Why Do Different Satellite Datasets Produce Different Global Temperature Trends?

January 6th, 2015

I thought it would be useful to again outline the basic reasons why different satellite global temperature datasets (say, UAH and RSS) produce somewhat different temperature trends.

They all stem from the fact that there is not a single satellite which has been operating continuously, in a stable orbit, measuring a constant layer of the atmosphere, at the same local time every day, with no instrumental calibration drifts.

Instead, what we have is multiple satellites (we use 14 of them for the UAH processing) with relatively short lifetimes (2 to 16+ years), most of which have decaying orbits which causes the local time of measurement to slowly change over the years, slightly different layers sampled by the earlier (pre-1998) MSU instruments compared to the later (post-1998) AMSU instruments, and some evidence of small calibration drifts in a few of the instruments.

An additional complication is that subsequent satellites are launched into alternating sun-synchronous orbit times, nominally 1:30 a.m. and p.m., then 7:30 a.m. and p.m., then back to 1:30 a.m. and p.m., etc. Furthermore, as the instruments scan across the Earth, the altitude in the atmosphere that is sampled changes as the Earth incidence angle of view changes.

All of these effects must be accounted for, and there is no demonstrably “best” method to handle any of them. For example, RSS uses a climate model to correct for the changing time of day the observations are made (the so-called diurnal drift problem), while we use an empirical approach. This correction is particularly difficult because it varies with geographic location, time of year, terrain altitude, etc. RSS does not use exactly the same satellites as we do, nor do they use the same formula for computing a lower tropospheric (“LT”) layer temperature from the different view angles of AMSU channel 5.

We have been working hard on producing our new Version 6 dataset, revamping virtually all of the processing steps, and it has taken much longer than expected. We have learned a lot over the years, but with only 2-3 people working part time with very little funding, progress is slow.

In just the last month, we have had what amounts to a paradigm shift on how to analyze the data. We are very hopeful that the resulting dataset will be demonstrably better than our current version. Only time will tell.

UAH Global Temperature Update for December, 2014: +0.32 deg. C

January 6th, 2015

2014 was Third Warmest Year Since 1979, but Just Barely
(with input from John Christy and Phil Gentry)

The Version 5.6 global average lower tropospheric temperature (LT) anomaly for December, 2014 is +0.32 deg. C, essentially the same as the November value of +0.33 deg. C (click for full size version):

The global, hemispheric, and tropical LT anomalies from the 30-year (1981-2010) average for the last 12 months are:

2014 1 +0.291 +0.387 +0.194 -0.029
2014 2 +0.170 +0.320 +0.020 -0.103
2014 3 +0.170 +0.338 +0.002 -0.001
2014 4 +0.190 +0.358 +0.022 +0.092
2014 5 +0.326 +0.325 +0.328 +0.175
2014 6 +0.305 +0.315 +0.295 +0.510
2014 7 +0.304 +0.289 +0.319 +0.451
2014 8 +0.199 +0.244 +0.153 +0.061
2014 9 +0.294 +0.187 +0.401 +0.181
2014 10 +0.365 +0.333 +0.396 +0.189
2014 11 +0.329 +0.354 +0.303 +0.247
2014 12 +0.320 +0.464 +0.177 +0.298

Notes on data released Jan. 6, 2015:

2014 was the third warmest year in the 36-year global satellite temperature record, but by such a small margin (0.01 C) as to be statistically similar to other recent years, according to Dr. John Christy, a professor of atmospheric science and director of the Earth System Science Center at The University of Alabama in Huntsville. “2014 was warm, but not special. The 0.01 C difference between 2014 and 2005, or the 0.02 difference with 2013 are not statistically different from zero. That might not be a very satisfying conclusion, but it is at least accurate.”

The 2014 average temperature anomaly is also in keeping with temperatures since late 2001, when the global average temperature rose to a level that is generally warmer than the 30-year baseline average. The most recent 13 complete calendar years, from 2002 through 2014, have averaged 0.18 C (about 0.33 degrees Fahrenheit) warmer than the 30-year baseline average, while the global temperature trend during that span was a warming trend at the rate of +0.05 C per decade — which is also statistically insignificant.

Compared to seasonal norms, the coldest annual average temperature on Earth throughout 2014 was just south of Wilmar, Minnesota. The average 2014 temperature there was –1.27 C (about 2.29 degrees F) colder than normal. The ‘warmest’ place throughout 2014 was just south of the North Pole along the International Date Line. Temperatures there averaged 1.65 C (about 2.97 degrees F) warmer than normal for the year.

