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1.
The present study is about the analysis of mean maximum and mean minimum temperatures carried out on annual, seasonal, and monthly timescales examining the data from 15 meteorological stations in Bangladesh for the period 1961–2008. Various spatial and statistical tools were used to display and analyze trends in temperature data. ArcGIS was used to produce the spatially distributed temperature data by using Thiessen polygon method. The nonparametric Mann–Kendall test was used to determine whether there is a positive or negative trend in data with their statistical significance. Sen’s method was also used to determine the magnitude of the trends. The results reveal positive trends in annual mean and mean maximum temperatures with 95 % significance. Trend test reveals that the significant positive trend is found in June to November in case of mean maximum temperature, but according to the mean minimum temperature, the situation is different and a significant positive trend was found from November to February. The analysis of the whole record reveals a tendency toward warmer years, with significantly warmer summer periods and slightly colder winters. These warming patterns may have important impacts on energy consumption, water supply, human health, and natural environment in Bangladesh. 相似文献
2.
3.
Manish Kumar Goyal 《Theoretical and Applied Climatology》2014,118(1-2):25-34
Rainfall is a principal element of the hydrological cycle and its variability is important from both the scientific as well as practical point of view. Wavelet regression (WR) technique is proposed and developed to analyze and predict the rainfall forecast in this study. The WR model is improved combining two methods, discrete wavelet transform and linear regression model. This study uses rainfall data from 21 stations in Assam, India over 102 years from 1901 to 2002. The calibration and validation performance of the models is evaluated with appropriate statistical methods. The root mean square errors (RMSE), N-S index, and correlation coefficient (R) statistics were used for evaluating the accuracy of the WR models. The accuracy of the WR models was then compared with those of the artificial neural networks (ANN) models. The results of monthly rainfall series modeling indicate that the performances of wavelet regression models are found to be more accurate than the ANN models. 相似文献
4.
Michael J. Newark 《大气与海洋》2013,51(3):343-353
Abstract Other than the ground‐breaking work of McKay and Lowe (1960), little has been known about the incidence of tornadoes and the risk of tornado damage in Canada. Data concerning tornadoes during the period 1950 to 1979 (and earlier) have been gathered from many sources and processed to arrive at a set of quantitative conclusions concerning some of their physical characteristics and climatology. The data indicate that tornado incidence (the number of tornadoes per unit area per unit time) in populated sections of Canada is compatible with the incidence values published for adjacent American States, and that the highest annual probability of tornado damage is in southwestern Ontario (0.05 to 0.1%) followed by southeastern Manitoba (0.05%). In terms of size, the Canadian tornado (regardless of intensity) has median damage dimensions of 6 km in length, 80 m in width, and 1 km2 in area. In southwestern Ontario, the return period of a strong or violent tornado is 5 years, and it is likely to have median damage dimensions of 57 km in length, 790 m in width, and 78 km2 in area. 相似文献
5.
Goutami Chattopadhyay Parthasarathi Chakraborthy Surajit Chattopadhyay 《Theoretical and Applied Climatology》2012,110(3):321-328
The present work reports studies on the spatial distribution of tropospheric ozone extending over both southern and northern hemispheres. This study is based on a univariate approach to the spatial data series obtained at regular spatial intervals. Mann?CKendall's (MK) trend analysis has been carried out to discern the trend within the spatial distribution of the tropospheric ozone, and it has been observed that in all seasons, except monsoon (JJAS), there is a linear trend within the spatial distribution. Studying both monthly and seasonal behavior through autoregressive integrated moving average (ARIMA), it has been revealed that ARIMA (0,2,2) can be used as a representative of the spatially distributed tropospheric ozone over southern and northern hemispheres. The representative model has been confirmed through the study of Willmott's index and prediction yield. 相似文献
6.
