From Dr. Roy Spencer's Global Warming Blog
Author: Dr. Roy W. Spencer
In Part 1, I claimed that using sites around Death Valley was a good way to “fact check” the warm season high temperatures (Tmax) of Death Valley sites, using elevation correction, since all surrounding sites are at higher temperatures (and therefore more cooler) altitude. Each July, a large tropospheric ridge of high pressure makes the air mass temperature in the region spatially uniform (at any given pressure altitude), and daily convective heating of the troposphere results in a fairly predictable temperature lapse rate (the rate at which temperature decreases with altitude). . This makes it possible to estimate Death Valley daytime temperatures from surrounding (colder) stations, even though those stations are thousands of feet higher in elevation than Greenland Pastures, which is 168 feet below sea level.
Failure rates calculated from sites around Death Valley
If I use all available GHCN daily monitoring stations within 100 miles of Greenland Ranch (aka Furnace Creek, aka Death Valley NP) for each July from 1911 to 2024 to calculate the monthly average failure rate (excluding the Death Valley monitoring station )[s]), the result I got is shown in Figure 1.
Figure 1. Estimated lower tropospheric temperature lapse rates for all weather stations within 100 miles of Greenland Ranch, Death Valley, California. The number of sites available for these calculations ranges from a few in early years to 25 or more in later years. Here I will assume a constant decline rate of -0.004 over the 20th century. Fitting a fourth-order polynomial to the data would be another way to hypothesize how the failure rate changes over time.
The calculated lapse rates for all years fall between dry adiabatic values and US standard atmospheric values. Given that few sites are available in the early years, I will base subsequent calculations on an assumed lapse rate of -0.004 degrees Fahrenheit per foot during the first half of the record and assume that the steepening of lapse rates observed during the first half of the record in the 1980s is true, with a value of -0.0048 degrees. F per foot in the early 2020s. In Part 1, I used the actual values for each year in Figure 1 to estimate temperatures in Death Valley. This time I use average failure rate values over many years, keeping in mind that there were very few sites in the first few decades, so the values in Figure 1 are more uncertain.
Death Valley daily estimated Tmax in July: 2021-2024
How accurately can we estimate the daily maximum temperature in Death Valley from surrounding high-altitude stations? The figure below (Figure 2) shows the daily observed Tmax temperature in Death Valley in July (2021, 2022, 2023, 2024, Orange in Death Valley National Park) compared with that based on surrounding high-altitude stations (blue) Compare estimates of , assuming a slope of -0.0048 degrees. F per foot (see Figure 1).
Figure 2. Daily estimated July Tmax temperature in Death Valley National Park at surrounding sites (blue) compared to observations (orange, 194 feet below sea level) 2021, 2022, 2023 and 2024.
Each year, daily estimates from surrounding sites (blue) are reasonably close (within a few degrees) to observations at Death Valley National Park (orange) and the nearby Stovepipe Wells site. For example, the “near record” value observed on July 7, 2024 was 129 degrees. The F degree agrees well with the failure rate estimate of 128 degrees. F. Note that over the years, many sites (27 of 28) within 100 miles of Death Valley were available for these estimates.
Death Valley daily estimated Tmax in July: 1935-1938
Next, let's go back to the 1930s, when fewer sites made these estimates (Figure 3).
Figure 3. Daily estimated Tmax temperatures in Death Valley (blue) during 1935, 1936, 1937, and 1938 compared with observations at Greenland Ranch (orange, 168 ft below sea level) and Cow Creek (gray, 151 t). temperatures compared to those below sea level).
Although there are only 7 or 8 stations where temperatures in Death Valley can be estimated, the agreement in 1935 is still quite good, with no deviation between observations and estimates, only 1-3 degrees. F bias for Greenland pastures and estimates for the next 3 years. There were also some low temperature anomalies in Greenland Pastures and Cow Creek in 1937-38; the cause of these is unknown to me.
Death Valley daily estimated Tmax in July: 1912-1915
Finally we examine the period in question, which is 134 degrees. The F world record temperature was recorded on July 10, 1913 (Figure 4).
Figure 4. Daily estimated Tmax temperatures in Death Valley (blue) during 1912, 1913, 1914, and 1915 compared with Greenland pasture observations (orange, 168 feet below sea level).
During these years, only 3 to 7 stations could calculate Death Valley Tmax. In 1912, despite having only three weather stations, the average reported temperature was only 3 degrees Celsius. F is higher than estimates from surrounding sites. But in 1913 (the year records were kept), the average angle observed was an astonishing 9 degrees. F is higher than the recommended temperature for the 5 surrounding stations. On July 10, the temperature exceeded the standard by 15 degrees. F!
The second week of July 1913 was indeed unusually hot, and it was during this time that the ranch foreman responsible for taking temperature readings from the official instrument shelter provided by the United States Weather Bureau apparently wrote a letter regarding the USWB measurements. High indicates disappointment. This led William T. Reid to speculate (and I agree) that the ranch foreman (Fred Corkill, foreman from 1911 to 1925) replaced the official values with values that more closely matched the heat he felt on his balcony, which was most likely the sun shining on the balcony On the roof, the temperature rises.
So, how much thermal bias is there at 134 degrees? F “World Record”?
We'll never know exactly how much warmth bias exists in the world record values. But compared to the deviation in 1912 and 1914, I would say 9 to 12 degrees. F is a reasonable estimate.
Of course, some adjustments might be made to this if one assumes that the slope is slightly different than -0.004 degrees. F per foot. For example, what if the air mass on July 10, 1913, had an unusually steep lapse rate such that a larger adjustment in elevation would be required to estimate the high temperatures in Death Valley? If I use the estimated lapse rate from 5 surrounding sites on July 10, 1913 (see Figure 5), the lapse rate value is indeed “steeper” at -0.0053 degrees. F per foot. It's still 10 degrees. Below 134 degrees. F record value. This is still within the 9 to 12 degrees deviation I mentioned above.
Figure 5. The world record value F (red) of 134 degrees is 10 degrees. F is higher than indicated by temperature changes with altitude at surrounding high altitude stations.
in conclusion
134 degrees. The world's highest temperature record set in Death Valley may be around 10 degrees. F is too high compared to altitude-adjusted temperatures at surrounding sites. The most likely reason is that the measurements reported by the ranch foreman were (shall we say) recorded non-academically. I find it remarkable that the record for the world's hottest temperature in Death Valley was not revised many years ago, as the “fact-checking” recording method is fairly simple and based on well-known meteorological principles for over 50 years.
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