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Towards air quality forecasting with Hirlam & Harmonie: An introductory investigationGertie Geertsema*, Huseyin Toros, Gerard Cats and Selahattin Incecik
Air quality levels in the urban area of Istanbul are a serious issue. Chemical
weather forecasts of high quality will be highly valuable. For this goal, the
possibilities of Hirlam and its successor Harmonie will be investigated. The
intention is to apply the model for similar episodic events for Istanbul as case
studies. This part of the investigation will be divided in two steps: first the model
is run for flash flooding in Istanbul and surrounding area. With the knowledge
acquired during this phase the model will then be applied for air quality Istanbul
and surrounding areas. In this study the first results will be discussed.
Figure 1. An example for the air quality levels in the
urban area of Istanbul (Aksaray).
Evaluation of Hirlam and Harmonie
precipitation forecasts for the Istanbul
flash flood event of September 2009
1. IntroductionIn the beginning of September 2009 a flash
flood in and around the megacity Istanbul
caused 31 deaths and resulted in material
damage which was estimated to be of the
order of 90 million dollars.
Figure 2. Partially submerged cars are seen next to boats
after heavy rains flooded on September 8th, 2009.
2. Observation1.1 Synoptic description
On 6 September 2009 a low pressure system
with a central sea level pressure of 1005 hPa
is located over the Southwest of Anatolia and
a high with a centre pressure of 1025 hPa
over central Europe.
Figure 3. The surface analysis and Meteosat 9 MSG IR image
for 8 September 2009 00 UTC.
1.2 Climate
Istanbul is the business, cultural capital of
Turkey and is home to about 13 million
people. The climate can be characterized
as a transition between Mediterranean and
Temperate.
1.3 Observations
Precipitation data from 28 stations are
used.
Figure 4. The precipitation stations, relevant catchment
and flooding areas.
Figure 5 shows the precipitation on 8-9
September. The rain-gauge observations
show large spatial variability between
Northwest and Southwest of Marmara
region. The amount of precipitation is up
to some 250 mm. The average annual
precipitation in the region is approximately
700 mm.
Figure 5. The 24-hour rainfall totals (mm) in Istanbul and its
surroundings.
3. Model setupThe models were run at ECMWF using the
default settings with below setup.Table 1. Details of the model setup
Model feature Hirlam Harmonie PE Hydrostatic Non-hydrostaticResolution 11 km 2.5 kmGridpoint 438x400 400x400
4. ResultsThe Hirlam forecast shows the peak value
area Northwest of the flooding area and
South of the research area. The Harmonie
forecasts peak South of the observed area
on 8 September 2009. Both Hirlam and
Harmonie forecast the main precipitation
area to the Northwest of the catchment area
on 9 September 2009.
Figure 6. The 24-hours forecast from Hirlam and Harmonie
for 8-9 September 2009.
5. ConclusionThe goal of this experiment was to
investigate whether the NWP models
Hirlam and Harmonie can forecast the
excessive rainfall in the Istanbul area
which caused the flash floods on
September 8-9 in 2009. Result shows that
the high resolution models are capable of
predicting the large rainfall amounts
References:
Toros et al, 2010 Hirlam Newsletter No. 56
(in press, see http://www.hirlam.org).
* Royal Netherlands Meteorological Institute. PO Box 201, 3730 AE De Bilt, The Netherlands, E-mail: [email protected]
