How is Global Temperature stitched together? from Chiefio

Dec 4, 2009

A long post but well worth reading if you want to understand why NASA/GISStemp is claiming that global temperature is rising at an unprecedented rate and why this is wrong and due to non-climatic factors affecting the record

GIStemp – A Human View

November 9, 2009 by E.M.Smith

GIStemp: Goddard Institute for Space Studies, temperature Series.

If we would study global temperature change over time, we need a temperature record over time, and over the globe. GIStemp attempts to create a temperature history with full coverage over time and over space. Unfortunately, the (GHCN – Global Historical Climate Network) data start with one thermometer in Germany: Berlin Tempel in 1701

Over time, thermometers are added, and they slowly migrate south and to both the New, and Old Worlds. Eventually, about 1900 A.D., there are sufficient thermometers on the globe to get a partial idea what is happening. But climate is subject to cyclical changes. Some, like the Pacific Decadal Oscillation, have about a 40 to 60 year full cycle length. Others, like solar cycles that run 178 years, and Bond Events – a 1500 year cycle, are a bit longer. A 100 year record is inadequate to allow for these events.

At its core, GIStemp tries to bridge this gap, both in time and in space, between the one thermometer and the globe, and between the 100 years and the 1500. This is a noble goal, but is just “A thermometer too far” to bridge.

How does it do this?

First, it glues together some added data from Hohenpeissenburg, and from the Antarctic research stations. It squashes together the U.S. data from USHCN with the same U.S. data from GHCN. And to deal with the poor spacial coverage in the 1700’s, it deletes everything older than 1880. (While this gives a smoother spacial coverage, it does not handle the past quite as well; it now “starts history” at the bottom of the end of the Little Ice Age.)

By Bits

In many cases, our thermometer record is made of fragments. A thermometer may appear in the record for a decade (sometimes less) then disappear just as quickly. W.W.II caused a great ‘drop out’ of Pacific Island thermometers, for example. The growth of The Jet Age added thermometers at vacation spots around the globe at Tropical Vacation Destinations, but not all “stuck”. And folks move to new homes. So we have a thermometer here, and it moves there. Two records from different places. One over grass near the woods, the next over tarmac at the Jet Airport. GIStemp tries to stitch these patchworks together into a smooth quilt of coverage. Some thermometers get stretched this way or that (over time and over space). Some get their temperatures adjusted higher or lower (via a thing called “The Reference Station Method”) to better join with their neighbours. Where needed, missing data are often fabricated to try and glue the bits together. If a piece, even after such a stretch, is shorter than 20 years, it gets thrown away.

In the end, we are still left with gaps. (The entire southern hemisphere ocean band has less than 1% of the thermometers, and those are at the airport on a few specific islands for the most part). So we have a patchwork quilt, but with some rather large holes, and some pieces are stretched out of all recognition. (A thermometer may be stretched to 1000 km away. Rather like saying that London is a good proxy for the beach in the south of France.)

Adjusting for Urban Growth

Some places have changed over time. Cities grow, and get hotter, as they fill with cars, tarmac, heaters or A/C vents, airports and jet engines, and coal or nuclear power plants. To adjust for this, GIStemp looks at “nearby” stations up to 1000 km away and guesses who is rural and who is urban and “adjusts” for it. Unfortunately, like all guesses, this sometimes does not work well. Large airports are often marked as “rural” since they have few residents living there. The largest US Marine Air Station, Quantico Virginia, is classed as rural, for example. Pisa Italy takes a look at Hohenpeissenburg on the German approach to the Alps as a ‘nearby’ rural station and Pisa promptly has it’s past made colder (an odd way to adjust for the present being too warm… making it look even warmer in comparison).

So we’ve ironed out our quilt, even if some bits stuck to the iron and got scorched a bit and others were melted and smeared.

But still we have “holes” in time and in space.

At this point, the globe is divided into a “grid” of “boxes”. The data that we do have (after the stitching and stretching and ironing and…) are now assumed to be pristine and pure and suitable for telling about even more places where we have no data. A station of the record may now fill in a set of boxes on the grid up to 1200 km away. This means, for example, that the airport on Diego Garcia can “fill in” the ocean covering an area roughly the size of Western Europe.

