{"id":263076,"date":"2023-06-20T19:41:47","date_gmt":"2023-06-20T17:41:47","guid":{"rendered":"https:\/\/climatescience.press\/?p=263076"},"modified":"2023-06-20T19:41:51","modified_gmt":"2023-06-20T17:41:51","slug":"sun-temperatures-and-models","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=263076","title":{"rendered":"Sun, Temperatures, and Models"},"content":{"rendered":"\n
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From Watts Up With That?<\/a><\/p>\n\n\n\n

Guest Post by Willis Eschenbach<\/em><\/strong><\/p>\n\n\n\n

PART THE FIRST \u2013 REAL WORLD<\/strong><\/p>\n\n\n\n

Well, my monkey mind started thinking about the relationship between how much sunshine is absorbed at the surface and the surface temperature. Here\u2019s the CERES satellite data showing the relationship:<\/p>\n\n\n\n

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Figure 1. Surface temperature and how much solar radiation is absorbed at the surface. Radiation is in watts per square meter (W\/m2).<\/em><\/p>\n\n\n\n

As we\u2019d expect given our daily experience, more sunshine raises the temperature and less sunshine lowers the temperature.<\/p>\n\n\n\n

The question naturally arises\u2014just how much does the surface temperature go up for each additional W\/m2 of absorbed radiation at the surface?<\/p>\n\n\n\n

We can approach this question in three different ways. First, here\u2019s a scatterplot of the monthly values shown in Figure 1, along with the trendline.<\/p>\n\n\n\n

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Figure 2. Scatterplot, monthly surface temperature versus how much solar radiation is absorbed at the surface. Because there is uncertainty in the monthly averages, I have used Deming regression rather than standard linear regression.<\/em><\/p>\n\n\n\n

The second way to calculate the relationship between the surface temperature and surface absorbed sunshine is by linear regression on a gridcell basis, weighted by the area of the gridcells. This gives us the same answer, 0.22 \u00b0C per each additional W\/m2 of absorbed solar radiation.<\/p>\n\n\n\n

The third way to examine the relationship looks at the long-term averages of both temperature and absorbed solar radiation as a scatterplot on a gridcell-by-gridcell basis. This allows us to see what is happening at different temperatures.<\/p>\n\n\n\n

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Figure 3. Scatterplot, gridcell averages, temperature versus average absorbed solar radiation. The slope of the red line shows the trend of temperature with respect to absorbed solar radiation at various temperatures.<\/em><\/p>\n\n\n\n

There are several interesting things about this graph. First, over most of the earth (central region above), the relationship between absorbed solar and temperature is pretty linear, with an average trend (slope of the red line) being 0.21 \u00b0C per W\/m2.<\/p>\n\n\n\n

To assist in understanding this, here\u2019s a graphic showing how much solar radiation is absorbed at the surface.<\/p>\n\n\n\n

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Figure 4. Surface absorbed solar radiation (downwelling radiation minus reflected radiation)<\/em><\/p>\n\n\n\n

You can see the effect of the nearly continuous clouds at the Intertropical Convergence Zone (ITCZ) as a yellow stripe just above the equator.<\/p>\n\n\n\n

To return to Figure 3, in the areas where there is little sunlight, the temperature increases very rapidly with increasing sunshine. Here is a map of where those areas are.<\/p>\n\n\n\n

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Figure 5. Parts of the world where the annual average absorbed solar radiation is less than fifty watts per square meter.<\/em><\/p>\n\n\n\n

And at the right-hand end of the scale in Figure 3, surprisingly, in areas where average absorbed solar is above about 210 W\/m2, increasing the absorbed sunlight doesn\u2019t warm the surface much at all. The average response in the colored areas shown below is 0.03\u00b0C per W\/m2. Go figure. Here are those locations.<\/p>\n\n\n\n

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Figure 6. Parts of the world where the annual average absorbed solar radiation is greater than two hundred ten watts per square meter.<\/em><\/p>\n\n\n\n

The horizontal dotted lines above and below the Equator on the map in Figure 6 show the limits of the tropics. Note that most of the tropical oceans don\u2019t warm much further in response to absorbed solar radiation increasing byond 210 W\/m2.<\/p>\n\n\n\n

