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Atmospheric radiation is the main driver of weather and climate, yet due to a complicated absorption spectrum, the precise treatment of radiative transfer in numerical weather and climate models is computationally unfeasible. Radiation parameterizations need to maximize computational efficiency as well as accuracy, and for predicting the future climate many greenhouse gases need to be included. In this work, neural networks (NNs) were developed to replace the gas optics computations in a modern radiation scheme (RTE+RRTMGP) by using carefully constructed models and training data. The NNs, implemented in Fortran and utilizing BLAS for batched inference, are faster by a factor of 1-6, depending on the software and hardware platforms. We combined the accelerated gas optics with a refactored radiative transfer solver, resulting in clear-sky longwave (shortwave) fluxes being 3.5 (1.8) faster to compute on an Intel platform. The accuracy, evaluated with benchmark line-by-line computations across a large range of atmospheric conditions, is very similar to the original scheme with errors in heating rates and top-of-atmosphere radiative forcings typically below 0.1 K day(-1) and 0.5 W m(-2), respectively. These results show that targeted machine learning, code restructuring techniques, and the use of numerical libraries can yield material gains in efficiency while retaining accuracy.

Atmospheric radiation is the main driver of weather and climate, yet due to a complicated absorption spectrum, the precise treatment of radiative transfer in numerical weather and climate models is computationally unfeasible. Radiation parameterizations need to maximize computational efficiency as well as accuracy, and for predicting the future climate many greenhouse gases need to be included. In this work, neural networks (NNs) were developed to replace the gas optics computations in a modern radiation scheme (RTE+RRTMGP) by using carefully constructed models and training data. The NNs, implemented in Fortran and utilizing BLAS for batched inference, are faster by a factor of 1-6, depending on the software and hardware platforms. We combined the accelerated gas optics with a refactored radiative transfer solver, resulting in clear-sky longwave (shortwave) fluxes being 3.5 (1.8) faster to compute on an Intel platform. The accuracy, evaluated with benchmark line-by-line computations across a large range of atmospheric conditions, is very similar to the original scheme with errors in heating rates and top-of-atmosphere radiative forcings typically below 0.1 K day(-1) and 0.5 W m(-2), respectively. These results show that targeted machine learning, code restructuring techniques, and the use of numerical libraries can yield material gains in efficiency while retaining accuracy.

The emergence of the exascale era necessitates development of new techniques to efficiently perform high-performance scientific simulations, online data analysis and on-the-fly visualization. Critical applications like cyclone tracking and earthquake modeling require high-fidelity and high- performance simulations involving large-scale computations and generate huge amounts of data. Faster simulations and simultaneous online data analysis and visualization enable scientists provide real-time guidance to policy makers. In this thesis, we present a set of techniques for efficient high-fidelity simulations, online data analysis and visualization in environments with varying resource configurations. First, we present a strategy for improving throughput of weather simulations with multiple regions of interest. We propose parallel execution of these nested simulations based on partitioning the 2D process grid into disjoint rectangular regions associated with each subdomain. The process grid partitioning is obtained from a Huffman tree which is constructed from the relative execution times of the subdomains. We propose a novel combination of performance prediction, processor allocation methods and topology-aware mapping of the regions on torus interconnects. We observe up to 33% gain over the default strategy in weather models. Second, we propose a processor reallocation heuristic that minimizes data redistribution cost while reallocating processors in the case of dynamic regions of interest. This algorithm is based on hierarchical diffusion approach that uses a novel tree reorganization strategy. We have also developed a parallel data analysis algorithm to detect regions of interest within a domain. This helps improve performance of detailed simulations of multiple weather phenomena like depressions and clouds, thereby in- creasing the lead time to severe weather phenomena like tornadoes and storm surges. Our method is able to reduce the redistribution time by 25% over a

This master's thesis analyzes the I/O process of IFS. It is presented an easy-to-use development that integrates an asynchronous parallel I/O server called XIOS into IFS. Moreover, different optimization techniques are applied in the integration to minimize the I/O overhead in the IFS execution.

This master's thesis analyzes the I/O process of IFS. It is presented an easy-to-use development that integrates an asynchronous parallel I/O server called XIOS into IFS. Moreover, different optimization techniques are applied in the integration to minimize the I/O overhead in the IFS execution.