In the final steps, the grid of boxes is compared to the past for those grids of boxes (said past having been dutifully made up if need be) and an “anomaly map” is made which would then show that the ocean 1200 km out to sea (but reflecting the tarmac at the new military jet airport in Diego Garcia today) is now warmer than when a passing ship dunked a bucket in it during a passage of the 1950’s. (Or a Ship of the Line passing in the late 1800’s. Hadley CRU provides historical sea surface temperature anomalies that are merged at the very end, as an option).

Is an Anomaly an Odd Thing?

If you compare a temperature now with what it has typically been, the difference is the “anomaly”. If the average is 15 C, and today is 16 C; you have a 1 C “anomaly”.

It is important here to note that GIStemp creates an anomaly map. I have frequently run into folks who assert that “Since GIStemp uses anomalies and not temperatures, changes of thermometer locations will have no effect.”. But in reality, GIStemp uses averages of thermometer readings, sometimes dozens of them, to create an anomaly map. You can not use the nature of the product to protect you from the process…

The Thermometer Great Dying

One final note: There has been A Great Dying lately for thermometers. Since about 1990, there has been a reduction in thermometers globally. In the USA, the number dropped from 1,850 in 1968 to 136 in 2009). As you might guess, this has presented some “issues” for our thermal quilt. But do not fear, GIStemp will fill in what it needs, guessing as needed, stretching and fabricating until it has a result.

In Japan, no thermometers now record above 300 meters. Japan has no mountains now. For California, where we once had thermometers in the mountain snow and in the far north near Oregon; there are now 4 surviving thermometers near the beach and in the warm south. But GIStemp is sure we can use them as a fine proxy for Mount Shasta with it’s glaciers and for the snows and ice of Yosemite winters.

In Conclusion

In the end, it will produce it’s quilt. Scorched in some spots? Sure. A few holes, some patched over with tropical airport tarmac? Well, yes. But a fine quilt all the same! Bright thermal reds sometimes reaching far out to sea and way up north. And even reaching from an Island near the Falklands (Base Orcadas) over to Antarctica for those years before we had thermometers on the continent.

A patchwork quilt I’m sure we can all trust to keep us comfortable.

After all, we only have this history, so we must make do with what we’ve got. Even if it isn’t enough and even if riddled with holes. And even if, in re-imagining it, some parts get melted, scorched and smeared. Otherwise we’d have to admit we just don’t have the data to describe the globe in such detail in the past; and that would not be very comforting at all.


http://chiefio.wordpress.com/2009/11/09/gistemp-a-human-view/

Here’s what the Chiefio has to say about Bolivia and another excuse to post that exquisite photograph of South America. from space




http://upload.wikimedia.org/wikipedia/co...._42.9920 3S.jpg



GHCN – GIStemp Interactions – The Bolivia Effect
January 8, 2010 by E.M.Smith

GIS Anomaly Map for November 2009
This “Anomaly Map” was produced for the most recent month at the NASA / GISS web site here:
http://data.giss.nasa.gov/gistemp/maps/






You can create many maps, and many of them will not show The Bolivia Effect as well as this one (while some may be better). This map was not “cherry picked”, it is just the most recent month with data available. It does, however, have a very nice example of The Bolivia Effect in it. (At least 2, in fact).

Alright Already, what is this Bolivia Effect?

Notice that nice rosy red over the top of Bolivia? Bolivia is that country near, but not on, the coast just about half way up the Pacific Ocean side. It has a patch of high cold Andes Mountains where most of the population live. It’s the patch of yellow / whitish mountains near the top in the photograph.

White, Green, or Brown? Decisions Decisions
South American Andes

We originally saw this picture, and this problem, in this posting:
http://chiefio.wordpress.com/2009/11/16/ghcn-south-america-andes-what-andes/
One Small Problem with the anomally map. There has not been any thermometer data for Bolivia in GHCN since 1990.
None. Nada. Zip. Zilch. Nothing. Empty Set.

