Modelling 3 Flashcards
What is the scientific basis behind the General Circulation Model (GCM)?
Conservation law
- energy
- mass
- momentum
Atmosphere is described in grid boxes (100km x 100km)
- altitude
- latitude
- longitude
Each grid boxes calculate 3 basic variables
- temperature
- humidity
- horizontal wind speed
Other variables are determined by the 3 basic variables
- pressure
- vertical wind speed
- precipitation
- clouds
- energy flux
For sub-grid experiments, use parameterization schemes to explain its effects
- turbulence
- cloud microphysics
- precipitation
- aerosol chemistry
What are the differences between meteorological models vs climate models?
Meteorological Models
- deals with the present moment and short-term changes
- e.g. predicting the weather tomorrow
- models are continuously reinitialised
Climate Models
- deals with the past
- analyse change in weather patterns in the long-term
- models are only initialised once
(Feedback Loops)
What is the Stefan-Boltzmann Feedback?
Stefan-Boltzmann Feedback (negative)
- as Earth’s temperature increase, it loses heat by radiation faster than before
- there is a net loss of energy
- as Earth’s temperature decreases, it loses heat by radiation more slowly than before
- there is a net gain of energy
(Feedback Loops)
What is the Ice Albedo Feedback?
Ice Albedo Feedback (Positive)
- as temperature increases, ice melt exposing darker soil
- surface albedo decreases, absorbing more radiation
- as temperature decreases, more ice forms
- surface albedo decreases, reflecting more radiation
(Feedback Loops)
What is the Water Vapour Feedback?
Water Vapour Feedback (positive)
- when atmospheric temperature rises, it can hold more water vapour
- more upward infrared radiation is absorbed, more downward infrared radiation is emitted, resulting in warmer surface
- effect doubles the sensitivity of rising CO2 concentration
(Feedback Loops)
What is the Cloud Infrared Feedback?
Cloud Infrared Feedback (positive)
- as temperature increase, water vapour concentration in atmosphere increase, greater formation of clouds
- clouds let to greater aborption and emission of infrared radiation
- net warming effect
(Feedback Loops)
What is the Cloud Albedo Feedback?
Cloud Albedo Feedback (negative)
- as temperature increase, water vapour concentration in atmosphere increase, greater formation of clouds
- as clouds have high albedos, more solar radiation is reflected back to space
- net cooling effect
(Feedback Loops)
What is the Ocean-dissolved CO2 Feedback?
Ocean-dissolved CO2 Feedback (positive)
- increased greenhouse effect, lead to increase CO2 and warmer oceans
- warmer oceans leads to less of the CO2 being dissolved
- more CO2 remains in the atmosphere, net warming effect
(Feedback Loops)
What is the Terrestrial Vegetation Feedback?
Terrestrial Vegetation Feedback (positive)
- as CO2 increases, forests and vegetation expands
- surface albedo decreases
- net warming effect
(Feedback Loops)
What is the Thermohaline Circulation Feedback?
Thermohaline Circulation Feedback (negative)
- as temp increases, snow melts in North America
- more fresh water is discharged into North Atlantic Ocean, slowing down thermohaline circulation
- less heat is transferred Northwards
- net cooling effect
(Feedback Loops)
What is the Transpiration Feedback?
Transpiration Feedback (positive)
- increased vegetation helps to trap surface moisture
- help to saturate the atmosphere and encourage rain formation
- net heating effect
