153 research outputs found

    Simulation and sensitivity analysis for cloud and precipitation measurements via spaceborne millimeter-wave radar

    Get PDF
    This study presents a simulation framework for cloud and precipitation measurements via spaceborne millimeter-wave radar composed of eight submodules. To demonstrate the influence of the assumed physical parameters and to improve the microphysical modeling of the hydrometeors, we first conducted a sensitivity analysis. The results indicated that the radar reflectivity was highly sensitive to the particle size distribution (PSD) parameter of the median volume diameter and particle density parameter, which can cause reflectivity variations of several to more than 10 dB. The variation in the prefactor of the mass–power relations that related to the riming degree may result in an uncertainty of approximately 30 %–45 %. The particle shape and orientation also had a significant impact on the radar reflectivity. The spherical assumption may result in an average overestimation of the reflectivity by approximately 4 %–14 %, dependent on the particle type, shape, and orientation. Typical weather cases were simulated using improved physical modeling, accounting for the particle shapes, typical PSD parameters corresponding to the cloud precipitation types, mass–power relations for snow and graupel, and melting modeling. We present and validate the simulation results for a cold-front stratiform cloud and a deep convective process with observations from a W-band cloud profiling radar (CPR) on the CloudSat satellite. The simulated bright band features, echo structure, and intensity showed a good agreement with the CloudSat observations; the average relative error of radar reflectivity in the vertical profile was within 20 %. Our results quantify the uncertainty in the millimeter-wave radar echo simulation that may be caused by the physical model parameters and provide a scientific basis for optimal forward modeling. They also provide suggestions for prior physical parameter constraints for the retrieval of the microphysical properties of clouds and precipitation.</p

    Retrieving cloud ice masses from geostationary images with neural networks

    Get PDF
    Clouds are essential to the Earth\u27s energy budget and atmospheric circulation. Despite this, many cloud parameters are poorly known, including the mass of frozen hydrometeors. On the one hand, there will be specialized satellite missions targeting such hydrometeors. On the other hand, existing satellite data can be leveraged. There should be a particular interest in using geostationary satellite observations since they provide continuous coverage. Traditionally, retrievals of cloud ice masses from geostationary measurements require solar reflectances, ignore any spatial correlations, and solely retrieve the vertically-integrated ice mass density, known as the ice water path.This thesis challenges the traditional approach by applying supervised learning against CloudSat collocations, the only existing satellite mission targeting ice clouds. A set of neural networks is assembled to compare the performance of using different visible or infrared channels as retrieval input as well as the added value of using spatial context. The retrievals are probabilistic, in the sense that all neural networks predict quantiles to estimate the retrieval irreducible uncertainty, and thus represent the state of the art for atmospheric retrievals.With several spectral channels, infrared retrievals are found to have a similar performance compared to the peak accuracy offered by the combination of visible and infrared channels. However, the infrared-only retrievals enable a consistent diurnal performance. The use of spatial information reinforces the retrievals, which is demonstrated by the ability to provide skilful three-dimensional estimates of ice masses, known as ice water content, from only one infrared channel. The latter retrieval scheme is supported by an extensive validation with independent measurements.These neural network-based retrievals offer the possibility to derive new insights into cloud physics, reduce present ice cloud uncertainties, and validate climate models. Ideally, such retrieval schemes will complement the sparse measurements from specialized instruments. Finally, this thesis contains the groundwork for executing retrievals on multidecadal geostationary observations, offering unprecedented spatially and temporally continuous three-dimensional data for the tropics and mid-latitudes. The implementation of these ongoing retrievals is publicly released as part of the Chalmers Cloud Ice Climatology

    OBSERVING MINERAL DUST IN NORTHERN AFRICA, THE MIDDLE EAST AND EUROPE: CURRENT CAPABILITIES AND CHALLENGES AHEAD FOR THE DEVELOPMENT OF DUST SERVICES

