AbstractAbstract Egyptian Meteorological Authority EMA have 6 upper air stations which used two sounding systems Egyptian Meteorological Authority EMA have 6 upper air stations which used two sounding systems

Digicoraiii with Radiotidotite RT 20A ( Vaisala ) and Air sounding system with Radiotidotite (Air) since Digicoraiii with Radiotidotite RT 20A ( Vaisala ) and Air sounding system with Radiotidotite (Air) since 2007 , so we started at 2007 to new development for two upper air station in (Matrouh and Asswan) 2007 , so we started at 2007 to new development for two upper air station in (Matrouh and Asswan) from Air sounding system with Radiotidotite (Air) to usingfrom Air sounding system with Radiotidotite (Air) to using Digicoraiii with Radiotidotite RT 20A and GPS Digicoraiii with Radiotidotite RT 20A and GPS wind finding stations and update the software of DigicoraIII in the upper air stations , In this paper the wind finding stations and update the software of DigicoraIII in the upper air stations , In this paper the available data of wind has been analyzed and We will show that the loosing of upper wind strong available data of wind has been analyzed and We will show that the loosing of upper wind strong relationship with the seasons by using RDF system so we will explain how to avoid and solve this relationship with the seasons by using RDF system so we will explain how to avoid and solve this problems by using new development and operational experience problems by using new development and operational experience in this paper also , we will use in this paper also , we will use DigicoraIII dual-mode GPS/RDF wind finding data Comparison flights executed in Marsa Matrouh st .during DigicoraIII dual-mode GPS/RDF wind finding data Comparison flights executed in Marsa Matrouh st .during 2006 to 2007 by the EMA .2006 to 2007 by the EMA .

The DigiCORA® Sounding System MW31The DigiCORA® Sounding System MW31 with the Radiotheodolite RT20A and GPS wind finding ( Vaisala )( Vaisala ) containscontains

1. Radiotheodolite RT20 system :- Radiotheodolite windfinding is best suited for situations where the balloon elevations from the ground

station remain high throughout the flight. ie. If the balloon elevations remain above about 16°, At low balloon elevations, the measurement errors with Radiotheodolites increase rapidly with decreasing elevation even with larger tracking aerials It is extremely difficult to satisfy the accuracy , if upper winds are consistently very strong,

2. GPS wind finding system :- portable system with small antennas for 403 MHz telemetry and GPS 0wind finding RS92-SGP Radiosonde portable system with small antennas for 403 MHz telemetry and GPS 0wind finding RS92-SGP Radiosonde

for GPS wind Technology, Major Features for GPS wind Technology, Major Features All-digital All-digital code-correlating GPS code-correlating GPS Radiosonde Higher level of PTU Radiosonde Higher level of PTU measurement performance Continuously available, highly accurate wind data codemeasurement performance Continuously available, highly accurate wind data code correlating GPS . correlating GPS .

VaisalaVaisala GPS GPS stationstation

Global Global Positioning Positioning System (GPS)System (GPS)

GPS GPS Signal Signal PathPath

Egyptian Meteorological Authority (EMA) Koubry ELQuobba EMA , Cairo , Egypt , P. BOX :

11784

Fax : 00202 226852789 zanb_f@hotmail.com

Max heights of wind for Matorh st. from (Sep to Dec 2007) RDF

0

10000

20000

30000

40000

12 3456 789101112131415161718192021222324252627282930

No of observations

Max

hei

ght

by m

Sep Oct Nov Dec

Max height of wind for Matroh st. from ( Sep- Dec 2007)GPS

0

10000

20000

30000

40000

1234567 89101112131415161718192021222324252627282930

No of observations

Max

hei

ght

by m

Sep Oct Nov Dec

Max heights of wind for Matroh st. from (J an 2008 to April 2008) GPS

0

10000

20000

30000

40000

123456789101112131415161718192021222324252627282930

No of observations

Max

hei

ght

by

m

J an Feb Mar Apr

Max heights of wind for Matroh st. From ( J an to April 2007 ) RDF

0

10000

20000

30000

40000

1 23 4 56 78 9101112131415161718192021222324252627282930

No of observations

Max

hei

ght

by m

J an Feb Mar Apr

Comparison between two system RDF and GPS in Matroh st.

