September Sea Surface Temperatures (SSTs) are now available, and we see downward spikes in ocean temps everywhere, led by sharp decreases in the Tropics and SH, reversing the bump upward last month. The Tropical cooling in particular factors into forecasters favoring an unusually late La Nina appearance in coming months.

HadSST is generally regarded as the best of the global SST data sets, and so the temperature story here comes from that source, the latest version being HadSST3.

The chart below shows SST monthly anomalies as reported in HadSST3 starting in 2015 through September 2017.

The August bump upward was overcome with the Global average matching the lowest level in the chart at February 2015.  September NH temps almost erased a three-month climb; even so 9/2017 is well below the previous two years.  Meanwhile SH and the Tropics are setting new lows for this period.  With current reports from the El Nino 3.4 grid sector, it seems likely October will go even lower, with downward moves across all oceans.

Note that higher temps in 2015 and 2016 were first of all due to a sharp rise in Tropical SST, beginning in March 2015, peaking in January 2016, and steadily declining back to its beginning level. Secondly, the Northern Hemisphere added two bumps on the shoulders of Tropical warming, with peaks in August of each year. Also, note that the global release of heat was not dramatic, due to the Southern Hemisphere offsetting the Northern one.

Note:  Last month someone asked about HadSST calculations, especially as the Global appeared to be a simple average of NH and SH, which would be misleading.  My queries to Met Office received these clarifying responses:

My colleague in the Climate Monitoring and Research team has advised the following:

For HadSST3, we take an area-weighted average of all the grid boxes with data in to calculate the global average. We don’t calculate the two hemispheric series and then average them. In the case of SST, this wouldn’t work because the southern hemisphere ocean area is larger than the northern hemisphere.

The uncertainty that arises from incomplete sampling is estimated and incorporated into the global average SST files. Coverage varies throughout the record with the northern hemisphere being generally better observed, but at other times, coverage is concentrated other places, dictated by where shipping happened to be at those times. Since the mid 2000s drifting buoys have provided a more uniform sampling of the world’s oceans. When we compare to other data sets, we typically compare where both data sets have data which minimizes the coverage problems.

Kind regards,  Misha,  Weather Desk Climate Advisor

Summary

We have seen lots of claims about the temperature records for 2016 and 2015 proving dangerous man made warming.  At least one senator stated that in a confirmation hearing.  Yet HadSST3 data for the last two years show how obvious is the ocean’s governing of global average temperatures.

USS Pearl Harbor deploys Global Drifter Buoys in Pacific Ocean

The best context for understanding these two years comes from the world’s sea surface temperatures (SST), for several reasons:

• The ocean covers 71% of the globe and drives average temperatures;
• SSTs have a constant water content, (unlike air temperatures), so give a better reading of heat content variations;
• A major El Nino was the dominant climate feature these years.

Solar energy accumulates massively in the ocean and is variably released during circulation events.

August Sea Surface Temperatures (SSTs) are now available, and we see an upward spike in ocean temps everywhere, led by sharp increases in the Tropics and SH, reversing for now the downward trajectory from the previous 12 months.  It seems likely the Tropical warming in particular factored into the active hurricane season peaking this month and next.

HadSST is generally regarded as the best of the global SST data sets, and so the temperature story here comes from that source, the latest version being HadSST3.

The chart below shows SST monthly anomalies as reported in HadSST3 starting in 2015 through August 2017.

In May despite a slight rise in the Tropics, declines in both hemispheres and globally caused SST cooling to resume after an upward bump in April.  Then in July a large drop showed in both in the Tropics and in SH, declining over 4 months.  The sharp upturn in August in the Tropics is the unusual feature this month, along with SH rising, resulting in a global average matching the previous two Augusts. Meanwhile the NH is peaking in August as in the past two years, but somewhat lower.  Despite the August warming, ENSO has gone below neutral toward La Nina, and no one expects a rise like 2015 in the coming months.

Note that higher temps in 2015 and 2016 were first of all due to a sharp rise in Tropical SST, beginning in March 2015, peaking in January 2016, and steadily declining back to its beginning level. Secondly, the Northern Hemisphere added two bumps on the shoulders of Tropical warming, with peaks in August of each year. Also, note that the global release of heat was not dramatic, due to the Southern Hemisphere offsetting the Northern one.

Note:  Last month someone asked about HadSST calculations, especially as the Global appeared to be a simple average of NH and SH, which would be misleading.  My query to Met Office received this clarifying response:

My colleague in the Climate Monitoring and Research team has advised the following:

For HadSST3, we take an area-weighted average of all the grid boxes with data in to calculate the global average. We don’t calculate the two hemispheric series and then average them. In the case of SST, this wouldn’t work because the southern hemisphere ocean area is larger than the northern hemisphere.

