Global Oceanic Climate Update for August 2009
Dr. Roy Spencer September 1st, 2009
This is the first of what might turn into a series of monthly updates of some maritime climate parameters monitored by the AMSR-E instrument on NASA’s Aqua satellite. All monthly statistics have been computed by me from daily global gridpoint data produced and archived by Remote Sensing Systems (RSS) under the direction of Frank Wentz, a member of our U.S. AMSR-E Science Team. Since Aqua was launched in 2002, the data are available only since June, 2002. A description of how these products were derived, and where they reside, is provided here.
There are 5 “ocean products”: sea surface temperature [SST]; near-surface wind speed; vertically-integrated water vapor; vertically integrated cloud water; and rain rate. I will present time series of monthly anomalies averaged over the global, ice-free oceans (56 deg. N to 56 deg. S latitude), and separately for the deep tropics (20 deg. N to 20 deg. S latitude). ‘Anomalies’ are departures from the average seasonal cycles in those parameters, which will be recomputed as each new month of data is added.
GLOBAL OCEANS
In the first figure below are plotted the 5 ocean products for the global ice free-oceans (56N to 56S). As can be seen in the top panel, SSTs in August cooled slightly from the unusually warm conditions experienced in July.
I have added linear trend lines to each time series, which you are free to misinterpret as you wish. 
Since the AMSR-E period of record is only 7.25 years long, a calculated trend won’t have much meaning…although it will be interesting to see how long it takes before the climate system obeys the UN’s command to warm, and the SST trend line begins to go uphill again.
How these different variables change relative to each other is illustrated in the following lag-correlation plot of SST versus the other variables. “PDO” is the Pacific Decadal Oscillation Index, while “SOI” is the Southern Oscillation Index (negative for El Nino, positive for La Nina). A discussion of these curves is provided later, below.
TROPICAL OCEANS
The next figure shows the ocean product anomalies for just the deep tropics, 20N to 20S latitude….
…and the lag correlation plot for the deep tropics is next:
DISCUSSION
Using the 20N-20S lag correlation plot as an example, you can see that total integrated water vapor is highly correlated with SST, which in turn is highly correlated with El Nino conditions (negative SOI values).
Also note that sea surface temperature tends to peak after months of anomalously low wind conditions, then falls as wind speeds increase.
Cloud water and rain rates increase as SST increases, reaching a maximum 1 to 3 months after the SST peaked.
lgl (01:18:50)
The period 2005 to 2008 shows two peaks of high SST with a dip in the middle. During that period the wind speed increases in fits and starts. All that means is that the dip in the middle was not enough to disrupt the overall progression of warming SSTs and consequent increase in wind speed.
The warming SSTs cause increasing wind speed until the cooling effect of the extra wind offsets the energy release from the oceans.
From 2007/8 SSTs drop and all the other variables drop to follow the new ocean trend.
“Refer to the lag correlations not the ‘anomalies’ themselves. SST rises to a peak then winds increase, SST falls and wind decreases both with a three month lag. The charts do not reveal whether wind or water initiates the process but going back to basic principles it must be the water.”
Where do ITCZ Cu-Nims fit in? Seems they should be the main SST -> wind converter.
Stephen,
Do you deny that there is more energy in the oceans than in the air ?
No, but ‘all’ the energy is in the Sun, and the thing with the atmosphere is not it’s heat content but it’s ability to emit LWR down to the surface.
If there is 500 W received by the ocean and 499,5 W sent out again (yes it’s not the exact values) I don’t see why the tiny OHC increase is so interesting.
Sandy,
Tell us more.
Sandy (02:59:21)
The ITCZ represents the first step in the response of the air to oceanic forcing. I’m not sure what proportion of the process is attributable to the ITCZ alone.
As you will be aware it moves latitudinally on a seasonal basis but I aver that it also (over and above the seasonal movement) moves latitudinally in response to oceanic forcing.
As the ITCZ shifts so does every other air circulation system on the planet but it is not always obvious because of an element of chaotic variability imposed on the results of the oceanic forcing.
Essentially a faster rate of energy release from the oceans expands the equatorial air masses and pushes the entire air circulation system poleward. in each hemisphere. The speed of the hydrological cycle increases and the rate of energy transfer from surface to space increases.
