The California Urban Heat Island Effect

Last week Anthony Watts had a post at WUWT in which he talked about a new effort to find out just how much the urban environment was affecting the temperatures at Californian weather stations. The study is being carried out in conjunction with the EPA, and the announcement came by e-mail rather than a more conventional press release.

I was interested since, as part of series that I carried out looking at the US Historic Climate Network (USHCN) data, I plotted temperatures for the stations in each state as a function of latitude, longitude, elevation and local population. The first three values were identified with the information at each station. The local population for a town can be found on the web in several different places, and very largely I relied on the city-data web sites for information (see, for e.g. this for Sacremento).

The question arose as to which particular temperature should be used for that of the station, since the USHCN provides annual average temperatures, as raw data, Time of Observation (TOBS) corrected and “adjusted.” When the original post for California was written, only the last of these was available, and thus it formed the basis of the analysis. Shortly thereafter, in 2010, the USHCN site also provided the raw data, and the TOBS temperatures for each station, each year. The data was therefore re-analyzed using the TOBS values. But the plot that was originally generated was plotting the current population against the average temperature since 1895.

As the study grew to include more states, that plot seemed to be an error, since populations can change very rapidly, and go up as well as down. So, towards the end of the series the average temperature was taken only for the past five years, since this was likely to reflect the impact of current populations. At the same time, since there is little difference between the two sets of values in this period, the “adjusted” values were used to derive the plot. It looks like this:


Figure 1. The comparison of average California station temperature plotted relative to adjacent population, with a log-normal plot.

Now the “discovery” of a log-normal relationship is not new. Oke has been studying the topic for decades, and has proposed such a relationship. But it does have a side effect. Consider what happens when the trend line is shown on a normal plot:

Figure 2. The comparison of average California station temperature plotted relative to adjacent population, with a normal scale on both axes.

There is a “kick-over” in the rate of temperature rise at around a population of 10,000. (In fact this is a curve and the sharp transition is an artifact of the software, but it illustrates the trend). Temperature gains for smaller gains in population are higher below that level, while those above that population require a larger population growth to get the same increase. (Failure to recognize this is one of the underlying faults of the Berkeley Earth Project work on the topic.) Since the GISS data on temperatures also does not recognize any difference in population size below 10,000 it is also a fault of that data set.

I am curious to see how the California study pans out, I did drop a note with this finding to William Dean, as the e-mail suggested, and he was courteous enough to reply noting that this was “an interesting approach.”

As I pointed out to him, the strength of that relationship is, perhaps, borne out not only by the R^2 value, but by the consistency of the coefficient over the plots for a number of states. The tabulation is as follows:



I have had to cut the list in two to allow screen capture.


Figure 3. Correlation Coefficients for the relationship of temperature to local conditions with temperatures in degrees C.



And similarly for the table where I have converted the temperatures to def F.


Figure 4. Correlation Coefficients for the relationship of temperature to local conditions with temperatures in degrees F.

OGPSS - Venezuela after Hugo Chavez

With the death of the Venezuelan President Hugo Chavez the future production, and exports of Venezuelan crude are gaining a little new attention. I had noted in the last post that there is a difference of around 400 kbd between the 2.379 mbd that outside observers report to OPEC that the country is producing, and the 2.768 mbd that Venezuela itself reported. The question now becomes one as to whether the new President will be able to resurrect an industry that has overseen a slow decline in overall production, with a more rapid decline in exports.


Figure 1. Venezuelan oil statistics (Energy Export Databrowser)

My short answer to that question is No! It is based on a number of reasons, and may be swamped by the voices that note that the country has a vast remaining pool of oil in the Orinoco Basin, that the USGS has estimated to be more than a trillion barrels in size, of which some 513 billion barrels are technically recoverable. But there have been a number of posts about those numbers and the more critical number which is that of the rate of oil production.

