By Joseph D’Aleo, CCM
Remember this story long ago on New York’s Central Park multiple very different data sets to which Steve McIntyre responded here. McIntyre wrote then:
…has the temperature of New York City increased in the past 50 years? Figure 1 below is excerpted from their note, about which they observed.
Note the adjustment was a significant one (a cooling exceeding 6 degrees from the mid 1950s to the mid 1990s.) Then inexplicably the adjustment diminished to less than 2 degrees …The result is what was a flat trend for the past 50 years became one with an accelerated warming in the past 20 years. It is not clear what changes in the metropolitan area occurred in the last 20 years to warrant a major adjustment to the adjustment. The park has remained the same and there has not been a population decline but a spurt in the city’s population in the 1990s.
Well, NCDC has a shiny new very cool tool for plotting data for regions, states and some city locations by month(s), seasons, years. They describe it this way.
Data for the Contiguous U.S., statewide, climate divisions, climate regions, and agricultural belts come from the U.S. Climate Divisional Database, which have data from 1895 to the present.
Information is also available at the city level for the following 60 cities. The 27 cities highlighted in blue below are Automated Surface Observing System (ASOS) stations which are part of the U.S. Historical Climatology Network (USHCN) (temperature data for the USHCN stations were converted to version 2.5 in October 2012). The other 33 cities use Global Historical Climatology Network (GHCN) data. These cities have data from varying beginning periods of record to the present.
Source: http://www.ncdc.noaa.gov/cag/data-info
New York’s Central Park was one of the blue cities (new USHCN v2.5). So I plotted it for July since that was one of the months in the original comparison.
Source: http://www.ncdc.noaa.gov/cag/
The surprise (when I plotted the source data myself rather than use NCDC’s tool) was how flat it was in the dust bowl heat of the 1930s. I know that on the NWS NYC web site, they have archived raw monthly means back well into the 1800s. So I downloaded that and compared.
It was dramatically cooler in the NCDC v2.5 than the original data. This plot shows the differences between the original recorded temperature data at Central Park and the final adjusted data that NCDC presents to the public:
As is clearly evident, adjustments made the dust bowl period cooler, while post 1995 had no adjustments applied. This results in a temperature trend that is steeper because the past is cooler than the present. The only problem is that it isn’t what the data actually recorded then.
I think maybe we need to coin a new term for NOAA NCDC – ‘dust bowl deniers’. Yes it appears there is man made warming underway but the men are in Asheville, North Carolina at NOAA’s National Climatic Data Center.
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Addendum by Anthony:
Cooling the past increases the trend. We’ve seen this effect happen several times before, yet there seems to be no justification for it. Probably this most dramatic example is what we see in this NOAA GISS plot comparison:
I’ve also written before about this tampering with data from the past. Such tampering with new adjustments like USHCN V2.5 allow claims of “warmest ever” to be made when the past gets cooled:
Dear NOAA and Seth, which 1930′s were you comparing to when you say July 2012 is the record warmest?
Gunga Din says:
July 15, 2013 at 11:29 am
Yeah, I could do that. Check out http://home.comcast.net/~ewerme/wuwt/index.html in the next to last section – Linking to past comments.
I have read a lot of papers by the warmalists, but I have never seen a discussion of how the average downward adjustment of 2 degrees F was arrived at. why not 1 dgree, or 4?
There was a commenter over on Powerline blog [http://www.powerlineblog.com/archives/2013/07/he-who-controls-the-present-controls-the-past.php] who stated that; “Axiom: the rise in global temperature increase is directly related to the increase in Federal grants purported to study global temperatures.” I thought that this would make an interesting, and telling, chart.
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Thanks!
I would add that it might help to give a clue as to what the comment is about.
(PS I think you have a typo. You have “they” instead of “the” in one line in the last section.)
I don’t usually post here nor am I a frequent visitor, but this caught my attention. A few years ago, I did my own research into temperature readings in Central Park. Being a longtime NYC resident, I’m quite familiar with the area.
Historically, the weather readings were taken at two locations in the park. Up until 1920, the weather station was located at a building called The Arsenal, which is located at 65th Street just off of 5th Avenue. The building is now part of the grounds of the Central Park Zoo and houses the administrative offices for the park. In 1920, the weather station was moved 0.8 miles north to Belvedere Castle where it remains to this day. Belvedere Castle sits on top of a crag of rock just off the 79th Street traverse and almost exactly on the north-south axis of the park.
I wondered about the possible reasons for moving this station and I think I hit upon the cause: wind. Starting in the 1920’s, some rather tall apartment buildings were constructed right along 5th Avenue, which blocked the free flow of wind. If you’ve ever been in Manhattan on a windy day, you probably experienced the well known “canyon effect” that buildings have on wind. You can walk along a street with the wind blowing at your back, then come to an intersection and have it blowing in your face, cross the street and it will come at you from the side, etc. The new construction probably played havoc with wind measurements at The Arsenal. So, the solution was to move the weather station to Belvedere Castle, which was far away from any obstructions and above the treetops.
The link I used to access GISS data for Central Park doesn’t work anymore. However, one of the things that I found somewhat mystifying was that, for the purpose of calculating yearly averages, GISS starts the year on December 1st. So I recalculated the averages if the year starts in January. The most obvious difference between the two sets is that, in the original GISS data, 2002 is the hottest year on record (13.94 ºC) while in the recalculated version, the hottest year is 1998 (13.95 ºC). In fact, in the recalculated version, the value for 2002 is almost a half a degree cooler (13.57 ºC). The reason for the discrepancy was an abnormally warm December 2001 (5 ºC above the 1.7 ºC average across the entire series for December). Just the simple action of moving December to the correct year is enough to account for a 0.77 ºC difference in 1990. In other years, it accounts for more than a ±0.5 ºC difference in certain years (notably 1911, 1918, 1958, and 2001). The fact that moving one data point can skew the results this much makes me wonder how valid an average annual temperature value really is.
In poking around the NOAA website, I found this page of climate data for New York City: (http://www.erh.noaa.gov/okx/climate_cms.html). Under “Temperature”, there is a link for “Average Monthly and Annual”. Clicking on that brings up this page of monthly and annual temperature readings from Central Park going back to January 1869 (http://www.erh.noaa.gov/okx/climate/records/monthannualtemp.html). According to NOAA, the readings were taken at The Arsenal building until December 1919 and, afterwards from Belvedere Castle. This appears to be “raw” data before it goes through homogenization, pasteurization, whatever. And unlike the “real scientists” at GISS, the “real weathermen” at NOAA start the year in January for the purpose of calculating annual averages.
I got sidetracked before I could go further with this, being a hobby and all. But I did notice that GISS consistently reported that past temperatures as cooler than originally reported. Between 1895 and 1920, GISS data is 1˚C or more cooler than NOAA data. Between 1920 and 1995, GISS is 0.5˚- 0.7˚C cooler. After 1995, the discrepancy disappears and the only differences I could see are probably rounding errors in the conversion between Fahrenheit and Celsius.
Gunga Din says:
July 17, 2013 at 1:53 pm
Nah, I’ll just leave the link as a little surprise explanation and a way to mess with the readers’ heads. 🙂
Typo fixed, will show up tomorrow morning.