Building resilience to El Niño‐related drought: experiences in early warning and early action from Nicaragua and Ethiopia

Forecast‐based drought early warning/early action has been hampered by both inadequate decision‐making frameworks and a lack of appropriate funding mechanisms. Rural communities in Nicaragua and Ethiopia that have participated in resilience‐building interventions of varying durations demonstrate the value of community‐based actions informed by early warning, forecasts and drought management advice, both before and during the agricultural season. While drought affected all crops negatively, participants were better able to mitigate impacts, were more organised in accessing relief and recovered more effectively. These results are consistent with other research on the cost/benefit of anticipatory actions, use of climate services and appropriate drought management advice. They also confirm the importance of embedding short‐term early action in long‐term resilience‐building. Despite this, formal systems, national and local, remain essentially unimplemented. Systems being developed at global level now need to be operationalised and translated into effective local drought management standard operating procedures for the most vulnerable.     

分层型水库夏季水质对极端厄尔尼诺事件的响应

为探究极端厄尔尼诺事件对分层型水库夏季水质的影响,分别于正常年(2012年)和厄尔尼诺年(2015年)的5~8月对枣庄周村水库主库区和入库径流的物理和化学指标进行了监测.结果表明,周村水库正常年夏季降雨量明显高于厄尔尼诺年夏季;正常年夏季水位由124.26 m上升至127.14 m,恒温层厚度增加3.1 m;而厄尔尼诺年夏季水位由121.65 m下降至119.46 m,恒温层厚度减少3.2 m.周村水库入库径流属表层流,其营养盐浓度明显高于库区变温层.正常年夏季外源营养盐的汇入导致库区变温层总氮由1.00 mg·L~(-1)升至2.60 mg·L~(-1),硝态氮由0.19 mg·L~(-1)升至1.28 mg·L~(-1),总磷由0.023mg·L~(-1)升至0.088 mg·L~(-1),而厄尔尼诺年夏季库区变温层营养盐浓度变化不大.厄尔尼诺年夏季恒温层水体还原性污染物浓度明显高于正常年同期水平,其中铁、锰、氨氮和硫化物浓度的最大值分别为0.38、1.36、2.36和1.67 mg·L~(-1),均超过地表水Ⅲ类水质标准.极端厄尔尼诺事件对周村水库夏季变温层水体营养盐浓度和恒温层水体污染物浓度均有较大的影响.     

华北降水资源的变化及其与厄尔尼诺的关系

对华北地区１９５１年以来的降水测站记录进行了趋势分析、相关分析和小波分析。发现４７年来,华北夏季和秋季降水都有明显的减少趋势。夏季和年总降水在１９６４年前后发生了一次明显的变化,以后降水显著减少。１９８５年左右,秋季降水也发生了一次显著减少的变化。夏季华北降水变化的周期主要集中于２～４年、８年左右和２０年左右。秋季最突出的周期是２～４年和８年左右。厄尔尼诺对华北降水的变化有重要影响,发生厄尔尼诺时,华北春季降水偏多,夏季和秋季降水显著偏少。冬季关系不显著。发生厄尔尼诺的次年春季,华北降水偏多。     

1991年江淮流域特大洪涝与厄尼诺

1991年初夏,持续性大暴雨导致江淮流域特大洪涝灾害.本文分析了降水量与洪涝的分布和演变及其基本大气环流特征,并着重研究了洪涝的主要成因——厄尼诺现象.文中指出.江淮流域的大或特大洪涝,大多发生在厄尼诺事件的同年或次年.厄尼诺、反厄尼诺与北半球低纬100和500hpa大气环流有长达15个月(从同年6月至次年8月)的显著性相关.厄尼诺事件的影响以各种复杂机制,先在低纬作纬向扩展传播.再向中高纬度频散传播.从而对气象与海洋灾害作出严重影响.     

2003年北京地区年雨量的预测

通过对北京地区1870年以来年雨量与太阳活动和厄尔尼诺年关系的处理分析,给出了一种预测北京地区年雨量的数学模型,在前5年预测的基础上,给出2003年北京地区年雨量的预测值为450±50mm。     

VARIATION IN THE RELATIONSHIP BETWEEN SNOWMELT RUNOFF IN OREGON AND ENSO AND PDO1

ABSTRACT: The value of using climate indices such as ENSO or PDO in water resources predictions is dependent on understanding the local relationship between these indices and streamflow over time. This study identifies long term seasonal and spatial variations in the strength of El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) correlations with timing and magnitude of discharge in snowmelt streams in Oregon. ENSO is best correlated with variability in annual discharge, and PDO is best correlated with spring snowmelt timing and magnitude and timing of annual floods. Streams in the Cascades and Wallowa mountains show the strongest correlations, while the southernmost stream is not correlated with ENSO or PDO. ENSO correlations are weaker from 1920 to 1950 and vary significantly depending on whether Southern Oscillation Index (SOI) or Niño 3.4 is used. PDO correlations are strong from 1920 to 1950 and weak or insignificant other years. Although there are not consistent increasing or decreasing trends in annual discharge or spring snowmelt timing, there are significant increases in fractional winter runoff that are independent of precipitation, PDO, or ENSO and may indicate monotonic winter warming.     