0

10000

20000

30000

40000

1 2 3 4 5 6 7 8 910111213141516171819202122232425262728293031

No of observations

Max h

eight

by m

Dec RDF Dec GPS

Comparison between two systems RDF and GPS in Matroh st.

0

10000

20000

30000

40000

1 2 3 4 5 6 7 8 910111213141516171819202122232425262728293031

No of observations

Max h

eight

by m

JanRDF JanGPS

Comparison between two systems RDF and GPS in Matroh st.

0

10000

20000

30000

40000

1 2 3 4 5 6 7 8 9 1011121314151617181920212223242526272829

No of observations

Max

hei

ght b

y m

Feb RDF Feb GPS

Max heights of wind for Matroh st. from (May to J un 2008) GPS

0

10000

20000

30000

40000

1 2 34 5 67 8 9101112131415161718192021222324252627282930

No of observations

Max

hei

ght

by m

May J un

In Egypt their are two kinds of jet stream polar and subtropical jet stream passes in winter and autumn this effects the upper winds are very strong which leads to the balloon elevations at about 13 km altitude remains below 20 degree .At low balloon elevations , the measurement errors with Radiotheodolite wind observations increase rapidly with decreasing Elevation even with larger tracking aerials , It is extremely difficult to satisfy the accuracy if upper winds are very strong ,

• We studied the accuracy of data for upper wind observations at all heights by using ( RDF and GPS ) systems in Matroh station since The period from ( 2006 to 2008 ).

from the figures We found that from ( jan to Mar ) the RDF wind observations are smoothed and good accuracy over thick layer at all heights apart from bout 10 km , this layer increasing to about 20 km from ( Oct to Dec) , and becomes about 25 km from ( Apr to Sep) .Also We found that the GPS wind observations are smoothed over average 25 km altitude .

• By comparison of wind observations between the two systems RDF and GPS at ( Dec to feb ) we found that the upper wind bservations of GPS system is giving informations of wind at higher altitude than the RDF system, But from ( Apr to Sep ) the information of wind observations have relatively the same value and altitude because this season is summer in Egypt and weak upper wind so the Radiotheodolite wind observations are smoothed and good accuracy until the balloon burst .so we sugested to using GPS system in the period from ( Oct to Mar ) to avoid the loosing of upper wind observations .

Max heights of wind for Matroh st. from ( May to Aug 2007) RDF

0

10000

20000

30000

40000

12345678910111213141516171819202122232425262728293031

No of observations

Max

heig

ht

by m

May J une J uly Aug

•

Elevation angleElevation angledegreesdegrees

TimeTime

20

True wind speedTrue wind speed

Wind data disturbed Wind data disturbed by ground reflectionsby ground reflectionsbelow 17 below 17 -- 20 degrees20 degrees

Very inaccurate wind data at low antenna elevation anglesVery inaccurate wind data at low antenna elevation angles

Typical Behavior of RadiotheodoliteTypical Behavior of Radiotheodolite

–– Ground levelGround level

Direct Direct signalsignal

Reflected signalReflected signaldistorts data atdistorts data atlow elevationlow elevationanglesangles

Unique antenna designUnique antenna designprovides > 20 dB provides > 20 dB suppression of harmfulsuppression of harmfulground reflectionground reflection

RT20A RT20A -- Ground ReflectionsGround Reflections

TTAA 55124 62337 99008 14060 24023 00094 13260 2403592743 07456 25543 85433 02431 27545 70978 06159 2804250552 25160 27051 40713 26383 27592 30914 40577 2503843381 20186 48784 15372 56982 10622 627// 88106 665/////// 66380 27102 423// 31313 46702 81130=

