JOANNEUM RESEARCH Institute of Applied Systems Technology (IAS) (Director Prof. Otto Koudelka)

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Institute ofApplied Systems Technology

The Second International Workshop on Global Precipitation Measurement Ground Validation, September 27-30, 2005. Taipei, Taiwan

JOANNEUM RESEARCH

Institute of Applied Systems Technology (IAS)(Director Prof. Otto Koudelka)

Graz / Austria

Precipitation Ground Validation in Austria

M. Schönhubere-mail: [email protected]

phone: +43 – 316 – 876 – 2512fax: +43 – 316 – 876 - 92512

IAS Radar and Propagation Research Group:Head: Prof. W.L. RandeuK. Köck, E. Kubista, G. Lammer, T. Prechtl, E.M. Richter, M. Schönhuber, N. Witternigg

Close cooperation with Radar and Propagation Research Group IBK / TU Graz / Austria

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IAS Contribution to GPM Ground Validation

CONTENTS

• Motivation

• IAS Expertise

• Proposed IAS actions for GPM GV

• Summary and Conclusion

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Motivation

Why an Austrian contribution to GPM GV

• geographical situation of Austria rises specific questions to GPM analyses

• special orographic conditions

• Austria faces precipitation related phenomena like floods and droughts

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Motivation: Austria‘s geographical situation:high precipitation totals in the Alpine mountain regions

Annual Precipitation in Europe

Austria, mainly located in the Alpine mountain region, faces high precipitation totals, which elsewhere in Europe are reached by the western coastal areas only. Solid and mixed phase precipitation events are frequent.

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Motivation: mountaineous terrain, half Atlantic and half continentally oriented (= high storm probability at the southern rim of the Alps)

Mountaineous terrain in Austria: map section of valley Salzach, not far from the city of Salzburg. Height profile leads to questions arising when interpreting satellite data.

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Motivation: Geographical situation of Austria rises specific questions to GPM analyses

Important specific aspects for GPM analyses:

- considerable part of precipitation reaches ground in solid or melting state

- steep mountain height profiles cause even nadir looking instruments to observe non-uniformly filled beams (partly clutter, partly precipitation).

- specific climate type in Europe

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Some precipitation related phenomena in Austria:Austrian winter: skiing resorts and avalanches

Skiing in Austria: competition at the traditional JOANNEUM RESEARCH skiing trip, March 2005

Avalanches: the Austrian Armed Forces assisting rescue work

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Some precipitation related phenomena in Austria:Floods and droughts

Crop damage during drought and heat in 2003;in Graz / Austria 40 ‚tropic days‘ ( > 30 deg C)instead of 4 usual ones

Flood of August 21, 2005, in Graz / Andritz

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IAS relevant experience (1)

IAS expertise in atmospheric observations and research:

- Atmospheric observations and analyses of precipitation phenomenaBased on data of ground based instruments (Radar, Lidar, Radar Network, disdrometers, ...) IAS has wide experience in observing and analysing precipitation phenomena. This includes statistical analyses for communication purposes (e.g. worst month considerations, site diversity statistics, ...), statistics on cloud layers derived from Lidar data, as well studies on precipitation microstructure comparing imaging 2D-Video-Distrometer with polarimetric radar data.

- Recent focus on mixed phase and solid precipitation eventsIAS in cooperation with TU Graz recently carried out investigations on particle characteristics and wave propagation in mixed phase and solid precipitation in more detail, including calculations of scattering amplitudes for snowflake models derived from 2D-Video-Distrometer data.

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IAS relevant experience (2)

IAS expertise in atmospheric observations and research:

- Flood related issues:e.g. within the EU Project MEFFE (FP4), contributing to comparisons with space borne data

- Hardware development and system maintenanceIAS has a long tradition of developing, manufacturing and operating instruments and systems for tropospheric observations, via cooperation with TU Graz also in weather radar networking. IAS is the supplier of the 2D-Video-Distrometer, which originally was developed to meet own needs.

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IAS expertise: modelling work for propagation, navigation and hydrological purposes.

Rain event recorded by Austrian weather radar network in August 21, 2005, when severe floods occurred (Courtesy: Austro Control GmbH, Vienna).

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IAS expertise: modelling work for propagation, navigation and hydrological purposes.