The University of Oklahoma’s Advanced Regional Prediction System (ARPS) was used to examine the impacts of varying mean soil moisture and model resolution on the magnitude and frequency of precipitation events in the U.S. Central Plains and to determine whether modeled soil moisture and precipitation fields exhibit scale invariance using the statistical moments. It was found that high soil moisture resulted in greater precipitation amounts and a higher frequency of events, suggesting the occurrence of a positive soil moisture–precipitation feedback. The scaling analysis performed on cumulative precipitation determined that these fields did not exhibit signs of self-similarity and, therefore, statistical properties cannot be predicted at other resolutions. The scaling properties of soil moisture were highly variable in time which has important implications for the use of remotely sensed data, as scaling properties from 1 day cannot necessarily be applied to subsequent days. 相似文献
7.
Dr. T. Murakami 《Meteorology and Atmospheric Physics》1990,44(1-4):85-100
Summary Interannual modes are described in terms of three-month running mean anomaly winds (u,v), outgoing longwave radiation (OLR), and sea surface temperature (T
*
). Normal atmospheric monsoon circulations are defined by long-term average winds (u
n,v
n) computed every month from January to December. Daily winds are grouped into three frequency bands, i.e., 30–60 day filtered winds (u
L,v
L); 7–20 day filtered winds (u
M,v
M); and 2–6 day filtered winds (u
S,v
S). Three-month running mean anomaly kinetic energy (signified asK
L
, K
M
, andK
S
, respectively) is then introduced as a measure of interannual variation of equatorial disturbance activity. Interestingly, all of theseK
L
, K
M
, andK
S
perturbations propagate slowly eastward with same phase speed (0.3 ms–1) as ENSO modes. Associated with this eastward propagation is a positive (negative) correlation between interannual disturbance activity (K
L
, K
M
, K
S
) and interannualu (OLR) modes. Namely, (K
L
, K
M
, K
S
) becomes more pronounced than usual nearly simultaneously with the arrival of westerlyu and negativeOLR (above normal convection) perturbutions. In these disturbed areas with (K
L
, K
M
, K
S
>0), upper ocean mixing tends to increase, resulting in decreased sea surface temperature, i.e.T
*
0. Thus, groups (not individual) of equatorial disturbances appear to play an important role in determiningT
*
variations on interannual time scales. HighestT
*
occurs about 3 months prior to the lowestOLR (convection) due primarily to radiational effects. This favors the eastward propagation of ENSO modes. The interannualT
*
variations are also controlled by the prevailing monsoonal zonal windsu
n, as well as the zonal advection of sea surface temperature on interannual time scales. Over the central Pacific, all of the above mentioned physical processes contribute to the intensification of eastward propagating ENSO modes. Over the Indian Ocean, on the other hand, some of the physical processes become insignificant, or even compensated for by other processes. This results in less pronounced ENSO modes over the Indian Ocean.With 10 FiguresContribution No. 89-6, Department of Meteorology, University of Hawaii, Honolulu, Hawaii. 相似文献
8.
The precipitation over eastern China during January–March 2010 exhibited a marked intraseasonal oscillation (ISO) and a dominant period of 10-60 days. There were two active intraseasonal rainfall periods. The physical mechanisms responsible for the onset of the two rainfall events were investigated using ERA-interim data. In the first ISO event, anomalous ascending motion was triggered by vertically integrated (1000–300 hPa) warm temperature advection. In addition to southerly anomalies on the intraseasonal (10–60-day) timescale, synoptic-scale southeasterly winds helped advect warm air from the South China Sea and western Pacific into the rainfall region. In the second ISO event, anomalous convection was triggered by a convectively unstable stratification, which was caused primarily by anomalous moisture advection in the lower troposphere (1000–850 hPa) from the Bay of Bengal and the Indo-China Peninsula. Both the intraseasonal and the synoptic winds contributed to the anomalous moisture advection. Therefore, the winter intraseasonal rainfall events over East Asia in winter could be affected not only by intraseasonal activities but also by higher frequency disturbances. 相似文献
9.