Colin Campbell reminded us in his 2006 Review of the country that the Venezuelan Government was one of those urging the creation of OPEC, back in 1960. Back when that piece was written Colin expected that production, which had been falling as the reserves in the Lake Maracaibo region declined, would start to wind back up, as the heavy and extra heavy oils of the Orinoco were brought into a higher level of production. And he anticipated that, by now, the country would be producing around 3 mbd, which it is not.

One of the requirements before one can market the heavy oil is to have refineries that can process the oil. The United States, which imports around 1 mbd of Venezuelan crude, has the Citgo refineries, which are wholly owned by PDVSA (the Venezuelan oil company). Whether that will influence their switch to Canadian crude if the Keystone pipeline is put in place is an open question. But easing the American demand might help with Venezuelan relations with China.


Figure 2. US Monthly imports of crude and Petroleum Products from Venezuela (EIA )

China, which has refineries that Sinopec built that can also handle the crude, has stepped in here and spent over $40 billion with much of this in loans to be repaid through increased oil exports. Back in 2007 China had made the decision to pull out of Canada, and to concentrate its investments in Venezuela instead. Since that time they loaned Venezuela over $20 billion, in return for a commitment for oil exports that were to reach 1 mbd in 2012. The date to reach that target has now slipped to 2015 as overallproduction has continued to decline.

Last August President Chavez announced a $130 billion plan for investment in the Orinoco.

He said that there are 150 different clusters of oil wells in the Belt, but the goal in the next six years is to increase that number to 500. Before the nationalization of the Belt, there were just 37 clusters.

The clusters are comprised of 24 separate oil wells, each of which extract around 1,200 barrels per day. At these facilities, hydrocarbons are extracted using 45-meter drills purchased in Venezuela and assembled in Venezuela.

“All this has been nationalized, which before was the property of multinationals, and production has also been increased,” the president said. He recalled that before the government took control of the Belt, there were just 2,800 wells, while now there are more than 4,000.

Because the Orinoco crude is very heavy, to an API gravity of 9 degrees, it is difficult to produce and requires a considerable energy investment to extract and process the crude.

Last September two joint ventures came on stream. That at Petromiranda, where PDVSA has Russian partners began producing 1,500 bd, after an investment of $800 million, with a goal of eventually reaching 45,000 bd. At the same time Petromacareo, where PDVSA is partnering with the Vietnamese, came on line at 800 bd, with an initial target production of 4,000 bd. (The project has slipped from a target start date of early 2011, and the ultimate goal of 200 kbd from Petrimacareo is in more doubt.)

The crude has to be upgraded, and TNK-BP is partnering to double the capacity of the Petromangas upgrader from 120 to 250 kbd. Until that capacity is increased Orinoco production may be limited.

There is thus a history of project slippage and missed targets that is unlikely to improve in the short term. New plans for further investment either by the Chinese, Indians or Russia are now on hold, while the Presidential election to replace President Chavez is decided, but the experience in the last couple of years is likely indicative that progress in increasing production will be difficult to achieve and when set against a rising domestic consumption (as the Export Land Model predicted) is already leading to a fall in exports.

One of the drivers for that increase in domestic consumption is that the price of gasoline in Venezuela is $0.04 per gallon (four cents). In contrast, in Saudi Arabia it is around $0.61. The low price of gas means that there has been a significant increase in demand, exceeding that domestically available. As a result the country has been importing gas at up to $100 a barrel to sell it for $5 – you can’t balance those books by increasing the volume of sales!!

Yet cutting back on domestic consumption, or increasing prices could prove difficult for the incoming President. So maybe it would be a good idea to invest in the Keystone pipeline, as a simple precaution??

Waterjetting 6d - Plywood and Pork, and jet effectiveness

In the last two posts I have tried to show that there is a benefit to running an occasional calibration test on equipment, to ensure that it is giving the best performance. This does not mean that the nozzle needs to be tested every day, although some of the cheaper pressure washer nozzles, for example, will wear out in less than an hour. An operator will learn, over time, about how long a nozzle will last, and can, after a while, tell when it is starting to lose performance. But in working on a number of different jobs in succession that sense of the performance may be missed, and it can be handy to have a standard target that a jet can be pointed at that it should be able to cut in a known time.

