical depth dataset". . 2020; ():1.
Chicago/Turabian StyleAntonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Alexandra Tsekeri; Eleni Marinou; Nikos Hatzianastassiou; Carlos Pérez García-Pando. 2020. "Supplementary material to "ModIs Dust AeroSol (MIDAS): A global fine resolution dust optical depth dataset"." , no. : 1.
Monitoring and describing the spatiotemporal variability of dust aerosols is crucial to understand their multiple effects, related feedbacks and impacts within the Earth system. This study describes the development of the MIDAS (ModIs Dust AeroSol) dataset. MIDAS provides columnar daily dust optical depth (DOD at 550 nm) at global scale and fine spatial resolution (0.1° × 0.1°) over a decade (2007–2016). This new dataset combines quality filtered satellite aerosol optical depth (AOD) retrievals from MODIS-Aqua at swath level (Collection 6, Level 2), along with DOD-to-AOD ratios provided by MERRA-2 reanalysis to derive DOD on the MODIS native grid. The uncertainties of MODIS AOD and MERRA-2 dust fraction with respect to AERONET and CALIOP, respectively, are taken into account for the estimation of the total DOD uncertainty (including measurement and sampling uncertainties). MERRA-2 dust fractions are in very good agreement with CALIOP column-integrated dust fractions across the dust belt, in the Tropical Atlantic Ocean and the Arabian Sea; the agreement degrades in North America and the Southern Hemisphere where dust sources are smaller. MIDAS, MERRA-2 and CALIOP DODs strongly agree when it comes to annual and seasonal spatial patterns; however, deviations of dust loads' intensity are evident and regionally dependent. Overall, MIDAS is well correlated with ground-truth AERONET-derived DODs (R = 0.882), only showing a small negative bias (−0.009 or −5.307 %). Among the major dust areas of the planet, the highest R values (up to 0.977) are found at sites of N. Africa, Middle East and Asia. MIDAS expands, complements and upgrades existing observational capabilities of dust aerosols and it is suitable for dust climatological studies, model evaluation and data assimilation.
Antonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Alexandra Tsekeri; Eleni Marinou; Nikos Hatzianastassiou; Carlos Pérez García-Pando. ModIs Dust AeroSol (MIDAS): A global fine resolution dust optical depth dataset. 2020, 2020, 1 -62.
AMA StyleAntonis Gkikas, Emmanouil Proestakis, Vassilis Amiridis, Stelios Kazadzis, Enza Di Tomaso, Alexandra Tsekeri, Eleni Marinou, Nikos Hatzianastassiou, Carlos Pérez García-Pando. ModIs Dust AeroSol (MIDAS): A global fine resolution dust optical depth dataset. . 2020; 2020 ():1-62.
Chicago/Turabian StyleAntonis Gkikas; Emmanouil Proestakis; Vassilis Amiridis; Stelios Kazadzis; Enza Di Tomaso; Alexandra Tsekeri; Eleni Marinou; Nikos Hatzianastassiou; Carlos Pérez García-Pando. 2020. "ModIs Dust AeroSol (MIDAS): A global fine resolution dust optical depth dataset." 2020, no. : 1-62.
Aerosols, due to their interaction primary with the shortwave, but also with the longwave radiation, constitute a significant climate component, and at the same time an important, but still uncertain, factor of the contemporary climatic change. Apart from radiation, aerosols also interact with clouds, acting as Cloud Condensation Nuclei (CCN) and/or Ice Nuclei (IN), modifying the cloud optical and physical properties like cloud albedo, extent, lifetime or precipitation producing ability. Hence, it is also expected that high loads of specific aerosol types, such as desert dust, can induce even stronger effects on the above mentioned cloud properties.
More specifically, dust aerosols, which are inserted in the atmosphere mainly from the great world deserts, represent the major global aerosol component. These aerosols can remain suspended in the air and travel for several days, reaching areas far away from their sources. The Mediterranean Basin (MB), which is one of the most responsive regions to climate change, due to its location (nearby the Sahara desert in North Africa and the deserts of Middle East), is frequently affected from massive and extended dust transport. Because of the potentially significant role of these dust episodes, and their seasonal and inter-annual variability, they are worth to be studied and monitored through time.
