Record 1 of 14
Christy JR
When was the hottest summer? A state climatologist struggles for an answer
BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 2002, Vol 83, Iss 5, pp 723+
To answer this very common though surprisingly difficult question, a technique was developed to
Abstract:
reconstruct a local temperature time series of summer average maximum temperatures in northcentral Alabama since 1893. The results show that the warmest summer was 1925 at 34.9degrees
+/- 0.4degreesC but that 5 other years are statistically so close they could not be eliminated as
contenders. (The trend is -0.13degreesC decade(-1).) Our insistence that this ambiguity be
recognized by the inquirer, usually the media, causes confusion and reduces their interest level
because they desire an absolute answer to, in their view, a very simple question.
Source item page count: 13
MAY
Publication Date:
554UH
IDS No.:
29-char source abbrev: BULL AMER METEOROL SOC
Author(s):
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Record 2 of 14
Maugeri M; Buffoni L; Delmonte B; Fassina A
Daily Milan temperature and pressure series (1763-1998): Completing and homogenising the data
CLIMATIC CHANGE 2002, Vol 53, Iss 1-3, pp 119-149
Daily meteorological observations have been made at the Brera astronomical observatory in Milan
since 1763. Even if the data have always been collected at this observatory, the Milan series are far
from being homogeneous as several changes were made to instruments, station location and
observation methods. Within this context, the purpose of the paper is to discuss data
homogenisation. Homogenisation is based both on objective information extracted from the station
history (direct methodology) and on some statistical estimates (indirect methodology).
Homogenisation by indirect methodology is mainly performed by comparison with other series
whereas, if no other homogeneous series are available, it is based on the hypothesis that some
statistics, such as the daily temperature range or the day to day variability, have no significant
trends within some selected periods. Besides homogenisation also the completion of the series is
discussed. The resulting series are complete and homogenised daily minimum, mean and
maximum temperatures and complete and homogenised daily mean pressures. They all cover the
period 1763-1998.
Source item page count: 31
APR-MAY
Publication Date:
537KJ
IDS No.:
29-char source abbrev: CLIMATIC CHANGE
Author(s):
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Record 3 of 14
Peterson TC; Gallo KP; Lawrimore J; Owen TW; Huang A; McKittrick DA
Global rural temperature trends
GEOPHYSICAL RESEARCH LETTERS 1999, Vol 26, Iss 3, pp 329-332
Using rural/urban land surface classifications derived from maps and satellite observed nighttime
surface lights, global mean land surface air temperature time series were created using data from
all weather observing stations in a global temperature data base and from rural stations only. The
global rural temperature time series and trends are very similar to those derived from the full data
set. Therefore, the well-known global temperature time series from in situ stations is not
significantly impacted by urban warming.
Source item page count: 4
FEB 1
Publication Date:
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163YK
IDS No.:
29-char source abbrev: GEOPHYS RES LETT
Record 4 of 14
Bohm R; Auer I; Brunetti M; Maugeri M; Nanni T; Schoner W
Regional temperature variability in the European Alps: 1760-1998 from homogenized instrumental
time series
INTERNATIONAL JOURNAL OF CLIMATOLOGY 2001, Vol 21, Iss 14, pp 1779-1801
Source:
This paper investigates temperature variability in the Alps and their surroundings based on 97
Abstract:
instrumental series of monthly mean temperatures. A discussion of the initial homogenizing
procedure illustrates its advantages and risks. A comparison of the homogenized series with the
original series clearly shows the necessity to homogenize. Each of the original series had breaks
(an average of five per series) and the mean of all series was systematically biased by non-climatic
noise. This noise has subdued the long-term amplitude of the temperature evolution in the region
by 0.5 K. The relatively high spatial resolution of the data enabled a regionalization within the
study area of 680 000 km(2) into six sub-regions based on principal component analysis of the
monthly series. Long-term temperature evolution proved to be highly similar across the region-thus
making a mean series (averaged over all 97 single series) representative of the study area. Trend
analysis (based on progressive forward and backward Mann-Kendall statistics and on progressive
analysis of linear regression coefficients) was performed on seasonal and annual series. The results
diverge from those of global datasets. This is mainly due to the extension of the 240-year Alpine
dataset by 100 years prior to the mid-19th century, and also due to the advantages of a dense and
homogenized regional dataset. The long-term features include an initial decrease of the annual and
seasonal series to a minimum followed by a positive trend until 1998. The minima are 1890 for the
entire year and winter, 1840 for spring and 1920 for summer and autumn, respectively. The initial
decreasing trend is more evident in spring and summer, less in autumn and smallest in winter. The
mean annual temperature increase since 1890 in the Alps is 1.1 K, which is twice as much as the
0.55 K in the respective grid boxes of the most frequently used global dataset of the Climatic
Research Unit (CRU), University of East Anglia. To enable an easier and more systematic
handling of the dataset, these data have been interpolated to a 1degrees x 1degrees longitudelatitude grid. The 105 low-elevation and 16 high-elevation grid point series are widely available
without restrictions for scientific research and can be obtained from the authors. Copyright (C)