Variations of atmospheric conditions cause Atmospheric Phase Screen (APS) in Interferometric Synthetic Aperture Radar (InSAR), which affects accuracy and reliability of its applications. Recent studies reveal that empirical models, auxiliary data (GPS, MERIS, etc.) and atmospheric models can mitigate tropospheric delays in some case studies. The method of using GAM is considered the state of the art and an ongoing evolving technique. As the resolution and accuracy of GAM products are improved significantly, using these products to correct tropospheric delays is promising. Here we explore the performance of three different GAM datasets on correcting Sentinel-1 interferograms in a mountainous and coastal area of Tenerife island, Spain. © VDE VERLAG GMBH  Berlin  Offenbach., Peer Reviewed, Postprint (published version)

Fire emissions associated with tropical land use change and maintenance influence atmospheric composition, air quality, and climate. In this study, we explore the effects of representing fire emissions at daily versus monthly resolution in a global composition-climate model. We find that simulations of aerosols are impacted more by the temporal resolution of fire emissions than trace gases such as carbon monoxide or ozone. Daily-resolved datasets concentrate emissions from fire events over shorter time periods and allow them to more realistically interact with model meteorology, reducing how often emissions are concurrently released with precipitation events and in turn increasing peak aerosol concentrations. The magnitude of this effect varies across tropical ecosystem types, ranging from smaller changes in modeling the low intensity, frequent burning typical of savanna ecosystems to larger differences when modeling the short-term, intense fires that characterize deforestation events. The utility of modeling fire emissions at a daily resolution also depends on the application, such as modeling exceedances of particulate matter concentrations over air quality guidelines or simulating regional atmospheric heating patterns.

Solar cycle activity effects (SCAE) in the lower and middle atmosphere, reported in several studies, are difficult to explain on the basis of the small changes in solar radiation that accompany the 11-year cycle. It is therefore natural to speculate that dynamical processes may come into play to produce a leverage. Such a leverage may be provided by the quasi-biennial oscillation (QBO) in the zonal circulation of the stratosphere, which has been linked to solar activity variations (e.g., Labitzke (J. Meteorol. Soc. Jpn. 60 (1982) 124; Geophys. Res. Lett. 14 (1987) 135); Labitzke and Van Loon (J. Atm. Terr. Phys. 50 (1988) 197; J. Atm. Terr. Phys. 54 (1992) 1453)). Driven primarily by wave mean flow interaction, the QBO period and its amplitude are variable but are also strongly influenced by the seasonal cycle in the solar radiation. This influence extends to low altitudes and is referred to as "downward control". Small changes in the solar radiative forcing may produce small changes in the period and phase of the QBO, but these in turn may produce measurable differences in the wind field. Thus, the QBO may be an amplifier of solar activity variations and a natural conduit of these variations to lower altitudes. To test this hypothesis, we conducted experiments with a 2D version of our numerical spectral model that incorporates Hines' Doppler spread parameterization for small-scale gravity waves (GW). Solar cycle radiance variations (SCRV) are accounted for by changing the radiative heating rate on a logarithmic scale from 0.1\% at the surface to 1\% at 50 km to 10\% at 100 km. With and without SCRV, but with the same GW flux, we then conduct numerical experiments to evaluate the magnitude of the SCAE in the zonal circulation. The numerical results show that, under certain conditions, the SCAE is significant and can extend to lower altitudes where the SCRV is small. For a modeled QBO period of 30 months, we find that the seasonal cycle in the solar forcing acts as a

