Ocean Circulation and Weather

This is an article from the American Meteorological Association explaining the role the oceans play in our climate.  It is rather long, however it is a good explanation of how the ocean currents affect our weather.  The ocean is just another piece of the puzzle albeit a large one when figuring our forecasts.  I hope you take the time to read it and see how it figures into the big picture on how our atmosphere works.

This is all explained in one of the books I have also by the AMS which covers all aspects of the weather and how everything works – luckily I found this article on the AMS website which was freely available for publication.


The lower atmospheric circulation and the upper oceanic circulation are closely linked, with the sun being the ultimate source of energy for both circulations. Unequal heating of the atmosphere produces atmospheric circulation and wind. The wind blowing over the surface of the water drives the ocean’s major surface currents. These currents, along with the wind, transfer heat from tropical regions, where there is a surplus, to polar regions, where there is a deficit. The ocean, in turn, releases energy to the atmosphere, which helps maintain the general atmospheric circulation.

The main features of the wind-driven surface circulation are the large, roughly circular current systems, called gyres, which are found in most ocean basins. Driven by the prevailing wind systems and deflected by continental boundaries and Earth’s rotation, the gyres help to redistribute heat from low to high latitudes. Along the western margins of ocean basins, warm ocean currents, such as the Gulf Stream, transport heat poleward. The meanders of these fast moving currents give rise to large rotating warm and cold water rings which are similar to high and low pressure cells observed in the atmosphere. Along the eastern margins of the major ocean basins, currents, such as the California Current, transport cold water to the lower latitudes.

Related to the gyre circulation patterns are other surface circulation features. In the land-locked higher latitudes of the Northern Hemisphere, the prevailing winds drive smaller gyres which redistribute heat to the polar regions. In the higher latitudes of the Southern Hemisphere where there are no blocking continents, strong westerly winds drive the largest volume surface current in the world around Antarctica. Limited by land boundaries, the surface circulation in the northern Indian Ocean actually reverses itself, driven by the seasonally reversing monsoon winds.

Along with widespread horizontal currents at the surface of the world ocean, there are limited regions where vertical circulation is set in motion by persistent winds. In some coastal and equatorial regions, the wind transports warm surface water away from the coast or equator, to be replaced by water from below. This process, called upwelling, brings to the sunlit surface cool, nutrient-rich water which can lead to an increase in biological production.  Recent research is investigating the global connections between the wind-driven surface circulation and the density-driven deep circulation. This is a possible mechanism by which small changes in the surface circulation can influence not only the weather, but climate and climate change.


The Role of the Sun

1.The Sun is the ultimate source of energy that brings about the surface circulation of the ocean.

2.Because of astronomical and atmospheric factors, ocean surfaces in tropical regions receive more of the Sun’s energy over the course of a year than do those at higher latitudes.

3.In tropical regions, the radiant energy received from the Sun exceeds the radiant energy lost from Earth to space. At higher latitudes, radiation loss from Earth is greater than the solar input.

4.The imbalance between radiant energy gains and losses at different latitudes results in a poleward flow of heat that is almost entirely accomplished by atmospheric and oceanic motions.

The Role of the Atmosphere

1.Unequal heating of the atmosphere from underlying ocean and land surfaces produces atmospheric circulations and winds.

2.The frictional effects between the resulting winds and the ocean surface produce the broad-scale horizontal water movements of the ocean’s surface, called surface currents, that tend to resemble the patterns of surface winds.

3.If the Earth were not rotating, the friction of wind blowing on the ocean surface would push a thin layer of the water in the same direction, but at a small percent-age of the wind’s speed. This layer, in turn, would push on the layer beneath and push it into motion. This would continue downward through successive layers, like pages in a book, each with a lower speed than that of the layer above.

Ekman Circulation

1.Since the Earth does rotate, the shallow layer of surface water set in motion by the wind will be deflected to the right of the wind’s direction in the Northern Hemisphere and to the left of the wind’s path in the Southern Hemisphere. This deflection is called the Coriolis effect.

2.Except at the Equator, where there is no Coriolis effect, each layer of water put into motion by the layer above will be further turned in direction because of the Earth’s rotation.

3.When viewed from above, the changes in current direction and decreased speed with increased depth form a spiral pattern called the Ekman spiral.

4.Although the motion of the surface water layer can be up to 45 degrees to the right or left of the wind, the Ekman spiral phenomenon can cause the direction of net transport of water in around the top 100 meters of the ocean to be at right angles to the wind direction. This is called the Ekman transport.

Gyre Circulation

1.The surface circulation of most of the major ocean basins is dominated by large, roughly circular patterns, called gyres, centered at about 30 degrees latitude. As seen from above, they flow clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. The locations are largely determined by the locations of the Earth’s major wind belts, the blocking effects of the continents, and the effects of the Earth’s rotation.

2.Due to Ekman transport, water at and near the surface is moved towards the middle of the gyres from all sides, producing a broad mound of water as high as one meter at the gyres’ centers.