2001 Royal Meteorological Society.
Source item page count: 23
NOV 30
Publication Date:
509VG
IDS No.:
29-char source abbrev: INT J CLIMATOL
Author(s):
Title:
Record 5 of 14
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Tuomenvirta H
Homogeneity adjustments of temperature and precipitation series - Finnish and Nordic data
INTERNATIONAL JOURNAL OF CLIMATOLOGY 2001, Vol 21, Iss 4, pp 495-506
An analysis is made of the adjustments needed to produce three homogeneous data sets, namely the
1961-1990 mean temperatures in Finland, the North Atlantic Climatolological Dataset (NACD)
temperature and precipitation series (1890-1990), and the Finnish daily mean maximum and
minimum temperature series (1910-1995), as well as the reasons for making such adjustments. The
adjustments in the annual (seasonal) mean temperatures are up to +/- 1 degreesC (+/- 2 degreesC),
and annual precipitation adjustments can be +/- 40%. In Finland, the homogeneity breaks in the
normal period temperatures and in the long-term daily mean maximum and minimum temperatures
appear to be random, and thus, do not bias averages based on large numbers of stations. However,
both the temperature and precipitation series of the NACD would have been statistically
significantly biased without adjustments. Station relocations appear to be the most common cause
of homogeneity breaks in the temperature series. In the NACD, the adjustments resulting from
relocations are statistically significant and reflect changes to colder observing sites. Also, changes
in the formula used for the calculation of mean temperatures and urbanization both cause
systematic biases in the data. The installation of improved precipitation gauges has been systematic
in the NACD; thus, the original series need to be adjusted upwards in the early years. The applied
adjustments are of the same order of magnitude as the observed long-term trends, which stresses
the importance of the testing and adjusting of long-term series before analysis of climatic changes.
In order to monitor climatic changes in a reliable manner, the observing network should be
designed to withstand the common discontinuities (e.g. relocations, observer and environment
changes etc.) in observation series, because the number of homogeneity breaks appears to be
roughly constant in time. Moreover, the introduction of new technology may cause systematic
changes in the observations, and comprehensive comparison measurements are needed. Copyright
(C) 2001 Royal Meteorological Society.
Source item page count: 12
MAR 30
Publication Date:
424JD
IDS No.:
29-char source abbrev: INT J CLIMATOL
Record 6 of 14
Peterson TC; Easterling DR; Karl TR; Groisman P; Nicholls N; Plummer N; Torok S; Auer I;
Boehm R; Gullett D; Vincent L; Heino R; Tuomenvirta H; Mestre O; Szentimrey T; Salinger J;
Forland EJ; Hanssen-Bauer I; Alexandersson H; Jones P; Parker D
Homogeneity adjustments of in situ atmospheric climate data: A review
Title:
INTERNATIONAL JOURNAL OF CLIMATOLOGY 1998, Vol 18, Iss 13, pp 1493-1517
Source:
Long-term in situ observations are widely used in a variety of climate analyses. Unfortunately,
Abstract:
most decade- to century-scale time series of atmospheric data have been adversely impacted by
inhomogeneities caused by, for example, changes in instrumentation, station moves, changes in the
local environment such as urbanization, or the introduction of different observing practices like a
new formula for calculating mean daily temperature or different observation times. If these
inhomogeneities are not accounted for properly, the results of climate analyses using these data on
be erroneous. Over the last decade, many climatologists have put a great deal of effort into
developing techniques to identify inhomogeneities and adjust climatic time series to compensate
for the biases produced by the inhomogeneities. It is important for users of homogeneity-adjusted
data to understand how the data were adjusted and what impacts these adjustments are likely to
make on their analyses. And it is important for developers of homogeneity-adjusted data sets to
compare readily the different techniques most commonly used today. Therefore, this paper reviews
the methods and techniques developed for homogeneity adjustments and describes many different
approaches and philosophies involved in adjusting in situ climate data. (C) 1998 Royal
Meteorological Society.
