comparing the 42 ‐
rural station data used in the 1990 GRL and Nature papers with those adjusted for homogeneity of a 728 ‐ station network yield very much the same results, implying that the station moves, if any, really did not matter when a representative set of stations (here 42 ‐ stations) was used.
For another discussion (where to find the effect of aerosols) I was looking for more or less reliable
rural station data for North - West Russia for the period 1945 - 2004.
Not exact matches
These can arise from many technical issues, including
data selection, substandard temperature
station quality, urban vs
rural effects,
station moves, and changes in the methods and times of measurement
First they used the weather
station data to determine how temperatures in Philadelphia's urban and surrounding
rural areas had changed over time.
We carefully studied issues raised by skeptics: biases from urban heating (we duplicated our results using
rural data alone), from
data selection (prior groups selected fewer than 20 percent of the available temperature
stations; we used virtually 100 percent), from poor
station quality (we separately analyzed good
stations and poor ones) and from human intervention and
data adjustment (our work is completely automated and hands - off).
Quixeramobin is the nearest
rural station with more or less reliable
data over a longer time span, and shows very different trends than Salvador.
For instance, GISTEMP uses satellite - derived night light observations to classify
stations as
rural and urban and corrects the urban
stations so that they match the trends from the
rural stations before gridding the
data.
To provide a baseline for projecting temperature to the projected maximum of solar cycle 25,
data from five
rural, continental US
stations with
data from 1905 to 2003 was averaged and smoothed.
Quixeramobin is the nearest
rural station with more or less reliable
data over a longer time span, and shows very different trends than Salvador.
with — it shows what happens when you average raw («unskewed») and homogenized («skewed»)
data from 1 to 40 random
rural stations: http://tinyurl.com/ghcn-animation
This takes public domain
data provided by the Met Services, homogenises it and makes a correction for urban warming based on nearby
rural stations.
In my experimentation with the
data, I found that it was virtually impossible to get results inconsistent with the NASA results —
rural stations, urban
stations, raw
data, adjusted
data — once you average
data from a few dozen
stations scattered around the world, everything settles right down to something that looks very much like the NASA land - temp.
UHI effects will generally lead to long term trends in an affected
station (relative to a
rural counterpart), whereas micro-site changes could lead to jumps in the record (of any sign)-- some of which can be very difficult to detect in the
data after the fact.
For instance, GISTEMP uses satellite - derived night light observations to classify
stations as
rural and urban and corrects the urban
stations so that they match the trends from the
rural stations before gridding the
data.
The «50 random
rural stations» adjusted
data results are plotted in green.
The «50 random
rural stations» raw
data results are plotted in red.
As Hansen indeed only used
rural stations for his global temperature trend outside the USA, I need to change the challenge: find out the
station density of
rural stations in the GISS database for the tropics (20N - 20S or 30N - 30S) where in the 1979 - 2005 period the
data show some reliability... Good luck with that!
To provide a baseline for projecting temperature to the projected maximum of solar cycle 25,
data from five
rural, continental US
stations with
data from 1905 to 2003 was averaged and smoothed.
There is good evidence that the answer to both these question is no: (The insensitivy of the results to methodology of selecting
rural stations, the Parker et al windy days study, and the fact that
data from satellite skin surface measurements, from sea surface temperatures, deep ocean temps as we as tropospheric temps are all in good agreement).
Is it the process of taking raw temp
data from a
rural site and mathematically combining it with
data from a nearby
station with warming to make the
rural data have a warming trend?
However, they could evaluate urban bias and found that once the
data were fully adjusted the 30 % most urban
stations had about the same trend as the remaining more
rural stations.
Since about 20 years, GISS and NOAA adapt UHI
station output by homogenizing the
data with that of their
rural neighbours.
Only eight of the
rural stations have
data for at least 95 of the last 100 years!
Only EIGHT of the
rural stations had
data for at least 95 of the last 100 years!
And with all the one way
data manipulations, the urban heat island effect, and the vanishing
rural stations, one could infer that worldwide the 1930s were likely hotter than today!
------------------------------------ And here's what the proxies vs. the highly adjusted instrumental
data that have been hopelessly corrupted by removing thousands of
rural stations and keeping urban
stations, moving
rural sites to airports, «mostly made up» SH sea surface temperatures, cooling down the 1930s and 1940s artificially to remove 0.5 C from the early 20th century warming... look like.
