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1.
Timothy Ball 《Climatic change》1983,5(1):85-93
Observations and records maintained by the Hudson's Bay Company at York Factory and Churchill Factory on Hudson Bay between
1714 and 1825, serve as the source of information for a study of changes in the date of arrival of geese as a phonological
indicator of climatic change. Changes in the migration pattern of geese are reflected in the changing date of arrival at the
same location over a long period of time. Variations in this date are determined to be a function of southerly or tailwinds
in the northward spring migration. 相似文献
2.
Annual indices of sea ice severity in Hudson Strait, for the period 1751 to 1870, are derived from written historical evidence
contained in ships' log-books. These logs were all kept on Hudson's Bay Company ships sailing from London to the Company's
trading posts. The log-books are homogeneous in nature and this property facilitates their numerical interpretation. The annual
indices are subjected to face validity testing which indicates that they may plausibly be accepted as measures of sea ice
severity. The results are examined in relation to the presentday behaviour of sea ice in Hudson Strait and they provide evidence
that the summer severity of ice conditions is mainly determined by atmospheric circulation conditions. 相似文献
3.
Indices of summer sea ice severity in the eighteenth and nineteenth centuries have been reconstructed from sailing ships' log-books. The ice record for Hudson Strait extends from 1751 to 1889. Ice records are available for two parts of Hudson Bay and these extend from 1751 to 1870. The three records were derived from the same sources but the method of derivation applied in the bay was different to that applied in the strait. The years having the five largest ice indices in each of these records were identified. Also identified were the years in which major volcanic eruptions occurred between 1751 and 1889. The number of concurrences between the years with severe ice in Hudson Strait and the years with major eruptions was significant at the 99.5% level. In the western part of Hudson Bay this significance level was 95%. The years with severe ice in eastern Hudson Bay did not concur with major eruptions. 相似文献
4.
Richard D. Ray 《大气与海洋》2016,54(2):108-116
Since the late 1990s the semi-diurnal tide at Churchill, on the western shore of Hudson Bay, has been decreasing in amplitude, with M2 amplitudes falling from approximately 154?cm in 1998 to 146?cm in 2012 and 142?cm in 2014. There has been a corresponding small increase in phase lag. Mean low water, decreasing throughout most of the twentieth century, has levelled off. Although the tidal changes could reflect merely a malfunctioning tide gauge, the fact that there are no other measurements in the region and the possibility that the tide is revealing important environmental changes calls for serious investigation. Satellite altimeter measurements of the tide in Hudson Bay are complicated by the seasonal ice cover; at most locations less than 40% of satellite passes return valid ocean heights and even those can be impacted by errors from sea ice. Because the combined TOPEX/Poseidon, Jason-1, and Jason-2 time series is more than 23 years long, it is now possible to obtain sufficient data at crossover locations near Churchill to search for tidal changes. The satellites sense no changes in M2 that are comparable to the changes seen at the Churchill gauge. The changes appear to be localized to the harbour, or to the Churchill River, or to the gauge itself. 相似文献
5.
Historical and future changes in maximum and minimum temperature records over Europe 总被引：1，自引：0，他引：1
Recent studies examining changes in temperature record frequency over the continental United States have reported that the number of Tmax records has been increasing over the past 50 years and occurring at twice the frequency of Tmin records. In a stationary climate, the number of records should decrease with time as 1/n, where n is the number of years of record-keeping. Here we seek to understand how European temperature records have changed during the late 20th century and how they are expected to change as greenhouse gases increase during the 21st century, using a new ensemble method to filter out the effect of the starting year in the calculation of the records. We find that until 1980, the ratio of Tmax to Tmin records remains close to one, indicating that the climate was relatively stationary. After 1980, there is a distinct positive trend where the observed ratio averages around four during the early part of the 21st century, indicative of a warming trend. We note considerable spatial variability in the observations. Further, the ratio of Tmax to Tmin records set by the year 2100 as simulated by five RCM simulations reaches values of up to several hundred by the end of the 21st century. However, the changes in record frequency vary spatially over Europe. The models project the highest numbers of Tmax records over the Mediterranean during summer, and Scandinavia during the spring and fall. Tmin records decrease most substantially over eastern Europe and western Russia, and the Mediterranean. Our analysis confirms the value of the use of maximum and minimum temperature records in regional climate change studies. 相似文献
6.
