thunderstorm effects on mid-latitude sporadic e ? first results of a data analysis project in...

Thunderstorm Effects on Mid-latitude Sporadic E ?

First results of a data analysis project in amateur radio

Grassmann V. (DF5AI), Cremer S. (DL1DBC)

CAL Mid-term Review and Science MeetingJune 20-24, 2005Elounda, Crete, Greece


Thunderstorm Effects onMid-latitude Sporadic E

Grassmann V., Cremer S.

VHF forward scatter

Examples of 144 MHz long-distance radio propagation via the sporadic E layer (2004)

June 27, 2004

July 08, 2004

June 24, 2004

July 11, 2004

Courtesy of U. Langenohl, DK5YA

– Every year between May and August, radio amateurs establish many hundreds of long-distance communiation links (800-3.500 km) in 144 MHz

– All this communication links are enabled by the scattering properties of sporadic E irregularities resulting in ionospheric single (and rarely double) hop propagation




The speculation of thunderstormstriggering the generation of sporadic E

– Occasionally, severe thunderstorms may be found near the center of the radio paths

– ... leading to the speculation of thunderstorms triggering the generation of sporadic E

– This speculation is however not generally accepted in the community of radio amateurs because thunderstorms effects on sporadic E forward scatter haven‘t yet been demonstrated with scientifc conviction




Launching the project

– 144 MHz forward scatter: represented by ham observation reports including date, time, radio frequency and geographical positions

– Thunderstorms: represented by sferic registrations (low frequency radio pulses emitted by lightning strokes) published by various internet weather services

To verify the speculation, we wish to investigate the spatio-temporal correlation between 144 MHz sporadic E forward scatter and thunderstorms




Automatic data acquisition (1/2)– The sum of all amateur radio stations (in Germany: 1 station per 10 km2)

may be considered a permanent radio observation network

– ... which is supported by various alert systems distributing actual radio propagation reports in the internet and in the packet-radio networks; one of those is the Finnish OH9W/OH2AQ DX Cluster

– The so-called DXrobot internet service (operated by our team member A. Munters, PE1NWL) reads the DX Cluster data and filters the sporadic E reports; it finally triggers ...

– ... our Sferic Retriever system (operated by our team member S. Cremer, DL1DBC) which then accesses the internet weather services to download actual sferic data

– ... resulting in an automated data acquisition system by using existing infrastructure in ham radio and in the internet




Automatic data acquisition (2/2)

The project benefits from various internet services distributing actual radio propagation reports and sferic information




The June 27, 2004 event144 MHz long distance radio paths

Actual sporadic E position = radio path center

Using 144 MHz amateur radio observations, we may recover the spatio-temporal distribution of sporadic E in central Europe on June 27, 2004




The June 27, 2004 eventSporadic E distribution

The number of radio links (bar chart) indicates various phases of high sporadic E activity (green, yellow, red).

Note that red band of high activity extending from southern France to eastern Germany (12-17 UT)




The June 27, 2004 eventSferic distribution

Between 1230 and 1700 UT (right panel), the geographical distribution of sferics (the colour code denotes the number of sferics per 30 minutes) corresponds to the

band of high sporadic E activy (blue dots).




Animated view - introduction

Upper / lower panels: sferics / sporadic ELeft/ right panels: 30 min. interval / cumulated view

Note the band of sporadic E and sferic activity developing from southwest to northeast

Note that the geographical correlation disappears in the northeast

Note, in the animation, the

geographical and temporal

correlation between sferics and sporadic E

in southern France (orange

frame)

1

2

3




Animation




Discussion (1/2)

In the month of June, high sporadic E and high sferic activity are very common; localizing both features in the same geographical region is therefore no surprise.

In this particular case, however, sporadic E and sferic positions show a very similar spatio-temporal distribution.

Does this result indicate the effect of convective thunderstorms generating gravity waves that propagate from the lower into the upper atmosphere which finally supports or stimulates the generation of sporadic E?

Does this result indicate dynamical processes in mid-latitudes similar to the tropical atmosphere where F region phenomena such as travelling ionospheric disturbances (TID) and equatorial spread-F (ESF) are indeed caused by convective thunderstorms?




Discussion (2/2)

We cannot answer this questions with the existing limited material, at present. We cannot even exclude an accidential result.

However, we believe that this result motivates further analyses and also motivates a closer cooperation between scientfic experts and VHF radio amateurs (similar to Aurora research from the 1960s and 1970s).

Amateur radio studies can only consider tracers rather than direct measurements, i.e. 144 MHz radio observations representing the existence of sporadic E and sferics representing the existence of thunderstorms.

Thus, scientific data is required to analyse this phenomenon in detail, i.e. remote sensing techniques by using MST radars and ionosondes in the central European area.




Additional information

This international project is managed and financed on a private and personal basis and does not represent any institution or organisational body. Latest publication:

Thunderstorm effects on sporadic E propagation in 144 MHzGrassmann V., Cremer S., Kraft J., Langenohl U., Munters A., Sampol G.Dubus 1, 9-44, 2005 (ham radio magazine)See also: http://www.df5ai.net/ArticlesDL/Thunderstorm/ThunderstormEffects_v2.pdf

Please refer to this web site to find the authors‘ email address and to retrieve latest project information (http://www.df5ai.net):

We will continue our studies in 2005 and would very much appreciate scientific support from experts in meteorology and upper atmosphere physics.




Acknowledgements

We are grateful to the Blitzinformationsdienst von Siemens (BLIDS), to the

WetterOnline Meteorologische Dienstleistungen GmbH and to the

Wetterzentrale Georg Müller for granting permission of accessing their data

in our analyses.

We thank our ham colleagues J. Kraft (DL8HCZ), U. Langenohl (DK5YA),

A. Munters (PE1NWL) and G. Sampol (EA6VQ) for cooperation and

project support.

thunderstorm effects on mid-latitude sporadic e ? first results of a data analysis project in...

Documents

sporadic e reports

generation of sporadic

sporadic e layer

radio frequency

ham radio

amateur radio grassmann

thunderstorms effects

radio paths