Quasi-decadal oscillations (QDO) have been observed in the stratosphere and have been linked to the quasi-biennial oscillation (QBO) in the zonal circulation and to the 11-year solar activity cycle. With the use of a 2D version of our numerical spectral model that incorporates Hines' Doppler spread parameterization for gravity waves (GW), we demonstrate that beat periods between 9 and 11 years can be generated by the QBO as it interacts through GW filtering with the annual oscillation (AO) or semi-annual oscillation (SAO). Results are discussed from model runs covering up to 50 years, and our analyses lead to the following conclusions. A QDO is generated in the zonal circulation of the upper mesosphere. The largest signature of the QDO, however, appears in the form of amplitude modulations of the QBO, AO and SAO, and these extend into the lower stratosphere. The downward control that characterizes the QBO apparently comes into play, and the longer time constants for diffusion and radiative loss at lower altitudes facilitate the QDO response. Although excited by the QBO, which is confined to low latitudes, the QDO is shown to extend to high latitudes. The effect is particularly large for a QBO with period around 33 months (near the upper limit of observations), which interacts with the SAO to produce a hemispherically symmetric QDO. (The same dynamical condition also holds for a 28-month QBO.) Our analysis indicates that the QDO is transferred to high latitudes by the meridional circulation, which prominently exhibits this periodicity particularly in the amplitude modulation of the AO. (C) 2003 Elsevier Ltd. All rights reserved.

Quasi-decadal oscillations (QDO) have been observed in the stratosphere and have been linked to the quasi-biennial oscillation (QBO) in the zonal circulation and to the 11-year solar activity cycle. With the use of a 2D version of our numerical spectral model that incorporates Hines' Doppler spread parameterization for gravity waves (GW), we demonstrate that beat periods between 9 and 11 years can be generated by the QBO as it interacts through GW filtering with the annual oscillation (AO) or semi-annual oscillation (SAO). Results are discussed from model runs covering up to 50 years, and our analyses lead to the following conclusions. A QDO is generated in the zonal circulation of the upper mesosphere. The largest signature of the QDO, however, appears in the form of amplitude modulations of the QBO, AO and SAO, and these extend into the lower stratosphere. The downward control that characterizes the QBO apparently comes into play, and the longer time constants for diffusion and radiative loss at lower altitudes facilitate the QDO response. Although excited by the QBO, which is confined to low latitudes, the QDO is shown to extend to high latitudes. The effect is particularly large for a QBO with period around 33 months (near the upper limit of observations), which interacts with the SAO to produce a hemispherically symmetric QDO. (The same dynamical condition also holds for a 28-month QBO.) Our analysis indicates that the QDO is transferred to high latitudes by the meridional circulation, which prominently exhibits this periodicity particularly in the amplitude modulation of the AO. (C) 2003 Elsevier Ltd. All rights reserved.

Solar cycle activity effects (SCAE) in the lower and middle atmosphere, reported in several studies, are difficult to explain on the basis of the small changes in solar radiation that accompany the 11-year cycle. It is therefore natural to speculate that dynamical processes may come into play to produce a leverage. Such a leverage may be provided by the quasi-biennial oscillation (QBO) in the zonal circulation of the stratosphere, which has been linked to solar activity variations (e.g., Labitzke (J. Meteorol. Soc. Jpn. 60 (1982) 124; Geophys. Res. Lett. 14 (1987) 135); Labitzke and Van Loon (J. Atm. Terr. Phys. 50 (1988) 197; J. Atm. Terr. Phys. 54 (1992) 1453)). Driven primarily by wave mean flow interaction, the QBO period and its amplitude are variable but are also strongly influenced by the seasonal cycle in the solar radiation. This influence extends to low altitudes and is referred to as "downward control". Small changes in the solar radiative forcing may produce small changes in the period and phase of the QBO, but these in turn may produce measurable differences in the wind field. Thus, the QBO may be an amplifier of solar activity variations and a natural conduit of these variations to lower altitudes. To test this hypothesis, we conducted experiments with a 2D version of our numerical spectral model that incorporates Hines' Doppler spread parameterization for small-scale gravity waves (GW). Solar cycle radiance variations (SCRV) are accounted for by changing the radiative heating rate on a logarithmic scale from 0.1\% at the surface to 1\% at 50 km to 10\% at 100 km. With and without SCRV, but with the same GW flux, we then conduct numerical experiments to evaluate the magnitude of the SCAE in the zonal circulation. The numerical results show that, under certain conditions, the SCAE is significant and can extend to lower altitudes where the SCRV is small. For a modeled QBO period of 30 months, we find that the seasonal cycle in the solar forcing acts as a