    Get PDF
    Mineral dust produced by wind erosion of arid and semi-arid surfaces is a major component of atmospheric aerosol that affects climate, weather, ecosystems, and socio-economic sectors such as human health, transportation, solar energy, and air quality. Understanding these effects and ultimately improving the resilience of affected countries requires a reliable, dense, and diverse set of dust observations, fundamental for the development and the provision of skillful dust forecasts tailored products. The last decade has seen a notable improvement of dust observational capabilities in terms of considered parameters, geographical coverage, and delivery times, as well as of tailored products of interest to both the scientific community and the various end-users. Given this progress, here we review the current state of observational capabilities including in-situ, ground-based and satellite remote sensing observations, in Northern Africa, the Middle East and Europe for the provision of dust information considering the needs of various users. We also critically discuss observational gaps and related unresolved questions while providing suggestions for overcoming the current limitations. Our review aims to be a milestone for discussing dust observational gaps at a global level to address the needs of users, from research communities to nonscientific stakeholdersAuthors acknowledge dr Sangboom Ryoo of Korean Meteorological Administration in Seoul for his help and support.The research leading to these results has received funding from the COST ActionCA16202, supported by COST Association (European Cooperation in Science and Technology), from DustClim Project as part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462) and by the European Union’s Horizon 2020 research program for societal challenges – smart, green and integrated transport under grant agreement no.723986 (project EUNADICS-AV – European Natural Disaster Coordination and Information System for Aviation). L. Mona acknowledges the ACTRIS-IMP (Implementation project), funded by the European Union’s Horizon 2020 research and innovation programme (Grant no 871115) and the contribution of the ACTRIS-ITALIA JRU (CNR prot. n. 0067310/2017). S. Basart acknowledges CAMS-84 and CAMS2-82 (part of the Copernicus Atmospheric Monitoring Services, CAMS) and the Spanish Jose Castillejo mobility programme (CAS18/0033). V. Amiridis acknowledges support from the European Research Council (grant no. 725698, D-TECT). A. Gkikas acknowledges support by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers” (project acronym: ATLANTAS, project number: 544). S. Kazadzis acknowledges the ACTRIS-CH (Aerosol, Clouds and Trace Gases Research Infrastructure–- Swiss contribution) funded by the State Secretariat for Education, Research, and Innovation, Switzerland. Work of P. Dagsson-Waldhauserova was partly funded by the Czech Science Foundation (HLD-CHANGE project, no. 20-06168Y). C. PĂ©rez GarcĂ­a-Pando acknowledges the long-term support from the AXA Research Fund, as well as the support received through the RamĂłn y Cajal programme (grant RYC-2015-18690) of the Spanish Ministry of Economy and Competitiveness, and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 773051).B. Weinzierl acknowledges funding under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 640458, A‐LIFE).Peer Reviewed"Article signat per 26 autors/es: Lucia Mona, Vassilis Amiridis, Emilio Cuevas, Antonis Gkikas, Serena Trippetta, Sophie Vandenbussche, Angela Benedetti, Pavla Dagsson-Waldhauserova, Paola Formenti, Alexander Haefele, Stelios Kazadzis, Peter Knippertz, Benoit Laurent, Fabio Madonna, Slobodan Nickovic, Nikolaos Papagiannopoulos, Gelsomina Pappalardo, Carlos PĂ©rez GarcĂ­a-Pando, Thomas Popp, Sergio RodrĂ­guez, Andrea Sealy, Nobuo Sugimoto, Enric Terradellas, Ana Vukovic Vimic, Bernadette Weinzierl, and Sara Basart "Postprint (author's final draft

