Chapter 5 – The Oceanic Heat Budget
Chapter 5 Contents
(5.1) The Oceanic Heat Budget
(5.2) Heat Budget Terms
(5.3) Direct Calculation of Fluxes
(5.4) Indirect Calculation of Fluxes: Bulk Formulas
(5.5) Global Data Sets for Fluxes
(5.6) Geographic Distribution of Terms in the Heat Budget
(5.7) Meridional Heat Transport
(5.8) Meridional Fresh Water Transport
(5.9) Variations in Solar Constant
(5.10) Important Concepts
5.6 Geographic Distribution of Terms in the Heat Budget
Various groups have used ship and satellite data in numerical weather models to calculate globally averaged values of the terms for Earth’s heat budget. The values give an overall view of the importance of the various terms (Figure 5.6). Notice that insolation balances infrared radiation at the top of the atmosphere. At the surface, latent heat flux and net infrared radiation tend to balance insolation, and sensible heat flux is small.
Figure 5.6 The mean annual radiation and heat balance of the Earth. From Houghton et al., (1996: 58), which used data from Kiehl and Trenberth (1996).
Note that only 20% of insolation reaching Earth is absorbed directly by the atmosphere while 49% is absorbed by the ocean and land. What then warms the atmosphere and drives the atmospheric circulation shown in Figure 4.3? The answer is rain and infrared radiation from the ocean absorbed by the moist tropical atmosphere. Here’s what happens. Sunlight warms the tropical oceans which must evaporate water to keep from warming up. The ocean also radiates heat to the atmosphere, but the net radiation term is smaller than the evaporative term. Trade-winds carry the heat in the form of water vapor to the tropical convergence zone where it falls as rain. Rain releases the latent heat evaporated from the sea, and it heats the air in cumulus rain clouds by as much as 500 W/m2 averaged over a year (S
Phytoplankton strongly influence cloud formation.
Clouds influence the reflection sunlight from earth, which influences earth’s temperature (Meskhidze and Nenes (2006). The phytoplankton release great quantities of a sulfurous gas called dimethyl sulfide which changes the way clouds are formed in the atmosphere. First, sunlight causes chemical reactions that change the gas to sulfate aerosols (microscopic particles in the air). The tiny aerosol particles cause water vapor to condense to form cloud drops. Because about one-third of the sunlight reaching earth is reflected back to space by clouds, any process that influences cloudiness also influences the amount of sunlight that is absorbed by earth.
role of dimethylsulfide in climate systematem
Phytoplankton in the ocean produce dimethyl sulfide (DMS) that is converted to sulfate aerosols (SO4), which influence the amount of sunlight reflected by clouds.
From Oceanic Dimethylsulfide (DMS) and Climate by the Atmospheric Chemistry Program at the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory.
The ocean stores and transports heat.
Temperature in the atmosphere, even global changes in temperature are slowed by the exchange of heat with the ocean. Thus, 18 times more heat has been stored in the ocean since the mid 1950s due to global warming than has been stored in the atmosphere. Most of the heat trapped by greenhouse gases has gone into the ocean, not the atmosphere.
Earth’s climate is the result of the uneven distribution of the temperature at the surface. The difference in temperature between the poles and the tropics eventually leads to winds and ocean currents that carry heat heat from the tropics to the polar regions. The ocean carries heat out of the tropics, and the winds carry heat to higher latitudes.
The tropics are warm because they receive so much sunlight.
The poles are cold because they receive much less sunlight, and because the polar atmosphere is transparent to infrared radiation. They radiate away much more heat than they receive from the sun.
zonal aveage of insolation and emitted radiation
Zonal average of heat gained from the sun (red line) and lost to space by emitted infrared radiation (green line).
Image from Lyndon State College Survey of Meteorology course by Nolan Atkins.
tower based jet fuel production
steering sunlight with radiowaves.. and sound…
Everything Is Connected
From this simple discussion of the climate system, we can conclude that we must understand how earth, with its atmosphere, greenhouse gases, ocean, life, winds, and currents all interact to produce our climate. The ocean is one big part of the earth system. The ocean, atmosphere,and land are connected through the climate system. Changes in one area cause changes everywhere else. Everything is connected, and everything influences everything else.
For example, rain heats the atmosphere. The warm air rises, creating wind. Wind drives ocean currents. Currents help determine where phytoplankton live. Phytoplankton help determine where clouds are formed. Clouds influences where the atmosphere is heated. Heating determines where the ocean evaporates, and the amount of evaporation.
leaving cost to much…