In due course stability is restored and the equatorial air masses contract again as the rate of energy release from the oceans declines.
A constant climate balancing act induced by the oceans as they vary the rate at which solar energy is released to the air.
It is those latitudinal shifts in all the air circulation systems that account for all observed regional climate changes such the northward and southward oscillation of the position of the Saharan Desert region over the adjoining regions.
wkkruse (06:12:13) :
Richard, RE anomalies. Dr Spencer says in the second paragraph above that “‘Anomalies’ are departures from the average seasonal cycles in those parameters, which will be recomputed as each new month of data is added.”
What Dr Spencer has said there seems pretty clear to me. For example, for the temperature graph, if the data starts from June 2002 through to August 2009. Thats 87 months. You take the absolute global temperatures for each month add them up and divide by the number of months 87. You get the average for those months. Let us assume that comes to 17C. Then the anomalies for each of those 87 months will be the difference from 17C.
Now let us assume that the sept sea temp comes to 16.7. A new average will be computed for 88 months after adding 16.7 to the total, which would be slightly less than 17.
I agree with you, if I get you correctly, that I would be happier if one average were stuck to and that this average were not changed for subsequent graphs. Like Hadley uses the 1961-90 average to compute anomalies for Global temperatures.
Perhaps Dr Spencer might like to tell us if he will recompute the anomalies as I understand it and why this would be better than keeping one standard average?
“lgl (03:29:45) :
Stephen,
Do you deny that there is more energy in the oceans than in the air ?
No, but ‘all’ the energy is in the Sun, and the thing with the atmosphere is not it’s heat content but it’s ability to emit LWR down to the surface.
If there is 500 W received by the ocean and 499,5 W sent out again (yes it’s not the exact values) I don’t see why the tiny OHC increase is so interesting.”
Reply:
OHC is interesting because it is the product of an ever changing balancing act that drives all climate.
The thing with the air is that it loses energy to space as fast as it receives it from sun and oceans.
The downwelling long wave is an irrelevance because it cannot warm the oceans due to it’s inability to get past the layer of water involved in the evaporative process. There is no evidence that any amount of longwave can heat the oceans on a time scale at all relevant to humanity. Some AGW proponents have tried to get round that problem by proposing an ‘ocean skin’ effect but there is little evidence that it actually happens and after much investigation I judge that it should be ignored as unproved, speculative and highly unlikely.
Stephen,
The downwelling long wave is an irrelevance because it cannot warm the oceans due to it’s inability to get past the layer of water involved in the evaporative process
Wrong, the ocean is well mixed several tens of meters down.
There is no evidence that any amount of longwave can heat the oceans on a time scale at all relevant to humanity
And I’m trying to say that OHC is not important. If the downwelling increases 5 W and the upwelling also increases 5 W the OHC is unchanged but the surface is warmer.
lgl (11:20:16)
What does the degree of mixing tens of metres down have to do with infra red longwave hitting the surface and being removed back to the air by increased evaporation ?
“If the downwelling increases 5 W and the upwelling also increases 5 W the OHC is unchanged but the surface is warmer.”
The topmost molecules might be warmer than they otherwise would have been for an instant before they are removed by evaporation. If anything, the water surface that remains should be cooler because the energy taken up as latent heat when the change of state from liquid to gas takes place is more than the energy required to provoke the change of state. I have dealt with that misapprehension of yours previously when others have displayed it. Overall, evaporation is a net cooling process so the faster the rate of evaporation the faster the general flow of energy from ocean to air to compensate for the net cooling effect of the surface evaporation.
Stephen,
Are you saying that increased downwelling will cool the surface? I have an open mind but not that open.
No I don’t go quite that far although it seems logical. More likely the evaporative process just takes the energy it needs from the most readily available source and so it is split between water and air in such a way as not to interrupt the ‘normal’ background flow of energy from sun to sea to air.
All I need is for all or virtually all of any additional downwelling IR to be removed by faster evaporation so that the background energy flow from ocean to air is unaffected by changes in the air.
No one has so far given me evidence that there is ANY net addition of energy to the water as a result of increased downwelling IR, AFTER accounting for the energy required by the extra evaporation.
Can you do so ?