• Development and application of a high-resolving atmosphere-microphysics-chemistry model for prediction of aerosol characteristics in the vicinity of sources
• Influence of nesting on the results of meteorological models
• Development of a resolution dependent parameterisation of surface fluxes with inclusion of subgrid land use effects
• Simulation of biogenic emissions within and above a forest using a microscale model system
• Mesoscale and large scale influences on the development of small scale mesoscale systems over the North Atlantic
• Development of an evaluation concept for prognostic microscale models of the urban canopy layer
• Development and application of a model for the dynamics and composition of secondary and marine aerosols
• Simulation of Influence of aerosol formation on nitrogen input in coastal areas
• Simulation of pollen transport using an atmospheric model

PhD Thesis by Álvaro M. Valdebenito B.

Supervisors: Prof. Dr. K. Heinke Schlünzen, Prof. Dr. Gerhard Lammel

Funding

Baden-Württemberg Programm Lebensgrundlage Umwelt und ihre Sicherung (BW-PLUS), Ministry of the Environment and Transport, State of Baden-Württemberg, Germany: Project number ZO3K23005 between March 2004 and April 2007. Additional founding was provided by the Max Planck Institute for Meteorology (MPI-Met) between May and October 2007.

Subject

Characterisation of transport and optical properties of aerosol particles near an animal facility.

Abstract of thesis:

This work describes the development and first results of a new high-resolution microphysics-chemistry-transport model (LES-AOP). The LES-AOP model was developed to simulate the aerosol optical properties during the plus1 measurement campaign, which was performed in the vicinity of a livestock farm in northern Germany. The model is an extension of a Large-Eddy Simulation (LES) model, where a simple aerosol module was developed to calculate the aerosol optical properties. Only a limited number of aerosol processes is included due to the high computational demand.

The project in which the model was developed aimed to combine high-resolution model results with 3-D lidar measurements performed by the University of Hohenheim. This combination would allow an insight view of the aerosol characteristics on high spatial and temporal scales, even at low aerosol concentrations (e.g. faint sources). One of the major model achievements is the prediction of the aerosol optical properties (with resolutions below 100 m and 1 min) upon initialisation by meteorological and aerosol data. In addition, the model is able to positively detect faint aerosol plumes (with aerosol backscattering coefficient down to 10^−6/(sr m)) and discard false positives identified by the lidar. Furthermore, it is possible from the model results and ground measurements to estimate budget-related quantities, such as the emission flux and mass change of the particulate matter.

Publications

• Full-Text of PhD Thesis
• Pal, S.; Behrendt, A.; Wulfmeyer, V.; Valdebenito, Á. M. & Lammel, G.: A novel approach for the characterization of transport and optical properties of aerosol particles emitted from an animal facility --- Part I: Detection and analyses of aerosol plumes using a scanning eye-safe elastic lidar. Atmospheric Environment, Submitted 2009.
• Valdebenito, Á. M.; Lammel, G.; Pal, S.; Behrendt, A. & Wulfmeyer, V.: A novel approach for the characterization of transport and optical properties of aerosol particles emitted from an animal facility --- Part II: Microphysics-chemistry-transport model development and application. Atmospheric Environment, Submitted 2009.

PhD Thesis by Ursula Maria Bungert

Supervisor Prof. Dr. K. Heinke Schlünzen

Funding

Graduate school "Conservation principles in the modelling and simulation of marine, atmospherical and technical systems", DFG (1. July 2003 - 31. December 2005) DFG, "Two-way nesting and dynamic grid refinement for the simulation of small-scale atmospheric processes" (1. January 2006 - 30. June 2006)

Subject

In this work, the influence of time-depenedent boundary values on model performance of one-way-nested simulations is investigated. An existing analysis procedure has been improved to generate realistic three-dimensional forcing fields from measurements. Furthermore, I investigated which update interval is needed for these or alternative forcing data to represent the temporal development of the large-scale situation in nested simulations.