One simple target is plywood, and, to continue the saga of nozzle comparisons through a slightly different approach, Mike Woodward used plywood sheets to compare different nozzles in one of the earliest comparisons of performance. We since duplicated his test equipment and ran tests with a more modern selection of nozzles, but the basic results and conclusions remain the same.

In its simplest form the idea is to build a holding frame that will hold small squares of plywood at fixed distances from the nozzle. In the frame shown below the plywood pieces are set at one-foot distances apart, with the nozzle held at a fixed point at the end of the test frame. Tests showed that it takes around 2,700 psi to cut through the plywood.


Figure 1. A simple frame to hold plywood samples

The initial tests that Dr. Woodward ran were run on nozzles that were run at 10,000 psi with a nominal flow rate of 10 gpm. The nozzles that were used cost in the range from $10.00 to $250 apiece. (And these costs were reported in 1985 at the 3rd American Waterjet Conference). Tests such as this are simple to run. Plywood pieces are set into the frame, the nozzle is placed at the end of the frame, and the jet run for ten seconds. Over that time, the jet will cut through any of the pieces of plywood that it reaches with enough power to cut through, and generally the jet will punch a hole through several pieces.


Figure 2. The different designs of nozzle that Mike Woodward tested in 1985.

The profiles show that there was only one of the common nozzles at the time that fitted smoothly onto the end of the feed pipe. In the other cases there is a small gap between the nozzle piece and the feed tube, so that turbulence would be generated just as water entered the acceleration section of the nozzle.

The hole size in each plate was then measured, and that width plotted as a function of the distance from the nozzle, so that a profile of the jet cutting path could then be drawn.


Figure 3. Profiles cut into the different pieces of wood, showing the cutting power of the different jets, as a function of distance and the actual amount of water flow as measured.

As an additional part of the testing a rough measure was kept of the effective nozzle life Some other performance parameters for the different nozzles can be put into a table.


Figure 4. Performance of the different nozzles.

Clearly just going out and buying the most expensive nozzle on the block is not necessarily the best idea. But it also depends on the use to which the nozzle is going to be applied. There are two different applications, that of cleaning a surface, and that of cutting into it. The broader path achieved by nozzle 1, for example, which also removed the largest volume of wood per horsepower, makes it a good selection for cleaning, and for reaching further from the nozzle, as would be needed if one were cleaning the pipes of a heat exchanger bundle.

On the other hand the more coherent flow through nozzle 2, which gave a narrower cut might be a more effective tool in a cutting operation. In other cleaning operations where the nozzle is being operated very close to the surface, then nozzle 3, which has a wider path, might be a better choice, though that is lost if the target surface is further away. And though there was not a great deal of difference in performance between nozzles 1 and 5, there is a considerable difference in price.

A smaller, lighter nozzle may be a beneficial trade-off if the nozzle body is fitting on the end of a lance that will be operated manually for several hours at a time.

There is an alternate way of using plywood as a target that I have also used in teaching class. The student is using a manually operated high-pressure cleaning gun at 10,000 psi and is to swing the gun horizontally so that the jet cuts into a piece of plywood that is set almost parallel with the jet path, but with the stream hitting the wood from the side initially further from the operator, but as the swing completes the jet cuts up where the nozzle almost touches it and then sweeps on past.

The result is that, over the distance that the jet can cut into the wood, a groove is carved into the wood.


Figure 5. Horizontal cuts into plywood. There were about half-a-dozen students who had swiped the nozzle so that it just cleared the left edge of this 4-ft wide piece of plywood, and you may note that the cuts extend roughly ¾ of the way along the surface.