Global increase in record-breaking monthly-mean temperatures 总被引：2，自引：1，他引：1
The last decade has produced record-breaking heat waves in many parts of the world. At the same time, it was globally the warmest since sufficient measurements started in the 19th century. Here we show that, worldwide, the number of local record-breaking monthly temperature extremes is now on average five times larger than expected in a climate with no long-term warming. This implies that on average there is an 80 % chance that a new monthly heat record is due to climatic change. Large regional differences exist in the number of observed records. Summertime records, which are associated with prolonged heat waves, increased by more than a factor of ten in some continental regions including parts of Europe, Africa, southern Asia and Amazonia. Overall, these high record numbers are quantitatively consistent with those expected for the observed climatic warming trend with added stationary white noise. In addition, we find that the observed records cluster both in space and in time. Strong El Niño years see additional records superimposed on the expected long-term rise. Under a medium global warming scenario, by the 2040s we predict the number of monthly heat records globally to be more than 12 times as high as in a climate with no long-term warming. 相似文献
7.
We analyze the occurrence and the values of record-breaking temperatures in daily and monthly temperature observations. Our aim is to better understand and quantify the statistics of temperature records in the context of global warming. Similar to earlier work we employ a simple mathematical model of independent and identically distributed random variables with a linearly growing expectation value. This model proved to be useful in predicting the increase (decrease) in upper (lower) temperature records in a warming climate. Using both station and re-analysis data from Europe and the United States we further investigate the statistics of temperature records and the validity of this model. The most important new contribution in this article is an analysis of the statistics of record values for our simple model and European reanalysis data. We estimate how much the mean values and the distributions of record temperatures are affected by the large scale warming trend. In this context we consider both the values of records that occur at a certain time and the values of records that have a certain record number in the series of record events. We compare the observational data both to simple analytical computations and numerical simulations. We find that it is more difficult to describe the values of record breaking temperatures within the framework of our linear drift model. Observations from the summer months fit well into the model with Gaussian random variables under the observed linear warming, in the sense that record breaking temperatures are more extreme in the summer. In winter however a significant asymmetry of the daily temperature distribution hides the effect of the slow warming trends. Therefore very extreme cold records are still possible in winter. This effect is even more pronounced if one considers only data from subpolar regions. 相似文献
8.
Nancy S. Grumet Cameron P. Wake Paul A. Mayewski Gregory A. Zielinski Sallie I. Whitlow Roy M. Koerner David A. Fisher James M. Woollett 《Climatic change》2001,49(1-2):129-145
Comparison of an ice core glaciochemical time-series developed from thePenny Ice Cap (PIC), Baffin Island and monthly sea-ice extent reveals astatisticallysignificant inverse relationship between changes in Baffin Bay spring sea-iceextent andPenny Ice Cap sea-salt concentrations for the period 1901–1990 AD.Empiricalorthogonal function analysis demonstrates the joint behavior between changesin PICsea-salt concentrations, sea-ice extent, and changes in North Atlanticatmosphericcirculation. Our results suggest that sea-salt concentrations in snowpreserved on thePIC reflect local to regional springtime sea-ice coverage. The PIC sea-saltrecord/sea-ice relationship is further supported by decadal and century scalecomparisonwith other paleoclimate records of eastern Arctic climate change over the last700 years. Our sea-salt record suggests that, while the turn of the century wascharacterized bygenerally milder sea-ice conditions in Baffin Bay, the last few decades ofsea-ice extentlie within Little Ice Age variability and correspond to instrumental recordsof lowertemperatures in the Eastern Canadian Arctic over the past three decades. 相似文献
9.
Principal component or Empirical Orthogonal Function (EOF) analysis is applied to tsunameter records by treating them as two-dimensional signals, where the second dimension is created by breaking a single time series into cycles and treating the cycle number as a second dimension. Under certain conditions, principal components calculated from different records are shown to determine the same functional space. Signal decomposition into pre-calculated principal components is used to predict or extract the tidal component of a record. This work shows that EOF processing allows for short-term tidal predictions at tsunami buoy locations with the precision of more advanced methods and with minimal a priori knowledge about tidal dynamics. Also shown is that filtering in EOF domain is sensitive to the non-tidal component of a record and therefore presents a tool for early tsunami detection and quantification. 相似文献
10.
The digitization and homogenization of a record with four daily thermometer and two daily barometer readings is described
for the meteorological journal of Dr. E. A. Holyoke of Salem (Massachusetts). These records begin in January 1786 and span
the period to March 1829 for temperature, and the period to December 1820 for pressure. The records are reconstructed and
some inhomogeneities are identified and corrected for. The temperature data compares favourably with monthly temperature data
from New Haven (Connecticut) and a comparison with independently reconstructed daily pressure data for nearby Cambridge (1780–1789)
show that the temporal variations of the data agree very well. It is shown that the number of extremely cold days was considerably
greater during 1786–1829 than recent times, while the number of warm days in the early and modern records are comparable.
A probability distribution of daily winter pressure values shows a mean of the distribution which is 3 to 4 hPa lower during
1786–1820. 相似文献
11.