We analyze climate change in a cost–benefit framework, using the emission and concentration profiles of Wigley et al. (Nature
379(6562):240–243, 1996). They present five scenarios that cover the period 1990–2300 and are designed to reach stabilized concentration levels of
350, 450, 550, 650 and 750 ppmv, respectively. We assume that the damage cost in each year t is proportional to the corresponding gross world product and the square of the atmospheric temperature increase (ΔT(t)). The latter is estimated with a simple two-box model (representing the atmosphere and deep ocean). Coupling the damage
cost with the abatement cost, we interpolate between the five scenarios to find the one that is optimal in the sense of minimizing
the sum of discounted annual (abatement plus damage) costs over a time horizon of N years. Our method is simpler than ‘traditional’ models with the same purpose, and thus allows for a more transparent sensitivity
study with respect to the uncertainties of all parameters involved. We report our central result in terms of the stabilized
emission level E
o
and concentration level p
o
(i.e. their values at t = 300 years) of the optimal scenario. For the central parameter values (that is, N = 150 years, a discount rate r
dis
= 2%/year and a growth rate r
gro
= 1%/year of gross world product) we find E
o
= 8.0 GtCO2/year and p
o
= 496 ppmv. Varying the parameters over a wide range, we find that the optimal emission level remains within a remarkably
narrow range, from about 6.0 to 12 GtCO2/year for all plausible parameter values. To assess the significance of the uncertainties we focus on the social cost penalty,
defined as the extra cost incurred by society relative to the optimum if one makes the wrong choice of the emission level
as a result of erroneous damage and abatement cost estimates. In relative terms the cost penalty turns out to be remarkably
insensitive to errors. For example, if the true damage costs are three times larger or smaller than the estimate, the total
social cost of global climate change increases by less than 20% above its minimum at the true optimal emission level. Because
of the enormous magnitude of the total costs involved with climate change (mitigation), however, even a small relative error
implies large additional expenses in absolute terms. To evaluate the benefit of reducing cost uncertainties, we plot the cost
penalty as function of the uncertainty in relative damage and abatement costs, expressed as geometric standard deviation and
standard deviation respectively. If continued externality analysis reduces the geometric standard deviation of relative damage
cost estimates from 5 to 4, the benefit is 0.05% of the present value G
tot
of total gross word product over 150 years (about $3.9 × 1015), and if further research reduces the standard deviation of relative abatement costs from 1 to 0.5, the benefit is 0.03%
of G
tot
. 相似文献
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11.
News organizations constitute key sites of science communication between experts and lay audiences, giving many individuals their basic worldview of complex topics like climate change. Previous researchers have studied climate change news coverage to assess accuracy in reporting and potential sources of bias. These studies typically rely on manually coding articles from a handful of prestigious outlets, not allowing comparisons with smaller newspapers or providing enough diversity to assess the influence of partisan orientation or localized climate vulnerability on content production. Making these comparisons, this study indicates that partisan orientation, scale of circulation, and vulnerability to climate change correlate with several topics present in U.S. newspaper coverage of climate change. After assembling a corpus of over 78,000 articles covering two decades from 52 U.S. newspapers that are diverse in terms of geography, partisan orientation, scale of circulation, and objectively measured climate risk, a coherent set of latent topics were identified via an automated content analysis of climate change news coverage. Topic model results indicate that while outlet bias does not appear to impact the prevalence of coverage for most topics surrounding climate change, differences were evident for some topics based on partisan orientation, scale, or vulnerability status, particularly those relating to climate change denial, impacts, mitigation, or resource use. Overall, this paper provides a comprehensive study of U.S. newspaper coverage of climate change and identifies specific topics where outlet bias constitutes an important contextual factor. 相似文献
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13.
Gordon Manley 《Theoretical and Applied Climatology》1958,9(3-4):413-433
Summary Comparable figures representative of the mean temperature at inland places in Central England are provided for every month from 1698 to the end of 1957. These are based on the assemblage of a number of early and scattered records brought to modern standards and to centigrades. Diagrams are added for purposes of illustration and comparison with Holland and elsewhere in Europe.