Once the students had seen this cut, I would ask them how far away they thought, based on that measurement, that the jet would cut into a person. Typically they said about three feet, and then, as a precaution, I suggested they add a foot or so more.

Then I took them over to a metal frame where we had hung a piece of pork. We carefully measured off the “safe” distance from the end of the nozzle to the pork.

“Now assume that is you”, I would say, “swing the jet as fast as you can, so that it barely has time to hit “your arm”, and we’ll just check that distance is correct.”


Figure 6. Piece of pork that has been traversed by a 10,000 psi jet several times, with a typical standoff distance from the nozzle of more than four feet.

Invariably we got the result shown in Figure 6. The jet would cut into the meat to a typical depth of around two inches and groove the underlying bone. It was a salutary way of getting their attention about the safe use of the tool, and I noticed that the staff also got a bit more cautious after we ran this class every year.

The Iditarod is running

For those who follow these things, this year's Iditarod race has started. Alaskan papers are best for following the race.

Transient publicity

James Stafford was kind enough to interview me for his site at Oilprice.com and the interview has been published at a number of other sites.

http://www.nakedcapitalism.com/2013/03/peak-oil-the-shale-boom-and-our-energy-future-interview-with-dave-summers.html
http://www.cnbc.com/id/100512246
http://peakoil.com/generalideas/peak-oil-the-shale-boom-and-our-energy-future-interview-with-dave-summers

One or two may have generated a little discussion. The one at Naked Capitalism has raised enough questions that I did write the occasional response. I will comment more as this develops. Heading Out (Dave to most of you). No more yet.

OGPSS - An update on Russian plans and the OPEC MOMR

The Arctic is a less forgiving place than many folk care to recognize. Shell have just moved back the date on which they plan to restart drilling in the Chukchi Sea and won’t be going up there this year. At the same time, last August, Gazprom announced that the development of the Shtokman gas field off the Russian coast and also in the Arctic had been put on an indefinite delay. Yet the region still shows considerable promise. ExxonMobil and Rosneft have agreed to exploration in the Chukchi, Laptev and Kara Seas, with the latter considered as possibly having the highest potential.


Figure 1. Location of the Kara and Laptev Seas. (Google Earth)

The blocks that will be explored are South of the island of Novaya Zemlya, in relatively shallow water. They lie north of the Yamal Peninsula, and the Shtokman field is on the other side of the island.


Figure 2. The locations of the East Prinovozemelsky blocks south of the island of Navoaya Zemlya (Rosneft)

Rosneft estimates that the reserves that are recoverable are 6.2 billion tons of oil, and a total of 20.9 billion tons of oil equivalent when the natural gas content is included. The first wildcat well is scheduled to be drilled in 2015.

While Gazprom and Rosneft share access to these offshore resources, Lukoil has found a site at Khatanga Bay in the Laptev Sea where it believes that it can be successful. Despite the difficulties, the need for Russia to sustain production is forcing the companies offshore into more difficult waters, it is where the future production lies, and the Russian economy needs the income.

The February OPEC Monthly Oil Market Report notes that Chinese demand has now topped 10 mbd on a quarterly average, the highest to date and growing at 6%. The greatest increase has been in the use of gasoline. Global demand is anticipated to top 91 mbd by the end of the year. Russia is anticipated to produce some 10.42 mbd on average this year. OPEC has, however, a few caveats:

The Vankor oil field is expected to average 435 tb/d in 2013, a minor increase from the level of 410 tb/d achieved by the end of 2012. Some operators provided that new technologies will be utilized to stop natural decline. On the other hand, the supply forecast remains associated with a high level of risk, due to technical, political, geological and price factors. On a quarterly basis, Russian oil supply is expected to average 10.43 mb/d, 10.42 mb/d, 10.42 mb/d and 10.42 mb/d, respectively. Preliminary figures indicate that Russian oil production stood at 10.46 mb/d in January, steady from the previous month.

