El Nino, Cryosphere & Biosphere Flashcards
El Niño/Southern Oscillation
- Internal climate variability in Tropical
Pacific based on interaction between ocean
and atmosphere - “Little Boy” or “Christ Child”
- Characteristic warming of surface ocean
waters off Peru - 2-7 year period: El Niño / La Niña
Walker Circulation:
The Walker Circulation regulates global exchange of momentum, heat, and water vapor within the tropics via massive overturning motions. In doing so, it plays an important role in the balance of atmospheric energy in the equatorial region and in determining the characteristics of weather and climate in the tropics.
Tropical Pacific Mean State
- At the equator, the Coriolis Force = 0
- Easterly surface winds => westward
surface ocean current - Warm surface waters get piled up in the
Western Pacific - Horizontal pressure gradient => eastward
equatorial countercurrent below the
surface westward current
Tropical Pacific Mean State
- Upwelling in the Eastern Pacific
- Sloped thermocline
- Warm water in the W. Pacific fuels atmospheric convection
- Cold water in E. Pacific encourages descending air
- Walker circulation in atmosphere drives and is reinforced by the ocean =>
coupled ocean-atmosphere system
Tropical Pacific Mean State
Tropical Pacific climate mean state is more similar to El Niño-like condition during interglacial periods. * ENSO-like conditions along the tropical Pacific are controlled by the earth’s orbital. * Southern Ocean greatly influenced the ENSO-like conditions through the expansion of water masses.
El Niño
- Increased E. Pacific sea surface temperatures
- Shift in convection from W. Pacific to
Central/Eastern Pacific - More precipitation over S. America, less
precipitation over S.E. Asia - Less tilt to the ocean thermocline
- Less upwelling of water in E. Pacific
La Niña
- Decreased E. Pacific sea surface temperatures
- Increased convection in the E. Pacific,
decreased in central/W. Pacific - less precipitation over S. America, more
precipitation over S.E. Asia - Increased tilt to the ocean thermocline
- More upwelling of water in E. Pacific
Local El Nino Impacts
- Fisheries in the E. Pacific are
impacted due to decreased
upwelling of nutrients - Drought and fires are more
prevalent in W. Pacific, affecting
countries such as Indonesia (top)
and Australia (bottom) - Flooding is more prevalent in E.
Pacific, affecting countries such as
Peru - Higher than normal ocean
temperatures can lead to coral
bleaching - Tropical storms in the Pacific are
more common; Hurricanes in the
Atlantic are less common
Global Effects of El Nino
In general, El Nino
conditions lead to
slightly higher global
temperatures due
to more heat
release from the
ocean to the
atmosphere
Cryosphere
Sea ice reflects sunlight, keeping the polar regions
cool and moderating global climate. According to
scientific measurements, Arctic sea ice has
declined dramatically over at least the past thirty
years, with the most extreme decline seen in the
summer melt season.
Land ice (Greenland, Antarctica, glaciers on
mountains) is critically important to global sealevel.
Cryosphere 1
- Sea-ice
- insulation
- ice-albedo feedback
- annual vs. multi-year ice (sea water freezes at -1.9 °C)
Sea-ice stops the release of heat from the oceans to the
atmosphere in winter.
Cryosphere 2
- Glacial ice
- mountain glaciers
‣ > 5 km in tropics => sea level at poles - continental ice sheets
‣ 1000s km extent
‣ 1 to 4 km thick
‣ Greenland and Antarctica
Ice-sheet terminology
- Domes and saddles
- Ice streams and ice lobes
- Basal sliding and surges
- Ice shelves and icebergs and calving
- Marine ice sheets
- Accumulation and ablation
Biosphere
- Organic components of the climate system
- Carbon cycle
- reservoirs and exchanges
- Exchange rate in carbon cycle ~ 1/reservoir
size - Terrestrial biosphere vs. Ocean biosphere
Terrestrial Carbon Cycle
- Photosynthesis and Oxidation
- 6CO2 + 6H2O C6H12O6 + 6O2
- Oxidation => fast (burning) or slow (decomposition) = reverse
of photosynthesis
Transpiration
