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Re: Re: [DX] Keleistä ja R Juventud Don Bosco
Thomas Giellan juttuihin on syytä suhtautua varauksella; hän mm. kuuluu
siihen laajahkoon amerikkalaiseen koulukuntaan, jonka mukaan ilmiötä nimeltä
globaali lämpiäminen ei ole olemassakaan. Samoin olen nähnyt häneltä
joitakin varsin erikoisia keskiaaltojen etenemistä koskevia näkemyksiä.
Mutta olisipa kiva tietää, onko stratwarm alertin edellytykset olemassa
tällä hetkellä!
73, MR
----- Original Message -----
From: "Tarmo Kontro" <Tarmo.Kontro@xxxxxxxx>
To: <dx@xxxxxxxxxxxxx>
Sent: Wednesday, December 07, 2005 6:06 PM
Subject: Vs: Re: [DX] Keleistä ja R Juventud Don Bosco
Moro
Tiedemiehet voisivat kommentoida tuota "anomaliaa". Siitähän oli puhetta jo
1970-luvulla. Paradoksaalista on, että häiriöitä on eniten juuri syksyn ja
kevään tasauspäivien lähellä, mutta myös hyviä kelejä. Tämä liittynee tuohon
D-kerroksen "anomaaliseen" absorptioon. Toisena tekijänä voisi olla myös
elektronien "aktiivisuus" (en ole katsonut tarkasti, mutta olivat hiljakkoin
korkealla) - vai liittyvätkö nämä yhteen? Tarvitaanko vähän enemmän auringon
valoa täällä pohjan perillä, jotta "ionosfääri toimisi paremmin".
Stratwarm-hälytyksiä ei valitettavasti enää anneta, mikäli ymmärrän oikein.
Ja edelleen häilyy vielä tuo epäilys kelien, saastumisen ja
ilmastonlämpenemisen yhteydestä toisiinsa ...
Pari jutttua kn4lf:n sivuilta
"D Region Mid Winter Absorption Anomaly-
A period of increased MF radio wave absorption at high and mid latitudes
occurring in mid winter and is associated with sudden stratospheric warming
and the Quasi Biennial Oscillation (QBO). If you look in your radio logs for
160 meters you will notice that most of your good DX contacts are in the
fall and spring. This is due to the D Region Mid Winter Absorption Anomaly.
(See definition #17. Sporadic-D (Ds) Absorption & Wave Guiding). (See
definition #19. Sudden Stratospheric Warming (STRATWARM ALERT).
"
"
Sudden stratospheric warming is a major temperature change of the winter
time polar and middle atmosphere from the Tropopause (where the troposphere
transitions into the stratosphere) to the base (D-layer) of the ionosphere,
lasting for many days at a time and characterized by a warming of the
stratospheric temperature by some tens of degrees (temperature inversion),
in unison with adjacent tropospheric cooling.
"
Another way to explain stratospheric warming is a major disturbance of the
winter polar middle atmosphere from the Tropopause to D-region which is at
the base of the Mesosphere resulting from a breakdown of the polar vortex
into two circulation cells. Air trapped in the vortexes is mixed by the new
meridional flow and is exposed to sunlight. Solar lyman alpha ionizes the
nitric oxide gasses resulting in an increase in electron density and
producing strong MF absorption.
A little related Troposphere Meteorology:
Interrelated with the splitting and shifting of the Arctic Circumpolar
Vortex, is a Troposphere level negative North Atlantic Oscillation (NAO) and
Pacific-North America Anomaly (PNA), mid and upper air height anomaly
pattern. This equates to a large high pressure ridge in Western North
America extending northward all the way into the Yukon region of Canada and
a deep trough in the Eastern North America, from the eastern U.S. extending
down into the Yucatan region of Mexico, with a second ridge in the western
North Atlantic Ocean. This pattern is also called a dual blocking ridge and
taps Siberian Arctic air, sending it across the North Pole into the eastern
2/3's of Canada and the U.S. providing for very cold surface temperatures.
As the stratosphere lies below the ionosphere, which is at mesosphere and
thermosphere height, you would not expect to see stratospheric warming
effect medium frequency propagation in any way BUT medium frequency signals
do propagate off of temperature inversions and moisture discontinuities and
a temperature inversion is involved with stratospheric warming. So it's
probable that a medium frequency signal could do any number of things when
scattering off of a temperature inversion, at any height. Unfortunately
though some otherwise very knowledgeable Physicists stubbornly resist this
concept.
You can almost always correlate the coldest weather occurrences with poor
medium frequency propagation conditions.
Also Stratospheric Warming (STRATWARM) has a negative effect on medium
frequency propagation, due to increasing medium frequency radio wave
absorption by the D layer, via upward propagating Internal Buoyancy/Gravity
Waves (IBGW's).
This phenomenon also occurs in southern hemisphere winter but is less
pronounced.
"
73 tk
Tarmo Kontro
Kymenlaakso Polytechnic
PL 13
FIN-48231 Kotka
+358 44 7028 342
fax +358 5 2208209
>>> mauno.ritola@xxxxxxxxx 12/07/05 11:15 >>>
Sama Itä-Suomessa, ei kuulunut mitään Atlantin takaa.
Onko se midwinter anomaly jokin täysin näiden tavallisten indeksien
ulkopuolinen ilmiö?
73, MR
----- Original Message -----
From: "Ari Kilponen" <ari.kilponen@xxxxxxxxxx>
To: <dx@xxxxxxxxxxxxx>
Sent: Wednesday, December 07, 2005 10:51 AM
Subject: [DX] Keleistä ja R Juventud Don Bosco
Moi kaikki,
no jopas jotakin taas, kaikki ennusteet vihreällä, mutta ei vain kuulu
yhtään
mitään lännestä. Siis
tänään keskiviikkoaamuna. Yöllä en kuunnellut. Mitenkäs Etelä-Suomessa?
Apropos R Juventud Don Bosco 1640, Dominikaaninen tasavalta: onko kukaan
raportoinut englanniksi ja saanut vastausta? Meikäläisen espanjan taito kun
on
heikon ja säälittävän rajamailla... Vai
pitääkö alkaa vääntämään raporttia espanjaksi? Toimiiko aseman e-mailosoite?
73's,
ARK
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and/or modified under the conditions set down in the Design Science License
published by Michael Stutz at http://dsl.org/copyleft/dsl.txt
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THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
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published by Michael Stutz at http://dsl.org/copyleft/dsl.txt