El Niño影响下春季南海北部表层水体CO2分压变化

采用走航连续观测系统分别在2011年5月和2015年5月对南海北部表层水体温度、盐度、溶解氧、叶绿素a和pCO_2进行了现场观测.在El Nio影响下,2015年5月华南地区及广东省降雨量偏多,大量冲淡水入海,南海北部冲淡水区域海表盐度显著降低,2015年5月冲淡水区域海表盐度平均值为(28.05±6.18),低于2011年5月的海表盐度平均值(29.65±2.58),同时实测冲淡水区域海表温度平均升高约2.10℃.冲淡水携带的营养物质和适度升高的海表温度共同促进了冲淡水区域浮游植物的繁殖.浮游植物光合作用不断地将海水中的游离CO2转化为有机碳,同时释放出氧气,使得水体pCO_2降低,2015年5月冲淡水区域pCO_2平均值为(286±95)μatm,低于2011年5月的pCO_2平均值(300±42)μatm.2015年5月实测获得离岸海域pCO_2平均值为(421±9)μatm,高于2011年5月pCO_2平均值(386±13)μatm,二者差值为35μatm,海表温度是离岸海域pCO_2的主要影响因子,2015年5月El Nio期间离岸海域SST升高1.96℃.El Nio影响下冲淡水区域的碳汇作用增加,离岸海域的碳源作用增强,冲淡水区域碳汇增加与离岸海域碳源增强基本抵消,2015年5月南海北部整体仍是CO_2弱汇区,约为-0.40 mmol·m~(-2)·d~(-1),与2011年5月通量值-0.58 mmol·m~(-2)·d~(-1)差别不明显.     

厄尔尼诺-拉尼娜事件对新疆环境气候的影响研究

基于近54年发生的厄尔尼诺/拉尼娜事件和新疆气候资料,分析新疆环境气候变化特点表明:1961年以来新疆降水量和气温均呈现明显增加的趋势.厄尔尼诺/拉尼娜事件呈现出起伏波动的特点,且1980年以后波动趋势更为剧烈,厄尔尼诺事件发生强度要大于拉尼娜事件.强厄尔尼诺年极端降水事件增多.厄尔尼诺/拉尼娜事件年对新疆各地区降水、气温影响不同,厄尔尼诺年塔城、阿勒泰北部、巴州北部、南疆西部喀什至和田一带增湿明显,阿勒泰东部、哈密北部升温作用显著.     

Fires in tropical forests – what is really the problem? lessons from Indonesia

Fires have attracted interest and generated alarm since the early 1980s. This concern has been particularly evident in tropical forests of Southeast Asia and the Amazon, but disastrous fires in recent summers in Australia, Europe, and the United States have drawn worldwide attention. Concern about forest fires, and related air pollution and biodiversity impacts, led international organisations and northern countries – such as the Asian Development Bank, the European Union, the Food and Agriculture Organisation, the United Nations Environment Programme, the World Bank, and the government of Germany – to undertake fire assessments and provide technical assistance. Nongovernmental organisations, such as the International Union for Conservation of Nature and Natural Resources and World Wide Fund for Nature, have also devoted increased attention to fires. Aiming at prevention of future fires, 40 fire projects and missions costing well over US$30 million have worked in Indonesia over the last 20 years. Despite the money and effort spent on them, fires continue to burn every year. It may appear to some that efforts to address the ‘fire problem’ have not been effective as fires still occur. There remains a lack of clarity about ‘fire problems’, which has, at times, led to the adoption of policies that may have negative impacts on livelihoods, the environment, and the economy. Two ‘simple’ changes in the way fires are considered would significantly improve fire-related policies and initiatives.

Long-Term Relationships Between Ocean Variability and Water Resources in Northeastern Utah1

Tingstad, Abbie H. and Glen M. MacDonald, 2010. Long-Term Relationships Between Ocean Variability and Water Resources in Northeastern Utah. Journal of the American Water Resources Association (JAWRA) 46(5):987-1002. DOI: 10.1111/j.1752-1688.2010.00471.x Abstract: The Uinta Mountains in the northwestern Colorado River Basin are an important source of water for Utah and the western United States. This article examines 20th Century hydrology in the Uinta Mountains region in the context of the previous four to eight centuries as well as possible relationships with Pacific and Atlantic Ocean variability using new tree-ring based reconstructions for streamflow and snowpack. The 20th Century appears to have been unusually wet compared with previous centuries. Relationships between hydrology in the region and the El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) are largely insignificant in instrumental datasets but may have been stronger, although inconsistent, over the longer time spans represented by the paleoclimate records. Impacts of individual modes of sea surface temperature variability may sometimes be enhanced by periods when climate forcing by ENSO, PDO, and/or AMO coincide. Such episodes are associated with deviations from mean hydrology as high as +14% and as low as −18%. The 20th Century could be a misleading benchmark to base water resource estimates upon and flexible water management strategies are necessary to take into account the large range of natural variability observed in the longer-term hydroclimatology as well as the challenges to predictability due to the apparently complex and inconsistent influence of ocean-driven variability.