Friday, January 31, 2014

What's so gneiss about this?

This photo was taken in the Spanish Peaks south of Bozeman, MT. To learn more about the processes that form gneiss, CLICK HERE.

Friday, January 17, 2014

Pacific Decadal Oscillation - Another Player in the Climate Game

An anchorman on one of the major networks recently mentioned the "Pacific Decadal Ocsillation" during a story about weather. I'd heard about the PDO during my involvement in a research program at the Montana State University Paleoclimatology Lab a couple years ago, but never really understood it - and certainly didn't expect to be hearing about it on the 5 o'clock news!

In my quest to learn more, I found a few websites that provided explanations posted by various organizations. The State Climate Office of N. Carolina provides a general explanation that was very helpful, considering my limited expertise in this area. According to the climate office, The Pacific Decadal Oscillation (PDO) is a pattern of Pacific climate variability similar to ENSO (El Niño - Southern Oscillation) in character, but which varies over a much longer time scale. The PDO can remain in the same phase for 20 to 30 years, while ENSO cycles typically only last 6 to 18 months. The PDO, like ENSO, consists of a warm and cool phase which alters upper level atmospheric winds (compare PDO and ENSO). Shifts in the PDO phase can have significant implications for global climate, affecting Pacific and Atlantic hurricane activity, droughts and flooding around the Pacific basin, the productivity of marine ecosystems, and global land temperature patterns. Experts also believe the PDO can intensify or diminish the impacts of ENSO according to its phase. If both ENSO and the PDO are in the same phase, it is believed that El Niño/La Nina impacts may be magnified. Conversely, if ENSO and the PDO are out of phase, it has been proposed that they may offset one another, preventing "true" ENSO impacts from occurring.

According to the University of Washington's Joint Institute for the Study of the Atmosphere and Ocean (JISAO), during the warm phase (aka positive phase), higher than normal sea-surface heights caused by warm water form a horseshoe pattern that connects the north, west and southern Pacific, with cool water in the middle (map). During most of the 1980s and 1990s, the Pacific was locked in the PDO's warm phase (see graph below), during which these warm and cool regions are reversed. The JISAO site also notes that "Pacific Decadal Oscillation" was coined by fisheries scientist Steven Hare in the mid-1990's while researching connections between Alaska salmon production cycles and Pacific climate.

Like the ENSO, the cause of the PDO is not understood - and like the ENSO, we may be hearing (and learning) more about the PDO in the years to come. Finally, here is a 6-minute YouTube explanation of the POD.

Thursday, January 9, 2014

Polar Vortex Grabs Media Attention!

Several years ago, in attempt to understand ozone depletion, I learned of the role that the (southern) polar vortex plays in the forming the "hole in the ozone" over Antarctica every September-November (spring in the southern hemisphere). The southern vortex contributes to the formation of the hole by isolating the air over Antarctica every winter-spring, and then breaks up every December (summer in the southern hemisphere), so the hole goes away. Although the vortex forms during the winter, the hole doesn't form until the spring because sunlight is needed separate Cl atoms from the CFC molecules - and there is no sunlight over the South Pole during the winter. To learn more about the role the southern vortex plays in ozone depletion, CLICK HERE (NASA site).

The NASA graphic above shows the correlation between ozone depletion, the location of the vortex, and temperature over the Arctic. The globe on the left shows that there is ozone depletion over the Arctic (every spring), but it is not bad enough to be called a "hole". To learn more about why ozone loss is worse over the South Pole, why the hole only forms in the spring (Sept-Oct), and the conditions that team up to cause the hole, CLICK HERE.

Although, the southern vortex is bigger, stronger, and lasts longer than its northern counterpart, it was the northern polar vortex grabbing all the headlines last week. There's NEVER been as much news coverage about the vortex as there was during the recent cold spell - In fact, very few Americans had ever heard of the polar vortex until this outbreak of cold weather. Here are some sources that may be helpful:

1. The Washington Post has a informative page about how the (northern) polar vortex caused those bitter cold temperatures. The page includes links and graphics.

2. Take a look at this NOAA site.

3. Here is a site that has great graphics from Climate Central.

To view a convenient list of all the resources that have been posted on this "Earth Science Guy" blog site, CLICK HERE.

Friday, January 3, 2014

Mr. Bouchard's Site for Earth Science Teachers

This week's resource is a site created by Mr. Bouchard, a teacher at Earl L. Vandermeulen High School in New York. The site includes dozens of PowerPoints 31 labs, and other resources. CLICK HERE to access the many resources Bouchard has to share.

If you know of any other sites designed specifically for Earth Science teachers, please let me know. Here is my "Rodney's Homepage for Earth Science Teachers": You will find my email address there.