Analysis of radar reflectivities and propagation parameters along slantpath. Melting layer model integrated

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IAS expertise: flood related issues, e.g. within project MEFFE (EU FP4)

3D representation of storm event, as recorded by dual pol. C-band research weather radar Graz / Hilmwarte, for verification of space borne data

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IAS expertise: data acquisition for atmospheric studies

Part of scenario proposed for acquisition of ground validation data

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IAS expertise: mixed phase scattering studies

Investigations on mixed phase and solid precipitation. Award winning conference contribution in this field (best poster paper on propagation, AP2000, Davos / Switzerland).

Ongoing analyses of calculation of precipitation particles scttering for ice and snow, first tests of algorithms for nonrevolution particles.

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IAS expertise, in cooperation with TU Graz:Modelling a 3D particle from 2DVD snowflake data

front and side view of a snowflake, as recorded by the imaging 2D-Video-Distrometer (2DVD)

modelling a 3D particle from snowflake data, volume cut out from spheroid is 78 mm3

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IAS expertise, in cooperation with TU Graz:radar cross section results for snowflake model

Scattering direction given by and . Incidence: along x-axis (from neg. to pos. x-values!) vertical polarisation

RCS plot for 78 GHz, based on preconditions shown in above figures

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Proposed IAS actions for GPM Ground Validation:collection of a data base

Collection of a data base for atmospheric studies, with focus on Austria, especially on Styria and the city of Graz:

including for a period of three years (at least):

* the Austrian Weather Radar network (4 C-band radars)

* raingauge network, focus on the federal state of Styria

* 2D-Video-Distrometer (2DVD) in Graz / Austria

* a Lidar in Graz / Austria

* auxiliary data

* potentially a research radar in Graz / Austria (depending on availability)

* a second 2DVD at Mt. Schöckel, some 1000 meters above Graz, in 12 km distance only

REALIZATION OF PLANS DEPENDS ON AVAILABILITY OF PROJECT FUNDING

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Proposed IAS actions for GPM Ground Validation:Data analysis and modelling work (1)

Prediction of space borne observables (1):

Ground validation data shall be analysed to predict the reflectivities of a space borne precipitation radar, also considering issues of passive space borne measurements. These analyses would include discussions of the following questions, some of them already partly answered in relevant literature:

• individual particles: what is the typical shape of raindrops, snow- flakes, hailstones. Scattering amplitudes for raindrops are well known, how could a reliable model for solid precip. particles look like.

• microstructure: what are typical size distributions in rain, snow and hail events. What are the characteristics of the melting layer in terms of thickness, size distributions, fall velocities, etc.


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Proposed IAS actions for GPM Ground Validation:Data analysis and modelling work (2)

Prediction of space borne observables (2):

* height profile of the precipitation events: what are the individual portions (rain, melting, ice), how is the satellite signal affected

* cloud properties: obtain cloud base height and cloud optical thickness, investigate particle characteristics during drizzle, snow and mixed phase

* geographical considerations: how is the interference of rain and clutter echos in mountaineous terrain.

* spatial distribution of rain: what are typical cell sizes, does the integration over antenna footprint size distort the results ?


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Proposed IAS actions for GPM Ground Validation:Comparisons of predicted and measured spaceborne data

Comparisons of predicted and measured spaceborne data

* IAS will seek cooperation with institutions analysing space borne GPM data and then carry out comparisons between ground based predictions and directly measured precipitation.

* Such comparisons are the only way to answer open questions of space borne data products, improve and enhance precipitation models, explain system insufficiencies, ...


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Summary and Conclusion

GPM and Austrian ground validation work will result in mutual benefits for local interests and for the worldwide GPM community:

* analysing global data the specific local situation (geographic and climatic circumstances) may better be considered and explained with high

quality ground validation data available

* detailed analysis of local situations leads to improved atmospheric modelling with wider validity

* enhanced understanding of precipitation processes may help for improved answers to local requirements, like mitigating the threats by floods, droughts, avalanches, or like securing future fresh water supply and many others more.

JOANNEUM RESEARCH Institute of Applied Systems Technology (IAS) (Director Prof. Otto Koudelka)

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Transcript of JOANNEUM RESEARCH Institute of Applied Systems Technology (IAS) (Director Prof. Otto Koudelka)