swi – storm and wastewater informatics

Præsentation af Aalborg Universitet 1 af 24

UWT seminar 2010Jesper Ellerbæk Nielsen

”Combining C-band and X-band weather radars for accurate precipitation measurements over urban areas”

Supervisors:Michael R. Rasmussen (AAU)

Rasphal Gill (DMI)Niels Ejner Jensen (DHI)


SWI – Storm and Wastewater Informatics


SWI – Storm and Wastewater Informatics

The PhD project is located withinWP2

• Aalborg University• DMI• DHI• 2 PhD• 2 Post Doc

WP 1

WP 3WP 2 WP 4

WP 5


SWI – Storm and Wastewater Informtic

The purpose of the project is toimprove the overall data qualityof weather radar precipitationmeasurements.

WP 1

WP 3WP 2 WP 4

WP 5


Weather radar measurements

How does the weather radar work?

Its all about timing!

It measures the electromagnetic waves reflected by the precipitation

Indirect measurement of precipitation


The traditional tipping bucked rain gauge


Tipping bucked rain gauges - Rimco

The tipping bucked rain gauge is measuring the weight of the water.

Read Contact

Tipping bucked

OutletBubble level


C-band and X-band radars

C-Band radar operated by DMI

LAWR X-Band radar developed by DMI


Weathers in Denmark

C-band Radars, range 240 kmDanish Metrological Institute (DMI)2000 x 2000 m spatial resolution

10 min. temporal resolution

Marine X-band Radars, range 60 kmDeveloped by DHI

500 x 500 m , 100 x 100 m spatial resolution,

5 min. temporal resolution

X-bånd (Århus)X-bånd (Aalborg)X-bånd (Hvidovre)X-Bånd (Hørsholm)X-bånd (Odense)X-bånd (Vejle)X-bånd (Egedal)


2 x 2 km(C-Band)

Kilde: COWI A/S og Aalborg kommune

Spatial resolution


Kilde: COWI A/S og Aalborg kommune

100 x 100 m(LAWR X-Band)

Spatial resolution


But why all these radars? – Hypothesis for the project

It is possible to combine X-band radars with C-band weather radars, so that the

combination outperforms the individual radar.

Strategy:Strengths of one radar type can compensatethe other radar types weaknesses.

• Range• Resolution• Atmospheric attenuation• Ground clutter


Exampel18/7-2009

C-band X-band


Challenges in combination of radar data

What is detected by the radar, and how is the atmosphere integrated?


Vertikal scanning radar

Based on a Furuno 1715 X-band marine radar a highly flexible radar has been

develobed

The purpose of the radar is by profiling the precipitation it will reveal what the

individual radar detects.


Micro Radar Test BedStepper motor controlling the direction

Analog - Digital converter

Laptop managing the stream of data and the direction of the antenna

Furuno 1715 antenna

Furuno 1715 display unit


Laser based distrometer – OTT Parsivel

Describing the precipitation by drop size and drop velocity


Laser based distrometer – OTT Parsivel


Strategy for combination

Spectral analysis:

Break down the radar images into its spectralcomponents

Use the components as building bricks inrebuild of a single result with properties ofboth radars

swi – storm and wastewater informatics

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