Summary ¶Many scientists have suggested that variations in cosmic ray flux may impact cloudiness at regional, hemispheric, or global scales. However, considerable debate surrounds (a) whether high or low clouds are most strongly impacted by cosmic rays, (b) the degree of seasonality in cloud responses to cosmic rays, and (c) the determination of physical processes involved in cosmic ray/cloud interactions. Some scientists find strong correlation coefficients between cloud measurements and cosmic ray flux, while others find no relationship whatsoever; virtually all scientists working on this issue are hampered by the relatively short time period with accurate cloud and cosmic ray flux records. In an attempt to extend the period of record, we assembled surface and radiosonde data for the United States over the period 1957–1996 along with sunspot records which are known to be strongly, but inversely, related to cosmic ray flux. We also assembled cloud cover data and cosmic ray measurements over a reduced time period. We found that periods with low sunspot number (times with high cosmic ray flux) are associated with significantly higher dew point depressions, a higher diurnal temperature range, and less cloud cover. Our results do not support suggestions of increased cloud cover during periods of high cosmic ray flux.Received May 14, 2002; accepted February 17, 2003
Published online May 26, 2003 相似文献
12.
R. D. D’Arrigo E. R. Cook M. J. Salinger J. Palmer P. J. Krusic B. M. Buckley R. Villalba 《Climate Dynamics》1998,14(3):191-199
Distinct periods of warmth have been identified in instrumental records for New Zealand and the surrounding southwest Pacific
over the past 120 years. Whether this warming is due to natural climate variability or the effects of increasing greenhouse
gases is difficult to determine given the limited length of instrumental record. Longer records derived from tree rings can
help reduce uncertainties in detection of possible causes of climatic change, although relatively few such records have been
developed for the Southern Hemisphere. In this work, we describe five temperature-sensitive tree-ring width chronologies for
New Zealand which place the recent warming trend into a long-term (pre-anthropogenic) context. Included are three pink pine
(Halocarpus biformis) chronologies, two for Stewart Island and one for the North Island of New Zealand. Two silver pine (Lagarostrobus colensoi) series, one each from the North and South Islands, are updated from previous work. The length of record ranges from AD 1700
for Putara, North Island to AD 1400 for Ahaura, South Island. The pink and silver pine are different species from those used
previously to reconstruct temperatures for New Zealand. All five chronologies are positively and significantly correlated
with warm-season (November-April) individual station temperature records, a New Zealand-wide surface air temperature index
and gridded land/marine temperatures for New Zealand and vicinity. The highest 20 and 40-year growth periods in all five tree-ring
series coincide with the New Zealand temperature increase after 1950. An exception is found for the 40-year interval at Ahaura,
the least temperature-sensitive of the five sites. A t-test comparison indicates that these recent growth intervals are significantly
higher (0.01 to 0.0001 level) than any of those prior to the twentieth century for three of the five sites, dating as far
back as AD 1500. The results suggest that the recent warming has been distinctive, although not clearly unprecedented, relative
to temperature conditions inferred from tree-ring records of prior centuries.
Received: 18 February 1997/Accepted: 11 September 1997 相似文献
13.
Abstract Three sites were instrumented to measure all components of the energy balance. The sites were located in the Churchill, Manitoba region and comprised a Sea Site on a sand spit 1 km seaward from the mainland, a Nearcoast Site 2 km inland from the coast and an Inland Site 65 km inland. Measurements were made continuously over a 90‐day period from 19 May to 16 August 1984. This period encompassed the bulk of the growing season. The measurements were stratified into onshore and offshore wind directions and were compared for 10‐day periods. The comparisons show very significant differences attributable to the cold summer conditions promoted by the sea ice in Hudson Bay. The ground heat flux and latent heat flux were much greater during offshore winds but the sensible heat flux was greatest for onshore winds. Air temperatures averaged 7°C warmer for offshore than for onshore winds. The reasons for these differences are detailed and the climatic modifications that would probably result from earlier sea‐ice melt are discussed. Some implications of climatic modification are also noted. 相似文献
14.
Based on a new and unique compilation of surface ship data over the world ocean, the Comprehensive Ocean-Atmosphere Data Set (COADS), the temperature records since 1870 were thoroughly analyzed. Results for the air and sea surface temperature are presented for the two hemispheres and for individual 10°-latitude wide belts. The results support most earlier results of a relatively warm period over the oceans in the late 19th century, a cool period between about 1905 and 1930, and a warm period from the 1940's onward. Of considerable interest and perhaps unique in the historical record are the diverging trends in the midlatitude sea and air temperatures of the two hemispheres during the 1960's and early 1970's with relative cooling in the Northern Hemisphere and relative heating in the Southern Hemisphere. 相似文献
15.