    Ocean carbon from space: Current status and priorities for the next decade

    Get PDF
    This is the final version. Available on open access from Elsevier via the DOI in this recordData availability: Data for Fig. 1a were generated from a free Scopus (https://www.scopus.com/) search of the terms "Ocean carbon satellite" (using All fields) in March 2022. Data from Fig. 1b and 1c were generated from the workshop registration and are available within the figure (participation number, geographical representation and gender split).The ocean plays a central role in modulating the Earth’s carbon cycle. Monitoring how the ocean carbon cycle is changing is fundamental to managing climate change. Satellite remote sensing is currently our best tool for viewing the ocean surface globally and systematically, at high spatial and temporal resolutions, and the past few decades have seen an exponential growth in studies utilising satellite data for ocean carbon research. Satellite-based observations must be combined with in-situ observations and models, to obtain a comprehensive view of ocean carbon pools and fluxes. To help prioritise future research in this area, a workshop was organised that assembled leading experts working on the topic, from around the world, including remote-sensing scientists, field scientists and modellers, with the goal to articulate a collective view of the current status of ocean carbon research, identify gaps in knowledge, and formulate a scientific roadmap for the next decade, with an emphasis on evaluating where satellite remote sensing may contribute. A total of 449 scientists and stakeholders participated (with balanced gender representation), from North and South America, Europe, Asia, Africa, and Oceania. Sessions targeted both inorganic and organic pools of carbon in the ocean, in both dissolved and particulate form, as well as major fluxes of carbon between reservoirs (e.g., primary production) and at interfaces (e.g., air-sea and land–ocean). Extreme events, blue carbon and carbon budgeting were also key topics discussed. Emerging priorities identified include: expanding the networks and quality of in-situ observations; improved satellite retrievals; improved uncertainty quantification; improved understanding of vertical distributions; integration with models; improved techniques to bridge spatial and temporal scales of the different data sources; and improved fundamental understanding of the ocean carbon cycle, and of the interactions among pools of carbon and light. We also report on priorities for the specific pools and fluxes studied, and highlight issues and concerns that arose during discussions, such as the need to consider the environmental impact of satellites or space activities; the role satellites can play in monitoring ocean carbon dioxide removal approaches; economic valuation of the satellite based information; to consider how satellites can contribute to monitoring cycles of other important climatically-relevant compounds and elements; to promote diversity and inclusivity in ocean carbon research; to bring together communities working on different aspects of planetary carbon; maximising use of international bodies; to follow an open science approach; to explore new and innovative ways to remotely monitor ocean carbon; and to harness quantum computing. Overall, this paper provides a comprehensive scientific roadmap for the next decade on how satellite remote sensing could help monitor the ocean carbon cycle, and its links to the other domains, such as terrestrial and atmosphere.European Space AgencySimons FoundationUK National Centre for Earth Observation (NCEO)UKRIAtlantic Meridional Transect ProgrammeSwiss National Science Foundatio

    Development and applications of a cloud regime dataset over Europe using satellite observations

    Get PDF
    Within the framework of the present dissertation, a cloud regime dataset was developed over Europe using satellite observations. The climatology of the “Cloud Regime dAtAset based on the CLAAS-2.1 climate data record” (CRAAS) is thoroughly investigated and the derived cloud regimes are used in a number of applications. The cloud regimes are generated over Europe on a 1°x1° spatial resolution and extend over a 14-year period (from 2004 until 2017) with a high temporal resolution of 15-minutes. In particular, the cloud optical thickness (COT) and cloud top pressure (CTP) products of CLAAS-2.1 are used in order to compute 2D histograms. Then, the k-means clustering algorithm is applied to the generated 2D histograms for the derivation of the cloud regimes. Eight cloud regimes are identified, which assist in providing a detailed description of the climate of the cloud properties over Europe. Three of these cloud regimes are associated with high-level clouds and, in particular, with cirrus, cirrostratus and dense cirrus from deep convection and frontal systems. An additional cloud regime is connected to alto- and nimbo-type clouds, while a fifth one is related to mid-level clouds. Two cloud regimes are found to represent low-level clouds, specifically stratocumulus, shallow cumulus and fog. The final cloud regime is associated mainly with fair weather clouds and joint cloud histograms with no distinguishable structure. The spatiotemporal variability and changes of the CRAAS cloud regimes are investigated over the European region from 2004 until 2017. The last cloud regime is found to be the most dominant, in terms of frequency of occurrence, reaching values up to 85.5% over regions of lower latitude. The annual and diurnal cycles are also dominated by the last cloud regime, while features of the main representative cloud type of each cloud regime can be observed as well. The biggest decrease in the frequency of occurrence, -0.65% during the time period of the study, is observed for the cloud regime representing the alto- and nimbo-type clouds. In contrast, the largest increase, +0.70% during the time period of the study, is noted for the cloud regime associated with shallow cumulus and fog. The majority of the statistically significant trends are observed over lower latitudes, focusing mostly over the Mediterranean. An intercomparison against a similar classification, based on cloud optical properties from the International Satellite Cloud Climatology Project (ISCCP), showed that it is important to distinguish between regionally and globally derived cloud regimes. Furthermore, in order to identify relations between large-scale weather patterns and the cloud regimes, co-occurrences between the cloud regimes and the Objective Weather Type Classification are studied. Finally, the combination of the cloud regimes with vertical profiles from ground based measurements is used for a detailed description of cloud structures and their temporal evolution in frontal systems