Source item page count: 25
NOV 15
Publication Date:
138HW
IDS No.:
29-char source abbrev: INT J CLIMATOL
Author(s):
Record 7 of 14
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Vincent LA; Zhang X; Bonsal BR; Hogg WD
Homogenization of daily temperatures over Canada
JOURNAL OF CLIMATE 2002, Vol 15, Iss 11, pp 1322-1334
A method to homogenize daily maximum and minimum temperatures over Canada is presented.
The procedure is based on previously defined monthly adjustments derived from step changes
identified in annual Canadian temperature series. Daily temperatures are adjusted by incorporating
a linear interpolation scheme that preserves these monthly adjustments. The temperature trends and
variations present in the homogenized monthly and annual datasets are therefore preserved.
Comparisons between unadjusted and adjusted daily temperatures at collocated sites show that the
greatest impact of the adjustments is on the annual mean of the daily maximum and minimum
temperatures with little effect on the standard deviation. The frequency and distribution of the
extremes are much closer to those provided by the target observations after adjustments.
Furthermore, the adjusted daily temperatures produced by this procedure greatly improve the
spatial pattern of the observed twentieth century extreme temperature trends across the country.
Source item page count: 13
JUN 1
Publication Date:
547UC
IDS No.:
29-char source abbrev: J CLIMATE
Record 8 of 14
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Allen RJ; DeGaetano AT
A method to adjust long-term temperature extreme series for nonclimatic inhomogeneities
JOURNAL OF CLIMATE 2000, Vol 13, Iss 20, pp 3680-3695
A method to homogenize nonclimatic discontinuities in temperature extreme exceedence series Is
developed and evaluated. The method is based on a set of complementary rests with the application
of an individual rest depending on the availability of an adequate network of nearby homogeneous
reference stations and the presence of significant trends in the resulting difference or original
exceedence series. Given a suitable set of neighboring reference stations, a comparison of the
differences in exceedences between the inhomogeneous station and neighboring sites is made for
the periods before and after the documented discontinuity. In the absence of one or more reference
stations, the exceedences at the inhomogeneous station are compared before and after the
nonclimatic change. A method by which nonstationary series are detrended and subsequently
evaluated is also presented.
When tested using homogenized data series into which an artificial discontinuity of known
magnitude was introduced, as many as 80% of the +/-1 degreesF discontinuities were
detected by the difference series approach. The performance of the single-station
exceedence series test was less accurate. Although in a few cases, less than 40% of the
+/-1 degreesF discontinuities were detected, between 60% and 76% of the +/-2 degreesF
discontinuities were identified. Using both tests, the probability of falsely detecting a
discontinuity (i.e., identifying an inhomogeneity when none existed) was 5%. Provided
both methods deemed a documented inhomogeneity significant, the magnitude of the
adjustments imposed by both methods was similar.
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IDS No.:
29-char source abbrev:
16
OCT 15
369JR
J CLIMATE
Record 9 of 14
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Tuomenvirta H; Alexandersson H; Drebs A; Frich P; Nordli PO
Trends in Nordic and Arctic temperature extremes and ranges
JOURNAL OF CLIMATE 2000, Vol 13, Iss 5, pp 977-990
The national meteorological institutes in the Nordic countries have produced a comprehensive
dataset of climatic extreme temperatures (monthly mean daily maximum and minimum, and
monthly absolute highest and lowest temperatures) comprising stations from Fenno-Scandia, the
Nordic Seas, and Greenland. Mean maximum and minimum temperatures show statistically
significant negative trends in western coastal Greenland during the period 1950-95, while over the
Nordic Seas and Fenno-Scandia the trends are generally positive. The diurnal temperature range
(DTR) is decreasing significantly throughout the study area and is unrelated to regional
temperature trends, which show both warming and cooling. The opposite temperature trends
between western coastal Greenland and Fenno-Scandia since the 1950s are in accordance with a
strengthening of the North Atlantic Oscillation (NAO). However, the simple NAO index fails to
explain the decrease of DTR. In Fenno-Scandia, the reliable long-term mean maximum and
minimum temperatures show cooling in winter and warming in spring and summer during the
period 1910-95. Simultaneously, DTR has been decreasing in all seasons except winter. Most of
the decrease has occurred since the 1940s. Atmospheric circulation indices defined by zonal and
meridional sea level pressure differences, along with sea level pressure and cloud cover anomalies
were used to build a multiple linear regression model for the Fenno-Scandian DTR. During the
period 1910-95 the model explains from 53% (winter) to 80% (summer) of the variation in DTR
and reproduces the statistically significant decreasing trend on annual level. Cloud cover is the
dominant predictor, while circulation provides substantial improvement in explanation.
