<p>Millimeters per year measurements have an area component built into them, they're actually in cubic millimeters per square millimeter. So one millimeter of rainfall is enough to cover the given area that rainfall is for to an average depth of one millimeter. For example if the area is a 100 square kilometer catchment then 1mm of rainfall is 100,000,000 cubic millimeters (also millilitres), or 100,000 litres of water. Evapotranspiration is measured using exactly the same unit conventions. Hope that helps.</p>

CC BY-SA 4.0
2018-05-23T14:10:22.463Z
2018-05-23T14:10:22.463Z
Ash
<p>I have been looking for information regarding the total amount of water that evaporates from terrestrial systems and found some global estimates like this one</p>

<p><a href="http://www.waterandclimatechange.eu/evaporation/average-monthly-1985-1999" rel="nofollow noreferrer">http://www.waterandclimatechange.eu/evaporation/average-monthly-1985-1999</a></p>

<p>However, the units are mm/year but that doesn't mean much without the area. Are there any estimates of evapotranspiration that are available? Or how could I calculate evapotranspiration by area using maps such as the ones I have linked to?</p>

<meteorology><evaporation>
Data of terrestrial evapotranspiration over large areas?
Herman Toothrot
# Data of terrestrial evapotranspiration over large areas?

(Asked by: username_0 on 2018-05-23)

I have been looking for information regarding the total amount of water that evaporates from terrestrial systems and found some global estimates like this one

<http://www.waterandclimatechange.eu/evaporation/average-monthly-1985-1999>

However, the units are mm/year but that doesn't mean much without the area. Are there any estimates of evapotranspiration that are available? Or how could I calculate evapotranspiration by area using maps such as the ones I have linked to?

**Tags:** meteorology, evaporation


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## 1 answers

### Answer by username_1 on 2018-05-23. Score: 3

Millimeters per year measurements have an area component built into them, they're actually in cubic millimeters per square millimeter. So one millimeter of rainfall is enough to cover the given area that rainfall is for to an average depth of one millimeter. For example if the area is a 100 square kilometer catchment then 1mm of rainfall is 100,000,000 cubic millimeters (also millilitres), or 100,000 litres of water. Evapotranspiration is measured using exactly the same unit conventions. Hope that helps.


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