Kind regards,  Misha,  Weather Desk Climate Advisor

Summary

We have seen lots of claims about the temperature records for 2016 and 2015 proving dangerous man made warming.  At least one senator stated that in a confirmation hearing.  Yet HadSST3 data for the last two years show how obvious is the ocean’s governing of global average temperatures.

USS Pearl Harbor deploys Global Drifter Buoys in Pacific Ocean

The best context for understanding these two years comes from the world’s sea surface temperatures (SST), for several reasons:

• The ocean covers 71% of the globe and drives average temperatures;
• SSTs have a constant water content, (unlike air temperatures), so give a better reading of heat content variations;
• A major El Nino was the dominant climate feature these years.

Solar energy accumulates massively in the ocean and is variably released during circulation events.

July Sea Surface Temperatures (SSTs) are now available, and we can see further ocean cooling led by plummeting temps in the  Tropics and SH, continuing the downward trajectory from the previous 12 months.

HadSST is generally regarded as the best of the global SST data sets, and so the temperature story here comes from that source, the latest version being HadSST3.

The chart below shows the last two years of SST monthly anomalies as reported in HadSST3 including July 2017.

In May despite a slight rise in the Tropics, declines in both hemispheres and globally caused SST cooling to resume after an upward bump in April.  Now in July a large drop is showing both in the Tropics and in SH, declining the last 4 months.  Meanwhile the NH is peaking in July as usual, but well down from the previous July.  The net of all this is a slightly lower Global anomaly but with likely additional future cooling led by the Tropics and also SH hitting new lows for this period.

Note that higher temps in 2015 and 2016 were first of all due to a sharp rise in Tropical SST, beginning in March 2015, peaking in January 2016, and steadily declining back to its beginning level. Secondly, the Northern Hemisphere added two bumps on the shoulders of Tropical warming, with peaks in August of each year. Also, note that the global release of heat was not dramatic, due to the Southern Hemisphere offsetting the Northern one. Note that Global anomaly for July 2017 matches closely to April 2015.  However,  SH and the Tropics are lower now and trending down compared to an upward trend in 2015.

We have seen lots of claims about the temperature records for 2016 and 2015 proving dangerous man made warming.  At least one senator stated that in a confirmation hearing.  Yet HadSST3 data for the last two years show how obvious is the ocean’s governing of global average temperatures.

USS Pearl Harbor deploys Global Drifter Buoys in Pacific Ocean

The best context for understanding these two years comes from the world’s sea surface temperatures (SST), for several reasons:

• The ocean covers 71% of the globe and drives average temperatures;
• SSTs have a constant water content, (unlike air temperatures), so give a better reading of heat content variations;
• A major El Nino was the dominant climate feature these years.

Solar energy accumulates massively in the ocean and is variably released during circulation events.

Roger Andrews as promised has published his analysis of SST (Sea Surface Temperatures) datasets, based on some years of research. The essay is Making the Measurements Match the Models – Part 2: Sea Surface Temperatures and well worth a look.

Some years ago while reading to get up to speed on climate science, I was struck by a Roger Pielke Sr. comment. He said that surface temperatures are serving as a proxy for changes in heat content of the earth climate system, which is the real concern.  And air temperatures are contaminated by fluctuations in water content, such that a degree difference in the humid tropics involves much more additional heat than does the same change in extremely dry polar air.

For those who want to see the math, here it is from the Engineering Toolbox.

The enthalpy of humid air at 25C with specific moisture content x = 0.0203 kg/kg (saturation), can be calculated as 76.9 (kJ/kg). . .The same calculation for moist air at 20C gives a heat capacity of 58.2, so the 5C increase requires 18.7 kj/kg for moist air vs. 5.0 kj/kg for dry air, or a ratio of 1:3.7. Similar ratios apply at all air temperatures above 0C. Subzero air, like that in the Arctic most of the year, shows little difference in heat content between dry or saturated, since cold air doesn’t hold much water vapor. See Arctic Amplication?

One implication is that polar air temperatures lacking moisture are 2-3 times more volatile, leading to the “Arctic Amplication” effect. Even so, a thorough look into weather station records around the Arctic circle undermines fears on that account. See Arctic Warming Unalarming.