Solar cycle activity effects (SCAE) in the lower and middle atmosphere, reported in several studies, are difficult to explain on the basis of the small changes in solar radiation that accompany the 11-year cycle. It is therefore natural to speculate that dynamical processes may come into play to produce a leverage. Such a leverage may be provided by the quasi-biennial oscillation (QBO) in the zonal circulation of the stratosphere, which has been linked to solar activity variations (e.g., Labitzke (J. Meteorol. Soc. Jpn. 60 (1982) 124; Geophys. Res. Lett. 14 (1987) 135); Labitzke and Van Loon (J. Atm. Terr. Phys. 50 (1988) 197; J. Atm. Terr. Phys. 54 (1992) 1453)). Driven primarily by wave mean flow interaction, the QBO period and its amplitude are variable but are also strongly influenced by the seasonal cycle in the solar radiation. This influence extends to low altitudes and is referred to as "downward control". Small changes in the solar radiative forcing may produce small changes in the period and phase of the QBO, but these in turn may produce measurable differences in the wind field. Thus, the QBO may be an amplifier of solar activity variations and a natural conduit of these variations to lower altitudes. To test this hypothesis, we conducted experiments with a 2D version of our numerical spectral model that incorporates Hines' Doppler spread parameterization for small-scale gravity waves (GW). Solar cycle radiance variations (SCRV) are accounted for by changing the radiative heating rate on a logarithmic scale from 0.1\% at the surface to 1\% at 50 km to 10\% at 100 km. With and without SCRV, but with the same GW flux, we then conduct numerical experiments to evaluate the magnitude of the SCAE in the zonal circulation. The numerical results show that, under certain conditions, the SCAE is significant and can extend to lower altitudes where the SCRV is small. For a modeled QBO period of 30 months, we find that the seasonal cycle in the solar forcing acts as a

Quasi-decadal oscillations (QDO) have been observed in the stratosphere and have been linked to the quasi-biennial oscillation (QBO) in the zonal circulation and to the 11-year solar activity cycle. With the use of a 2D version of our numerical spectral model that incorporates Hines' Doppler spread parameterization for gravity waves (GW), we demonstrate that beat periods between 9 and 11 years can be generated by the QBO as it interacts through GW filtering with the annual oscillation (AO) or semi-annual oscillation (SAO). Results are discussed from model runs covering up to 50 years, and our analyses lead to the following conclusions. A QDO is generated in the zonal circulation of the upper mesosphere. The largest signature of the QDO, however, appears in the form of amplitude modulations of the QBO, AO and SAO, and these extend into the lower stratosphere. The downward control that characterizes the QBO apparently comes into play, and the longer time constants for diffusion and radiative loss at lower altitudes facilitate the QDO response. Although excited by the QBO, which is confined to low latitudes, the QDO is shown to extend to high latitudes. The effect is particularly large for a QBO with period around 33 months (near the upper limit of observations), which interacts with the SAO to produce a hemispherically symmetric QDO. (The same dynamical condition also holds for a 28-month QBO.) Our analysis indicates that the QDO is transferred to high latitudes by the meridional circulation, which prominently exhibits this periodicity particularly in the amplitude modulation of the AO. (C) 2003 Elsevier Ltd. All rights reserved.

A first inversion of the backscatter profile and extinction-to-backscatter ratio from pulsed elastic-backscatter lidar returns is treated by means of an extended Kalman filter (EKF). The EKF approach enables one to overcome the intrinsic limitations of standard straightforward nonmemory procedures such as the slope method, exponential curve fitting, and the backward inversion algorithm. Whereas those procedures are inherently not adaptable because independent inversions are performed for each return signal and neither the statistics of the signals nor a priori uncertainties (e.g., boundary calibrations) are taken into account, in the case of the Kalman filter the filter updates itself because it is weighted by the imbalance between the a priori estimates of the optical parameters (i.e., past inversions) and the new estimates based on a minimum-variance criterion, as long as there are different lidar returns. Calibration errors and initialization uncertainties can be assimilated also. The study begins with the formulation of the inversion problem and an appropriate atmospheric stochastic model. Based on extensive simulation and realistic conditions, it is shown that the EKF approach enables one to retrieve the optical parameters as time-range-dependent functions and hence to track the atmospheric evolution; the performance of this approach is limited only by the quality and availability of the a priori information and the accuracy of the atmospheric model used. The study ends with an encouraging practical inversion of a live scene measured at the Nd:YAG elastic-backscatter lidar station at our premises at the Polytechnic University of Catalonia, Barcelona., Peer Reviewed

