Changes in weather and climate extremes: phenomenology and empirical approaches

The terms “weather extremes” and “climate extremes” are widely used in meteorology, often in relation to climate change. This paper reviews the empirical investigations into parallel changes in extreme events and climate change published in recent years and looks at their relevance for the global energy system. Empirical investigation into the correlation of extremes with global warming covers five groups: changes in temperature, precipitation, wind (storm) extremes, tropical and extra-tropical circulation phenomena. For temperature extremes, extensive analyses demonstrate that extreme hot days and nights will likely become more frequent, and extreme cold days and nights less frequent. Intense precipitation events will likely become more frequent in most continental regions. Scientific confidence in the trends of the frequency, duration, and intensity of tropical cyclones, is still low. A poleward shift is observed for extratropical cyclones, whereas no convincing tendencies of many smaller-scale phenomena, for example, tornados, or hail, can yet be detected. All these extremes have serious implications for the energy sector.     

Daily weather mapping from 1781:

An account is given of the preparation of daily weather maps within the historical-instrumental period, with details concerning the detection and location of source material and its subsequent examination, collection and reduction to provide a workable synoptic network of comparable meteorological observations over the eastern North Atlantic-European sector. The application of the Lamb British Isles weather types and Grosswetterlagen for the statistical analysis of circulation patterns derived from these charts is discussed. An objective test was devised whereby the frequency of monthly extremes of nine variables was examined with the following important conclusions:

1. the synoptic charts of the 1780s show no evidence of systematic errors when compared with rainfall figures,
2. the early 1780s was a period of unusually high climatic variability on the month-to-month time-scale, especially in the frequencies of cyclonic and of anticyclonic days.

An account is given of the impact of climate on the affairs of man in the 1780s, highlighting some specific historical case studies and discussing agriculture and industry in general.     

Coping with extreme weather: communities in Fiji and Vanuatu share their experiences and knowledge

Local communities across the Pacific Island region have long prepared for and managed extreme weather events. Strategies to cope with extreme weather, particularly cyclones and droughts, have involved using particular planting techniques, initiating innovative water storage practices, and employing food preservation tactics to survive. These local experiences and knowledge have been passed on between generations through stories and sharing practical know-how; however, very little formal documentation has transpired to date. This research attempts to document and synthesis these experiences and knowledge to safeguard them through written accounts but also demonstrate how Pacific communities can provide valuable, appropriate and effective strategies to prepare for and respond to extreme weather events. In-depth interviews (n?=?40) were conducted with community members from three villages in Fiji (Naselesele, Qeleni and Yanuca) and three villages in Vanuatu (Piliura, Tassiriki and Lonamilo). While typically missing from community vulnerability and risk assessments in the Pacific, local experiences and knowledge are a core strength in enhancing adaptive capacity and planning community-based activities.     

IPCC AR6报告解读：极端天气气候事件变化

与IPCC第五次评估报告（AR5）相比,在第六次评估报告（AR6）评估中,观测的极端天气气候事件变化证据,特别是归因于人为影响的证据加强。人类活动造成的气候变化已影响到全球每个区域的许多极端天气气候事件。随着未来全球变暖进一步加剧,预估极端热事件、强降水、农业生态干旱的强度和频次以及强台风（飓风）比例等将增加,越罕见的极端天气气候事件,其发生频率的增长百分比越大。这些结论再次凸显了应对气候变化和极端天气气候事件的必要性和紧迫性。     

Insurance against weather risk: Use of heating degree-days from non-local stations for weather derivatives

Summary ?Weather derivatives enable policy-holders to safeguard themselves against extreme weather conditions. The effectiveness and the efficiency of the risk transfer is determined by the spatial risk basis, which is the stochastic dependency of the local weather outcome being insured and the outcome of the weather underlying the insurance instrument. The lower this risk basis the higher the effectiveness and the efficiency of the risk transfer. To study the spatial risk basis component in relation to the design and evaluation of a weather derivative contract to insure for heating degree-days (HDD), the historical temperature records were analyzed for five sites across the Netherlands. Sensitivity and specificity of the insurance instrument were used to quantify the potential spatial risk basis. Setting indemnification beyond a half standard deviation above the mean meant that between 60% and 76% of the indemnable HDD were classified correctly, while 82% to 99% of the non-indemnable HDD were classified correctly. These results indicate that the spatial risk basis is a major concern and that successful weather derivatives require the utilization of carefully selected weather data obtained from meteorological stations in close proximity to the area being insured. Received November 5, 2001; revised July 3, 2002; accepted July 7, 2002     

