A comparison of regional monsoon variability using monsoon indices

The present study aims to (a) examine meteorological basis for construction of regional monsoon indices and (b) explore the commonality and differences among tropical regional monsoons, especially the teleconnection and monsoon–ENSO relationship. We show that the area-averaged summer precipitation intensity is generally a meaningful precipitation index for tropical monsoons because it represents very well both the amplitude of annual cycle and the leading mode of year-to-year rainfall variability with a nearly uniform spatial pattern. The regional monsoon circulation indices can be defined in a unified way (measuring monsoon trough vorticity) for seven tropical monsoon regions, viz.: Indian, Australian, western North Pacific, North and South American, and Northern and Southern African monsoons. The structures of the tropical monsoons are commonly characterized by a pair of upper-level double anticyclones residing in the subtropics of both hemispheres; notably the winter hemispheric anticyclone has a barotropic structure and is a passive response. Two types of upper-level teleconnection patterns are identified. One is a zonal wave train emanating from the double anticyclones downstream along the westerly jets in both hemispheres, including Indian, Northern African and Australian monsoons; the other is a meridional wave train emanating from the double anticyclones polewards, such as the South American and western North Pacific monsoons. Over the past 55 years all regional summer monsoons have non-stationary relationship with ENSO except the Australian monsoon. The regional monsoon–ENSO relationship is found to have common changing points in 1970s. The relationships were enhanced for the western North Pacific, Northern African, North American and South American summer monsoons, but weakened for the Indian summer monsoon (with a recovery in late 1990s). Regardless the large regional differences, the monsoon precipitations over land areas of all tropical monsoon regions are significantly correlated with the ENSO, suggesting that ENSO drives global tropical monsoon rainfall variability. These results provide useful guidance for monitoring sub-seasonal to seasonal variations of the regional monsoons currently done at NCEP and for assessment of the climate models’ performances in representing regional and global monsoon variability.     

What drives food insecurity in southern Africa? a meta-analysis of household economy studies

Food insecurity, and the factors that determine it, are experienced at the level of the household and the individual. Food insecurity is also spatially varied across regions. In this paper meta-analysis is used to synthesize 49 household economy local-level studies that focus on community-level livelihood strategies to identify drivers of food insecurity in southern Africa. The results reveal entrenched cycles of vulnerability in southern Africa's food insecure communities, where socio-economic issues feature prominently. The direct causes of inadequate food access are poverty, environmental stressors and conflict: these account for 50% of the identified indirect drivers of food insecurity. Meta-analysis is used to suggest the common processes behind food insecurity that take specific forms in particular communities. The findings underscore the need to understand the multiple social and political dimensions of food insecurity, such as the breakdown in social capital associated with poverty, conflict and HIV/AIDS, that run deeper than environmental constraints to food production.     

Combining climatological and participatory approaches for assessing changes in extreme climatic indices at regional scale

This paper combines the climatological and societal perspectives for assessing future climatic extremes over Kangasabati River basin in India using an ensemble of four high resolution (25 km) regional climate model (RCM) simulations from 1970 to 2050. The relevant extreme indices and their thresholds are defined in consultation with stakeholders and are then compared using RCM simulations. To evaluate the performance of RCM in realistically representing atmospheric processes in the basin, model simulations driven with ERAInterim global re-analysis data from 1989 to 2008 are compared with observations. The models perform well in simulating seasonality, interannual variability and climatic extremes. Future climatic extremes are evaluated based on RCM simulations driven by GCMs, for present (1970–1999) and for the SRES A1B scenario for future (2021–2050) period. The analysis shows an intensification of majority of extremes as projected by future ensemble mean. The study suggests that there is a marked consistency in stakeholder observed changes in climate extremes and future predicted trends.     