So just how can it be so Hot Hot Hot! in Bolivia if there is NO data from the last 20 years?
Easy. GIStemp “makes it up” from “nearby” thermometers up to 1200 km away. So what is within 1200 km of Bolivia? The beaches of Chili, Peru and the Amazon Jungle.

Not exactly the same as snow capped peaks and high cold desert, but hey, you gotta make do with what you have, you know? (The official excuse given is that the data acceptance window closes on one day of the month and Bolivia does not report until after that date. Oh, and they never ever would want to go back and add date into the past after a close date. Yet they are happy to fiddle with, adjust, modify, and wholesale change and delete old data as they change their adjustment methods…)

The eastern side of Bolivia grades down into semi-tropical and eventually into the Amazon. More details on the climate of Bolivia can be found on this link that has a nice graphic as well.
http://www.travel-bolivia.com/bolivia-climate.html
The description of the mountain portion includes:

The Altiplano Region typically has a chilly climate and is considered to have a semi-arid climate. Since it is at a high altitude the thin air retains little heat and the air is typically dry, with cool temperatures and strong cold winds that can sweep over the region.
From the wiki page we have:

The geography of Bolivia is unique among the nations of South America. Bolivia is one of two landlocked countries on the continent, and also has the highest average altitude. The main features of Bolivia’s geography include the Altiplano, a highland plateau of the Andes, and Lake Titicaca (Lago Titicaca), the largest lake in South America and the highest commercially navigable lake on Earth (which it shares with Peru).

and

Temperatures and rainfall amounts in mountain areas vary considerably. The Yungas, where the moist northeast trade winds are pushed up by the mountains, is the cloudiest, most humid, and rainiest area, receiving up to 152 cm (60 in) annually. Sheltered valleys and basins throughout the Cordillera Oriental have mild temperatures and moderate rainfall amounts, averaging from 64 cm (25 in) to 76 cm (30 in) annually. Temperatures drop with increasing elevation, however. Snowfall is possible at elevations above 2,000 m (6,562 ft), and the permanent snow line is at 4,600 m (15,092 ft). Areas over 5,500 m (18,045 ft) have a polar climate, with glaciated zones. The Cordillera Occidental is a high desert with cold, windswept peaks.

If you do not have thermometers in those high cold parts, you are not measuring correctly. Though I am surpised that they did not keep a thermomeeter or two on the eastern side of the country with tropical exposure:

The eastern lowlands include all of Bolivia north and east of the Andes. [...]the region is sparsely populated and, until recently, has played a minor role in the economy.
Differences in topography and climate separate the lowlands into three areas. The flat northern area, made up of Beni and Pando departments and the northern part of Cochabamba Department, consists of rainforest. Because much of the topsoil is underlain by claypan, drainage is poor, and heavy rainfall periodically converts vast parts of the region to swamp.

Maybe it’s that lack of people and swamp thing…

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And why do climatechangeists so lurve the Mercator projections which exaggerate the extent of the poles? There are other ways of doing it which preserves the proper scale.

Here's one, the Equal area Mollweide projection.









And why does GISTemp use brilliant shades of red to indicate eversoslightly warmer anomalies?

You could almost believe it was designed to mislead the young, ignorant and scientifically-challenged, couldn't you? Why would anyone want to do that?

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Here's a good interview with Chiefio, aka EM Smith, on a San Diego TV channel last night.

http://www.kusi.com/weather/colemanscorner/81559212.html

One thing that I picked up from this that I hadn't grasped before is that the modern GHCN temperature anomaly maps of the post-1990(ish) cherry-picked warmer data are compared with a base line period constructed from the WHOLE global data set which included ALL the cold data which was later dropped in the "great dying of the thermometers", as the Chiefio so eloquently describes it.

I knew there had been a gross reduction in the network and a migration of the selected thermometers to warmer climes and lower altitude but I hadn't picked up that the anomaly maps were not a comparison of like with like.

I have been following the musings of Chiefio for quite a while here: http://chiefio.wordpress.com/

and also the surface station site here www.surfacestations.... which gives the low-down on the problems with the thermometer measuring stations in the USA (which has the very best spatial coverage) and other parts of the world.

You can't beat "going back to basics" if you want to understand how it has been possible to foist a con on to an ill-informed public.