The larger point made by Pielke Sr. was that a much better proxy for global warming or cooling is provided by SSTs. Measuring temperature changes in the water itself is a much better idea, giving a more exact indication of changes in heat content. There is also the point that SSTs cover 71% of the planet surface.

Andrews knows well the difficulties in assembling SST datasets, including the bucket era and the engine intake era. He addresses directly the problematic WWII measurements, suggesting they can simply be excluded as bad data without affecting the pattern. He also compares the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) raw global SST series used to generate the global HadSST3 series, which is the most widely cited of the currently-published SST series.

There he finds that prior to 1940, there was systematic warming adjustments making HadSST temps higher than ICOADS. He attributes this to the long-standing belief that Night Marine Air Temperatures (NMATs) should synchronize with SSTs. That assumes that air moisture over the water should be fairly consistent from one location to another, and that marine air would be in thermal equilibrium with the water.

But apparently no studies have proven that assumption. I know of one empirical study of the ocean-air interface which shows considerable fluctuation in both the heat exchange and evaporation rates. See Empirical Evidence: Oceans Make Climate

The graph displays measures of heat flux in the sub-tropics during a 21-day period in November. Shortwave solar energy shown above in green labeled radiative is stored in the upper 200 meters of the ocean. The upper panel shows the rise in SST (Sea Surface Temperature) due to net incoming energy. The yellow shows latent heat cooling the ocean, (lowering SST) and transferring heat upward, driving convection. From An Investigation of Turbulent Heat Exchange in the Subtropics James B. Edson

Thanks to Roger’s work on this, we can conclude that SSTs prior to 1950 have issues, but can be encouraged that HadSST3 since then is reasonably consistent with the raw data. And in the future the ARGO record will become long enough for us to follow the trends.

USS Pearl Harbor deploys Global Drifter Buoys in Pacific Ocean

Summary

The best context for understanding global temperature effects in recent years comes from the world’s sea surface temperatures (SST), for several reasons:

• The ocean covers 71% of the globe and drives average temperatures;
• SSTs have a constant water content, (unlike air temperatures), so give a better reading of heat content variations;
• Major El Ninos have been the dominant climate features these decades.

Solar energy accumulates massively in the ocean and is variably released during circulation events.

June Sea Surface Temperatures (SSTs) are now available, and we can see ocean temps dropping further after a short pause and resuming the downward trajectory from the previous 12 months.

HadSST is generally regarded as the best of the global SST data sets, and so the temperature story here comes from that source, the latest version being HadSST3.

The chart below shows the last two years of SST monthly anomalies as reported in HadSST3 including June 2017.

In May despite a slight rise in the Tropics, declines in both hemispheres and globally caused SST cooling to resume after an upward bump in April.  Now in June a large spike upward in NH was overcome by an even larger drop in SH, now three months into a cooling phase. The Tropics also cooled off so the Global anomaly continued to decline.  Presently NH and SH are both changing strongly but in opposite directions.

Note that higher temps in 2015 and 2016 were first of all due to a sharp rise in Tropical SST, beginning in March 2015, peaking in January 2016, and steadily declining back to its beginning level. Secondly, the Northern Hemisphere added two bumps on the shoulders of Tropical warming, with peaks in August of each year. Also, note that the global release of heat was not dramatic, due to the Southern Hemisphere offsetting the Northern one. Note that June 2017 matches closely to June 2015, with almost the same anomalies for NH, SH and Global.  The Tropics are lower now and trending down compared to an upward trend in 2015.

June satellite measures of air over the land and oceans also shows a sharp drop.  The graph below provides UAH vs.6 TLT (lower troposphere temps) confirming the general impression from SSTs.

In contrast with SST measurements, air temps in the TLT upticked in May with all areas participating in the rise of almost 0.2C.  Then in June SH dropped 0.4C, NH down 0.2C while the Tropics declined slightly. The end result has all areas back to March values except for the Tropics.  June 2017 compares closely with July 2015 but with no signs of an impending El Nino.

We have seen lots of claims about the temperature records for 2016 and 2015 proving dangerous man made warming.  At least one senator stated that in a confirmation hearing.  Yet HadSST3 data for the last two years show how obvious is the ocean’s governing of global average temperatures.

USS Pearl Harbor deploys Global Drifter Buoys in Pacific Ocean

The best context for understanding these two years comes from the world’s sea surface temperatures (SST), for several reasons:

• The ocean covers 71% of the globe and drives average temperatures;
• SSTs have a constant water content, (unlike air temperatures), so give a better reading of heat content variations;
• A major El Nino was the dominant climate feature these years.

Solar energy accumulates massively in the ocean and is variably released during circulation events.