The measurements are interpolated on a three-dimensional grid. The weighting factor depends on the distance between the measurement station and the model grid point. Tests of different weighting factors showed that an exponential decrease with increasing distance yields the best result. The radius of influence which is a measure for the spatial representativity of a measurement has to be small (about 50~km) near the ground to take into account local conditions. The radius of influence can increase with height up to ~ 300km.

The mesoscale non-hydrostatic model METRAS is used for each case in coarse and in high resolution for the simulations performed in this work. The coarse grid simulation yields the forcing data for the nested high-resolution simulation.

The time interval in which the coarse grid model writes its results is equal to the update interval of the forcing fields for the high-resolution case. With an idealized case (simulation of land sea breeze), a technique has been developed to control the writing of model results in the coarse grid simulation time-dependent. Therefor, changes on the coarse grid have been analyzed. The absolute value of the acceleration (changes in velocity) leads to very long writing intervals at the beginning of the simulation because of uniform changes in velocity. The resulting large update intervals reduce model performance of the nested simulations. In contrast, the characteristic time of velocity used for determining the update intervals leads to higher model performance compared to the standard three-hours update. This result could be confirmed by another idealized test case (vortex development over a polynya). For the realistic simulation of the meteorological situation in Europa in August 2003, the uncertain forcing fields have a larger impact on the model results than the update intervals.

The update intervals of a given forcing data set can be tested using the correlation coefficient between subsequent forcing fields. High values for the correlation coefficient mean that the update intervals are sufficiently short to describe the temporal development of the large-scale situation. On the other hand, aliasing effects can not be identified by calculating the correlation coefficients.

Publications

• Bungert, U., Schröder, G., Dierer, S., Schlünzen, K.H. (2004): Nestungsmethodik und der Einfluss auf die Güte von Modellergebnissen. Poster at DACH-MT 2004, Karlsruhe, Germany.
• Bungert, U., Schröder, G., Schlünzen, K.H. (2005): Impact of nesting methods on model performance. Presentation at EMS 5th Annual Meeting, Utrecht, The Netherlands.
• Bungert, U., K.H. Schlünzen (2007): Impact of nesting methods on model performance. Proceedings of the COST728-Workshop on Integrated Systems, Copenhagen, Denmark, 21.-23.05.2007 (in print).
• Bungert, U., K.H. Schlünzen (2007): Einfluss von Aktualisierungsintervallen auf die Ergebnisse genesteter Simulationen. Poster presentation at DACH-MT 2007, Hamburg,
• Bungert, U. M. (2008): Einfluss der Nestung auf die Ergebnisse meteorologischer Modelle. PhD-Thesis (in german). pdf-file can be downloaded from http://www.sub.uni-hamburg.de/opus/volltexte/2009/3957/

Collaborators

• K. Heinke Schlünzen

• S. Bohnenstengel

Cooperations

• Dr. Heinz Theo Mengelkamp, GKSS
• Dr. Frank Beyrich, DWD
• Close links exist to SPP 1167 "Quantitative Precipitation forecast"

Funded by

• DFG, SPP "Quantitative Precipitation forecast" 01. April 2004 - 31. March 2006
• Max-Planck-Institute for Meteorology, Hamburg since 01. April 2006

Subject

Evaporation from soil, water and vegetation is the source of water in the atmosphere. It depends on several factors; very relevant ones are atmospheric stratification and (sub-grid-scale) land-use.
Using different parameterisations for sub-grid-scale fluxes Schlünzen and Katzfey (2003) have shown for a locally driven meteorological situation that the impact of the parameterisation is largest on dew point and the two grid resolutions investigated.
This project aims to develop a resolution-dependent parameterisation for surface fluxes that considers sub-grid-scaleland-use effects. The parameterisation should work for grid sizes of 1km to 8 km for all meteorological situations. For
developing the parameterisation the well-established mesoscale model METRAS will be used that already includes three different resolution-independent schemes to consider sub-grid scale land-use effects on the surface fluxes. Starting from these parameterisations the dependence of model results on the meteorological situation grid resolution and used parameterisation is investigated.
Model performance will be rated by comparing with routine surface and flux measurements for meteorological situationsthat have a distinct difference in the relevance of local effects.This will be expressed by a newly introduced locality number Ild which is also put in relation to the amount of precipitation.
Inphase 1 of the SPP meteorological situations are classified into locally driven and advective situations by interpreting results of 1D-METRAS simulations that are initialised from 6-hourly radiosonde data and synoptic data provided by DWD for years 2002 ( summer precipitation above average) and 2003 ( summer precipitation below average).

