Midterm 1 Forced and Unforced Variability Flashcards
Forced variability is caused by an _____ driver (e.g., sun, volcano, us)
external
Unforced variability arises spontaneously or _____ due to interactions between various parts within the climate
system
Therefore, climate is always varying due to this unforced internal variability
on its own
Internal climate modes or Internal unforced variability cause different patterns of ______ around the world with different time scales
variability
El Nino-Southern Oscillation (ENSO)
Normal conditions: trade winds pile warm water in western tropical Pacific, ocean east-west
temp difference causes atmospheric pressure difference that strengthens easterly winds and
reinforces ocean temperature difference (ocean-atmosphere feedback)
El Nino: warm water sloshes back east, pressure difference and winds weaken
Has ripple effects around the world
Switches every ______ or so
few years
EL NINO changes the wind patterns, and therefore shifts heat and moisture from one region to another
North Atlantic Oscillation (NAO)
Based on atmospheric pressure difference between subpolar and subtropical Atlantic. Affects
waviness of storm track in North Atlantic region. Oscillates every few years.
Every few years
Atlantic Multidecadal Oscillation
Temperature of _______ ocean relative to rest of world. Sometimes warmer, sometimes
cooler, switches every few decades. Thought to be due to oscillations in strength of the ocean
conveyor belt.
North Atlantic
_________ reflects the sum of these unforced internal variations plus any forced changes –
we need to separate them to understand if/to what extent humans may be forcing climate change
Temperature variability
_______ has big effect on any given region, though largely cancels out at larger scales (usually
causes warm blob in one spot and cold blob in another), so forced climate changes are easiest to detect
with global temperature
It causes the largest fluctuations at local scales by sloshing heat from one place to another.
Internal variability
