daily timewaster

Monday, March 31, 2025

Stormy weather has returned, and avalanche danger is rising. Three inches of dry snow have fallen uniformly near treeline, with locally deeper amounts of six to ten inches in leeward locations and depressions. The dry snow made for easy wind loading on west, north, and east aspects at light to moderate rates. New drifts and wind lips formed quickly, displaying minor cracking and blocking. In sheltered areas, the snow displayed dry-loose properties. Snow transitioned to rain at 4,500 feet.

On top of Grey Butte.

Photos: Eric Falconer

This vast, developing phenomenon, called the South Atlantic Anomaly, has intrigued and concerned scientists for years, and perhaps none more so than NASA researchers.

The space agency's satellites and spacecraft are particularly vulnerable to the weakened magnetic field strength within the anomaly, and the resulting exposure to charged particles from the Sun.

The South Atlantic Anomaly (SAA) – likened by NASA to a 'dent' in Earth's magnetic field, or a kind of 'pothole in space' – generally doesn't affect life on Earth, but the same can't be said for orbital spacecraft (including the International Space Station), which pass directly through the anomaly as they loop around the planet at low-Earth orbit altitudes.

During these encounters, the reduced magnetic field strength inside the anomaly means technological systems onboard satellites can short-circuit and malfunction if they become struck by high-energy protons emanating from the Sun.

Something tells me this is a normal variation, but we haven't had the tech to notice it until now.

The primary source is considered to be a swirling ocean of molten iron inside Earth's outer core, thousands of kilometers below the ground. The movement of that mass generates electrical currents that create Earth's magnetic field, but not necessarily uniformly, it seems.

A huge reservoir of dense rock called the African Large Low Shear Velocity Province, located about 2,900 kilometers (1,800 miles) below the African continent, is thought to disturb the field's generation, resulting in the dramatic weakening effect – which is aided by the tilt of the planet's magnetic axis.

"The observed SAA can be also interpreted as a consequence of weakening dominance of the dipole field in the region," said NASA Goddard geophysicist and mathematician Weijia Kuang in 2020.

Glad they are studying it, though. The more we know, the better.