Source item page count: 14
MAR 1
Publication Date:
290UN
IDS No.:
29-char source abbrev: J CLIMATE
Record 10 of 14
Slonosky VC; Jones PD; Davies TD
Homogenization techniques for European monthly mean surface pressure series
JOURNAL OF CLIMATE 1999, Vol 12, Iss 8, pp 2658-2672
The quality of 51 series of surface pressure (extending back to between 1780 and 1871) over
Europe is assessed using three different homogenization techniques. A new technique introduced
here based on an iteration of multiple qualitative comparisons and adjustments (MCAs), and the
Caussinus and Mestre technique, based on multiple decision rules and Bayesian statistics, are two
methods that do not require a homogeneous reference series for the detection and adjustment of
inhomogeneities. The third technique, the standard normal homogeneity test, does require a
homogeneous reference series for the homogenization procedure, and has been used only on the
last 100 yr of each station series. The results of the three methods, as well as the original,
unadjusted data, are compared for differences in the variance of the individual series and in their
interstation correlations. Empirical orthogonal function analysis is also used to assess differences in
the results of the adjustment methods. The comparisons suggest that surface pressure in this
geographical domain may be considered as being stationary over periods ranging from decades to
centuries, and thus homogeneous parts of a surface pressure record can be used to adjust for
inhomogeneities, as is done using MCA. It is also seen that EOF analysis can be an effective tool
to assess the homogeneity of a dataset. The results of the EOF analysis show that inhomogeneities
and poorly adjusted series can have undue influence on subsequent analyses.
Source item page count: 15
AUG
Publication Date:
2
Part number:
232MM
IDS No.:
29-char source abbrev: J CLIMATE
Author(s):
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Record 11 of 14
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Hansen J; Ruedy R; Sato M; Imhoff M; Lawrence W; Easterling D; Peterson T; Karl T
A closer look at United States and global surface temperature change
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 2001, Vol 106, Iss D20, pp
23947-23963
We compare the United States and global surface air temperature changes of the past century using
the current Goddard Institute for Space Studies (GISS) analysis and the U.S. Historical
Climatology Network (USHCN) record [Karl et al., 1990]. Changes in the GISS analysis
subsequent to the documentation by Hansen et al. [1999] are as follows: (1) incorporation of
corrections for time-of-observation bias and station history adjustments in the United States based
on Easterling et al. [ 1996a], (2) reclassification of rural, small-town, and urban stations in the
United States, southern Canada, and northern Mexico based on satellite measurements of night
light intensity [Imhoff et al., 1997], and (3) a more flexible urban adjustment than that employed
by Hansen et al. [1999], including reliance: on only unlit stations in the United States and rural
stations in the rest of the world for determining long-term trends. We find evidence of local human
effects ("urban warming") even in suburban and small-town surface air temperature records, but
the effect is modest in magnitude and conceivably could be an artifact of inhomogeneities in the
station records. We suggest further studies, including more complete satellite night light analyses.
which may clarify the potential urban effect. There are inherent uncertainties in the long-term
temperature change at least of the order of 0.1 degreesC for both the U.S. mean and the global
mean. Nevertheless, it is clear that the post- 1930s cooling was much larger in the United States
than in the global mean. The U.S. mean temperature has now reached a level comparable to that of
the 1930s, while the global temperature is now far above the levels earlier in the century. The
successive periods of global warming (1900-1940), cooling (1940-1965), and warming (19652000) in the 20th century show distinctive patterns of temperature change suggestive of roles for
both climate forcings and dynamical variability. The U.S. was warm in 2000 but cooler than the
warmest years in the 1930s and 1990s. Global temperature was moderately high in 2000 despite a
lingering La Nina in the Pacific Ocean.