Annual Global Temperature Anomalies, ranked

1. 1998 0.42
2. 2010 0.40
3. 2014 0.27
4. 2005 0.26
5. 2013 0.24
6. 2002 0.22
7. 2009 0.21
8. 2007 0.20
9. 2003 0.19
10. 2006 0.19
11. 2012 0.17
12. 2011 0.13
13. 2004 0.11
14. 2001 0.11
15. 1991 0.02
16. 1987 0.01
17. 1995 0.01
18. 1988 0.01
19. 1980 -0.01
20. 2008 -0.01
21. 1990 -0.02
22. 1981 -0.05
23. 1997 -0.05
24. 1999 -0.06
25. 1983 -0.06
26. 2000 -0.06
27. 1996 -0.08
28. 1994 -0.11
29. 1979 -0.17
30. 1989 -0.21
31. 1986 -0.24
32. 1993 -0.25
33. 1982 -0.25
34. 1992 -0.29
36. 1985 -0.31
37. 1984 -0.35

With a global average temperature that was 0.32 C (about 0.58 degrees Fahrenheit) warmer than seasonal norms, December 2014 trailed only December 2003, which averaged 0.37 C (about 0.67 degrees Fahrenheit) warmer than seasonal norms, among the warmest Decembers in the satellite temperature record. While December 2014 ranked second warmest for both the globe and the Northern Hemisphere, it was only the sixth warmest December in the tropics despite an El Niño Pacific Ocean warming event that seems to be forming there.

Warmest Decembers (1979-2014)
(Global average, warmer than seasonal norms)

1. 2003 +0.37 C
2. 2014 +0.32 C
3. 1987 +0.27 C
2013 +0.27 C
5. 2009 +0.24 C
6. 2012 +0.23 C
7. 1997 +0.22 C
2006 +0.22 C
9. 1998 +0.19 C
2005 +0.19 C

Compared to seasonal norms, the coldest place in Earth’s atmosphere in December was in northwestern Greenland, where temperatures were as much as 2.70 C (about 4.86 degrees Fahrenheit) colder than seasonal norms. Compared to seasonal norms, the warmest departure from average in December was in central Russia, north of the town of Yeniseysk. Temperatures there were as much as 2.75 C (about 4.86 degrees Fahrenheit) warmer than seasonal norms.

The global image for December should be available in the next day or so here.

Popular monthly data files (these might take a few days to update):

uahncdc_lt_5.6.txt (Lower Troposphere)
uahncdc_mt_5.6.txt (Mid-Troposphere)
uahncdc_ls_5.6.txt (Lower Stratosphere)

Mt. Washington, NH: 110 mph Wind, -11 F Temp.

January 5th, 2015

The cold air spilling into the U.S. from Canada is really being felt at the Mt. Washington (NH) Observatory, where winds have been gusting to 110 mph this morning, and the temperature is rapidly dropping (from -11 F now to a predicted -22 F by this evening).

Here’s a current webcam pic of the Observatory deck, compared to “normal”:


Given its elevation (6,288 ft) and geographic location, bad weather is normal on Mt. Washington in the winter, and for many years Mt. Washington held the world record for the highest wind speed recorded on the surface of the Earth: 231 mph measured on April 12, 1934. That record was beaten by a 253 mph surface wind speed measured in 1996 in Australia in a tropical cyclone.

Current weather can be monitored at the Mt. Washington website.

Cold Wave to Fuel N. Europe Storms, Faster-than-Sound Jet Travel

January 5th, 2015

As the arctic air mass now spreading across the U.S. moves eastward, it will lead to some wild weather for the UK and Northern Europe.

Anytime a deep, cold air mass moves into the mid-latitudes, a strong jet stream forms above the transition zone between warm and cold air masses. That’s not unusual for this time of year, but the current situation will lead to an unusually strong, 260 mph jet stream on the jet traffic route from the U.S. to Europe.

This means that jets flying to Europe on Thursday could see ground speeds in excess of 800 mph (900 mph for a 747), which is faster than the speed of sound at sea level, 760 mph. (This is not the same as the jet “breaking the sound barrier”…its air speed remains the same, whether flying in a headwind or tailwind.)

The weak low pressure now spreading snow across the U.S. Midwest will intensify as it exits the East Coast and races across the Atlantic, generating surface wind gusts approaching 100 mph and wave heights to 50 ft as it approaches Scotland Thursday night.

While that storm will weaken as it crosses the North Sea to the Baltic, an equally strong storm will follow close on its heels, with near-hurricane force wind gusts across the North Sea and into the southern Baltic Sea for the weekend. Damaging winds could occur over Denmark and in other coastal areas around the southern Baltic Sea.

So, batten down those windmills.