In the present study, a modified version of a satellite algorithm, which is fully described by Gavrouzou et al. in another study of this conference, is used for the determination of strong and extreme dust episodes in the Mediterranean Basin over the period 2005-2018. The algorithm, using MODIS C6.1 spectral Aerosol Optical Depth (AOD) and OMI OMAERUV Aerosol Index (AI) as input data, ran on a daily and an 1°x1° pixel level basis and determined the occurrence and intensity of dust episodes whenever the AI is greater than 1 and the Angstrom Exponent (AE), which is calculated from spectral AOD data, is lower than 0.4. Any day is characterized as an episodic one when the dust optical depth (DOD) exceeds a computed threshold value (mean value plus two or four standard deviations for strong and extreme episodes, respectively) on at least 30 pixels of the study area. According to the algorithm results, 148 dust episode days (104 strong and 44 extreme) are found during the 2005-2018 period in the Mediterranean Basin. Most of the episodes occur in July (27 strong- and 3 extreme-episode days) and April (25 strong- and 6 extreme-episode days) while dust episodes are not detected at all in November and December. It is also found that in April, March and May take place the highest number of extreme MB episodes (23 out of the total 44 ones).
Nikos Hatzianastassiou; Maria Gavrouzou; Antonis Gkikas; Nikos Mihalopoulos. A climatology of dust episodes in the broader Mediterranean Basin using satellite MODIS C6.1 and OMI OMAERUV data. 2020, 1 .
AMA StyleNikos Hatzianastassiou, Maria Gavrouzou, Antonis Gkikas, Nikos Mihalopoulos. A climatology of dust episodes in the broader Mediterranean Basin using satellite MODIS C6.1 and OMI OMAERUV data. . 2020; ():1.
Chicago/Turabian StyleNikos Hatzianastassiou; Maria Gavrouzou; Antonis Gkikas; Nikos Mihalopoulos. 2020. "A climatology of dust episodes in the broader Mediterranean Basin using satellite MODIS C6.1 and OMI OMAERUV data." , no. : 1.
Aerosol particles influence the Earth’s radiation budget, and thus weather and climate, through their interaction primarily with solar, but also with terrestrial radiation. Moreover, aerosol-cloud interactions are essential, since aerosols act as Cloud Condensation Nuclei (CCN) and/or Ice Nuclei (IN), and thus crucially affect cloud properties. Dust is a major aerosol type, accounting for a great fraction of the global aerosol mass, mostly originating from the global deserts). Dust aerosols exert a strong radiative forcing, while acting as CCN and/or IN, thus modifying the cloud physical optical and radiative properties as well as also cloud lifetime and precipitation. However, the direct and indirect effects of dust are strongly dependent on their spatial and temporal distribution, which still has a considerable degree of uncertainty. This uncertainty is due to limitations of our knowledge about the dust spatiotemporal variability, which is due to the strong variability both of the dust sources and emissions as well as their transport and removal processes. However, in the last two decades, significant steps have been made towards improving the ability to observe dust from satellites. Advanced retrieval algorithms enable to effectively derive key aerosol optical properties which are characteristic of their physical properties such as size and absorptivity. The availability of such aerosol data since the early 2000s offers nowadays the possibility to build satellite-based dust climatologies.
In the present study a global dust climatology is constructed using a satellite based algorithm. The algorithm is initialized with the latest editions of Collection 6.1 MODIS-Aqua and OMAER-UV OMI-Aura data spanning the 14-year period from 2005 to 2018. The raw data of the algorithm are: (1) spectrally resolved MODIS Aerosol Optical Depth-AOD and (2) OMI Aerosol Index-AI), both available on a daily basis and at 1°x1° latitude-longitude spatial resolution. The algorithm computes, using the spectral AOD values, the aerosol Angstrom Exponent (AE), which is finally used along with AI as the main algorithm input data that are characteristic of aerosol size (AE) and absorptivity (AI). By applying appropriate thresholds that ensure the coarse size and significant absorptivity of dust, the algorithm identifies presence of dust in the atmospheric column on a daily and 1°x1° basis over the entire globe and the period 2005-2018. The algorithm estimates the frequency of presence and the associated loading (in terms of dust optical depth, DOD) of dust on a monthly and annual basis. The 14-year study period enables the computation of climatological mean values, as well as the intra-annual and inter-annual variability and trends of dust. Specific emphasis is given to the world’s great deserts, as well as to regions undergoing important transport of dust.
Maria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Nikos Mihalopoulos. Global dust climatology based on MODIS C6.1 and OMI-OMAERUV satellite data for the period 2005 to 2019. 2020, 1 .
AMA StyleMaria Gavrouzou, Nikos Hatzianastassiou, Antonis Gkikas, Nikos Mihalopoulos. Global dust climatology based on MODIS C6.1 and OMI-OMAERUV satellite data for the period 2005 to 2019. . 2020; ():1.
Chicago/Turabian StyleMaria Gavrouzou; Nikos Hatzianastassiou; Antonis Gkikas; Nikos Mihalopoulos. 2020. "Global dust climatology based on MODIS C6.1 and OMI-OMAERUV satellite data for the period 2005 to 2019." , no. : 1.