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no more than 100
150 years. Even these data series are heterogeneous, especially
with regard to the global database as the main source of information for proving
evidence for global warming idea. Also, it should be borne in mind that the globally
averaged secular trend of SAT values is based, to a large extent, on the use of
imperfect observed data of sea surface temperature (SST).
The most important (and controversial) conclusion concerning the anthropogenic
nature of present day climate change is based on the analysis of the SAT and SST
combined data, that is on the secular trend of mean global average annual surface
temperature (GST). There exist both positive and negative anomalies of the GST
that indicate the observed temperature deviation from the reference value. In this
connection, two questions arise:
-
(1) about the information content of the notion of GST (this problem was for-
mulated by Essex and McKitrick (2002); and
(2) about the reliability of GST values determined, in particular, by fragmentary
data for the Southern Hemisphere, as well as the still unresolved problem of
urban
“
heat islands
”
.
cantly warmer
than its surrounding rural areas due to human activities. The phenomenon was
An urban heat island (UHI) is a metropolitan area that is signi
rst
investigated and described by Luke Howard in the 1810s, although he was not the
one to name the phenomenon (Howard 1820). The temperature difference is usually
larger at night than during the day, and is most apparent when winds are weak.
Seasonally, UHI is seen during both summer and winter. The main cause of the
urban heat island is the modi
cation of the land surface by urban development,
which uses materials which effectively retain heat. Waste heat generated by energy
usage is a secondary contributor (Li and Zhao 2012). As a population center grows,
it tends to expand its area, and increase in its average temperature. The less-used
term heat island refers to any area, populated or not, which is consistently hotter
than the surrounding area.
Studies on the reliability of the SAT observations are continuing from the per-
spective of observational techniques. For more than 100 years, SAT was measured
with the glass thermometers, but now arrangements to protect the thermometers
from direct solar radiation and wind have been repeatedly changed. This dictates a
necessity for
filtering out SAT data to provide homogeneous data series. In the
period from April till August 2000 at the station of the Nebraska State University,
USA (40
W), Hubbard et al. (2004) carried out comparative SAT
observations over smooth grass cover with the use of various protections of ther-
mometers. At the same time, direct solar radiation and wind speed were measured.
Analysis of observations has shown that differences of observed data can reach
several tenths of a degree. Therefore, a technique has been proposed to increase the
homogeneity of observation series which substantially increases the homogeneity
of the series. However, it does not permit the exclusion of the effect of calibration
errors and drift of the temperature sensor
°
83
′
N; 96
°
67
′
'
s sensitivity.
For the diagnostics of the observational data, emphasis should be put on the
analysis of climate variability in which a consideration not of averages but moments
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