Atmospheric sea-salt aerosol concentrations are studied using both long-term observations and model simulations of Na+ at seven stations around the globe. Good agreement is achieved between observations and model predictions in the northern hemisphere. A stronger seasonal variation occurs in the high-latitude North Atlantic than in regions close to the equator and in high-latitude southern hemisphere. Generally, concentrations are higher for both boreal and austral winters. With the model, the production flux and removal flux at the atmosphere-ocean interface was calculated and used to estimate the global sea-salt budget. The flux also shows seasonal variation similar to that of sea-salt concentration. Depending on the geographic location, the model predicts that dry deposition accounts for 60–70% of the total sea-salt removed from the atmosphere while in-cloud and below-cloud precipitation scavenging accounts for about 1% and 28–39% of the remainder, respectively. The total amount of sea-salt aerosols emitted from the world oceans to the atmosphere is estimated to be in the vicinity of 1.17×1016 g yr−1. Approximately 99% of the sea-salt aerosol mass generated by wind falls back to the sea with about 1–2% remaining in the atmosphere to be exported from the original grid square (300×300 km). Only a small portion of that exported (∼4%) is associated with submicron particles that are likely to undergo long-range transport.

A simulation of the processes of sea-salt aerosol generation, diffusive transport, transformation, and removal as a function of particle size is incorporated into a one-dimensional version of the Canadian general climate model (GCMII). This model was then run in the North Atlantic between Iceland and Ireland during the period of January-March. Model predictions are compared to observations of sea-salt aerosols selected from a review of available studies that were subjected to strict screening criteria to ensure their representativeness. The number and mass size distribution and the wind dependency of total sea-salt aerosol mass concentrations predicted by the model compare well with observations. The modeled dependence of sea-salt aerosol concentration in the surface layer (χ, μg m−3) on 10-m wind speed (U10, m s−1) is given byequation image. Simulations show that both a and b change with location. The value a and b range from 0.20 and 3.1 for Mace Head, Ireland to 0.26, and 1.4 for Heimaey, Iceland. The dependence of χ on surface wind speed is weaker for smaller particles and for particles at higher altitudes. The residence time of sea-salt aerosols in the first atmospheric layer (0–166 m) ranges from 30 min for large particles (r=4–8 μm) to ∼60 hours for small particles (r=0.13–0.25 μm). Although some refinements are required for the model, it forms the basis for comparing the simulations with long-term atmospheric sea-salt measurements made at marine baseline observatories around the world and for a more comprehensive three-dimensional modeling of atmospheric sea-salt aerosols.

Tato diplomová práce se zabývá vytvořením knihovny pro volumetrické mraky. Jsou zde popsány jednotlivé techniky pro vytvoření a zobrazení volumetrických mraků, mezi něž patří samotná vizualizační technika oblaků a atmosferický rozptyl světla. Z vizualizační části je zde rozebrána teorie chování světla u participating médií., This master thesis deals with creation of library for volumetric clouds. The paper describes specific techniques for creation and rendering volumetric clouds as clouds and atmospheric scattering. For rendering this type of effects we have to cover theory for participating media.

Tato diplomová práce se zabývá vytvořením knihovny pro volumetrické mraky. Jsou zde popsány jednotlivé techniky pro vytvoření a zobrazení volumetrických mraků, mezi něž patří samotná vizualizační technika oblaků a atmosferický rozptyl světla. Z vizualizační části je zde rozebrána teorie chování světla u participating médií., This master thesis deals with creation of library for volumetric clouds. The paper describes specific techniques for creation and rendering volumetric clouds as clouds and atmospheric scattering. For rendering this type of effects we have to cover theory for participating media.

Tato diplomová práce se zabývá vytvořením knihovny pro volumetrické mraky. Jsou zde popsány jednotlivé techniky pro vytvoření a zobrazení volumetrických mraků, mezi něž patří samotná vizualizační technika oblaků a atmosferický rozptyl světla. Z vizualizační části je zde rozebrána teorie chování světla u participating médií., This master thesis deals with creation of library for volumetric clouds. The paper describes specific techniques for creation and rendering volumetric clouds as clouds and atmospheric scattering. For rendering this type of effects we have to cover theory for participating media.

