General Propagation Articles
Where Do K and A Come From?
Day-to-Day Variability of the F2 Region
Noise
The Formation of the Ionosphere
Polarization
Disturbances to Propagation
A Look Inside the Auroral Zone
Propagation Planning for DXpeditions
Measuring the Ionosphere
The Sun–Earth Interconnect
Since the late 1800s, it was noted solar activity affected telegraphic lines, and ater, radio communications. However, there was no scientific proof for this link. from the 1920s onward, radio amateurs clearly correlated HF propagation and the MUF to the solar cycle. But again, there was no scientific proof. Astronomers and physicists knew there was a sun–earth connection, but without direct observational data, it remained an un proven scientific theory. The scientific proof did not come until quite recently – basically, the space age – when we got our first look at the sun from outside our protective atmosphere. In the 1970s, the Voyager spacecrafts were the first to confirm the existence of the solar wind. It was not until Skylab that increases in radiation and the solar wind were linked to solar flares, and coronal mass ejections (CME) were first detected. The sun-earth interconnect finally became a scientific fact.
Since then, numerous satellites and ground based instruments monitor the sun and our geomagnetic field in realtime. Today, the radio amateur and QRPer has a wealth of solar information available via the internet that professional astronomers did not have a decade ago. This article, in part, describes how to interpret this internet data, and some of the terminology encountered in the daily reports and solar data from NOAA. Much of the solar physics in this article has been developed by astrophysicists in the past 15 years, and not yet available in other than scientific journals.
In this module you will learn hoe the lower frequency radio spectrum is affected by the environment. Particular emphasis is on HF transmissions and how knowledge about the sun and ionosphere will help you predict how and why HF transmissions vary with time of day, latitude, season and space weather. You should progress through the module in the order below. There are no online answers to the study questions, but you may contact the instructor if there is something you do not understand. Each page below will have navigation button at the bottom of the page that will allow you to return here (the index) or go to the previous or next page.
Nov. 7, 2008: After two-plus years of few sunspots, even fewer solar flares, and a generally eerie calm, the sun is finally showing signs of life.
"I think solar minimum is behind us," says sunspot forecaster David Hathaway of the NASA Marshall Space Flight Center.
ZoneProp uses a widely accepted propagation engine to determine the band on which a contestant in one CQ DX zone is likely to be able to contact a contestant in another CQ DX zone taking into account the current geomagnetic activity.
Sept. 30, 2008: Astronomers who count sunspots have announced that 2008 is now the "blankest year" of the Space Age.
As of Sept. 27, 2008, the sun had been blank, i.e., had no visible sunspots, on 200 days of the year. To find a year with more blank suns, you have to go back to 1954, three years before the launch of Sputnik, when the sun was blank 241 times.
"Sunspot counts are at a 50-year low," says solar physicist David Hathaway of the NASA Marshall Space Flight Center. "We're experiencing a deep minimum of the solar cycle."
Predicting the behavior of a sunspot cycle is fairly reliable once the cycle is well underway (about 3 years after the minimum in sunspot number occurs [see Hathaway, Wilson, and Reichmann Solar Physics; 151, 177 (1994)]). Prior to that time the predictions are less reliable but nonetheless equally as important. Planning for satellite orbits and space missions often require knowledge of solar activity levels years in advance.
A number of techniques are used to predict the amplitude of a cycle during the time near and before sunspot minimum. Relationships have been found between the size of the next cycle maximum and the length of the previous cycle, the level of activity at sunspot minimum, and the size of the previous cycle.
Drop in solar activity has potential effect for climate on earth.
The sun has reached a milestone not seen for nearly 100 years: an entire month has passed without a single visible sunspot being noted.
The event is significant as many climatologists now believe solar magnetic activity – which determines the number of sunspots -- is an influencing factor for climate on earth.
According to data from Mount Wilson Observatory, UCLA, more than an entire month has passed without a spot. The last time such an event occurred was June of 1913. Sunspot data has been collected since 1749.
The sun has reached a milestone not seen for nearly 100 years: an entire month has passed without a single visible sunspot being noted.
The event is significant as many climatologists now believe solar magnetic activity – which determines the number of sunspots -- is an influencing factor for climate on earth.
My website is a conglomeration of solar, space weather, geomagnetic data, as well as my KN4LF 160 Meter (LF, MF, HF, VHF) Radio Propagation.
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