Term
| What is a teleconnection? |
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Definition
correlations between weather and climate at widely separated locations.
major source of variability.
allow long-term weather forcasts |
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Term
| describe the normal condition off the West Coast of the US? |
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Definition
warm water piles up in the W. pacific.
Eastern Pac - upwelling along W.Coast creates cold ocean water. Cooling stable air |
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Term
| Describe the El Nino conditions off the west coast of the US |
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Definition
| trade winds die away, wind shifts direction. Low pressure next to W.Coast. thermocline cut off, upwelling stops. |
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Term
| What happens during La Nina? |
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Definition
| normal circulation is enhanced. central tropic pac becomes colder. India/S. america - drought. W. Pac - increased rainfall |
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Term
| What does a negative Southern Oscillation Index indicate? |
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Definition
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Term
| How does the Jet Stream change during an El Nino year? |
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Definition
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Term
| How does the shift of the Jet Stream during El Nino affect North America? |
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Definition
sig. warmer W. Half of continent, due to lack of polar front.
Pac. Subtrop. Jet Stream - cause S. Tier of US to have a wet winter.
Hurricanes bottom out, upper level westerlies strip off the tops of them |
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Term
| How does the Jet Stream affect North America during La Nina? |
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Definition
blocky anticyclone in the NW, ridge brings cold air.
Moisture off of tropics causes wet NW, dry S.
More atlantic hurricanes, not jet stream across S. Continent |
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Term
| What is the most important longscale event? |
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Definition
| Pacific Decadal Oscillation (PDO) |
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Term
| What happens during the cold phase of the PDO? |
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Definition
| big cool pool of water in the E.Pac. Warm pool in the N.E Pac. Fish productivity decreases. |
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Term
| What happens during the warm phase of the PDO? |
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Definition
| warm anomoly in the E. Pac. Cool anomoly in the W. Pac. |
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Term
| what are the impacts of the warm phase PDO |
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Definition
| increased ocean production in NW, reduced ocean production in S. precip and snowpack in high NW, warmer conditions in NW, more rainfall than snowfall |
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Term
| What are the impacts of the Cold Phase PDO |
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Definition
| increase in productivity in the S, decrease in NW ocean productivity, more snowpack and runoff in NW, less precip across US. |
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Term
| What happens during the negative shift in the NAO |
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Definition
H and L weaken and shift, mediteranian wet and stormy. N Eur- cold and drier. SE US - drier storm track, doesn't push storms. Stronger polar easterlies/Polar H/Arctic H.
Weakening of subtropical H and Icelandic L |
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Term
| What happens during the positive shift of the NAO? |
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Definition
| storm track and tropical air, moisture in scandanavia and N. Europe. Dryer Med., SE US - anomolous flow of moist air, onshore storms pushed into E.US. reduction in Arctic H. |
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Term
| Describe the positive arctic oscillation |
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Definition
| weak arctic H, colder stratosphere, stronger upper lvl gradient, stronger circumpolar vortex, warmer surface, wearker low level. less arctic air breaking out. |
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Term
| Describe the negative arctic oscillation |
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Definition
| warmer stratosphere, weaker circumpolar vortex, polar easterlies. stronger surface arctic H, cold air breaks out into N.Amer, N. Eur., coler temps, Polar H stronger |
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