3.b The pathways and processes which control the cycling of water and…
3.b The pathways and processes which control the cycling of water and carbon vary over time
Short term changes to the cycles and the significance of these
Diurnal (daily changes)
Lower temps at night reduce evapouration and transpiration
Convectional precipitation, dependent on direct heating of the ground by the sun, as a daytime phenomena often falling in the afternoon when temperatures hit a maximum.
Particularly significant in climatic regions in the tropics where the bulk of precipitation is from conventional storms.
C02 flows from the atmosphere to vegetation in the daytime.
At night this is reversed
Without sunlight photosynthesis switches off and vegetation loses CO2 to the atmosphere
Same diurnal pattern seen in phytoplankton in the oceans
Short term seasonal changes
Seasonal weather is due to the variations of solar intensity that we receive
The northern hemisphere tilts towards the sun our summer and away in winter.
Southern England receives 5 to 6 times more radiation in June compared to December.
Evapotranspiration highest in summer lowest in winter
Carbon cycle variations ar shown in monthly net primary productivity
In mid-high latitudes day length and temperature limit growth of plant growth and NPP rather than the water availability
During the summer in the northern hemisphere there is a net global flow of CO2 from the atmosphere to the biosphere
Causing a 2ppm in the atmosphere although this is reversed in winter
Conversely in the tropics water availability drives seasonal variations
Long term changes to the water and carbon cycle
4 glacial periods, massive flux of water from the hydrosphere to the cryosphere
Sea level falls by 100-300m during glacials
Biospheric water and carbon store shrinks as glaciers move equator wards and destroy forests and grasslands
General slowing of the water cycle
Lower rates of evapotranspiration during glacials reducing exchanges of water between the atmosphere, biosphere, oceans and soils.
Not sure why but atmospheric carbon drops by around 180ppm during glacials
Tundra replaces forests and huge amounts of carbon are stored in permafrost
The whole carbon cycle slows greatly
Arctic sea ice
NASAS Earth observing system satellites have monitored sea ice growth and retreat since 1978.
Measures microwave energy radiated from earths surface. Time comparison
As well as ground-based estimates of mass balance, satellite technology
Measures surface height of glaciers using laser technology. Shows extent and volume of changes
Sea surface temperatures
Radiometers measure the wave band of radiation emitted from the ocean surface. Changes in global SSTs and areas of upwelling and downwelling
NOAA polar orbiters
Measures cloud liquid water, total precipitable water. Long term trends in cloud cover and water vapour
ESA albedo images from various satellites
Measurments of reflectivity of earths surface and land use changes
NASAS orbiting carbon observatory. Ground based measurements Haiti
New satellite measurements of global atmospheric CO2. Also measures effectivenes of absorption of CO2 by plants.
Primary production in oceans
Measures net primary production in oceans and on land