ENSO与亚洲中低纬若干海气因子的遥相关及与华南降水的关系 总被引：1，自引：0，他引：1
本文在统计近一百年左右华南八站降水与ENSO关系基础上,分别探讨了春末夏初亚洲中纬冷空气活动,南海高压及副高脊、盂加拉湾北部低系统和中南半岛季风与ENSO的遥相关,以及它们对华南3—6月降水的影响;台风活动,南海SST与ENSO遥相关及其对华南7—11月降水的影响。指出,El Nino年春夏东亚中纬冷空气活动偏弱,南海高度场偏低,孟加拉湾北部低系统和中南半岛西南季风较活跃。使El Nino年3—6月华南内陆降水偏少而沿海偏多。在ElNino年,南海SSTA有一个由负转正的过程,它使华南沿海在秋台偏少情况下,秋冬有时还有较大的降水甚至带来洪涝。 相似文献
16.
Andrew R. Solow 《Climatic change》2001,49(3):359-366
In conjunction with early climate records, catch records from pre-industrialfisheries are a potentially valuable sourceof information about the effect of climate on fisheries. This paper describesa test for a temperature effect on an18th century catch record of Icelandic cod. The results of the test, which isbased on a model that incorporatesboth internal population dynamics and a potential temperature effect, supportthe existence of a temperature effect. 相似文献
17.
18.
Masakazu Yoshimori Christoph C. Raible Thomas F. Stocker Manuel Renold 《Climate Dynamics》2006,27(5):493-513
An increasing number of proxy records, which are related to changes in the hydrological cycle, have been collected for climate reconstructions of the last millennium. There has been, however, little attempt to test climate models with such proxy records or to interpret proxy records using climate model simulations. In the present study, we analyze the hydrological changes between three different types of experiments: a present-day control, a perpetual AD 1640, and an ensemble of six transient Maunder Minimum (AD 1640–1715) simulations. Atmospheric moisture transport is investigated in terms of contributions of specific humidity and circulation changes. The study points out the importance of the specific humidity contribution to changes in moisture transport reflected in hydrological proxy records. The moisture budget of the western tropical Pacific is also investigated to aid the interpretation of a proxy record in this specific region. The present-day freshening of the western tropical Pacific, compared to the Maunder Minimum, is explained by the increased zonal moisture transport via trade winds, mainly due to the increased amount of atmospheric water vapor content in the warming world. Due to the existence of several uncertainty factors, such as forcing reconstructions, the link between the model simulations and proxy records is, however, not definitive, but the thermal contribution to hydrological proxy records is important and not limited to the Maunder Minimum period. 相似文献
19.
Alexander Loew 《Theoretical and Applied Climatology》2014,115(3-4):427-440
Satellite-based observations provide a unique data record to study the Earth system. Recent efforts of the space agencies to reprocess the archives of satellite observations aim to provide Essential Climate Variable (ECV) data records for manifold applications in climate sciences. Varying lengths of a data record or gaps in a data time series are likely to affect the analysis results obtained from long-term satellite data records. The present paper provides a systematic assessment of the impact of variations in the observational record of terrestrial ECVs for selected climate applications like trend detection and the analysis of relationships between different ECVs. As an example, the Sahelian drought and the subsequent recovery in precipitation and vegetation will be analyzed in detail using observations of precipitation, surface albedo, vegetation index, as well as ocean indices. The paper provides a different perspective on the robustness of long-term satellite observations than previous studies. It shows in particular that the long-term significant trends in precipitation and vegetation dynamics are rather sensitive to the investigation period chosen and that small data gaps can already have a considerable influence on the analysis results. It is therefore a plea for continuous climate observations from space. 相似文献
20.
Temperature reconstructions for recent centuries provide a historical context for the warming over the twentieth century. We reconstruct annual averaged surface temperatures of the past 400?years on hemispherical and global scale from glacier length fluctuations. We use the glacier length records of 308 glaciers. The reconstruction is a temperature proxy with decadal resolution that is completely independent of other temperature records. Temperatures are derived from glacier length changes using a linear response equation and an analytical glacier model that is calibrated on numerical model results. The global and hemispherical temperatures reconstructed from glacier length fluctuations are in good agreement with the instrumental record of the last century. Furthermore our results agree with existing multi-proxy reconstructions of temperature in the pre-instrumental period. The temperature record obtained from glacier fluctuations confirms the pronounced warming of the twentieth century, giving a global cumulative warming of 0.94?±?0.31?K over the period 1830–2000 and a cumulative warming of 0.84?±?0.35?K over the period 1600–2000. 相似文献