    Observing mineral dust in northern Africa, the middle east and Europe: current capabilities and challenges ahead for the development of dust services

    Get PDF
    Mineral dust produced by wind erosion of arid and semi-arid surfaces is a major component of atmospheric aerosol that affects climate, weather, ecosystems, and socio-economic sectors such as human health, transportation, solar energy, and air quality. Understanding these effects and ultimately improving the resilience of affected countries requires a reliable, dense, and diverse set of dust observations, fundamental for the development and the provision of skillful dust forecasts tailored products. The last decade has seen a notable improvement of dust observational capabilities in terms of considered parameters, geographical coverage, and delivery times, as well as of tailored products of interest to both the scientific community and the various end-users. Given this progress, here we review the current state of observational capabilities including in-situ, ground-based and satellite remote sensing observations, in Northern Africa, the Middle East and Europe for the provision of dust information considering the needs of various users. We also critically discuss observational gaps and related unresolved questions while providing suggestions for overcoming the current limitations. Our review aims to be a milestone for discussing dust observational gaps at a global level to address the needs of users, from research communities to nonscientific stakeholders

    Ocean carbon from space: Current status and priorities for the next decade

    Get PDF
    The ocean plays a central role in modulating the Earth\u27s carbon cycle. Monitoring how the ocean carbon cycle is changing is fundamental to managing climate change. Satellite remote sensing is currently our best tool for viewing the ocean surface globally and systematically, at high spatial and temporal resolutions, and the past few decades have seen an exponential growth in studies utilising satellite data for ocean carbon research. Satellite-based observations must be combined with in-situ observations and models, to obtain a comprehensive view of ocean carbon pools and fluxes. To help prioritise future research in this area, a workshop was organised that assembled leading experts working on the topic, from around the world, including remote-sensing scientists, field scientists and modellers, with the goal to articulate a collective view of the current status of ocean carbon research, identify gaps in knowledge, and formulate a scientific roadmap for the next decade, with an emphasis on evaluating where satellite remote sensing may contribute. A total of 449 scientists and stakeholders participated (with balanced gender representation), from North and South America, Europe, Asia, Africa, and Oceania. Sessions targeted both inorganic and organic pools of carbon in the ocean, in both dissolved and particulate form, as well as major fluxes of carbon between reservoirs (e.g., primary production) and at interfaces (e.g., air-sea and land–ocean). Extreme events, blue carbon and carbon budgeting were also key topics discussed. Emerging priorities identified include: expanding the networks and quality of in-situ observations; improved satellite retrievals; improved uncertainty quantification; improved understanding of vertical distributions; integration with models; improved techniques to bridge spatial and temporal scales of the different data sources; and improved fundamental understanding of the ocean carbon cycle, and of the interactions among pools of carbon and light. We also report on priorities for the specific pools and fluxes studied, and highlight issues and concerns that arose during discussions, such as the need to consider the environmental impact of satellites or space activities; the role satellites can play in monitoring ocean carbon dioxide removal approaches; economic valuation of the satellite based information; to consider how satellites can contribute to monitoring cycles of other important climatically-relevant compounds and elements; to promote diversity and inclusivity in ocean carbon research; to bring together communities working on different aspects of planetary carbon; maximising use of international bodies; to follow an open science approach; to explore new and innovative ways to remotely monitor ocean carbon; and to harness quantum computing. Overall, this paper provides a comprehensive scientific roadmap for the next decade on how satellite remote sensing could help monitor the ocean carbon cycle, and its links to the other domains, such as terrestrial and atmosphere
    • 

    corecore