If you really want to draw conclusions about an entire data set (ie, from all the stations) from
a subset of the stations, then you have to do proper random sampling of many of those stations (the greater the number, the higher the confidence in the result, of course).
NASA does a UHI CORRECTION for
a SUBSET of stations
Doing so using satellite imagery is a practical approach, although it needs some sort of validation over
a subset of stations to check if the results are robust.
On climate, this same problem shows up when we have «The GLOBE is warming» vs «
This subset of stations warms and these others do not.».
Written by a NOAA National Climatic Data Center scientist, it examined only a small
subset of stations — all that had their siting checked at that time — and found no bias in long - term trends.
This approach also afforded Berkeley the opportunity to generate the result using
subsets of station data.
(2010) did this with the homogenized data from different
subsets of stations, and found very strong correlations with the entire USHCN dataset (r2 = 0.98 for Tmax, and r2 = 0.96 for Tmin).
Not exact matches
For a
subset of 14 relatively clear (cloudy)
stations, the mean temperature drop was 0.91 ± 0.78 (0.31 ± 0.40) degrees C, but the mean temperature drops for relatively calm and windy
stations were almost identical, indicating that cloud cover has a much greater effect than wind on the air temperature's response to an eclipse.
The Berkeley researchers developed their own statistical methods so that they could use data from virtually all
of the temperature
stations on land — some 39,000 in all — whereas the other research groups relied on
subsets of data from several thousand sites to build their records.
I think I have read
of analyses
of some
subset of the continental U.S.
stations that are
of high quality, called GHCN or something like that.
fahutex says: January 10, 2016 at 6:10 pm: I think I have read
of analyses
of some
subset of the continental U.S.
stations that are
of high quality...... Yes, it's called the CRN, Climate Reference Network.
In the rural
subset of U.S.
stations, the recent warm temperatures aren't actually that unusual, and it seems that it was at least as warm in the 1930s.
Because
of differences among the start, end and total length
of the
station records they examined, the authors decided to perform their analyses on three
subsets of the data.
In describing their findings, Do et al. report that across all three
subsets of data, «more
stations showed statistically significant decreasing trends [in streamflow] than statistically significant increasing trends,» which finding held regardless
of whether the
stations were filtered by the presence
of dams or changes in forest cover.
Muller et al., 2011 found that the linear trends
of the Unadjusted records for
stations with Ratings 1, 2 or 3 were comparable to those
of stations with Ratings 4 or 5, and that there was not much difference between estimates constructed from the Ratings 1 - 3 and Ratings 4 - 5
subsets of the USHCN.
For this reason, in our analysis, we grouped the
stations with Ratings
of 1 and 2 into the same
subset.
This warming bias artificially increased the apparent temperature trends
of the U.S. by about half for the Unadjusted version
of the dataset, with the trend for the
subset of the worst - sited
stations more than doubling, relative to the best - sited
stations.
The
subset of records (14
stations) extending back to the early 1960s suggests that the recent warming trends were preceded by similar widespread cooling trends.
«We make use
of the
subset of USHCNv2 metadata from
stations whose sites have been classified by Watts (2009)» and; «site rating metadata from Fall et al (2011)».
This is done by using a
subset of the CEC - A15 reporting
stations to estimate the characteristics
of the missing fueling
station population.
It is within our grasp to locate and collate
stations in the USA and in the world that have as long
of an uninterrupted record and freedom from bias as possible and to make that a new climate data
subset.
As seen in the map below, there are thousands
of temperature
stations in the US co-op and USHCN network in the USA, by our surface
stations survey, at least 80 %
of the USHCN is compromised by micro-site issues in some way, and by extension, that large sample size
of the USHCN
subset of the co-op network we did should translate to the larger network.
When you have those 100
stations, the next step is to use only a
subset of them.
Around Dec 8, 2009, the UK Met Office released «value added» data for a «
subset»
of 1741
stations — see here, describing the release as follows: The data downloadable from this page are a
subset of the full HadCRUT3 record
of global temperatures, which is one
of the global temperature records that have underpinned IPCC -LSB-...]
I wonder what
subset of the 779
stations would need to be analyzed in depth to validate the hypothesis?
A
subset of the 7,000 or so co-op
stations are part
of the U.S. Historical Climatological Network (USHCN), and are used to create the official estimate
of U.S. temperatures.
Overall, in this
subset, 86 %
of the
stations show warming.
These
stations are classified on proximity to artificial surfaces, buildings, and other such objects with unnatural thermal mass,» according to the study, entitled Comparing
of Temperature Trends Using an Unperturbed
Subset of the U.S. Historical Climatology Network.
The next step is probably to look at the
subset of rural CRN12
stations.
Bias at the microsite level (the immediate environment
of the sensor) in the unperturbed
subset of USHCN
stations has a significant effect on the mean temperature (Tmean) trend.
Equipment bias (CRS v. MMTS
stations) in the unperturbed
subset of USHCN
stations has a significant effect on the mean temperature (Tmean) trend when CRS
stations are compared with MMTS
stations.
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