Weather and international price shocks on food prices in the developing world

In the context of a changing climate, there is an urgent need to better understand the impact that weather disturbances have on food affordability in the developing world. While the influence of international markets on local food markets has received considerable attention, in contrast, the potential influence of weather disturbances on local food markets has received much less attention. In fact, local weather disturbances may have an adverse impact on the poorest households in developing countries. Here we quantify the short-run impact of both weather disturbances as well as international price changes on monthly food prices across 554 local commodity markets in 51 countries during the period between 2008 and 2012. We find that almost 20% of local market prices were affected by domestic weather disturbances in the short run, 9% by international price changes and 4% by both domestic weather disturbances and international price changes during the period. An improved understanding of the magnitude and relative importance of weather disturbances and international price changes on rural economies will inform public policies that are designed to mitigate the impact of adverse weather disturbances.     

The impacts of food price and income shocks on household food security and economic well-being: Evidence from rural Bangladesh

This paper examines the combined impacts of food price and income shocks on household food security and economic well-being in low-income rural communities. Using longitudinal survey data of 1800 rural households from 12 districts of Bangladesh over the period 2007–2009, we estimated a three-stage hierarchical logit model to identify the key sources of household food insecurity. The first-difference estimator was then employed to compare pre- and post-shock expenditure for those households that experienced acute food shortages and those that managed to avoid the worst impacts of the shocks. On the basis of our results we conclude that: (1) the soaring food prices of 2007–2009 unequivocally aggravated food insecurity in the rural areas of Bangladesh; (2) the subsequent income shocks of 2007–2009 contributed toward worsening food insecurity; (3) the adverse impacts of these shocks appeared to have faded over time due to labor and commodity market adjustments, regional economic growth, and domestic policy responses, leaving no profound impacts on households’ economic well-being in most cases; and (4) although the immediate adverse consequences of rising food prices were borne disproportionately by the poor, the longer term consequences were distributed more evenly across the rich and poor and were favorable for the day laborers.     

Comparison of two drought indices in studying regional meteorological drought events in China

The composite-drought index (CI), improved weighted average of precipitation index (IWAP), and the objective identification technique for regional extreme events (OITREE) were employed to detect China's regional meteorological drought events (CRMDEs) during 1961–2010. Compared with existing references, CI and IWAP both showed strong ability in identifying CRMDEs. Generally, the results of CI and IWAP were consistent, especially for extreme and severe CRMDEs. During 1961–2010, although the frequencies of extreme and severe CRMDEs based on CI and IWAP both showed weak decreasing trends, the two mean-integrated indices both showed increasing but not significant trends. However, the results of IWAP were more reasonable than CI’s in two aspects. Firstly, the monthly frequency of extreme and severe CRMDEs based on IWAP showed a clear seasonal variation, which coincided with the seasonal variation of the East Asian monsoon over central–eastern China, whereas the frequency based on CI presented a much weaker seasonal variation. Secondly, the two sets of results were sometimes inconsistent with respect to the start and end times of a CRMDE, and CRMDEs based on CI generally showed two unreasonable phenomena: (1) under non-drought conditions, a severe drought stage could suddenly occur in a large area; and (2) during the following period, drought could alleviate gradually in cases of non-precipitation. Comparative analysis suggested that the IWAP drought index possesses obvious advantages in detecting and monitoring regional drought events.     

改进的Holroyd云粒子形状识别方法及其应用

云降水粒子形状是影响云微物理过程的重要因素,准确的云粒子形状信息是诸多云微物理参量计算的前提。为获取机载云粒子成像仪(CIP)所测云粒子的形状信息,文中提出了一种改进的Holroyd云粒子形状识别方法,即先对云粒子形状进行预分类,然后针对预分类后的完整粒子和可识别的部分状粒子,分别选出合适的参数及其阈值再进行具体的分类,最终可将云粒子分为微小状、线形状、聚合状、霰、球形、板状、不规则和枝状。利用实测数据对原始的Holroyd方法和改进的Holroyd方法进行识别效果对比验证。结果表明改进的Holroyd方法在云粒子形状识别的准确度方面比原Holroyd方法有较大的提高。将所提方法应用于太原地区一次降水性层状云的云微物理飞机观测资料以分析不同的降水阶段云中冰晶粒子的形状分布、增长机制、冰晶粒子数浓度以及冰水含量的垂直分布特征,所获取的云中冰晶粒子属性表明新提出方法有助于云微物理分析。     

Characterization of regional hydrological drought using improved precipitation records under multi-auxiliary information

Theoretical and Applied Climatology - Drought is a complex natural hazard that has been recurrently occurred in many regions across the globe. Therefore, precise drought characterization and its...     