3.In the Northern Hemisphere, water flowing down the sloping mound of the gyres is deflected to the right, due to the Coriolis effect. This reinforces the clockwise circulation of the gyres. In the Southern Hemisphere, the left turning helps to maintain the counterclockwise pattern of the gyres.

4.An added effect of the Earth’s eastward rotation is the westward displacement of the ocean gyre mounds within their ocean basin. The resulting steeper ocean-surface slopes on the western sides of the gyres help produce higher water speeds in those regions. These western boundary currents that flow poleward include the fastest currents of the ocean. They play a major role in transporting heat from the tropics towards the poles.

5.The fast moving western boundary currents are also distinguished by the formation of large rotating warm and cold water rings that form as meanders in the current become pinched off to form eddies. These eddies, which may reach a size of 200 miles (325 km), a rotation speed of over 1 knot (0.5 m/sec), and ex-tend to the seafloor, have similarities with high and low pressure cells observed in the atmosphere.


Surface Circulation Features

1.In the northern Indian Ocean which extends to only 20 degrees North Latitude, the surface circulation is dominated by the monsoon wind systems and under-goes dramatic seasonal reversals in direction.

2.In tropical latitudes, warm surface water is piled up in the western margin of the ocean basins by the steady trade winds and westward flowing equatorial currents. The resulting downhill flows of water in an easterly direction are called equatorial counter currents.

3.Around the Antarctic, where there are no blocking continents, flows the largest volume surface current, the Antarctic Circumpolar Current. It is also known as the West Wind Drift, after the strong winds driving it.

4.In the high latitudes of the Northern Hemisphere, where current flow is driven by cyclonic wind systems and modified by land masses, smaller counterclockwise subpolar gyres form, bringing cold water currents south to the western ba-sins. One of these, the Labrador Current, carries icebergs, like the one instrumental in the sinking of the Titanic, into the North Atlantic shipping channels.

5.Farthest north, the Arctic Sea, which is almost surrounded by land and covered by ice, has a clockwise gyre.

Upwelling

1.There are regions where the winds and surface currents cause surface water to move away from the area and to be replaced by the vertical movement of colder water from below. Such occurrences are called upwelling.

2.In coastal regions, upwelling can result from water being moved by Ekman transport away from the coast by winds along the shore.

3.The Coriolis effect, acting on the westward flowing equatorial currents, moves water away from the equator, to be replaced by equatorial upwelling.

4.By replacing warm surface water with cooler nutrient-rich water from below, upwelling increases the concentration of nutrients in sunlit water that can lead to an increase in biological productivity.

Whole Ocean Circulation

1.On a global scale, the connections between wind-driven surface currents, density-driven deep circulation, and the atmosphere are being investigated.

2.This research into whole-ocean circulation may help to identify the mechanisms by which small changes in surface circulation can influence not only the weather, but climate and climate change as well.


Above it the moon beginning to set over lake Michigan this morning….

We have a large area of rain mainly from Grand Rapids to Lansing this morning.  There is a small chance of rain south of that line today with a better chance of rain and storms developing along the I69 corridor this afternoon.

Today we will see highs in the mid 70s.  Rain chances will be around right on through the weekend with increasing temperatures each day with the mid 80s being more the norm from Sunday on into next week.  We will also see humidity increase…


 

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Jeff(Portland)Mr. NegativeMookieBarry in ZeelandINDY Recent comment authors
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INDY
INDY

Leaves fall in 6 weeks!
Crisp mornings in 10 weeks!
Lights will glow in 14 weeks!
Keep America Great in 2020 …
INDY …

INDY
INDY

Currently 70* degrees out at thee YARDofBRICKS NE of GR nother below average day this Summer for this poor guy I guess lol..INDY

Barry in Zeeland
Barry in Zeeland

Better enjoy it. They’ve been few and far in between this Summer.

Barry in Zeeland
Barry in Zeeland

What is “hot” is going to vary tremendously from one person to another. Some people love to sweat and feel gross, others do not. Some people wear sweaters when it’s 90, others do not. Unfortunately temps are only half of what factors in to feeling hot, dew points are the real killer. Cooler temps today, but with the dew point back to 60 it is “hot” at work today. When we were in Denver a few weeks ago it was 104 degrees, but the dew point was 28. That felt way more tolerable than here when the temp is 85… Read more »

Slim

Indy, so far this year Grand Rapids has had 7 days of 90 or better the average number in the last 30 years for GR is 9. The range is from 0 in 2009 to 32 in 2012. Now for the number of “hot days” I will use a much cooler temperature of 85 as there are posters who feel that anything warmer then 85 is hot. So far this year there have been 27 days of 85 or better at GR the average in the last 30 years is 32 and the range has been from 9 in 2009… Read more »

Mookie
Mookie

GR has also had another 6 days at 89 degrees which feels basically like 90, so splitting hairs I think. It’s been a warm and muggy summer.

INDY
INDY

Just like 99.9 inches of snow = 100.00 inches lol…Love it …INDY

Jeff(Portland)
Jeff(Portland)

More above normal temps are on the way .. Heat returns by the weekend and next week .. No fall like temps in the near future ..

