Satellite-Radiosonde Temperature Data
This discussion is a quick focus on the satellite data alone. The top chart is based on the University of Alabama-Huntsville (UAH) satellite data.
The UAH data has been divided into a number of periods. The full temperature anomaly data set (1978-2018) is increasing at a rate of 1.28 °C per century. The good news is we’re on track to keep the global temperature increase to less than the 1.5 – 2.0 °C target laid out in the Paris Accord (and we don’t have to change anything we’re doing). The 1998-2018 time period is only increasing at 0.74 °C per century rate (even better). To be fair, the 1997-98 el Nino brings the early data up and tempers the overall incline. The temperature incline from 2002-2018 is back up to 1.23 °C per century (similar to the full data set). But with the same rationale, the 2015-16 el Nino is inflating the late data and overstating the recent temperature incline. If the two major el Nino spikes are taken out of the discussion, the temperature over the last couple of decades has been relatively flat. The temperature actually declined over the 2002-2015 period at a rate of 0.10 °C per century.
The July 2018 temperature anomaly was +0.32 °C. The August 2018 temperature anomaly was back down to +0.19 °C. The January – August 2018 temperature anomalies ranged between +0.18 and +0.32 °C.
The chart on the right, compares the UAH data with the RSS data (this interactive chart is available at woodfortrees.org/plot/).
The two satellite datasets begin to diverge around the turn of the century. Clearly the satellite data has been subject to some interpretation of the raw data inputs much like the interpretation applied to surface data sets. However, the satellite data manipulation is not as profound as the surface temperature data manipulation; as can be seen in the following charts, the satellite data is consistent with the radiosonde (weather balloon) data sets. As a result, the satellite data is still the more accurate global temperature estimate.
The radiosonde temperature data has also been included for comparison. I have not located the actual data sets yet so I’m using publicly available charts. The first chart is the pre-satellite radiosonde data. The second chart is the data available for both the radiosonde and satellite data. The later data chart was from an early 2016 press briefing NASA/NOAA released to announce that 2015 was the hottest year ever (based on their homogenized surface data estimates (not shown here)).
The adjacent table, from the same press briefing, shows that 2015 was not the warmest year based on both the satellite and radiosonde data sets (except for the temperature at an altitude of 18,000 feet).
What they did not show during the press briefing was the early radiosonde data (pre-satellite). If the only data shown is the satellite period, the temperature data is erratic but generally rising. If all of the radiosonde data is plotted together you get a much different picture.
The radiosonde temperatures from the early 1960’s were very similar to the current temperatures. The temperatures dropped off that early 1960’s period peak and have been recovering since the early 1990’s.
Apart from the el Nino peaks (1997/98, 2010 and 2015/16), the temperatures are still below the early 1960’s peak. Unfortunately, these data sets do not go back to the dirty 30’s. A large percentage of the current high temperature records were set back in that period. Older NASA/GISS datasets actually showed higher temperatures during the 1930s. Manipulation of the data over the last few decades has reduced older temperatures as well as augmenting more recent temperatures. The result is a NASA/GISS surface dataset that appears to rise continuously since the late 1800’s. The original temperature measurements look nothing like the “official” NASA/GISS temperature profile.