Linking Inuit knowledge and meteorological station observations to understand changing wind patterns at Clyde River,Nunavut

Connecting indigenous and scientific observations and knowledge has received much attention in the Arctic, not least in the area of climate change. On some levels, this connection can be established relatively easily, linking observations of similar phenomena or of various effects stemming from the same cause. Closer examinations of specific environmental parameters, however, can lead to far more complex and difficult attempts to make those connections. In this paper we examine observations of wind at Clyde River, Nunavut, Canada. For Inuit, many activities are governed by environmental conditions. Wind, in particular, is identified by Inuit as one of the most important environmental variables, playing a key role in driving sea ice, ocean, and weather conditions that can either enable or constrain hunting, travel, or other important activities. Inuit observe wind patterns closely, and through many means, as a result of their close connection to the land and sea. Inuit in many parts of Nunavut are reporting changes in wind patterns in recent years. At Clyde River, a community on the eastern coast of Baffin Island, Inuit have observed that at least three key aspects of wind have changed over the last few decades: wind variability, wind speed, and wind direction. At the same time, wind observations are also available from an operational weather station located at Clyde River. An analysis of this information shows little change in wind parameters since the mid-1970s. Though the station data and Inuit observations correspond in some instances, overall, there is limited agreement. Although the differences in the two perspectives may point to possible biases that may exist from both sources—the weather station data may not be representative of the region, Inuit observations or explanations may be inaccurate, or the instrumental and Inuit observations may not be of the same phenomena—they also raise interesting questions about methods for observing wind and the nature of Arctic winds.     

Advances in weather modification from 1997 to 2007 in China

Rapid and significant advances in issues relevant to weather modification have been made in the last decade in China due to high water resource stresses and severe weather hazards induced by climate change. This paper reported some progress in aspects of theoretical modeling, field experiment and cloud-seeding tools, as well as research projects regarding weather modification during the ten years from 1997 to 2007. More advanced theoretical models such as cloud models with bin-microphysics and glaciogenic and hygroscopic seeding processes, and mesoscale cloud-resolving models with AgI-seeding processes have been developed to study seeding-induced changes of cloud structure and precipitation as well as to understand critical issues in association with weather modification. More advanced cloud-seeding tools such as mobile ground-based launching system of AgI-rockets and aircraft-based AgI-flares have been developed and used in operation. Several important projects aimed at exploring weather modification techniques and their applications have been conducted during this period.     

Estimating crop top microclimates from weather station data

Abstract

A mathematical model (Microsim) was developed to estimate the microclimate at the top of nearby crops using inputs of weather station data and some knowledge about crop characteristics, such as height, albedo, and leaf area index. The model was tested using data measured simultaneously over a weather station and over each of two crops ‐ corn and soybean. Temperatures at the top of unstressed, uniform crops on level terrain within 1600 m of a recording weather station were estimated within 1.0° C 96% of the time for a corn crop and 92% of the time for a soybean crop. Winds at crop top were estimated within 0.4 m s^?1 92% of the time for corn and 100% of the time for soybean. Energy balance flux density estimates for the corn crop resulted in correlation coefficients of r > 0.89 for each of R_n, LE, H and G. microsim worked well under atmospheric conditions that ranged from very stable to unstable.

An enhancement was made to the model to describe wind and temperature profiles based on the complete fetch characteristics of the sites. This resulted in significantly better wind estimates, but had the disadvantage of requiring more information about the crop and weather station surroundings.     

Sila dialogues on climate change: Inuit wisdom for a cross-cultural interdisciplinarity

This research begins with the recognition that climate change researchers have become interested in Inuit ecological observations because of the importance of northern changes on the global climate system, but this research often marginalizes Inuit understandings of these climate-related changes. The direct translation of the Inuktitut term Sila in much of this research is a case study in this methodological problem. In contrast to climate research translations of Sila as weather, ethnographies of Inuit conceive of Sila as a spiritual power that is related to the weather. These diverging interpretations of Sila reflect the difficulty of conducting cross-cultural research. To mitigate this difficulty a dialogue was engaged with Inuit concerning their experience of climate change in relation to the different Inuit and Western understandings of Sila. The central goals of this paper are to clearly define Sila so as to identify implications it may have for Western approaches in conducting cross-cultural climate research, and, in the process, to begin a cross-cultural dialogue that aims at an agreed upon understanding of climate change that is respectful of different knowledges.     