Sustaining agricultural production and food security in Southern Africa: an improved role for climate prediction?

Livelihoods and household food security in the Southern African region can be extremely vulnerable to the negative effects of climate stress as shown by the 2002–2004 ‘complex emergency.’ Climate prediction may prove a valuable resource in mitigating these effects. If climate prediction is applied successfully, it may be able to help guide responses in populations at risk to reduce vulnerability to climate stress. The study presented here seeks to understand what would constitute an improved role for climate prediction in contributing to sustaining agricultural production and food security in Southern Africa. Investigation undertaken during the 2002/2003 rainy season under regional conditions of elevated disaster risk shows, however, that a number of weaknesses and gaps persistently characterize climate information systems in the Southern African region, and constrain such systems’ ability to benefit key sectors, particularly agriculture. The stakeholder identification of such gaps forms the basis for distilling concrete recommendations to improve process and organizational efficiency. Such recommendations, while developmental, should better enable institutions and stakeholders involved in climate prediction to fulfill their potential in supporting development of successful adaptation strategies in populations and sectors at risk.     

一个区域气候模式水文过程的改进及年尺度模拟研究

本文将更符合物理过程实际的考虑入渗非均匀和降水非均匀的水文模型VXM并入区域气候模式RegCM3模式,利用此区域水文气候模式分别对1988、1990、1991年3个不同气候年的水文气候进行了模拟.模拟结果表明,模式对入渗非均匀和降水非均匀的响应在年尺度上是敏感的:模式能成功模拟年平均降水及降水的年内变化,较好地再现了降水分布和大小;并入VXM模型后模式对南方径流的模拟能力得到较大的提高,模拟的年平均及年内变化与实际较为一致.结果还表明,径流机制的改进有助于改善降水模拟能力,并引起蒸发、温度等气候要素相应的变化;并入VXM模型后对模拟结果的影响更主要体现在夏季.     

1961—2016年我国区域性暴雨过程的客观识别及其气候特征

利用全国2287个气象观测站1961—2016年逐日降水资料,基于对暴雨区进行连续追踪的思路,采用暴雨相邻站点数和暴雨区中心距离确定了中国区域性暴雨过程的客观识别方法;根据区域性暴雨过程的平均强度、持续时间和平均范围构建了区域性暴雨过程的综合强度评估模型。利用该客观方法对1961—2016年中国的区域性暴雨过程进行识别,并分析其气候和气候变化特征。结果显示：我国区域性暴雨过程年均38.5次;区域性暴雨过程一年各月均可出现,但主要出现在4—9月,其中7、8月发生最为频繁,6月区域性暴雨过程持续时间长、范围广、综合强度强,这与长江中下游地区梅雨现象有关。一年中,区域性暴雨过程首次出现日期平均为3月6日,末次出现日期平均为11月14日;1961—2016年,我国年区域性暴雨过程首次出现日期呈明显提前、末次日期呈显著推后、暴雨期呈显著延长的变化趋势;年发生总频次呈微弱增多,较强区域性暴雨过程次数呈明显增加趋势;区域性暴雨过程的覆盖范围和综合强度均呈显著增大趋势。南方型区域暴雨过程变化趋势与全国的基本一致;北方型首次日期呈提前、末次日期呈推后趋势,发生频次有微弱减少趋势,覆盖范围、持续时间、综合强度均无明显变化趋势。     

Phosphorus vulnerability: A qualitative framework for assessing the vulnerability of national and regional food systems to the multi-dimensional stressors of phosphorus scarcity