Scottish windmill exploding in high winds on Dec. 8, 2011 (photo: Stuart McMahon)

Scottish windmill exploding in high winds on Dec. 8, 2011 (photo: Stuart McMahon)

Frigid Hump Day in Midwest: Chicago Won’t Get Above Zero, -20F Wind Chills

January 4th, 2015

Arctic air is making a return after a rather balmy December, and the Midwest will have a frigid wintry Wednesday this week after 2-4 inches of new snow falls.

By Wednesday morning, most of the U.S. will be below freezing, and the coldest air will be plunging southeastward across the upper midwest into northern Illinois and Indiana:

NWS statistical forecast temperatures for Wednesday morning, Jan. 7, 2014.

NWS statistical forecast temperatures for Wednesday morning, Jan. 7, 2014.

Midday Wednesday looks like much of the Midwest won’t even get above zero deg. F, even in Chicago (graphic courtesy of Weatherbell.com)…

Temperature forecast for midday Wednesday (Jan. 7, 2014) from the GFS model.

Temperature forecast for midday Wednesday (Jan. 7, 2014) from the GFS model.

…and stiff 20 mph winds will cause midday windchill temperatures of -20 F or lower. Across Iowa and Illinois, temperatures by Wednesday evening will be 30 to 40 deg. below normal for this time of year.

Top 10 Climate Discoveries of 2014

December 31st, 2014

Top 10 lists are popular this time of year, so I gave in to the peer pressure. Here’s my Top 10 list of totally true climate stories of 2014. Kind of like that movie “Fargo”, which was not “based on a true story”, but was a totally “true story”.

10. Weather did not even occur before Henry Ford automated the production of the automobile. No, really, look it up.

9. Climate modelers discovered that the Earth is not warming nearly as fast as their models predicted. A multi-billion dollar effort is now underway to make the climate system warm even faster.

8. The Koch Brothers were discovered to be extraterrestrials out to destroy the Earth. If you haven’t heard that yet…you are one of the stupid people who were deemed to be not trustworthy enough with the information.

7. Global sea ice reached a near record maximum, due to a bust-gut effort by Exxon-Mobil which has been making ice cubes in China and shipping them to the poles.

6. Global warming causes cooling. This had always been expected, but it was finally proved by two French literature graduates who Googled it.

5. It’s Bush’s fault.

4. A viable replacement for fossil fuels was finally discovered: Solar Freakin’ Roadways. (If solar panels tilted toward the sun and kept clean are a good idea, then putting them on the ground and running over them with 10-ton trucks is even better!)

3. Ninety-seven percent of climate scientists surveyed agreed that if the global warming issue (and their government funding) went away, their careers would end.

2. The 420th U.N. climate meeting in Lima, Peru, was finally made carbon-neutral with jet travel fueled by methane gathered from unicorn herds, and carbon offsets purchased from Al Gore which will go toward planting of 5.3 billion trees which never die.

1. Carbon dioxide (necessary for life on Earth) was discovered to be different from carbon monoxide (a poisonous gas). The full implications of this finding are still being investigated, but are not expected to interfere with continuing plans to increase energy prices and keep Third World people from becoming First World.

Storms are Normal: The Nuclear Weapons Equivalency

December 31st, 2014

One of the popular (but incorrect) memes of the global warming movement is that storminess is getting worse. While attractive on an emotional level, there is little to no evidence that supports the meme.

Whether it be tornadoes, hurricanes, floods, droughts, or any other class of weather event, there is simply no convincing evidence that any of it is getting worse. Storm damage gets worse over time, of course, as wealth and infrastructure grows (there are more targets for severe weather to strike). But that’s not due to “climate change”.

What people don’t realize is the very large amount of energy which courses through the climate system on a continuous basis which drives all weather and storminess.

Approximately 240 Watts per sq. meter of sunlight is absorbed by the Earth continuously, which equates to 122,000 terajoules (trillion joules) of total energy every second over the entire Earth.

To give that number some perspective, it is the same amount of energy released by all nuclear weapons testing over 50 years…but instead released every 20 seconds.

That’s three times all previous nuclear testing every minute.

180 times all nuclear testing every hour.

4,320 times all nuclear testing every day.

And it’s all entirely normal, occurring whether humans live on Earth or not.

Most of that solar energy is absorbed at the surface of the Earth, which then leads to air currents carrying energy vertically and from one place (where more energy has accumulated) to another (where less energy exists)…especially from the tropics to the polar regions.

Water bodies, especially the oceans, store absorbed solar energy for a period of time, and can release it in large quantities because the near-surface water can overturn, making lots of energy available to the atmosphere.

