Stories tagged La Nina

This old man is as horrified as you are: Summer is over, sir. Time to dig out your sweaters.
This old man is as horrified as you are: Summer is over, sir. Time to dig out your sweaters.Courtesy rocketlass
So ... long-range forecasting teams are predicting that this winter will be really cold and snowy. You know, like last winter.

Commence crying ... now!

Why is another brutal winter likely? Well, for a couple of reasons:

Primarily, the punishing weather is coming because of your bad behavior. I'm referring specifically to your naughty language, and the way you've been taking fivers out of your mom's purse. Did you think there would be no repercussions? Unbelievable. Obviously you've offended Thor, or something. (Not Science Buzz's own Thor, Thor the weather god. Well ... maybe also Science Buzz's Thor.)

Another big reason for the prediction is the angry girl-child herself: La Niña. As you probably know, La Niña is a cyclical weather pattern, originating in the Pacific Ocean off of South America. La Niña also treats the jetstream like a plaything, generally screwing things up for people.

So, you know, enjoy.

Jun
25
2010

Adios El Niño, Hello La Niña?: The Pacific has switched from warm (red) to cold (blue).
Adios El Niño, Hello La Niña?: The Pacific has switched from warm (red) to cold (blue).Courtesy NASA

How to measure ocean temperature

There are many ways to measure the temperature of an ocean. Oceans are big and temperatures at different locations vary. To get a sense of whether the ocean is warming or cooling, lots of spread out measurements need to be made.

  • Thermometers under buoys or ships Since about 1990 an extensive array of moored buoys across the equatorial Pacific Ocean has beamed temperature data from a 1 meter depth up to a satellite. Lots of ships are also recording their intake water temperatures but the depths and locations vary making this data harder to use.
  • Satellite remote sensing NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) SST satellites have been providing global SST (Sea Surface Temperature) data since 2000. Unlike buoys, the satellites can sense the surface temperature everywhere. The temp measured is of the surface only, though. The surface "skin" temp can be quite different than the temp of the water below because of things like evaporation, wind, sunshine, and humidity. Also, cloud cover prevents satellites from sensing surface temperatures.
  • Acoustic Tomography Sound, especially low frequencies, can travel long distances under water. Since the speed of sound under water varies with temperature, measuring how long sound takes to travel a certain distance will give you the average temperature of the water over that distance. Acoustic Thermometry of Ocean Climate (ATOC) is using trans-basin acoustic transmissions to observe the world's oceans, and the ocean climate in particular.
  • Ocean Surface Topography By bouncing microwaves off the the ocean surface and using GPS location, satellites can precisely measure the height of any spot on the ocean surface. Reasoning that water expands and contracts as it heats and cools, then so too would the height of the sea surface. I think Ocean Surface Topography is the easiest and best technique for measuring ocean temperature.
    In a 2005 study researchers compared satellite measurements of sea surface height in the northeast Pacific Ocean from 1993-2004 to recordings of sea surface temperature in the region during the same period. The sea surface height measurements proved to be as accurate as temperature measurements as indicators of ocean conditions resulting from long-term climate cycles as well as being more consistent. PhysOrg

El Niño and La Niña effect on hurricanes

Ocean temperature information is useful in predicting hurricane season severity and forecasting individual storm severity. The image above shows that the Pacific Ocean is changing from hot to cold.

A La Niña is essentially the opposite of an El Niño. During a La Niña, trade winds in the western equatorial Pacific are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. La Niñas change global weather patterns and are associated with less moisture in the air, resulting in less rain along the coasts of North and South America. They also tend to increase the formation of tropical storms in the Atlantic.

"For the American Southwest, La Niñas usually bring a dry winter, not good news for a region that has experienced normal rain and snowpack only once in the past five winters," said Patzert. NASA

Jan
23
2008

Edge of the avalanche: Skiers in Norway this winter were carefully navigating their way along a high-risk avalanche area.
Edge of the avalanche: Skiers in Norway this winter were carefully navigating their way along a high-risk avalanche area.Courtesy Jef Maion
Several recent winters of below average snow falls in the U.S. have left skiers and snowmobilers chomping at the bit. But this year there has been a steady diet of snow to keep everyone schussing and zooming about.

Great news, right? For the most part, yes. But with the increased snow comes increased risk of avalanches. And with the reported avalanche deaths in the country through mid January numbering 15, we’re on pace to top the national record of 35 avalanche-related deaths that was set in the 2001-02 snow season. Typically, there are about 25 avalanche deaths nationwide each winter. In Washington state alone, however, there have been nine deaths already this season compared to an annual average of just two avalanche-related deaths per season.

What’s to blame for the unusual spike in snowy deaths? Weather experts are putting out a couple theories.

Race that avalanche: Science Buzz recommends that you don't try this the next time you hit the slopes. Avalanches can get roll much faster than most of us can ever hope to ski.
Race that avalanche: Science Buzz recommends that you don't try this the next time you hit the slopes. Avalanches can get roll much faster than most of us can ever hope to ski.Courtesy Andre Charland
First, there’s the growing popularity of backcountry skiing and snowmobiling. What used to be the sole domain of specially trained and equipped backcountry experts is opening up to more people seeking those special thrills, some who are not well-trained in avalanche dangers. Snow can break free in an avalanche just from the sound of snowmobiles or the sudden push off of ski.

Second, the western mountain ranges are getting a different combination of snow this season, due in part to La Niña weather conditions. The La Niña has doubled the amount of snowfall in many places in the west, but warmer weather in the fall, and during the snowfalls, have left the snow crust on the top of recent snowfalls weaker and easier to break loose into an avalanche.

Should anything be done with this more-dangerous-than-normal situation? In Europe, they don’t allow people to drive snowmobiles in the Alps to decrease avalanche risks. Should we try something like that here? Or are these snow fans assuming the risks when partaking in activities in like this? Share your thoughts here with other Science Buzz readers.

And courtesy of National Geographic, here's an interactive experience where you can create your own mountain avalanche.

Jul
14
2007

In hot water: These thermal imaging maps show the difference between normal surface water temperatures and El Nino surface water temperatures in the Pacific Ocean. (Photo from the National Oceanic and Atmospheric Administraion Photo Library)
In hot water: These thermal imaging maps show the difference between normal surface water temperatures and El Nino surface water temperatures in the Pacific Ocean. (Photo from the National Oceanic and Atmospheric Administraion Photo Library)
As if our TV meteorologists didn’t have enough warnings and ratings to rattle our cages with, here come two more.

The Climate Prediction Center as announced that it has created a rating scale to measure the impacts up oncoming El Nino or La Nina weather patterns. The new ratings will likely first be issued starting this fall.

Not only will the weather patterns carry a rating on their severity, but warnings and advisories will also be issued through the new program, much like we get thunder storm or tornado warnings or watches. Here are the details:

• A watch will be issued when conditions are ripe for the creation of El Nino or La Nino patterns within the ensuing three to six months.

• An advisory will be issued when the conditions are underway.

• The rating scale will go from 1 to 5 and be done to measure the impact of the El Nino or La Nina after it’s passed, much like the F-scale used to measure tornados.

The strength of the weather conditions is determined by the warmth or coolness of the surface waters in the South Pacific. The names were given to the weather conditions by fishermen from Peru who noticed fluctuations in their catches based on the changing water temperatures.

The new scale will have a bigger impact on allowing researchers to compare weather conditions after they’ve happened, not in predicting how severe new ones will be.

Strong El Ninos and La Ninas can impact weather conditions worldwide. You can learn more about them at the Science Museum of Minnesota's Science on a Sphere display.