The equation developed by Riehl (1963) for a steady, symmetrical hurricane are used to specify a vortex over a fixed depth boundary layer, which interacts with a simple ocean model. Only vertical mixing in the surface layer is included in the oceanic portion of the model. Interaction of the atmosphere and the ocean occurs through the prediction of boundary layer parameters. Bulk aerodynamic equations are used to calculate the air-sea interaction, Comparison of the predicted boundary parameters with observed mature tropical storm shows good agreement for all variables except the specific humidity, which exceeds saturation. Two attempts to correct for this situation have shown that small changes in the surface moisture and temperature values strongly affect the maximum wind speed predicted. The proportion of the water vapor transported out of the top of the boundary layer without adding latent heat to the boundary layer appears to be an important factor in determining the intensity of a steafy-state hurricane. Although the ocean model is quite simple, realistic horizontal ocean temperature profiles with respect to the hurricane center were obtained. However, the magnitude of changes in oceanic heat content and the sea-surface temperatures were smaller than expected in actual hurricanes, since advection and upwelling effects were not included in the ocean model., http://archive.org/details/experimentswiths00corg, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

Tato diplomová práce se zabývá vytvořením knihovny pro volumetrické mraky. Jsou zde popsány jednotlivé techniky pro vytvoření a zobrazení volumetrických mraků, mezi něž patří samotná vizualizační technika oblaků a atmosferický rozptyl světla. Z vizualizační části je zde rozebrána teorie chování světla u participating médií., This master thesis deals with creation of library for volumetric clouds. The paper describes specific techniques for creation and rendering volumetric clouds as clouds and atmospheric scattering. For rendering this type of effects we have to cover theory for participating media.

Tato diplomová práce se zabývá vytvořením knihovny pro volumetrické mraky. Jsou zde popsány jednotlivé techniky pro vytvoření a zobrazení volumetrických mraků, mezi něž patří samotná vizualizační technika oblaků a atmosferický rozptyl světla. Z vizualizační části je zde rozebrána teorie chování světla u participating médií., This master thesis deals with creation of library for volumetric clouds. The paper describes specific techniques for creation and rendering volumetric clouds as clouds and atmospheric scattering. For rendering this type of effects we have to cover theory for participating media.

Tato diplomová práce se zabývá vytvořením knihovny pro volumetrické mraky. Jsou zde popsány jednotlivé techniky pro vytvoření a zobrazení volumetrických mraků, mezi něž patří samotná vizualizační technika oblaků a atmosferický rozptyl světla. Z vizualizační části je zde rozebrána teorie chování světla u participating médií., This master thesis deals with creation of library for volumetric clouds. The paper describes specific techniques for creation and rendering volumetric clouds as clouds and atmospheric scattering. For rendering this type of effects we have to cover theory for participating media.

Atmospheric sea-salt aerosol concentrations are studied using both long-term observations and model simulations of Na+ at seven stations around the globe. Good agreement is achieved between observations and model predictions in the northern hemisphere. A stronger seasonal variation occurs in the high-latitude North Atlantic than in regions close to the equator and in high-latitude southern hemisphere. Generally, concentrations are higher for both boreal and austral winters. With the model, the production flux and removal flux at the atmosphere-ocean interface was calculated and used to estimate the global sea-salt budget. The flux also shows seasonal variation similar to that of sea-salt concentration. Depending on the geographic location, the model predicts that dry deposition accounts for 60–70% of the total sea-salt removed from the atmosphere while in-cloud and below-cloud precipitation scavenging accounts for about 1% and 28–39% of the remainder, respectively. The total amount of sea-salt aerosols emitted from the world oceans to the atmosphere is estimated to be in the vicinity of 1.17×1016 g yr−1. Approximately 99% of the sea-salt aerosol mass generated by wind falls back to the sea with about 1–2% remaining in the atmosphere to be exported from the original grid square (300×300 km). Only a small portion of that exported (∼4%) is associated with submicron particles that are likely to undergo long-range transport.