As usual it is interesting to compare the OPEC production results for the last few months, based both on the reports obtained from secondary sources, and those numbers that the individual nations provide.


Figure 3. OPEC crude production based on secondary sources (OPEC February MOMR )

It is important to note that Saudi Arabia has dropped its production by around 300 kbd or so for the last couple of months. While I suspect that this to keep markets a little tighter and thus hold prices stable, others might suggest that the may have some slight difficulty sustaining the higher numbers.


Figure 4. OPEC oil production figures as reported by the producing countries. (sources (OPEC February MOMR )

Iran continues to have a disparity of around 1 mbd between the two tables, Iraq still seems to be struggling to get over 3 mbd, and Venezuela has a discrepancy of around 400 kbd. In short, not much new.

Turning back to look for just a moment at Gazprom activities, although they have continued to keep Lukoil out of the Arctic, they have also continued to seek resources abroad. The company has acquired territory in Iraqi Kurdistan and is reported to have an 80% stake in the Halabja project with reserves of around 700 mb. The field lies on the Iranian border in the Kurdish part of the country, and Baghdad objected to the deal going forward. It might, however, help raise Iraqi overall production. Gazprom has two other projects in the region at Garmian and Shakal, and one at Badra which falls under the control of the central government.

And, still in the Middle East, Gazprom is in talks with Israel to buy LNG from the offshore Tamar field and ship it to Asia to serve markets that it cannot easily reach with its pipelines. The intent is to use a floating liquefaction plant that will take gas from both Tamar and Dalit, at the rate of around 3 million tons a year with production starting in 2017.

Gazprom recognizes that, if it is to develop Asian customers it must provide LNG and so it has begun work on an LNG plant in Vladivostock with three trains, each capable of producing 5 million tons of LNG a year, from the Sakhalin, Yakutia and Irkutsk gas fields. With production aimed to begin in 2018, the market will, again, be in the Asia-Pacific region and may be one of the reasons to accelerate production from the Kovyktinskoye field. At the present time Gazprom has brought the Zapolyarnoye up to full production, and they estimate that this will produce 20% of Russian natural gas as the field moves to be the largest producer in the country.

And, while tracking down some of the information for this post, I did find a picture of a polar bear and cub in the region that ExxonMobil is venturing into. It was taken on the island of Novaya Zemlya. Hopefully environmental concerns won't raise the same sort of difficulties in developing these sites that they have in other places further East.


Polar Bear and cub on Novaya Zemlya on the Shores of the Kara Sea (the photo is on Google Earth and was taken at the red arrow in Figure 2 by

Oh, and before I forget the Alaska pipeline continues to run below 600 kbd with an average of 577, 604 bd. for January.

Waterjetting 6c - Cutting foam and testing with it.

Last week’s post discussed a simple test which helps to show not only how to compare the effect of different operating conditions (varying abrasive type, nozzle design, AFR etc) as a way of finding a possibly better and cheaper cut. It is also often handy to know when a nozzle is starting to wear out, so that different cutting operations might be scheduled to allow the nozzle to continue to work, without threatening the quality of critical product.


Figure 1. Change in the cutting depth of a jet stream, at 50,000 psi, when traversed over ASTM A108 steel as a function of the time that the nozzle had been in use.

While we have found that nozzles from a given manufacturer roughly agree in cutting performance and times before they wear out, the pattern of wear and performance change differs from one nozzle design to another. Also there is some variation in performance between nozzles even of the same design and under the same conditions.

There are also times when cuts are made without abrasive, or when the cutting/cleaning jet is hand held – what to do in those cases? Mainly we have used foam as the cutting target, set up so that the jet won’t cut all the way down through the foam all the way along the cut, so that, as with the steel, some idea of not only cutting depth but also cut quality can be seen.


Figure 2. Cuts through thick stiff packing foam. Note the rough edge at the bottom of the extracted pieces, but the good initial quality of cut that was achievable for some 14-inches.