Source item page count: 17
OCT 27
Publication Date:
489CG
IDS No.:
29-char source abbrev: J GEOPHYS RES-ATMOS
Record 12 of 14
Moberg A; Jones PD; Barriendos M; Bergstrom H; Camuffo D; Cocheo C; Davies TD; Demaree
G; Martin-Vide J; Maugeri M; Rodriguez R; Verhoeve T
Day-to-day temperature variability trends in 160-to 275-year-long European instrumental records
Title:
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 2000, Vol 105, Iss D18, pp
Source:
22849-22868
Day-to-day temperature variability is investigated in eight European series of daily mean
Abstract:
temperatures beginning between 1722 and 1833. Eight statistical measures of day-to-day
temperature variability are compared. The intramonthly standard deviation of daily temperature
anomalies is found to be a good measure. The absolute change in temperature anomaly from one
day to the next is sensitive to changes in observational procedures and is suggested as a diagnostic
tool for identification of inhomogeneities in instrumental temperature series. Because many
changes in observational procedures have taken place, quantitative estimates of trends in day-today variability, based on all series, could only be calculated for 1880-1998. A trend analysis over
this period indicates an increase by 5% in southwest Europe, 0 to -5% change in the northwest, and
a decrease by 5 to 10% in northeast Europe. On a longer time perspective, day-to-day temperature
variability in winter, spring, and autumn in northern Europe has decreased over the last 200-250
years. The frequency of extremely cold wister days in northern Europe was lower in the twentieth
century than in the eighteenth and nineteenth centuries. Day-to-day temperature variability in
winter in northern Europe was negatively correlated with a North Atlantic Oscillation index in the
period 1826-1997, but some other factor must also have contributed to the long-term variability
decrease. More long daily temperature series, and development of homogenization methods for
such data, are needed for an improved knowledge of long-term changes in day-to-day temperature
variability.
Source item page count: 20
SEP 27
Publication Date:
359EF
IDS No.:
29-char source abbrev: J GEOPHYS RES-ATMOS
Author(s):
Record 13 of 14
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Hansen J; Ruedy R; Glascoe J; Sato M
GISS analysis of surface temperature change
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 1999, Vol 104, Iss D24, pp
30997-31022
We describe the current GISS analysis of surface temperature change for the period 1880-1999
based primarily on meteorological station measurements. The global surface temperature in 1998
was the warmest in the period of instrumental data. The rate of temperature change was higher in
the past 25 years than at any previous time in the period of instrumental data. The warmth of 1998
was too large and pervasive to be fully accounted for by the recent El Nine. Despite cooling in the
first half of 1999, we suggest that the mean global temperature, averaged over 2-3 years, has
moved to a higher level, analogous to the increase that occurred in the late 1970s. Warming in the
United States over the past 50 years has been smaller than in most of the world, and over that
period there was a slight cooling trend in the eastern United States and the neighboring Atlantic
Ocean. The spatial and temporal patterns of the temperature change suggest that more than one
mechanism was involved in this regional cooling. The cooling trend in the United States, which
began after the 1930s and is associated with ocean temperature change patterns, began to reverse
after 1979. We suggest that further warming in the United States to a level rivaling the 1930s is
likely in the next decade, but reliable prediction requires better understanding of decadal
oscillations of ocean temperature.
Source item page count: 26
DEC 27
Publication Date:
273DQ
IDS No.:
29-char source abbrev: J GEOPHYS RES-ATMOS
Record 14 of 14
Datsenko NM; Moberg A; Sonechkin DM
Objective time-scale-dependent homogenization of early instrumental temperature series
THEORETICAL AND APPLIED CLIMATOLOGY 2002, Vol 72, Iss 1-2, pp 103-126
An objective method for homogenization of early (pre similar to 1850) instrumental near surface
air temperature records is developed. The method is grounded on the same variational principle as
used in the objective analysis of meteorological fields, i.e. the method consists of a statistically
optimal spatial-coherence-based adjustment of nearby station temperature records. The adjustments
are made for several different ranges of time scales, where the wavelet transform is used for the
decomposition. The method takes into account that early instrumental temperature records are
supposed to contain observational disturbances which are more or less smooth functions of time as
a result of summations of numerous sources of biases. The method differs from traditional
homogenization techniques in that corrections are not only made for a discrete number of abrupt or
linear changes, but for continuously changing errors. The power of the method is illustrated with an
example of homogenization of three very long temperature records from Sweden.
Source item page count: 24
558WK
IDS No.:
29-char source abbrev: THEOR APPL CLIMATOL
Author(s):
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