Here is a chart comparing, for the CONUS from 1880 till today, very
rural places with the rest: The
data was obtained by selecting, out of all US GHCN
stations, those showing in their metadata both
rural mode and least nightlight.
What do warmers such as Hanson / Giss do, well, they compare
data from a highly UHI contaminated urban city weather
station with CLEAN
data from a neighbouring
RURAL station.
There is accurate CO2
data but only since 1958 at Mauna Loa, as for temperature, well there are thousands of high quality
rural weather
stations throughout the world and especially in the US and the northern hemisphere that have long histories and NO UHI bias.
What's more, NASA GISS takes explicit steps in their analysis to remove any such spurious signal by normalizing urban
station data trends to the surrounding
rural stations.
Would it not have been more logical and possibly more honest to have discarded the contaminated
data from the Urban
stations and used only the clean
data from the
Rural sites.
This causes a cooling bias in the
data of the
rural stations.
Since urban
stations show a higher temperature (on average) compared to
rural stations (on average), having more urban
stations in the mix will increase the overall average temperature of even an unadjusted
data set.
And the OAA
data — the ocean air affected
stations far from the coast — are often hill or mountain
stations, quite
rural.
Secondly, and this is the more important issue related to the different
station data for different years — is what is the mix of
rural / urban
stations?
Just to be absolutely sure, we can do a further calculation using just
rural unadjusted
data (using the GHCN
station classifications)- the blue line.
We carefully studied issues raised by skeptics: biases from urban heating (we duplicated our results using
rural data alone), from
data selection (prior groups selected fewer than 20 percent of the available temperature
stations; we used virtually 100 percent), from poor
station quality (we separately analyzed good
stations and poor ones) and from human intervention and
data adjustment (our work is completely automated and hands - off).
Although the global network nominally contains temperature records for a large number of
rural stations, most of these records are quite short, or are missing large periods of
data.
Why would a
rural station that has never changed location or instrumentation have its
data adjusted?
If temperatures rose because previously
rural weather
stations were swallowed up by expanding megalopolises then some doubt is cast on whether that
data supports theories of human - caused global warming.
It concluded: Using satellite night - lights — derived urban /
rural metadata, urban and
rural temperatures from 289
stations in 40 clusters were compared using
data from 1989 to 1991.
Using groups for urban / suburban /
rural, altitude band, latitude band,
station id, and year in the R Project lmer function applied to the giss.dset0 annual temperature
data.
This entire debate about TOBS is a red herring, and here is why: if the difference between the raw
data and the final product is mainly due to the TOBS adjustments then you would expect to see the similar raw trends for
rural and urban
stations, and for «compliant» and «non compliant»
stations, don't you?
In the same time the raw
data for the non-compliant 3,4,5 class
stations show 0.212 C and for all
stations, urban and
rural 1,2 — 0,155, for the class 3,4,5
stations raw 0.246 and for all
stations adjusted 0.3.
It is one thing to say that the
rural stations may not be as reliable as some people think, because of the general problems with personal you note, but quite another to claim that the
data must of necessity exhibit a strong cooling bias!
As the trend in the US
rural stations, which at least until very recently employed these min / max
stations, has been from early evening observation (5 pm or 7 pm in most of the sources I've found) to early morning observation (usually 7 am), this has been presumed to put an artificial cooling bias into the temperature record, so a net positive, and increasing as more
stations have been converted, correction has been added to the raw
data.
# 167 / In all of the above posts there is no mention of the urban heat island effect, nor of the effect of
rural station drop out nor of the effect the GISS
data manipulation has on surface temperature.
(Note that there is no
data for the most recent years with some of the
rural stations.)
At a minimum it would necessarily include the miserable state the 4 global
data sets are in, the various methods and means of which this record consists, loss of ~ 70 % of reporting
stations (predominately high latitude, high altitude and
rural) post 1990, and what resides in my mind at least as pure horror at the state of the surface
stations Anthony et al have and are documenting.
When looking at the Tmin USHCNv2 adjusted
data for
rural stations, we observe that it is adjusted higher in value, from 0.127 °C / decade to 0.249 °C / decade, effectively doubling the trend,