A zonal-averaged model of the ocean's response to climatic change
- Victoria Univ., Wellington (New Zealand)
A new vertical mixing model is described. It combines a box-advection-diffusion model with a bulk mixed layer model, which simulates wind mixing and penetrative convection. It is shown that mixed layer models can have steady periodic solutions if either the mixing decays to zero at depth or vertical advection is included. The latter approach is adopted. This mixing model is applied to a series of latitude bands between 50{degree}N and 50{degree}S. It successfully simulates present-day seasonal cycles of temperature and mixed layer depth. It is then subjected to an additional heat flux resulting from an increase in greenhouse gases. For an equilibrium warming of 3C for CO{sub 2} doubling, the model predicts the following transient response: a 0.5-0.8C temperature rise from 1850 to 1990, and a 1.5-2.0C rise from 1850 to 2050. The ocean acts as a thermal buffer, so that the actual warming lags the equilibrium warming by 25-50 years. Mixed layer and deep ocean contribute about equally to this lag. The seasonal cycle of mixed layer depth pumps more heat down to deeper waters, compared to a fixed mixed layer depth model. The heat uptake depends strongly on possible changes in the global thermohaline circulation, which could therefore affect sea level predictions. The climatic warming also leads to a reduction in winter mixing depth in the higher latitudes, whereas the mixing depth in other seasons and latitudes would be mainly affected by wind changes. A scenario for reduced CO{sub 2} emissions shows that the surface warming can be slowed dramatically but that a long-term sea level rise from thermal expansion may be inevitable.
- OSTI ID:
- 5511700
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 96:C4; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
Similar Records
Development of a simple oceanic mixed-layer and sea-ice model for use with an atmospheric GCM. Volume 1
A reduced-gravity, primitive equation, isopycnal ocean GCM: Formulation and simulations
Related Subjects
CLIMATES
VARIATIONS
SEAS
GEOLOGIC MODELS
RESPONSE FUNCTIONS
ADVECTION
BOX MODELS
CARBON DIOXIDE
CONVECTION
DEPTH
DIFFUSION
EMISSION
GREENHOUSE EFFECT
HEAT TRANSFER
HEATING
LATITUDE EFFECT
LAYERS
MIXING
OCEANIC CIRCULATION
OCEANOGRAPHY
SEA LEVEL
SEASONAL VARIATIONS
THERMAL EXPANSION
TIME DELAY
WIND
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DIMENSIONS
ENERGY TRANSFER
EXPANSION
FUNCTIONS
GEOGRAPHICAL VARIATIONS
LEVELS
MASS TRANSFER
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
SURFACE WATERS
540310* - Environment
Aquatic- Basic Studies- (1990-)
540120 - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)