Tag Archives: JPL

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.

Orders Countermanded, Comrades! Strong El Nino Is Good For You!

Thus spoke Bill Patzert, an oceanographer and climatologist at NASA’s Jet Propulsion Laboratory, Pasadena, California on Sep 28. 2009:

A macho El Niño like that of 1997-1998 is off the board, but I’m hoping for a relaxation in the tropical trade winds and a surprise strengthening of El Niño that could result in a shift in winter storm patterns over the United States. If the trade winds decrease, the ocean waters will continue to warm and spread eastward, strengthening the El Niño. That scenario could bring atmospheric patterns that will deliver much-needed rainfall to the southwestern United States this winter. If not, the dice seem to be loaded for below-normal snowpacks and another drier-than-normal winter…Don’t give up on this El Niño. He might make a late break and put his spin on this fall and winter’s weather systems

Wait a moment…so now a non-weak El Niño is good? Is this the first time anybody has said anything positive about El Niño?

No, it isn’t. Still, the ENSO has often been described as some kind of scourge. For example, here’s an article from The Independent on Jan 1, 2007:

A combination of global warming and the El Niño weather system is set to make 2007 the warmest year on record with far-reaching consequences for the planet, one of Britain’s leading climate experts has warned.

Professor Jones said the long-term trend of global warming – already blamed for bringing drought to the Horn of Africa and melting the Arctic ice shelf – is set to be exacerbated by the arrival of El Niño, the phenomenon caused by above-average sea temperatures in the Pacific.

The WMO said its latest readings showed that a “moderate” El Niño, with sea temperatures 1.5C above average, was taking place which, in the worst case scenario, could develop into an extreme weather pattern lasting up to 18 months, as in 1997-98. The UN agency noted that the weather pattern was already having “early and intense” effects, including drought in Australia and dramatically warm seas in the Indian Ocean, which could affect the monsoons. It warned the El Niño could also bring extreme rainfall to parts of east Africa which were last year hit by a cycle of drought and floods

And from a brochure published the UK’s Met Office in Nov 2006:

Dry spells are not unusual in the Amazon, but normally occur in El Niño years.

[…] the large number of Indonesian fires and associated increase in carbon emissions during the 1997-1998 El Niño event

And the IPCC (TAR)? Here it is:

El Niño is associated with dry conditions in northeast Brazil, northern Amazonia, the Peruvian-Bolivian Altiplano, and the Pacific coast of Central America. The most severe droughts in Mexico in recent decades have occurred during El Niño years, whereas southern Brazil and northwestern Peru have exhibited anomalously wet conditions

More recently, from the IPCC’s AR4, WG2, chapter 1:

After the accelerated shrinkage of the glacier during the 1990s, enhanced by the warm 1997/98 El Niño, Bolivia lost its only ski area