References:

• DWD (2003): LITFASS - 2003, Experimentbericht; 19.05.2003 - 17.06.2003
• Schlünzen, K.H. and Katzfey, J.J. (2003): Relevance of sub-grid-scale land-use effects for mesoscale models. Tellus, 55A, 232-246.
  

Results

A new locality index Iet is successfully introduced and proofs to be applicable to distinguish meteorological situations (see 2005 progress report)

Publications

• Bohnenstengel, S. and Schlünzen, K.H. (2006): A locality index to classify meteorological situations with respect to precipitation, submitted to Journal of Applied Meteorology, in review.
• Bohnenstengel, S. and Schlünzen, K.H. (2006): A locality index to calssify Precipitation and conclude on Probability. Poster, 2nd International Symposium on Quantitative Precipitation Forecasting and Hydrology, Boulder, Colorado, USA, 04.-08.06.2006, accepted.
• Bohnenstengel, S. & Schlünzen, K.H. (2006): Model performance of different surface flux parameterisations dependend on the simulated meteorological situation. Presentation, EGU 2006 in Vienna, 02.-07.04.2006. (Presentation as pdf & film as pdf)
• Bohnenstengel, S. and Schlünzen, K.H. (2005): Development of a resolution-dependent parameterization for surface fluxes with inclusion of sub-grid-scale land-use effects. Poster, Expertise of the SPP proposals at the Center of Physics at Bad Honneff, 12./13.01.2005. ( Poster as pdf)
• Bohnenstengel, S. and Schlünzen, K.H. (2005): Impact of parameterisation of sub-grid-scale land-use-effects and resolution on model performance. Sixth International SRNWP-Workshop on Non-Hydrostatic Modelling. Talk, Bad Orb, 31.10.-02.11.2005.
• Schlünzen K.H., Bohnenstengel S., Trukenmüller A. (2005): Relevance of surface flux aggregation for different meteorological situations. Poster, EMS in Utrecht, 12.-16.09.2005. (Poster as pdf)
• Bohnenstengel, S. & Schlünzen, K.H. (2005): Classification of precipitation events by use of a locality index. Poster, EGU 2005 in Vienna, 25.–29.04.2005.
• Schlünzen, K.H. (2004): parameterisation (fluxes, convection). Presentation at the 1st COPS (Convective and Orographically-induced Precipitation Study) Workshop, a Field Program, 13.–14.09.2004, University of Hohenheim. (Presentation as pdf)

PhD Thesis by

Dipl.-Met. Ingo Schlüter

Supervisor

Prof. Dr. K. Heinke Schlünzen (Universität Hamburg)

Prof. Dr. Ralf Koppmann (Forschungszentrum Jülich, Bergische Universität Wuppertal)

Funding

Research Centre Jülich

Duration

August 2002 to June 2006

Subject

In this study, two days were selcted to simulate biogenic emissions from a forest. A model system is usd, which is adapted to the microscale. It consists of the microscale transport and stream model MITRAS and the microscale chemistry transport model MICTM. First of all, both models were adjusted to handle vegetation. MITRAS was extended by a parameterisation of a forest stand, while MICTM was upgraded with an algorithm for biogenic emissions. Data from the AFO2000-project ECHO ("emission and chemical transformation of biogenic volatile organic compounds") is taken as a basis to compare the model simulations with measurements. Two field campaigns were carried out in ECHO in a forest on the area of the Research Centre Juelich. The data obtained from different towers in different heights provide a good basis for the comparison with the model output. Meteorological data, i.e. temperature and wind, were well simulated with MITRAS, the boundary conditions at the inflow were taken partly from measurements. A modified Guenther-algorithm was used in MICTM to calculate diurnal cycles of isoprene corresponding to the meteorological parameters which were determined with MITRAS. If realistic isoprene concentrations at the inflow boundary were provided, the emissions of isoprene could be simulated by the model system in the right magnitude. They were underestimated by a factor of 3, if the concentrations were unknown and therefore assumed too low. Besides isoprene, OH could be simulated properly. With appropriate in flow conditions, NO, NO₂ and O₃ were also well simulated. These species were strictly dependent from the boundary conditions. The model area was too small for the model system to predict them self-dependant and in the correct magnitude. The simulation of SF₆ as a tracer is associated with great uncertainties, because the gradient of the concentrations was very high and the location where SF₆ was measured could be defined within an uncertainty of 25 m which is equivalent to a radius of 5 grid boxes.