There is a caution in cutting foam, in that some of the softer varieties are going to fold into the cut, and give a slightly inaccurate measure of true performance, although for a quick comparison to see how a nozzle is lasting that is not a real issue. When cutting thicker material, and also when going for higher quality cuts, that is, however, something that should be borne in mind.

The white expanded foam that is used as a packing material is also very easy to cut, even with the pressures that can be found with a pressure washer type of system. Thus, if you are going to clean a deck or other surface it helps to check, by swiping the jet across such a piece of material, to be sure that you have a good nozzle on the end of your lance before you start.

This may seem fairly logical, after all you just went to the hardware store and bought a new packet of nozzles. Well, as with the other nozzles we have looked at, quality is only assured after testing. In this particular case we ran as many different variety of fan nozzles as we could to see how they would perform when cutting across a piece of packing foam. It is not hard to cut packing foam with a high pressure jet. And since domestic cleaning is usually carried out at either 1,000 psi or 2,000 psi we ran tests at both levels.


Figure 3. Results from a good, top, and a poor nozzle with cuts at 1,000 and 2,000 psi. and with the foam moved through the jet at a distance of 3 inches. The number identifies the nozzle and note that at 3 inches number 18 could barely remove the top of the foam.

A fan jet is defined by the amount of water that it will allow to pass at a set pressure, and by the angle of the cone with which the jet spreads out from the orifice. In passing we found that the cone angle that the jet actually spread at was a little larger than that designated on the package.

The worst nozzle design that we found had difficulty in cutting into the foam, even at a very close range:

On the other hand the best nozzle was still able to cut the material with the nozzle held some nine inches from the foam.


Figure 4. Cutting result with the good nozzle held at nine inches above the foam target. At this distance the jet is removing as much material as the poor jet did at a 3-inch standoff.

A very typical result would have the jet fail to cut into the foam much beyond four inches from the nozzle. (I’ll use some photographs in a couple of weeks to explain in more detail why that is). And as a short editorial comment to those of you who clean around your house with a domestic unit, how many of you hold the nozzle that close to the surface? (Or at the car wash?) If you don't you are losing most of the power that you are paying for, and you are in the company of most of the students that I ran this demonstration with in my classes).

However there is one other feature to the photographs of the cuts that I would point out. Fan jets distribute the water over a diverging fan shape. But the results of the design fell into two different types, one where most of the water still concentrated in the middle of the jet, (as in Figure 4) and those where it was focused more on the side.


Figure 5. Cutting pattern with the jet streams more at the side of the flow. (arrow points), note that the two pressure cuts are on the other sides of the sample here).

The benefit of using foam is that it allows this picture of the jet structure to be easily seen, with very little time taken to swipe the nozzle over a test piece of material at the start of work, to make sure that the jet is still working correctly.

This is both an advantage and a disadvantage. Because the foam is relatively easy for a jet to cut, even at a lower pressure, this means that the cut can become more ragged with depth, where deep cutting is required.

One of the programs that we ran, some years ago, looked at how deeply you could cut into the stiff packing foam that is used in some industrial plants, where the item being packed needs to be held firmly, yet will be released easily when needed. This requires that the foam be cut to a very tight tolerance, and at the time, pieces were still being cut by hand and then glued together. (Figure 2 above)

We found that we could cut up to about a foot of material, before the small cut particles became sufficiently caught up in the cutting jet that the edge quality of the cut fell below specification. But in order to get to that depth we did have to add a small amount of a polymer to the cutting water. This helped to hold the jet more coherent over a greater distance, and also reduced the amount of particulate that got caught up in the jet, allowing the greater cutting depth.

Foam works as a simple sample to give some sense of the jet shape, where the pressures are lower. When they are higher then a stiffer material is needed, though it should still be cuttable by water without the need for abrasive. Plywood is a useful target in this case, and I will write about those tests next time.