EXERCISE 4:
The Dynamical and Thermal Effects
of Metropolitan Areas on Meteorology
Model used: Enviro-HIRLAM
(Enviro-HIRLAM is based on the DMI
version of the HIRLAM -
HIgh Resolution Limited Area Model)
Teacher: Alexander Mahura (DMI, Denmark)
Group 4.1:
Allan Christensen (Denmark), Anna Kanukhina (Russia),
Andres Luhamaa (Estonia), Suleiman Mostamandy (Russia), Elena
Savenkova (Russia)
Group 4.2:
Yulia Gavrilova (Russia), Adomas Mazeikis (Lithuania), Ekaterina
Suvorova (Russia), Tommaso Torrigiani (Italy)
Introduction Background:
Recently, the urbanization is considered as one of the important steps
for improvement of the numerical forecasts in the metropolitan areas and
surroundings. These steps are also included into the Enviro-HIRLAM model
developments (Korsholm et al., 2008), because due to rapidly extending
urban areas, the impact of cities on the formation of meteorological fields
became more evident. Since the urban areas change diurnal cycles of temperature,
humidity, and wind characteristics, etc., and hence, these influence the
quality of forecasts from the numerical weather prediction (NWP) models.
To improve these forecasts, modifications of the land surface scheme of the
model are required. For Enviro-HIRLAM these modifications include the following.
At first, the changes in albedo, anthropogenic heat flux, and roughness (AHF+R)
can be used for grid cells of modelling domain which are attributed to urban
areas (Baklanov et al., 2005; Mahura et al., 2008). At second,
the effects of buildings and street canyons can be implemented through the
building effect parameterization (BEP) module (Martilli et al., 2002).
At third, the re-classified land-use with respect to urban types of surfaces
(such as buildings, artificial surfaces with/without vegetation, etc.) and
urban districts with detailed morphological characteristics can be included
through the soil model for sub-meso scales urban version (SM2-U) module (Dupont
et al., 2006ab).
These mentioned approaches (to study possible urban effects on meteorological
patterns) have been preliminary tested and evaluated for the model for both
specific case studies (related to low, typical, and high winds conditions)
and long-term simulations.
Main Goal:
Study influence of the selected metropolitan area on a formation of meteorological
fields above the urban area and surroundings due to modification of the
land surface scheme of the numerical weather prediction (NWP) model by analysis
of temporal and spatial variability of diurnal cycle for meteorological
variables of key importance
Specific Objectives:
1) Modify the land surface scheme of NWP model by changing
– (a) roughness, (b) anthropogenic heat flux, (c) albedo for urban
grid cells;
2) Perform simulations for selected specific cases/dates
(meteorological conditions with dominating low and typical wind conditions
over the metropolitan area and surroundings) in two modes - the control
run and the modified run (with changes for roughness, anthropogenic heat
flux, albedo);
3) Evaluate diurnal cycle variability for – (a) air temperature,
(b) wind velocity, (c) relative humidity, (d) sensible heat flux, (e) latent
heat flux, and etc. – for two types of runs; estimate extension and
direction of boundaries under influence of metropolitan areas, magnitude
and signs of changes due to urban areas, etc.;
4) Summaries results of the exercise in a form of an
oral presentation (max 15 minutes).
Literature List:
Before the Summer School, the students should read, at least, the first
3 required papers; the three other papers are highly recommended to read
to be useful for the discussions/talks; the additional readings might be
useful too.
REQUIRED READINGS:
Korsholm U.S., A.
Baklanov, A. Gross, A. Mahura, B.H. Sass, E. Kaas, 2008: Online coupled
chemical weather forecasting based on HIRLAM – overview and prospective of
Enviro-HIRLAM. HIRLAM Newsletter, 54: 1-17.
Baklanov A., Mahura A., Nielsen
N.W., C. Petersen, 2005: Approaches for urbanization of DMI–HIRLAM
NWP model. HIRLAM Newsletter 49: 61-75.
Mahura A., Petersen C., Baklanov
A., B. Amstrup, U.S. Korsholm, K. Sattler, 2008: Verification of
long-term DMI–HIRLAM NWP model runs using urbanization and building effect
parameterization modules. HIRLAM HIRLAM Newsletter 53: 50-60.
RECOMMENDED READINGS:
Martilli, A., Clappier, A., and
Rotach, M. W., 2002: An Urban Surface Exchange Parameterisation for
Mesoscale Models, Boundary-Layer Meteorol. 104: 261-304.
Dupont S., P. Mestayer, 2006:
Parameterization of the Urban Energy Budget with the Submesoscale Soil Model.
J. of Appl. Meteor. and Climat., 45: 1744-1765.
Dupont S., P.G. Mestayer,
E. Guilloteau, E. Berthier, H. Andrieu, 2006: Parameterization
of the Urban Water Budget with the Submesoscale Soil Model. J. of Appl.
Meteor. and Climat., 45: 624-648.
ADDITIONAL READINGS:
Baklanov A., P. Mestayer, A. Clappier, S. Zilitinkevich, S. Joffre, A. Mahura,
N. W. Nielsen, 2008: Towards improving the simulation of meteorological
fields in urban areas through updated/advanced surface fluxes description.
Atmos. Chem. Phys., 8: 523-543.
Mahura A., S. Leroyer, P. Mestayer, I. Calmet, S. Dupont, N. Long, A. Baklanov,
C. Petersen, K. Sattler, N. W. Nielsen, 2005: Large eddy simulation
of urban features for Copenhagen metropolitan area. Atmos. Chem. Phys.
Discuss., 5: 11183–11213.