<blockquote>
  <p>The ocean plays a key role in this vital cycle of water. The ocean
  holds 97% of the total water on the planet; 78% of global
  precipitation occurs over the ocean, and it is the source of 86% of
  global evaporation. Besides affecting the amount of atmospheric water
  vapor and hence rainfall, evaporation from the sea surface is
  important in the movement of heat in the climate system. Water
  evaporates from the surface of the ocean, mostly in warm, cloud-free
  subtropical seas. This cools the surface of the ocean, and the large
  amount of heat absorbed the ocean partially buffers the greenhouse
  effect from increasing carbon dioxide and other gases. Water vapor
  carried by the atmosphere condenses as clouds and falls as rain,
  mostly in the ITCZ, far from where it evaporated, Condensing water
  vapor releases latent heat and this drives much of the the atmospheric
  circulation in the tropics. This latent heat release is an important
  part of the Earth’s heat balance, and it couples the planet’s energy
  and water cycles.</p>
</blockquote>

<p><a href="https://docsbay.net/water-cycle" rel="nofollow noreferrer">Water Cycle</a> from Global Environmental Change</p>

<p><a href="https://i.sstatic.net/nZpVn.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/nZpVn.png" alt="enter image description here"></a></p>

CC BY-SA 4.0
2019-06-25T02:04:44.173Z
2019-06-25T02:04:44.173Z
pat harkin
<p>Perhaps surprisingly, the average rainfall per unit area over the ocean and continents is not much different, namely about 3.0 mm per m2 per day between +/-60 degrees of latitude (where most of the rain occurs). The oceanic average is based upon IR satellite date of cloud-top temperatures, which correlates pretty well with rainfall. Thinking of tropical rainfall, and particularly monsoon rainfall, there are many regions where the mean annual rainfall exceeds 6.0 mm per day. Against this must be considered the great desert areas where average rainfall is almost nil. The latitudinal variation is graphed in
 <a href="http://www.roperld.com/science/PrecipLatitude_Longitude.htm" rel="nofollow">http://www.roperld.com/science/PrecipLatitude_Longitude.htm</a> .</p>

CC BY-SA 3.0
2015-10-09T14:11:12.147Z
I think you completely underestimate our current knowledge of precipitation over the ocean. The TRMM satellite (http://trmm.gsfc.nasa.gov/) provided 17 years of incredibly high quality precipitation data that has been calibrated. The data coming for a plethora of ship of opportunity is also extremely valuable. With regard to moisture over land, the SMOS satellite (https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/smos) is currently providing an immense amount of high-quality soil moisture data over most of the world.
arkaia
CC BY-SA 3.0
2015-10-09T14:13:14.463Z
Also, the literature on the topic is quite extensive (e.g., http://dx.doi.org/10.1029/2012RG000389, http://dx.doi.org/10.1175/2007JCLI1714.1)
arkaia
CC BY-SA 3.0
2015-10-09T10:02:26.227Z
2016-09-06T14:54:26.540Z
2016-09-06T14:54:26.540Z
Gordon Stanger
<p>The bulk of the planet's precipitation falls from convective storms that develop throughout the Intertropical Convergence Zone (ITCZ). The ITCZ transits north and south of the equator due tracking the sun's zenith throughout the year and is skewed by the position of land, but is generally situated near the equator over the ocean.</p>

<p><img src="https://i.sstatic.net/1tBJA.png" alt="Wikipedia ITCZ"></p>

<p><img src="https://i.sstatic.net/EWxEk.png" alt="Global Precipitation"></p>

<p><a href="http://acd.ucar.edu/~lsmith/GEWEX-JHydroMet8.pdf" rel="noreferrer">Trenberth et al (2006)</a> go into detail describing the different components of the global hydrological cycle, but the core of their research can be summed up in the image below.</p>

<p><img src="https://i.sstatic.net/4OoEj.png" alt="Hydrologic Cycle from Trenberth et all (2006)"></p>

