From Roy Spencer’s blog (h/t to Ron de Haan)
August 21st, 2009 by Roy W. Spencer, Ph. D.
Since NOAA has announced that their data show July 2009 global-average sea surface temperatures (SSTs) reaching a record high for the month of July, I thought I would take a look at what the combined AMSR-E & TMI instruments on NASA’s Aqua and TRMM satellites (respectively) had to say. I thought it might at least provide an independent sanity check since NOAA does not include these satellite data in their operational product.
The SSTs from AMSR-E are geographically the most complete record of global SSTs available since the instrument is a microwave radiometer and can measure the surface through most cloud conditions. AMSR-E (launched on Aqua in May 2002) provides truly global coverage, while the TMI (which was launched on TRMM in late 1997) does not, so the combined SST product produced by Frank Wentz’s Remote Sensing Systems provides complete global coverage only since the launch of Aqua (mid-2002). Through a cooperative project between RSS, NASA, and UAH, The digital data are available from the same (NASA Discover) website that our daily tropospheric temperatures are displayed, but for the SSTs you have to read the daily binary files and compute the anomalies yourself. I use FORTRAN for this, since it’s the only programming language I know.
As can be seen in the following plot of running 11 day average anomalies, July 2009 was indeed the warmest month during the relatively short Aqua satellite period of record, with the peak anomaly occurring about July 18.
The large and frequent swings in global average temperature are real, and result from changes in the rate at which water evaporates from the ocean surface. These variations are primarily driven by tropical Intraseasonal Oscillations, which change tropical-average surface winds by about 2 knots from lowest wind conditions to highest wind conditions.
As can be seen, the SSTs started to fall fast during the last week of July. If you are wondering what I think they will do in the coming months, well, that’s easy…I have no clue.
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news report video of the ocean temps :
http://www.breitbart.com/voxant.php?id=3772684
NOAA’s information does not agree with the satalite data, CRUT3, which shows a sharp downturn in sea temperatures. Could it be that NOAA is selectively choosing its data in order to be politcally correct. See Dr Roy Spencers latest blog about the comparision between AMSR-E and Crut3. His blog at; http://www.drroyspencer.com
Accurate satellite measurements? Perhaps the actual measurements are accurate, but after accounting for satellite drift and overlapping data, one of the biggest adjustments to any global temperature data series was the UAH satellite record (2005). But also satellite data needs to be calibrated against surface data because they’re measuring different quantities. The satellites ‘measure’ the temperatures (infer from spectral radiance) of ~8 km of the lower troposphere, whereas the surface measurements (thermometers) are taken within a couple of meters of the surface. Both have problems.
The principal cooling of the ocean in the tropics is from evaporation, (followed by cloud cover intensity) if there is a pattern of slower wind speeds across the surface, surface temps in those regions will increase, also higher wind speeds encourage deeper mixng of the surface water further reducing surface temps.. Is there any evidence of such a linkage ?
The tropical storm belt this season seems to have been fairly quiet so far, the recorded increase may simply reflect the atmospheres responce to a quiet sun.
Its been noted that the depth of the atmosphere has shrunk signifigantly in the last 3 years: what impact will this have ?
Then there is the issue of cloud cover : I havn’t seen any recent figures. has the planets cloud cover increased, as some theory’s have proposed in responce to GCR’s increasing. Then there is the issue of whether clouds have a net positive or negative effect on ocean surface temp.
Clouds increase albedo and decrease radiative energy loss.
Is there a link anywhere for the net difference globally ?
Different clouds have different effects and clouds come and go constantly so the calculation would have to be based on averages and assumptions with a sizeable error margin.
On balance I’m inclined to the view that cloudiness variations are not a first order effect in the way that changes in the rate of energy release from the oceans would be.
Thus I suspect that the warming and cooling of the air above the oceans as a result of ocean SST changes would drive cloudiness changes far more effectively than changes occurring in the air alone (such as from increased cosmic rays).
Is there any comparative data either way ?
Another thought…
Just as Willis Eschenbach described so convincingly the multiple tricks that the water and air elements have up their sleeve to provide balacing mechanisms through tropical storms that lower the temperature when solar heating increases… perhaps the opposite is also true in general. Perhaps the loss of tropical-storm-driven evaporation from spray has the general effect of raising sea surface temperatures. And perhaps we can now add the lowering of hurricane frequency to this effect.
Cooler sun >> cooler land temperatures but also >> less ocean storms >> warmer SST – eh??? any hard evidence of this?
“On balance I’m inclined to the view that cloudiness variations are not a first order effect in the way that changes in the rate of energy release from the oceans would be.”
ITCZ Cu-Nims reflect sunlight, they pump trade winds over areas larger than their albedo/shadow effects and they keep going well beyond sundown.
I reckon no clouds 20N to 20S for 6 months would lead to a sharp global temperature spike up, whereas all cloud would cause sharp cooling.
Does that conjecture seem feasible?
Sandy (15:47:42)
I currently see the ITCZ Cu-Nims and all other air circulation systems as part of the mechanism whereby the air responds to changes in the rate of ocean energy release.
The observed latitudinal movements of those systems in the air always seem to follow oceanic phase shifts at approximate 25 to 30 year intervals.
The 6 month example is unhelpful because it cannot happen. No clouds leads to more Outgoing Longwave Radiation from the surface to space so not necessarily a sharp spike up over land or in the air anyway but there would be more energy entering the ocean for a while until the rate of release came to match it so you could get an initial cooling in the air even while the oceans warmed then later the increased energy coming from the oceans would bring the air back to the previous temperature again.
Always remember that the oceans are cooling whilst the air warms and vice versa. There are two entirely seperate regimes in air and water usually (but not always – depending on solar variability) moving in opposite temperature trends
Similar complex consequences if there were solid clouds for 6 months or more but in reverse.
The July peak in SST`s would be from the June heat wave. Higher land temperatures through August will shortly show a new rise in global SST.
I have a question which maybe Dr Roy can best address or anyone else who knows; Just what the heck is the basic physics of these satellite based remote microwave radiometer measurement techniques.
I have a basic distrust of anything that smacks of a “proxy” for something else.
Having spent 25 or more years believing that the only good thermometer for ordinary temperatures is a silicon bandgap thermometer; but one thing it is not is a remote sensing device; in fact that is one of its strengths; it responds to the real temperature of a specific location that in practice can be an area that is as small as 50 x 50 microns or less.
But if Dr Spencer or some other expert can explain this microwave remote thermometer to us; it would be enlightening.
George
First, it has to be established that this ocean warming measurement is real.
I think it is already safe to conclude that whatever is happening is almost entirely natural and not humanmade.
Why? Because (I’m guessing that) humanity does not have nearly enough horsepower to effect such rapid warming and cooling changes.
George E. Smith (14:44:35)
But if Dr Spencer or some other expert can explain this microwave remote thermometer to us; it would be enlightening.
I don’t know exactly what your looking for, but I came across this primer on the methodology of satellite measurement of SSTs some time ago. I found it fairly tough sledding technically but was able to fathom most of it eventually. From the tenor of your comments that I’ve read here I suspect you’ll find it less challenging than I did.
http://fermi.jhuapl.edu/avhrr/primer/primer_html.html
I hope this is the kind of info you were looking for.