Characterizing atmospheric circulation signals in Greenland ice cores: insights from a weather regime approach

Greenland ice cores offer seasonal to annual records of δ¹⁸O, a proxy for precipitation-weighted temperature, over the last few centuries to millennia. Here, we investigate the regional footprints of the North Atlantic weather regimes on Greenland isotope and climate variability, using a compilation of 22 different shallow ice-cores and the atmospheric pressure conditions from the twentieth century reanalysis (20CR). As a first step we have verified that the leading modes of winter and annual δ¹⁸O are well correlated with oceanic (Atlantic multidecadal oscillation) and atmospheric [North Atlantic oscillation (NAO)] indices respectively, and also marginally with external forcings, thus confirming earlier studies. The link between weather regimes and Greenland precipitation, precipitation-weighted temperature and δ¹⁸O is further explored by using an isotope simulation from the LMDZ-iso model, where the 3-dimensional wind fields are nudged to those of 20CR. In winter, the NAO+ and NAO? regimes in LMDZ-iso produce the largest isotopic changes over the entire Greenland region, with maximum anomalies in the South. Likewise, the Scandinavian blocking and the Atlantic ridge also show remarkable imprints on isotopic composition over the region. To assess the robustness and model dependency of our findings, a second isotope simulation from the isotopic model is also explored. The percentage of Greenland δ¹⁸O variance explained by the ensemble of weather regimes is increased by a factor near two in both LMDZ-iso and IsoGSM when compared to the contribution of the NAO index only. Similarly, weather regimes provide a net gain in the δ¹⁸O variance explained of similar magnitude for the whole set of ice core records. Greenland δ¹⁸O also appears to be locally affected by the low-frequency variations in the centres of action of the weather regimes, with clearer imprints in the LMDZ-iso simulation. This study opens the possibility for reconstructing past changes in the frequencies of occurrence of the weather regimes, which would rely on the sensitive regions identified here, and the use of additional proxies over the North Atlantic region.     

The climate in Zafra from 1750 to 1840: history and description of weather observations

Weather observations in Zafra during the period 1750 to 1840 have been compiled and studied. Zafra was the capital of the Duchy of Feria, located in the southwest of the Iberian Peninsula. The documentary sources used in this work are weekly reports submitted to the Duke (who lived in Madrid) that contain a section describing the weather of the preceding week or less. Regular and updated meteorological information was vital to the government of this Duchy as farming and ranching constituted the bases of the economic activity in this region, allowing the estimation of crop yield and quality and a better management of the trade of agricultural products. Therefore, this documentary source is exceptional to study the climate of SW Iberia due to its continuity, homogeneity and high temporal-resolution.     

1961—2008年银川市灰霾天气的气候特征

对1961—2008年银川市灰霾天气日数资料进行分析。结果表明：银川市灰霾天气呈逐渐增加的趋势2,0世纪80年代前为缓慢增加阶段,20世纪后灰霾天气显著增加2,000年后灰霾天气急剧增加。银川市灰霾日数最多为12月,其次为11月,最少为5月,呈现出冬季大于秋季大于春季大于夏季的季节特征。一般情况下,银川市灰霾日数持续1—3d,持续2d及以上的灰霾天气占17%,持续5d及以上的灰霾天气占1%。持续时间较长的灰霾天气集中出现在冬季11月至翌年2月。灰霾天气持续时间与年代际变化有关,2000年前,银川未出现持续5d以上的灰霾天气过程;2000年后,随着灰霾天气日数增多,灰霾持续时间延长。     

Surface heat fluxes from a numerical weather prediction system

Twenty-two months (July 1983-April 1985) of surface heat fluxes predicted at day 1 from a numerical weather prediction system have been processed. Monthly means and monthly standard deviations of available surface short-wave, long-wave, latent and sensible heat fluxes as well as annual means have been computed. The global mean of the annual net sea-surface heat flux is about 40 Wm^–2 and is therefore far from equilibrium. When used to force an oceanic model, these fluxes would tend to warm the ocean and would produce an unrealistic transport of heat by the oceanic general circulation. They therefore need to be corrected. This correction appears feasible because the main difference between these fluxes and long-term climatologies appears largely independent of the month and the latitude. This suggests that the errors have a systematic origin. The corrected fluxes allow both the reproduction of a realistic seasonal migration of the zero net heat-flux line and the reproduction of the annual meridional heat transport in the different oceans, within the range of previous estimates.     