<ul>
<li>~96.5% of the world's water is held in the oceans.</li>
<li>~90% of evaporated ocean water leads to precipitation over the oceans.</li>
<li>~77% of precipitation falls over the ocean.</li>
<li>~10% of evaporated ocean water leads to precipitation over land. This equals the roughly ~10% of runoff that returns to the oceans.</li>
<li>Envirotranspiration from plants plays a noticeable role in the water cycle over land.</li>
</ul>

<p>Personally, I do wonder about the ~77% falling over the ocean.  That number seems a slight bit low given recent remote sensing data of global annual precipitation.</p>

CC BY-SA 3.0
2014-04-17T05:02:52.707Z
2014-04-17T05:15:40.120Z
2014-04-17T05:15:40.120Z
DrewP84
<p>Most of the water cycle studies focus on the processes and changes occurring over land with little emphasis on the ocean. Meanwhile, the ocean covers almost 3/4 of the surface of Earth. How much of the global precipitation and evaporation takes place over the ocean? Is it 75% of the total? If the percentage is higher, why does that occur?</p>

CC BY-SA 3.0
2014-04-16T23:48:09.010Z
The bulk of the planet's precipitation falls from convective storms that develop throughout the Intertropical Convergence Zone (ITCZ).  The ITCZ transits north and south of the equator due tracking the sun's zenith throughout the year, but is generally situated near the equator over the ocean. ~96% of all water available on earth is held by the oceans. Evaporation from the oceans makes ~85-90% of the water in the water cycle. Only ~10% of evaporated ocean water makes it back to land. Unsure about exact precip percents. See: http://www-das.uwyo.edu/~geerts/cwx/notes/chap10/global_precip.gif
DrewP84
CC BY-SA 3.0
2014-04-17T02:19:28.487Z
@DrewP84: that should probably be posted as an answer. It seems to cover it pretty well, and can be expanded later if necessary.
naught101
CC BY-SA 3.0
2014-04-17T02:29:44.727Z
@naught101 I wasn't sure if the answer I gave was detailed enough as a final answer. I don't have any number for the percent of precipitation that falls over ocean vs land.
DrewP84
CC BY-SA 3.0
2014-04-17T02:33:23.163Z
The 10% figure is probably a good first approximation though.
naught101
CC BY-SA 3.0
2014-04-17T05:17:35.587Z
@naught101 Okay, done!
DrewP84
<ocean><precipitation>
What is the percentage of the global water cycle (evaporation, precipitation) that occurs over the ocean?
arkaia
# What is the percentage of the global water cycle (evaporation, precipitation) that occurs over the ocean?

(Asked by: username_0 on 2014-04-16)

Most of the water cycle studies focus on the processes and changes occurring over land with little emphasis on the ocean. Meanwhile, the ocean covers almost 3/4 of the surface of Earth. How much of the global precipitation and evaporation takes place over the ocean? Is it 75% of the total? If the percentage is higher, why does that occur?

**Tags:** ocean, precipitation

> **Comments:**
> **username_1**: The bulk of the planet's precipitation falls from convective storms that develop throughout the Intertropical Convergence Zone (ITCZ).  The ITCZ transits north and south of the equator due tracking the sun's zenith throughout the year, but is generally situated near the equator over the ocean. ~96% of all water available on earth is held by the oceans. Evaporation from the oceans makes ~85-90% of the water in the water cycle. Only ~10% of evaporated ocean water makes it back to land. Unsure about exact precip percents. See: http://www-das.uwyo.edu/~geerts/cwx/notes/chap10/global_precip.gif  
> **username_2**: @username_1: that should probably be posted as an answer. It seems to cover it pretty well, and can be expanded later if necessary.  
> **username_1**: @username_2 I wasn't sure if the answer I gave was detailed enough as a final answer. I don't have any number for the percent of precipitation that falls over ocean vs land.  
> **username_2**: The 10% figure is probably a good first approximation though.  
> **username_1**: @username_2 Okay, done!  