Publications

Thesis (in German) to be downloaded from http://www.sub.uni-hamburg.de/opus/volltexte/2006/3054/

PhD Thesis by

Dipl.-Met. Silke Dierer 

Supervisor

Dr. K. Heinke Schlünzen 

Funding

German Research Council within the collaborative research centre 512-98 

Duration

January 1998 to December 2000 

Subject

Besides their effect on the local weather mesoscale cyclones in the region of the Greenland sea (Framstrait) strongly effect the fresh water transport into the Atlantic ocean which is important for the oceanic circulation. It has been observed that cyclonic activity has significant impact on the breaking of ice. Due to the spatial inhomogeneity and temporal variability of the wind fields the inner stress of the ice is reduced, the pack ice is broken up, and, consequently, it can move easier through the Framstreet into the Atlantic ocean. Apart from the Amazonas, this is the biggest transport of fresh water into the Atlantic ocean. 

Due to a lack of measurements there are only few informations about the development and the structure of small scale mesoscale cyclones in the North Atlantic region. The aim of this work is to investigate the development of mesoscale cyclones in this area and to study their effect on the ice drift. The goal is to make a distinction between mesoscale influences on the large-scale circulation. Furthermore, the effect of the cyclones on the ice drift as well as the feedback of the ice drift on the development of the cyclone are considered. 

For these investigations the mesoscale atmospheric model METRAS (7km resolution) is applied. It is nested inside REMO (1/6° resolution) and idealized data. The atmosphere model METRAS is interactively coupled with a mesoscale sea ice model. The coupling allows to study the interaction between the cyclone and the ice coverage. The quality of the model results is checked by comparing them with plane measurements taken during the FRAMZY '99 experiment (SFB 512 ). Furthermore, measurements of the ice drift are used for comparison with the ice model results. 

Based on a measured situation during the ARUTIS '93 experimnet when a mesoscale cyclone passed the region of Fram strait idealized studies are performed. Their objective is to investigate the influence of different mesoscale and large-scale parameters on the cyclone development and the interaction between cyclone and ice coverage. A sensitivity study is performed, simulating the situation coupled with a sea ice model and with fixed ice coverage in order to estimate the importance of the cyclone-sea ice-interaction. 

Additionally, the cyclone development is investigated by using the voaticity tendency equation. An idealized model set up with and without coupled sea ice model and without large-scale nesting is used to investigate situations in which a mesoscale cyclonic vortex develops. The vorticity tendency equation is used to judge if the cyclogenesis is mainly driven by advective, turbulent, Coriolis or buoyant processes. This gives a hint which parameters are important to create a situation which supports cyclogenesis

• Influence of coastal atmospheric phenomena on nitrogen input in coastal regions (ended 11/02)
• Development and test of an atmospheric flow model employing adaptive numerical methods (ended 07/02)
• Water and energy budget for the Arctic atmosphere (ended 04/02)
• Mesoscale and large scale influences on the development of small scale mesoscale systems over the North Atlantic (ended 01/02)
• On the application of Kalman filters and nudging methods in atmospheric data assimilation (ended 06/01)
• Wind regimes and air pollution transport over Qingdao area (ended 04/00)
• Development of an evaluation concept for prognostic microscale models of the urban canopy layer (ended 01/00)
• Development and application of a model for the dynamics and composition of secondary and marine aerosols (ended 09/97)