Tag Archives: Earth

Model Slaves A Common Feature At NASA

(Don’t miss out on the bonus atmospheric reference at the bottom of this blog)

Should computer modeling be banned from NASA premises? Recent grandiose public statements may suggest as much.

March 1, 2010: NASA.gov: “Chilean Quake May Have Shortened Earth Days

The Feb. 27 magnitude 8.8 earthquake in Chile may have shortened the length of each Earth day.

JPL research scientist Richard Gross computed how Earth’s rotation should have changed as a result of the Feb. 27 quake. Using a complex model, he and fellow scientists came up with a preliminary calculation that the quake should have shortened the length of an Earth day by about 1.26 microseconds (a microsecond is one millionth of a second).

Perhaps more impressive is how much the quake shifted Earth’s axis. Gross calculates the quake should have moved Earth’s figure axis (the axis about which Earth’s mass is balanced) by 2.7 milliarcseconds (about 8 centimeters, or 3 inches). Earth’s figure axis is not the same as its north-south axis; they are offset by about 10 meters (about 33 feet).

March 4, 2010: ASI (Italian Space Agency)’s Space Geodesy Centre in Matera, Italy – since 2004, the Official Primary Combination Centre for the International Laser Ranging Service (ILRS): “The earthquake in Chile and the polar axis: analysis from our centre in Matera

Using data from the International Laser Ranging Service, the global system which uses lasers to measure, with millimetre resolution, the distance between a network of stations on Earth and reflectors on satellites, the ASI Space Geodesy Centre in Matera[…]  calculated the residual motion of the pole in comparison with values from immediately before the earthquake. Preliminary results do not show significant disparities, i.e. greater than one millisecond of arc, equivalent to about three centimetres.

March 11, 2010: NASA.gov: “Did the Chilean Quake Shift Earth’s Axis?

On Feb. 27, 2010, the Chilean quake may have moved the figure axis as much in a matter of minutes as it normally moves in a whole year. It was a truly seismic shift—no pun intended. So far, however, it’s all calculation and speculation. “We haven’t actually measured the shift,” says Gross. “But I intend to give it a try.” The key is GPS.

[…] The stage is set for discovery. “Computing power is at an all-time high. Our models of tides, winds and ocean currents have never been better. And the orientation of the Chilean fault favors a stronger signal.” In a few months Gross hopes to have the answer. Stay tuned.

A dime to the first person that will make Dr Gross acquainted with ILRS!

ps Check out how doubt-free NASA’s outreach has been on the topic

Why did the earthquake in Chile shorten the day? As I explained previously in the chat, the earthquake in Chile caused the mass of the Earth to shift, which caused the figure axis (the axis about which the mass of the Earth is balanced) to change. This change in the mass of the Earth caused a changed in the rotation rate of the Earth, making it speed up slightly, thus shortening the day.

pps Finally, an atmospheric bonus…here’s how ASI explained their results being different from NASA’s

This evaluation differs from those obtained using theoretical models of the planet (such as the one produced by the Jet Propulsion Lab in Pasadena, California) which can estimate the extent of a shift on the basis of geophysical and seismological data. This is the type of calculation used in meteorological forecasts, which are based on data observed before a particular date and on theoretical models of how atmospheric phenomena develop.

And of course they are.

First Law of Planetary Building

First Law of Planetary Building: no two planets will ever be alike.

Corollary #1: if two planets are almost identical, then at least one of them will have at least one outrageously peculiar feature.

Corollary #2: Universes made of perfectly identical planets are not allowed.

The First Law is manifest in the fact that each planet in the Solar System and elsewhere appears to be a unique, very specific experiment with peculiar conditions that are never repeated elsewhere. Even single satellites are all very different from one another. And if you want to top strangeness, how about Corot-7b with its clouds of minerals?

Mineral clouds
Mineral clouds

One objection could be raised about Venus and Earth, or Uranus and Neptune, as both couples look like made of identical twins. However, Venus’s hellish atmosphere and very slow, retrograde rotation are truly outrageously peculiar features; and Uranus basically lies to one side (hence corollary #1).

Corollary #2 is necessary otherwise the First Law is invalidated. It seems plausible, since the number of universes is large but not infinite.

On Climate Sensitivity on Earth and Mars

Is it possible to estimate the most likely values for climate (temperature) sensitivity to CO2 concentrations by studying the atmosphere of the planet Mars?

If it is, the results suggest even a +1C/doubling of CO2 concentration may be too large a value.

—-

First the constants in the calculations (values from Wikipedia unless linked elsewhere):

CO2 molar mass: 44.0095

For Earth’s atmosphere
molar mass: 28.97
mass: 5.148 * 10^18 kg
CO2 concentration: 385ppmv
pre-industrial CO2 concentration: 278ppmv
Greenhouse effect: +33C
Contribution by CO2 to Greenhouse effect: 9% (+2.97C)
 
For Mars’s atmosphere
molar mass: 4.33
mass: 2.5 * 10^16 kg
CO2 concentration: 953,200ppmv
Greenhouse effect: +5C (only due to CO2)

What is then the mass ratio of CO2 between Mars and Earth?

In Earth’s atmosphere: 385ppm volume –> 585ppm mass –> 3.01 * 10^15 kg
In Mars’s atmosphere: 953,200ppm volume –> 967,925ppm mass –> 2.42 * 10^16 kg

Therefore:
CO2 (Mars) = 8.04 * CO2 (Earth) (by mass)

Let’s imagine now to increase CO2 (Earth) by 8.04 times by mass, equating what’s in the Martian atmosphere.

In that case, quick computations show terrestrial atmospheric CO2 concentration would increase to 4,680ppm mass, that is 3,081ppm volume: 8 times the current values, and 11 times the estimated pre-industrial concentration.

What would be the effect on Earth of such an increase? If we follow RealClimate’s and the IPCC’s estimation of a 3C/doubling sensitivity, the result is a whopping +12C compared to today’s, i.e. +14.97C in total.

If, instead, we stick to the estimation that, on its own, a doubling of CO2 should bring around +1C of temperature, the result is +4C compared to today’s. And that would provide a grand total for the CO2-related greenhouse effect of +6.97C

Compare now the figures of +14.97C and +6.97C with what is considered to be the same effect on Mars: +5C.

The above appears to indicate that a plausible value for climate sensitivity is in the region of +0.5C/doubling CO2 concentration.

NASA Discovers New Sun-Earth Connection

Very interesting new findings from Science@NASA (also involving the Goddard Space Flight Center):

Spring is aurora season. For reasons not fully understood by scientists, the weeks around the vernal equinox are prone to Northern Lights. […] This is a bit of a puzzle. Auroras are caused by solar activity, but the Sun doesn’t know what season it is on Earth […]

Such outbursts are called auroral substorms and they have long puzzled space physicists. […]

NASA’s THEMIS mission–a fleet of five spacecraft launched in Feb. 2007 to study the substorm phenomenon […] may have found the substorm power supply–and a springtime connection:

The satellites have detected magnetic ‘ropes’ connecting Earth’s upper atmosphere directly to the Sun,” says Dave Sibeck, project scientist for the mission at the Goddard Space Flight Center. “We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras.”

It turns out that rope-like magnetic connections between Sun and Earth are favored in springtime. It’s a matter of geometry: As Earth goes around in its orbit, Earth’s tilted magnetic poles make different angles with respect to the Sun, tipping back and forth with a one-year cadence. Around the time of the equinox, Earth’s magnetic field is best oriented for “connecting-up” with the Sun. […]

Geomagnetic disturbances are almost twice as likely in spring and fall vs. winter and summer, according to 75 years of historical records […]