---

## 3 answers

### Answer by username_1 on 2014-04-17. Score: 14 | Accepted answer

The bulk of the planet's precipitation falls from convective storms that develop throughout the Intertropical Convergence Zone (ITCZ). The ITCZ transits north and south of the equator due tracking the sun's zenith throughout the year and is skewed by the position of land, but is generally situated near the equator over the ocean.

![Wikipedia ITCZ](https://i.sstatic.net/1tBJA.png)

![Global Precipitation](https://i.sstatic.net/EWxEk.png)

[Trenberth et al (2006)](http://acd.ucar.edu/~lsmith/GEWEX-JHydroMet8.pdf) go into detail describing the different components of the global hydrological cycle, but the core of their research can be summed up in the image below.

![Hydrologic Cycle from Trenberth et all (2006)](https://i.sstatic.net/4OoEj.png)

* ~96.5% of the world's water is held in the oceans.
* ~90% of evaporated ocean water leads to precipitation over the oceans.
* ~77% of precipitation falls over the ocean.
* ~10% of evaporated ocean water leads to precipitation over land. This equals the roughly ~10% of runoff that returns to the oceans.
* Envirotranspiration from plants plays a noticeable role in the water cycle over land.

Personally, I do wonder about the ~77% falling over the ocean. That number seems a slight bit low given recent remote sensing data of global annual precipitation.


---

### Answer by username_3 on 2019-06-25. Score: 2

> The ocean plays a key role in this vital cycle of water. The ocean
> holds 97% of the total water on the planet; 78% of global
> precipitation occurs over the ocean, and it is the source of 86% of
> global evaporation. Besides affecting the amount of atmospheric water
> vapor and hence rainfall, evaporation from the sea surface is
> important in the movement of heat in the climate system. Water
> evaporates from the surface of the ocean, mostly in warm, cloud-free
> subtropical seas. This cools the surface of the ocean, and the large
> amount of heat absorbed the ocean partially buffers the greenhouse
> effect from increasing carbon dioxide and other gases. Water vapor
> carried by the atmosphere condenses as clouds and falls as rain,
> mostly in the ITCZ, far from where it evaporated, Condensing water
> vapor releases latent heat and this drives much of the the atmospheric
> circulation in the tropics. This latent heat release is an important
> part of the Earth’s heat balance, and it couples the planet’s energy
> and water cycles.

[Water Cycle](https://docsbay.net/water-cycle) from Global Environmental Change

[![enter image description here](https://i.sstatic.net/nZpVn.png)](https://i.sstatic.net/nZpVn.png)


---

### Answer by username_4 on 2015-10-09. Score: 1

Perhaps surprisingly, the average rainfall per unit area over the ocean and continents is not much different, namely about 3.0 mm per m2 per day between +/-60 degrees of latitude (where most of the rain occurs). The oceanic average is based upon IR satellite date of cloud-top temperatures, which correlates pretty well with rainfall. Thinking of tropical rainfall, and particularly monsoon rainfall, there are many regions where the mean annual rainfall exceeds 6.0 mm per day. Against this must be considered the great desert areas where average rainfall is almost nil. The latitudinal variation is graphed in
<http://www.roperld.com/science/PrecipLatitude_Longitude.htm> .

> **Comments:**
> **username_0**: I think you completely underestimate our current knowledge of precipitation over the ocean. The TRMM satellite (http://trmm.gsfc.nasa.gov/) provided 17 years of incredibly high quality precipitation data that has been calibrated. The data coming for a plethora of ship of opportunity is also extremely valuable. With regard to moisture over land, the SMOS satellite (https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/smos) is currently providing an immense amount of high-quality soil moisture data over most of the world.  
> **username_0**: Also, the literature on the topic is quite extensive (e.g., http://dx.doi.org/10.1029/2012RG000389, http://dx.doi.org/10.1175/2007JCLI1714.1)  

---

