The radiations reaching the surface of the ocean or emitted from it can be summarized in the following graph:

image

In summary:

- $I_{sev}$: Net solar radiation.

- $I_e$: Radiation emitted by the Earth.

- $I_H$: Exchange due to droplet input/output.

- $I_E$: Exchange due to water evaporation/condensation.

- $I_c$: Exchange due to conduction.

This graph provides a concise overview of the different forms of radiation interacting at the ocean's surface and the associated energy exchanges.

Radiation is divided into that from the sun (mostly visible) and that from the earth (mostly infrared). When represented as a function of wavelength, it appears as follows:

image

Typical satellite measurements, such as those from the MODIS project, are taken in different channels.

The visible part is measured with three channels:

The infrared part is estimated with the following channels:

The results from the first group are referred to as VIS, while those from the second group are referred to as NIR, although part of the observed spectrum falls within the visible range.

To understand why the separation is made around 750 nm instead of 3 microns, as is normally defined for the infrared range, one must consider the behavior of the albedo. It shows a substantial increase for wavelengths around 750 nm and above, not just from 3 microns onwards (see the albedo chart as a function of wavelength).

Si la intensidad visible del sol es I_s y el albedo de la superficie a_v, la intensidad reflejada ser con list

Of the incident solar radiation the average earth intensity ($I_p$), a fraction the atmosphere coverage for VIS radiation ($\gamma_v$) interacts with the cloud that absorbs a vIS intensity that interacts with the atmosphere ($I_{sav}$), calculated as follows:

equation=9986

If we consider the values from the D1+0 model, the solar radiation is approximately:

$I_s \sim 342 W/m^2$

and a total of:

$I_{sav} \sim 157 W/m^2$

interacts with the atmosphere, indicating that the visible coverage is approximately:

$\gamma_v \sim 0.46$

.

From the average earth intensity ($I_p$), only a fraction reaches the Earth's surface. The determining factor is the atmosphere coverage for VIS radiation ($\gamma_v$), so the vIS intensity reaching the earth's surface ($I_{sev}$) is expressed as:

equation=10324

With a solar intensity of

$I_s \sim 342 W/m^2$

and atmospheric coverage of

$\gamma_v \sim 0.459$

the radiation that reaches the Earth's surface is:

$I_{sev} \sim 185 W/m^2$

This corresponds to 54.1% of the solar radiation. This radiation, which accounts for the loss of intensity due to atmospheric coverage, is known as solar insolation.

From the vIS intensity reaching the earth's surface ($I_{sev}$), a fraction proportional to the albedo of the planet's surface ($a_e$) is reflected, while the remainder is absorbed by the Earth. Therefore, the vIS intensity absorbed by the ground ($I_{ev}$) is calculated as:

equation=10325,1

With an albedo of

$a_e \sim 0.125$

and incident solar radiation of

$I_{sev} \sim 184 W/m^2$

we find that:

$I_{ev} \sim 161 W/m^2$

is the amount of solar radiation absorbed by the Earth. This corresponds to 87.5% of the incident solar radiation.