Antarctica case study Flashcards
Location
- Southern Hemisphere
- Around the South Pole asymetrically
- Almost entireley within the Antartica circle
- 66^o latitude
- Sorrounded by the southern ocean
Length of antartica
14km 2
Latitude?
66 degrees south
Landscape
- Covered by thick ice sheet - avg 200m thick
- Fringed by ice shelves
- Dry valleys - found in high altitudes areas of extreme aridity
Antarticas ice shelves
Largest ross and Ronne ice shelf (larger than British Isles), Amery ice shelf
How much of antartica is ice?
98%
Example of Antarticas dry valleys?
Wright Valleu in McMurdo dry valley 5 coast near ross sea
Releif of Antartica
- Transantartic mountain range contains many peaks above 4000m - divides east west ice sheets
- Worlds largest continent avg 2,200 m above sea level
- Thickness of ice gives its highest elevation
- east antartic ice sheet is larger and thicker as it is older than the west ice sheet
- Ellesment mountains - west antartic ice sheet has a higher peak - mount vinsent 4822km
- Most is ice covered except from nunatuks
- Pinnacles of rocks emerging above ice sheets
- Steep - snow doesnt stay and accumulate
Is it worlds highest continent?
Yes - 2,200km above sea level
Transantartic mountain range
contains many peaks above 4000m - divides east west ice sheets
Ellesment mountains
Ellesment mountains - west antartic ice sheet has a higher peak - mount vinsent 4822km
Oceanic currents
- Antartica circumpolar currents
- Antartic convergence
Antartica circumpolar current ACC
- Flows clockwise from west to east around antartica (westwind drift) dominant southern ocean feature - driven by westerly winds
- Strongest current flows all the way around the world transporting the most water
- A lesser current flows in the opposite direction: westward by easterly winds
Antartica convergence
- A curve continuously encircling antartica where cold northward waters meet the relativley warmer waters of the sub antartica creating a zone of upwelling currents nutrients
- Stretches 32-48km
Climate
- Avg temp less than -50 degrees can be as low as -89
- Mean avg wind speed of 50 miles per hour - resulting from the convergent katabatic winds
- Gales can reach up to 200mph
- Mean annual precipitation < less than 50mm per annum
- Is a polar dessert
- Sorrounded by sea warmer temp
- Coastal areas especially peninsula - microclimatic and topographic condtions to allow ablation in the summer so biodiversity increases - climate change affects peninsula
- 97% covered by ice
Avg temp
Avg temp less than -50 degrees can be as low as -89
Avg wind speeds
Mean avg wind speed of 50 miles per hour - resulting from the convergent katabatic winds
Gales can reach up to 200mph
Mean precipitation
Mean annual precipitation < less than 50mm per annum
A polar dessert
Sorrounded by warmer sea
Coastal areas
microclimatic and topographic condtions to allow ablation in the summer so biodiversity increases - climate change affects peninsula
Marine enviroments
- Sea temp ranges from -1.8 near antartica coast and 3.8 near polar front
- Biologically niche area - temp doesnt affect biodiversity of marine - nutrients avaliability sowa (upwelling of currenst intrdouces more nutrients)
- Phytoplankton dirve the food web - very large biomass (bacteria, phyto,zoo)
- 50,000 tonnes of carbon is fixed per 1000km 2 of sea by phytoplankton
- 20% of all photosynthesis on earth. 50% oxygen on earth small as 0.2 diameter
- High levels of phytoplankton, copepods, krill and resultant food chains support fish, whales, seals and penguins
- Upwelling of currents- ice froms, expelling salt, sorrounding water increases in density (nutrient rich water)
- Brine rejection; salty water expelled into sorrounding area and this is aided by cooling water which is then replaced by the warmer water
Sea temp ranges
Sea temp ranges from -1.8 near antartica coast and 3.8 near polar front
Significance of Phytoplankton
Phytoplankton dirve the food web - very large biomass (bacteria, phyto,zoo)
50,000 tonnes of carbon is fixed per 1000km 2 of sea by phytoplankton
20% of all photosynthesis on earth. 50% oxygen on earth small as 0.2 diameter
High levels of phytoplankton, copepods, krill and resultant food chains support fish, whales, seals and penguins
Upwelling of nutrients
Upwelling of currents- ice froms, expelling salt, sorrounding water increases in density (nutrient rich water)
Brine rejection; salty water expelled into sorrounding area and this is aided by cooling water which is then replaced by the warmer water