Because of the orientation of land versus ocean, the spherical nature of the Earth, the Earth’s spin, energy storage by the oceans, and other features of the climate system, it is inevitable that there will be localized large differences in energy content of the atmosphere (which drives all weather) which then results in what we consider a severe weather event. Generally, the greater the temperature difference across a distance, the more the potential energy available for storm formation.

For example, the current surface temperature distribution over Asia exhibits temperature differences of over 150 deg F over a few thousand miles. This type of temperature gradient is what drives, directly or indirectly, almost all storm activity.

It worries me that an increasing portion of the public has the impression that storminess has any significance beyond what has been “normal” for thousands of years. The normal state of weather is to be stormy. Even if humans have caused an overall temperature increase of one degree in the last 50-100 years, it would be difficult to impossible to see such a small change reflected in weather when there is already so much energy available for storm formation. The current energy imbalance of the climate system is theoretically estimated to be about 1%. There is no way — given the chaotic nature of weather — to isolate such a small influence from natural variations.

Even a sunny, cloudless day is the result of storms, the rising air in which forces the air to sink over large regions, creating clear skies. In some sense, those clear skies are a necessary part of the storm circulation. Your sunny day is courtesy of someone else’s story day, hundreds or even thousands of miles away.

The final fate of most of the solar energy which was originally absorbed at the surface as sunlight is then emitted to space by “greenhouse gases” in the atmosphere as infrared radiation. The cycle is complete, and the sun has (for all practical purposes) enough energy to keep the process going forever.

Why am I even bringing this up? Because I saw a news story about some people thinking the localized lake effect snow event in Buffalo last month was due to “climate change”. The claim is so ludicrous that one hardly knows where to start.

Unfortunately, the President’s new initiative to “educate” young people about climate will probably make matters worse, not better.

Europe to Greet New Year with Snow and Cold

December 25th, 2014

Over the next seven days you can expect many news stories coming out of Europe concerning an unusually cold and snowy weather pattern setting up that will hit southern and eastern Europe the hardest.

Up to two feet of snow will occur in some areas with balmy Portugal being the only European country to escape snowfall.

As the following total snowfall forecast map through January 1 shows, even southern Italy, Greece, and far northern Africa can expect snow (graphic courtesy of Weatherbell.com, click to enlarge):

Total snowfall forecast from Dec. 25 to Jan. 1, from the GFS model (courtesy of Weatherbell.com).

Total snowfall forecast from Dec. 25 to Jan. 1, from the GFS model (courtesy of Weatherbell.com).

As is usually the case, the cold air is flowing from northwestern Russia westward and southward into Europe, north of persistent broad low pressure that will form over the Mediterranean Sea. The seven-day average temperature departures from normal for Dec. 28 to Jan. 4 will run 10 to 20 deg. F below normal over much of Europe:

Seven day average temperature departures from normal (deg. C) for the period 28 Dec. to Jan. 4 (GFS model graphic courtesy of Weatherbell.com).

Seven day average temperature departures from normal (deg. C) for the period 28 Dec. to Jan. 4 (GFS model graphic courtesy of Weatherbell.com).

This cold weather will not be welcome by most, as energy prices haven risen significantly across much of Europe, partly due to reliance on expensive renewable energy sources.

Drought Stricken California Suddenly Green

December 24th, 2014

Heavy rains over the last few weeks have led to a sudden greening of much of California, as revealed in yesterday’s color satellite image compared to exactly 1 year ago (click for full size):

NASA MODIS imagery of central and northern California on Dec. 23 of 2013 and 2014.

NASA MODIS imagery of central and northern California on Dec. 23 of 2013 and 2014.

Many stations in Northern California have recorded over 20 inches of rain, and Folsom Dam has received a whopping 62 inches of rain this month. Lake Shasta, the largest reservoir in California, has erased almost half of its deficit below its normal level for this time of year.

Drought Relief: Shasta Lake Rises 10 ft. in One Day

December 12th, 2014

The latest in a series of Pacific storms hit California yesterday with high winds and over 6 inches of rain at Shasta Dam. A number of mountain stations that feed the reservoirs in N. California, which are at very low levels from the continuing drought, have registered over 10 inches of rain in the last week.

With yesterday’s heavy rains, Lake Shasta rose a spectacular 10.6 feet in one day, which added over 130,000 acre feet of water volume to California’s largest reservoir. That’s enough water to fill 65,000 Olympic size swimming pools.

The following graph shows that there is still a long way to go to reach even normal water levels on Lake Shasta:

Nevertheless, it also shows how the reservoir can recover in only one year, as it did from the 1976-77 dry period to the 1977-78 wet period, the result of rains from weak El Nino conditions.

The current El Nino conditions in the Pacific are contributing to the current wet and stormy period, which will need to continue before we can even begin to talk about the drought being over.