TTAA 55121 62337 99008 14060 24023 00096 13260 2403792744 07456 25543 85434 02431 27545 70978 06159 2804250552 25160 27051 40713 26383 27599 30914 40577 2711825038 43381 26650 20186 48784 25643 15372 56982 2567210622 627// 25681 88120 647// 25133 77224 26659 4179577247 26650 41833 31313 46702 81130=

Temp message and CLIMAT ApplicationTemp message and CLIMAT ApplicationBy using S/W Digicoraiii v 2.7 ( Vaisala ) we found the observations which contains measurement errors with Radiotedolite wind observations as the figure .Then we loose the accuracy of data wind observations at all the levels of (core of jet stream ) so thisRequired many procedures from the operator to truncation errors of wind observations .So When upper winds are reported using either The TEMP AND CLIMATE report By using S/W Digicoraiii v 2.7 ( Vaisala) it should be checked against the detailed upper wind measurement and the reported messages should be edited to eliminate unacceptable fitting errors before issue. but by using new version Digicoraiii v3.52 with RDF or GPS systems their is no errors in upper wind observations so The TEMP AND CLIMATE reports is ok to issue without any modifications. So we obtain the good information of upper wind observations which it is important for weather forecasting at all latitudes , vital to the safety and economy of aircraft operations and important for safety in military operations also .

EMA suggested To development the all upper air EMA suggested To development the all upper air stations by dual-mode GPS/RDF system ( Vaisala stations by dual-mode GPS/RDF system ( Vaisala ) .) .And put programming for using this dual system And put programming for using this dual system which using RDF system in the summer and spring which using RDF system in the summer and spring and using GPS system in the autumn and winter and using GPS system in the autumn and winter when there is strong in upper wind over Egypt . when there is strong in upper wind over Egypt .

oct

Max height of wind for matroh station from (Aug2007 to Nov2007)

0

10000

20000

30000

40000

50000

1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930

No of observations

Max h

eig

ht

by m

Aug Sep Oct Nov

By statistical method We found the PTU are the same in the two system RDF/ GPS But Wind speed and But Wind speed and Wind direction are not the same .Wind direction are not the same .From figure (A) we found that the percentage of upper wind observations which not pass to 20 km heights is 33 % in month of Nov , 62 % in Dec , 66 % in Jan ,100 % in Feb , 100 % in Mar , 83 % in April but in figure (B) we found that in is period from ( Nov to Mar) the percentage of upper wind observations which not pass to 20 km heights is less than 18 % so we must avoid to using the RDF system in the period of months from ( Nov to Mar) .By using RDF system in the period from ( May to Jul ) this percentage is less than 7 % and from ( Aug to Oct ) is less than 30 % so in this period from ( May to Oct ) we can use RDF system .

2525

3131

2929

2020

2424

1111

44

33

99

22

11

11

NO OF OBS. NO OF OBS. LESS THAN LESS THAN 20 KM20 KM

J un 07J un 0700003.3 %3.3 %

J ul 07J ul 0700006.6 %6.6 %

Aug 07Aug 07111129 %29 %

Apr 07Apr 071414232383 %83 %

Sep 06Sep 06111110 %10 %

May 07May 0700113.3 %3.3 %

100 %100 % 2626 1010 Mar 07 Mar 07

100 %100 % 2626 1414 Feb 07Feb 07

66 %66 % 1818 99 J an 07J an 07

82 %82 % 2121 33 Dec 06Dec 06

33 %33 % 66 44 Nov 06Nov 06

13.3 %13.3 % 22 00 Oct 06Oct 06

PercentagePercentageLESS THAN LESS THAN 20 KM20 KM

NO OF OBS. NO OF OBS. LESS THANLESS THAN15 KM 15 KM

NO OF OBS. NO OF OBS. LESS THAN LESS THAN 10 KM10 KM

Month Month

figure (A)

figure (B)