And at the end of that, we have three different estimates of how much temperatures go up when solar goes up and go down when solar goes down. All three of them are on the order of a 0.2 \u00b0C temperature change for each 1 W\/m2 change in absorbed sunshine. And all three show that temperature varies with absorbed sunshine, going up with more sunshine and down with less sunshine, just as we see every day.<\/p>\n\n\n\n

PART THE SECOND \u2013 MODELWORLD<\/strong><\/p>\n\n\n\n

After I looked at what is actually happening, I thought I\u2019d take a look at what the models say is happening. The model data is available at the marvelous KNMI website by selecting \u201cMonthly CMIP5 scenario runs<\/a>. These are from the Fifth Computer Model Intercomparison Project (CMIP5). The surface air temperature is identified as \u201cTAS\u201d (temperature air surface). Downwelling solar at the surface is \u201cRSDS\u201d (radiation shortwave downwelling surface), and reflected surface solar is \u201cRSUS (radiation shortwave upwelling surface). The absorbed radiation is the downwelling solar minus the reflected solar.<\/p>\n\n\n\n

I started with the temperature data. I was interested in the historical data, which is essentially identical for the four \u201cScenarios\u201d, yclept RCP26, RCP45, RCP60, and RCP85. I used the RCP26 data. The historical data ends in 2012. Here\u2019s the CMIP5 mean global historical surface temperature reconstruction compared to the Berkeley Earth global surface temperature.<\/p>\n\n\n\n

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Figure 7. Berkeley Earth and CMIP5 model temperatures compared.<\/em><\/p>\n\n\n\n

Well, that\u2019s pretty respectable. The models have done a decent job of emulating the major changes in the historical temperature. (It does bring up the question of how different models with widely differing climate sensitivities can all hindcast the temperature so well, a question I discussed in \u201cDr. Kiehl\u2019s Paradox<\/a>\u201d \u2026 but I digress.)<\/p>\n\n\n\n

Having done all of that, I went to look at the modeled absorbed solar radiation \u2026 and my eyes bugged out of my head. Here\u2019s that modeled result. As with temperature, the solar results are basically identical for the four scenarios, so I\u2019m showing RCP26.<\/p>\n\n\n\n

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Figure 7. CMIP5 RCP26 historical surface absorbed solar radiation anomaly.<\/em><\/p>\n\n\n\n

YIKES! Temperatures are going up and absorbed sunlight is going down? Say what? How unbelievable is that?<\/p>\n\n\n\n

But wait, as they say on TV, there\u2019s more! Here\u2019s the same RCP26 solar data, this time including their projection of absorbed solar at the surface out to the year 2100.<\/p>\n\n\n\n

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Figure 8. CMIP5 RCP26 historical and projected surface absorbed solar radiation anomaly.<\/em><\/p>\n\n\n\n

It\u2019s \u2026 curious. Modeled surface absorbed solar is decreasing over the historical period all the way right up to 2012, and then it immediately turns around and starts increasing.<\/p>\n\n\n\n

Probably just a coincidence.<\/p>\n\n\n\n

But consider \u2026 if they somehow get rising historical temperatures with falling<\/em> historical absorbed solar radiation, think of how high their future projections will be with rising<\/em> absorbed solar radiation. It\u2019s a win-win situation for the alarmists!<\/p>\n\n\n\n

And how come I\u2019m the guy who notices these things and not the good folks running the models or the people at CMIP5?<\/p>\n\n\n\n

Always new questions.<\/p>\n\n\n\n

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Here on the northern California coastal hillside where I live, we are in the midst of an all-too-frequent occurrence \u2026 Pacific Gas and Electric, aka PG&E, can\u2019t keep the electricity on. Once again, we\u2019re out of power. Sigh. I just fired up my reliable fossil-fuel-powered Honda i2000 generator, strung the extension cords, and I\u2019m back in business.<\/p>\n\n\n\n

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But never fear, the geniuses running California have a brilliant solution for the endless outages, brownouts, rolling blackouts, and power shortages.<\/p>\n\n\n\n

You ready for their plan? Here it is:<\/p>\n\n\n\n