自动站资料在天气预警中的应用

介绍了贵州省自动站的分布情况以及自动站资料的整理、Micaps格式的标准化处理过程和自动报警系统。     

Changes in ice phenology characteristics of two Central European steppe lakes from 1926 to 2012 - influences of local weather and large scale oscillation patterns

This paper investigates how the role of climate in tourist destination choice has changed over the last 15 years. To this end, a demand model for international tourism is estimated, including the main classic determinants but allowing a time-varying climatic sensitivity of tourists. Moreover, a complete database considering international tourism movement between 178 countries for the period 1995 to 2010 is used. Results show how turning point temperatures in origin and destination countries have changed over the period of analysis, evidencing a loss of competitiveness for traditional warm destinations. Additionally, using data for the projected growth of Gross Domestic Product per capita and climatic conditions within A2, B1 and B2 scenarios, an updated vision of their expected impact on international tourism flows is assessed, evaluating how climate change would imply a greater loss of attractiveness for traditional warm destinations around the world but would increase attractiveness for high latitude countries.     

MV-WG: a new multi-variable weather generator

This paper presents a new stochastic multi-variable weather generator (MV-WG) and compares its performance with LARS-WG version 4.0. Daily data of 109 meteorological stations from a North American database were used in a twofold comparison of the two generators: (1) the capability of reproducing the mean and variance of annual, seasonal and monthly values, and (2) the capability of reproducing extreme weather events were compared. Both generators did very well on imitating the mean and the variance of the monthly values of the investigated variables, but both showed a more moderate performance as far as the generation of extreme events was concerned. The three-parameter Weibull function, which is first introduced in MV-WG, was found to be a powerful tool to describe not only the distribution of the daily precipitation amounts, but also the distribution of dry and wet spell lengths, as well.     

1991-2008年福建省强对流天气特征

利用1991-2008年强对流资料,分析福建省强对流天气时空分布和形成原因以及主导天气型。结果表明：3-6月是福建省强对流天气的高发期,7-8月是次高发期;主要发生在14-20时,且多为孤立日,1-2个站次较为多见。不同季节强对流天气的地理分布有较大差别,春季地域性强,内陆山区明显比沿海多,中北部地区明显比南部多,其他季节分布较为均匀。强对流天气主要发生在强切变类天气形势下,主要出现在春季和秋冬季,其中66.5%的伴有低空西南急流,并以急流适中型和偏北型居多,≥3站次或≥10站次的主导天气形势为低槽型和低涡切变与高空槽配合型;弱切变类强对流天气主要发生在7-9月,主导天气型为副热带高压边缘型和台风外围型。低层无西南急流,发生较大范围强对流天气的可能性小。     

贵阳降雪和凝冻天气的大气层结特征

根据历年气候及探空资料,分析贵阳降雪和凝冻天气的大气层结特征,结果表明:出现凝冻天气时大气中多有逆温层存在,地面气温多在0℃以下,中高层风速较降雪时大;降雪天气时中高层气温较凝冻天气要低,地面气温多在-3~3℃之间;2种天气的大气在垂直方向上均处于比较稳定的状态。     

Estimates of diabatic wind speed profiles from near-surface weather observations

In this paper we analyse diabatic wind profiles observed at the 213 m meteorological tower at Cabauw, the Netherlands. It is shown that the wind speed profiles agree with the well-known similarity functions of the atmospheric surface layer, when we substitute an effective roughness length. For very unstable conditions, the agreement is good up to at least 200 m or z/L–7(z is height, L is Obukhov length scale). For stable conditions, the agreement is good up to z/L1. For stronger stability, a semi-empirical extension is given of the log-linear profile, which gives acceptable estimates up to ~ 100 m. A scheme is used for the derivation of the Obukhov length scale from single wind speed, total cloud cover and air temperature. With the latter scheme and the similarity functions, wind speed profiles can be estimated from near-surface weather data only. The results for wind speed depend on height and stability. Up to 80 m, the rms difference with observations is on average 1.1 m s^–1. At 200 m, 0.8 m s^–1 for very unstable conditions increasing to 2.1 m s^–1 for very stable conditions. The proposed methods simulate the diurnal variation of the 80 m wind speed very well. Also the simulated frequency distribution of the 80 m wind speed agrees well with the observed one. It is concluded that the proposed methods are applicable up to at least 100 m in generally level terrain.