With 3 Figures 相似文献
Zusamenfassung Es werden Vergleichszahlen für die Mitteltemperatur an Inlandstationen in Mittelengland für alle Monate von 1698 bis 1957 mitgeteilt; sie beruhen auf der Verarbeitung einer Anzahl älterer und vereinzelter Serien, die auf neuzeitlichen Stand und auf Zentigrade reduziert wurden. Zur Veranschaulichung und zum Vergleich mit holländischen und anderen europäischen Stationen sind Kurvendarstellungen beigefügt.
Résumé Moyennes mensuelles de température de stations de l'Angleterre centrale, de la période 1698 à 1957, tirées de séries anciennes convenablement réduites et converties en degrés centigrades. Des représentations graphiques facilitent la comparaison avec les stations européennes.
With 3 Figures 相似文献
14.
The resource dependency literature argues that intensifying processes of dependency can lead to poorer socioecological outcomes, but the effects of reducing dependency remain untested. Some scholars argue that it improves socioecological conditions, while other strands of research suggest that it causes economic hardship, as evidenced by the deaths of despair crisis. Here, I examine the asymmetric effects of fossil fuel dependency (measured as the energy production-consumption ratio, the share of exports from the mining sector, and the share of GDP from the mining sector) on the carbon intensity of well-being (CIWB) at the U.S. state-level. I do so by estimating dynamic asymmetric models with fixed effects estimation. I find that increases in all three measures are associated with increases in the CIWB. Decreases in the energy production-consumption ratio and the share of exports from the mining sector do not affect the CIWB, while a decrease in the share of GDP from the mining sector produces a proportional reduction in the CIWB relative to an increase. The estimated net effect of all three variables suggests that an increase in fossil fuel dependency increases the CIWB, while a decrease has no effect. When the CIWB is disaggregated, I find that changes in the energy production-consumption ratio are driving changes in emissions and that changes in the share of GDP from the mining sector are responsible for changes in health-adjusted life expectancy. Given that the net effect of a decrease in fossil fuel dependency is not statistically significant, I conclude by arguing that a planned, managed transition away from fossil fuel extraction is critical to ensuring simultaneous improvements in human and environmental well-being. 相似文献
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16.
《大气和海洋科学快报》2022,15(6):100259
Intense and extensive dust, caused by a strong Mongolian cyclone, hit Mongolia and northern China on 14–15 March 2021. In this study, the development process of this cyclone is analysed from the perspective of high-frequency eddy energetics. During the low-frequency circulation field of early March of 2021, an amplified polar vortex intruding towards central Asia and a ridge straddling eastern and northeastern Asia worked in concert to comprise a strong baroclinic zone from central Asia to Lake Baikal. Under these favourable conditions, on 13 March, a migratory trough triggered the Mongolian cyclone by crossing over the Sayan Mountains. The downwards transfer of kinetic energy from the eddy at 850 hPa played a key role in the intensification and mature stage of the cyclone. This mechanism was primarily completed by the cold air sinking behind the cold front. The frontal cyclone wave mechanism became crucial once the cyclone started to rapidly develop. The authors emphasize that the anomalously large growth of high-frequency available potential energy, which characterized this super strong cyclone, was obtained by extracting energy first from the time-mean available potential energy and then from the low-frequency available potential energy. The interannual temperature anomaly pattern of “north cold south warm” facilitated the additional time-mean available potential energy, and the temperature anomaly pattern of “northwest cold southeast warm” conditioned the extra low-frequency available potential energy. The analysis results suggest that the interaction between high- and low-frequency waves was also important in the development of the intense cyclone.摘要2021年3月14-15日, 强蒙古气旋引起的大范围强沙尘天气袭击了蒙古国和中国北方地区. 本文从高频涡动能量学的角度分析了这一超强气旋的发展过程. 2021年3月初, 加强的极涡向中亚伸入, 并与横跨东亚和东北亚的一个大型脊协同作用, 由此形成了从中亚到贝加尔湖地区的强大斜压带. 在这一有利的低频环流条件下, 3月13日一个移动性小槽越过萨彦岭后触发了蒙古气旋. 850 hPa涡旋动能的下传在气旋的加强和成熟阶段起到了关键作用. 而这一机制主要由冷锋后侧的冷空气下沉过程完成. 一旦气旋开始快速发展, 锋面气旋波机制就变得至关重要.我们强调, 高频涡动有效位能是首先从时间平均有效势能中提取能量, 然后从低频有效位能中汲取能量而剧烈增长的, 这正是该超强气旋的鲜明特征. “北冷南暖”的近地面温度气候异常型为时间平均有效位能的增多和向高频涡动有效位能的转换提供了条件, 而“西北冷东南暖”的温度异常型则有利于低频有效位能的增加和向高频涡动有效位能的转换. 分析结果表明, 高低频波之间的相互作用对蒙古气旋的增强也很重要. 相似文献
17.
