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19 results on '"Strunk, Achim"'

1. Wind Power Resource Estimation with Deep Neural Networks

Author

Sehnke, Frank, Strunk, Achim, Felder, Martin, Brombach, Joris, Kaifel, Anton, Meis, Jon, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Mladenov, Valeri, editor, Koprinkova-Hristova, Petia, editor, Palm, Günther, editor, Villa, Alessandro E. P., editor, Appollini, Bruno, editor, and Kasabov, Nikola, editor

Published
2013
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3. Using Satellite Observations for Air Quality Assessment with an Inverse Model System

Author

Strunk, Achim, Elbern, Hendrik, Ebel, Adolf, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Dimov, Ivan, editor, Dimova, Stefka, editor, and Kolkovska, Natalia, editor

Published
2011
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5. Four-Dimensional Variational Assimilation of Atmospheric Chemical Data – Application to Regional Modelling of Air Quality

Author

Strunk, Achim, Ebel, Adolf, Elbern, Hendrik, Friese, Elmar, Goris, Nadine, Nieradzik, Lars Peter, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Lirkov, Ivan, editor, Margenov, Svetozar, editor, and Waśniewski, Jerzy, editor

Published
2010
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12. Tropospheric Chemical State Estimation by Four-Dimensional Variational Data Assimilation on Nested Grids

Author

Strunk, Achim

Subjects
ddc:550
Abstract

The University of Cologne chemistry transport model EURAD and its four-dimensional variational data assimilation implementation is applied to a suite of measurement campaigns for analysing optimal chemical state evolution and flux estimates by inversion. In BERLIOZ and VERTIKO, interest is placed on atmospheric boundary layer processes, while for CONTRACE and SPURT upper troposphere and tropopause height levels are focussed. In order to achieve a high analysis skill, some new key features needed to be developed and added to the model setup. The spatial spreading of introduced observational information can now be conducted by means of a generalised background error covariance matrix. It has been made available as a flexible operator, allowing for anisotropic and inhomogeneous correlations. To estimate surface fluxes with high precision, the facility of emission rate optimisation using scaling factors is extended by a tailored error covariance matrix. Additionally, using these covariance matrices, a suitable preconditioning of the optimisation problem is made available. Furthermore, a module of adjoint nesting was developed and implemented, which enables the system to operate from the regional down to the local scale. The data flow from mother to daughter grid permits to accomplish nested simulations with both optimised boundary and initial values and emission rates. This facilitates to analyse constituents with strong spatial gradients, which have not been amenable to inversion yet. Finally, an observation operator is implemented to get to assimilate heterogeneous sources of information like ground-based measurements, airplane measuring data, Lidar and tethered balloon soundings, as well as retrieval products of satellite observations. In general, quality control of the assimilation procedure is obtained by comparison with independent observations. The case study analyses show considerable improvement of the forecast quality both by the joint optimisation of initial values and emission rates and by the increase of the horizontal resolutions by means of nesting. Moreover, simulation results for the two airplane campaigns exhibit outstanding characteristics of the assimilation system also in the middle and upper troposphere region.

Published
2006

14. Implications of alternative assumptions regarding future air pollution control in RCP-like scenarios

Author

Chuwah, Clifford, van Noije, Twan, van Vuuren, Detlef, Hazeleger, Wilco, Strunk, Achim, Deetman, Sebastiaan, Mendoza Beltran, Angelica, van Vliet, Jasper, Chuwah, Clifford, van Noije, Twan, van Vuuren, Detlef, Hazeleger, Wilco, Strunk, Achim, Deetman, Sebastiaan, Mendoza Beltran, Angelica, and van Vliet, Jasper

Abstract

Estimation of future emissions of short-lived trace gases and aerosols from human activities is a main source of uncertainty in projections of future air quality and climate forcing. The Representative Concentration Pathways (RCPs), however, all assume that worldwide ambitious air pollution control policies will be implemented in the coming decades. In this study, we therefore explore the consequences of four alternative emission scenarios generated using the IMAGE integrated assessment model following the methods used to generate the RCPs. These scenarios combine low and high air pollution variants of the scenarios with radiative forcing targets in 2100 of 2.6 W/m2 and 6.0 W/m2 (the high air pollution variants assume no improvement in emission factors, representing a hypothetical upper end of emission levels). Analysis using the global atmospheric chemistry and transport model TM5 shows that climate mitigation and air pollution control policy variants studied here have similar large-scale effects on the concentrations of ozone and black carbon; the impact of climate policy, however, has a stronger impact on sulphate concentrations. Air pollution control measures could significantly reduce the warming by tropospheric ozone and black carbon and the cooling by sulphate already in 2020, and on the longer term contribute to enhanced warming by methane. These effects tend to cancel each other at the global scale. According to our estimates the effect of the worldwide implementation of air pollution control measures on the total global mean direct radiative forcing in 2050 is +0.09 W/m2 in the 6.0 W/m2 scenario and -0.16 W/m2 in the 2.6 W/m2 scenario.

Published
2013

19. CHEMICAL WEATHER ANALYSIS OPTIMISATION WITH EMISSION IMPACT ESTIMATION USING NESTED FOUR-DIMENSIONAL VARIATIONAL CHEMISTRY DATA ASSIMILATION.

Author

Ebel, Adolf, Davitashvili, Teimuraz, ELBERN, HENDRIK, and STRUNK, ACHIM

Abstract

Combined emission rate and chemical state optimization by fourdimensional variational data assimilation is presented. Using an adjoint nesting technique, a model setup focussing on the Berlin area is employed, enabling to analyze constituents with strong spatial gradients like NO and NO2. Possible requirements for satellite observations to be used for tropospheric chemical state estimation are shortly discussed. [ABSTRACT FROM AUTHOR]

Published
2007
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