Slim

Then in today’s NWS discussion comes this bit of info

GUIDANCE IS IN RELATIVE AGREEMENT IN SHOWING A MUCH COOLER
AIRMASS DROPPING DOWN THROUGH ONTARIO AND INTO THE GREAT LAKE
REGION FOR WEDNESDAY INTO THURSDAY.”
Not sure if that is fall like but it looks to be much cooler than we now have.
Slim

Mookie
Mookie

Is that the same NWS that said a cold front was coming in this weekend too? LOL Just curious because WOOD has 86,88,86,84,86 Sunday through Thursday now.

INDY
INDY

Cooler then the trio of 90’s that was once said coming for the weekend a few days ago on the blog … I will take mid 80*s thats not to bad for the start of my vacation ..Slim thanks for the stats always nice to have someone that knows what he’s talking about other then the chief Bill Steffens…INDY

Jeff(Portland)
Jeff(Portland)

Some just dont get it .. Let them play in there own world .. lol

INDY
INDY

Sun has poked out we can call this the perfect Summer day now up to 67* currently out at thee YARDofBRICKS NE of GR we will hit 70* degrees today now thanks sun…Time to cut the grass …INDY

INDY
INDY

Currently 63* degrees out at thee YARDofBRICKS NE of GR just missing the sun perfect day I will say will we even hit 70* degrees today? Stay tuned …INDY

Mookie
Mookie

LOL This poor guy. Thought we wouldn’t hit 80 yesterday and thought we wouldn’t hit 70 today…

Mr. Negative
Mr. Negative

ADA – two “rumbles” overnight, and 6/10 of an inch of rain.

Mookie
Mookie

The models keep the heat on for at least another 3-4 weeks! Today’s new CPC for September-November shows above average temps as well. Will 2019 turn out to be our 4th straight above average year?

INDY
INDY

Keep the Heat going?? We have not had any serious heat since the middle of July and that was not even that serious check out Arizona if you want serious heat lol….INDY

Mookie
Mookie

Two above average months in a row and counting. Lots of mid to upper 80’s with a few 90’s so far.

INDY
INDY

I believe only 6 90*s for GR this Summer maybe Slim can jump in with the correct stats ..My opinion of serious hot weather is mid 90*s + I really don’t think 80*s are hot ….Sure will be interesting to see how more 90*s we will squeak out this summer with only 37 days left time is flying..INDY

Slim

Indy the average last day for a 90 day at Grand Rapids is August 19 the latest in the last 30 years is September 26
Slim

Slim

see my new post for the answers to Indy’s questions on the number of “hot days” so far this summer at Grand Rapids’
Slim

Mookie
Mookie

GR hit 80 degrees again yesterday! The streak continues.

Barry in Zeeland
Barry in Zeeland

Good read again MV, ton of info there but in a easy to read style. Now we need a post explaining how average temps and means work. Seems to be some confusion with that.
We finally had rain! 1.23” in fact, way more than we’ve had in total for the past 2 months. The corn that survived the wet Spring was looking pretty spiny and pathetic, should help some.

INDY
INDY

58* degrees out at thee YARDofBRICKS NE of GR damp and cool again outside hopefully the sun comes out today I want to cut the grass its getting long again in some spots ..FAST FACT Yesterday GR had a high of 80* degrees that was below normal I’m thinking today will be below norma aslo in GR which is fine by me have a great Thursday..INDY. .

Barry in Zeeland
Barry in Zeeland

Fast fact: According to the NWS site yesterday’s average mean was 71 and yesterday’s actual mean was 71 making yesterday exactly average.

https://forecast.weather.gov/product.php?site=grr&product=cli&issuedby=grr

Slim

Great Write up today MV
Slim

Slim

Here at my house I recorded 0.94″ of rain last night and I see some sites had over a inch of much needed rain fall. I was outside and boy it feels cool out there this morning and the temperature here at my house is now at 59 with cloudy skies. And this from the NWS here in GR ” BEYOND THAT SEEMS WE GET MORE OF THE SAME, SHORT WAVE AFTER SHORTWAVE ON THE SOUTHERN STREAM. I COULD SEE AN ACTIVE WEATHER PATTERN HERE THROUGH A GOOD PART OF NEXT WEEK. SINCE NEITHER THE NORTHERN OR SOUTHERN STREAM SEEM… Read more »

Rocky (Rockford)
Rocky (Rockford)

Still no 90’s or any heat waves in sight despite the hype about 90’s and how hot it has been! It has been a great summer, not too hot at all! Incredible!

Slim

While it has been warm it has all in all been a very nice summer this year. I see no issues with it at all and here at my house the tomatoes have been great this year. And one last item I do not think you and Indy are the same person. As for next winter? my take at this time….Stay tuned.
Slim

INDY
INDY

Lol Slim you are so right again! I have had Bill Steffens over to thee YARDOFBRICKS I have talked to MV on the phone your on my weather page I believe I have smoked a few jaybirds with uncle Jack need I say more! The trio has a hard time understanding on here especially when it gets hot out….INDY is not ROCKY…INDY …

INDY
INDY

+1000 INDY