Wind speed variations are influenced by both natural climate and human activities. It is important to understand the spatial and temporal distributions of wind speed and to analyze the cause of its changes. In this study, data from 26 meteorological stations in the Jing–Jin–Ji region of North China from 1961 to 2017 are analyzed by using the Mann–Kendall(MK) test. Over the study period, wind speed first decreased by-0.028 m s-1 yr-1(p 0.01) in1961–1991, and then increased by 0.002 m s1-yr1-(p 0.05) in 1992–2017. Wind speed was the highest in spring(2.98 m s-1), followed by winter, summer, and autumn. The largest wind speed changes for 1961–1991 and1992–2017 occurred in winter(-0.0392 and 0.0065 m s-1 yr1-, respectively); these values represented 36% and 58%of the annual wind speed changes. More than 90.4% of the wind speed was concentrated in the range of 1–5 m s-1,according to the variation in the number of days with wind speed of different grades. Specifically, the decrease in wind speed in 1961–1991 was due to the decrease in days with wind speed of 3–5 m s-1, while the increase in wind speed in 1992–2017 was mainly due to the increase in days with wind speed of 2–4 m s-1. In terms of driving factors,variations in wind speed were closely correlated with temperature and atmospheric pressure, whereas elevation and underlying surface also influenced these changes. 相似文献
18.
《Global Environmental Change》1999,9(2):119-138
For more than a decade climate change has been the focus of much research and analysis. Despite the global implications of the problem, the overwhelming majority of the researchers involved worldwide in studying the problem and its possible solutions are from industrialized countries, and participation of lesser-industrialized countries has been limited. While the wide-ranging implications of this South–North divide are sometimes recognized, there is little analysis on the reasons for this divide, why it continues to exist, and what steps might be required to narrow it. Towards this end, this paper analyzes how climate change research and analysis is performed in India, a major lesser-industrialized country. Based on detailed interviews, it explores the factors that play a role in shaping the capability of India to perform, and respond to, climate-change analyses. Drawing on the Indian case study, the paper examines developing-country participation in the international climate science and assessment enterprise. This allows some reflection on the potential pitfalls for international discussions on climate change and what the international community and countries of the South can do to overcome them in order to address this conspicuous South–North divide. 相似文献
19.
We present an analysis of the inter-annual variability of hydrography—temperature and salinity – and ice conditions at the coastal site of Tvärminne, Gulf of Finland, Baltic Sea during the period 1927–2012. The aim is to analyze the natural variability and trends of the hydrographic characteristics, freezing and breakup dates, ice thickness, and the heat content during the last century. The study also includes the inter-connections between the ice season and the surface temperature and salinity in the open water season. The results showed a significant decrease of the ice season length, by almost 30 days. The maximum annual ice thickness decreased by 8 cm in the last 40 years. The surface water temperature increased by almost 1 °C and there was also an increasing trend in the heat content. The thermal memory of the system was 2–2.5 months. The surface salinity increased by 0.5 psu in the last 85 years. The results are discussed and compared to related studies. 相似文献