The element phosphorus underpins the viability of global and national food systems, by ensuring soil fertility, maximising crop yields, supporting farmer livelihoods and ultimately nutritional security of the global population. The implications of global phosphorus scarcity therefore have serious potential consequences for future food security, yet these implications have not been be comprehensively or sufficiently assessed at the global or national scales. This paper offers a new integrated framework for assessing the vulnerability of national food systems to global phosphorus scarcity—the Phosphorus Vulnerability Assessment framework. Drawing on developments in assessing climate and water vulnerability, the framework identifies and integrates 26 phosphorus-related biophysical, technical, geopolitical, socio-economic and institutional factors that can lead to food system vulnerability. The theoretical framework allows analysis of context-specific food system by examining impact due to exposure, sensitivity and adaptive capacity. The framework will also ultimately provide guidance for food and agriculture policy-makers, phosphate producers and phosphorus end-users (primarily farmers and consumers) to take action to reduce their vulnerability to this new global challenge.     

The story of phosphorus: Global food security and food for thought

Food production requires application of fertilizers containing phosphorus, nitrogen and potassium on agricultural fields in order to sustain crop yields. However modern agriculture is dependent on phosphorus derived from phosphate rock, which is a non-renewable resource and current global reserves may be depleted in 50–100 years. While phosphorus demand is projected to increase, the expected global peak in phosphorus production is predicted to occur around 2030. The exact timing of peak phosphorus production might be disputed, however it is widely acknowledged within the fertilizer industry that the quality of remaining phosphate rock is decreasing and production costs are increasing. Yet future access to phosphorus receives little or no international attention. This paper puts forward the case for including long-term phosphorus scarcity on the priority agenda for global food security. Opportunities for recovering phosphorus and reducing demand are also addressed together with institutional challenges.     

Secondary aerosol formation and identification of regional source locations by PSCF analysis in the Indo-Gangetic region of India

Secondary aerosol formation was studied at Allahabad in the Indo-Gangetic region during a field campaign called Land Campaign-II in December 2004 (northern winter). Regional source locations of the ionic species in PM₁₀ were identified by using Potential Source Contribution Function (PSCF analysis). On an average, the concentration of water soluble inorganic ions (sum of anions and cations) was 63.2 μgm⁻³. Amongst the water soluble ions, average NO₃⁻ concentration was the highest (25.0 μgm⁻³) followed by SO₄²⁻ (15.8 μgm⁻³) and NH₄⁺ (13.8 μgm⁻³) concentrations. These species, contributed 87% of the total mass of water soluble species, indicating that most of the water soluble PM₁₀ was composed of NH₄NO₃ and (NH₄)₂SO₄/NH₄HSO₄ or (NH₄)₃H(SO₄)₂ particles. Further, the concentrations of SO₄²⁻, NO₃⁻, and NH4⁺ aerosols increased at high relative humidity levels up to the deliquescence point (∼63% RH) for salts of these species suggesting that high humidity levels favor the conversion and partitioning of gaseous SO₂, NO_x, and NH₃ to their aerosol phase. Additionally, lowering of ambient temperature as the winter progressed also resulted in an increase of NO₃⁻ and NH₄⁺ concentrations, probably due to the semi volatile nature of ammonium nitrate. PSCF analysis identified regions along the Indo-Gangetic Plain (IGP) including Northern and Central Uttar Pradesh, Punjab, Haryana, Northern Pakistan, and parts of Rajasthan as source regions of airborne nitrate. Similar source regions, along with Northeastern Madhya Pradesh were identified for sulfate.     

The regional nature of global challenges: a need and strategy for integrated regional modeling

Glaciers of the conterminous United States have been receding for the past century. Since 1900 the recession has varied from a 24 % loss in area (Mt. Rainier, Washington) to a 66 % loss in the Lewis Range of Montana. The rates of retreat are generally similar with a rapid loss in the early decades of the 20th century, slowing in the 1950s–1970s, and a resumption of rapid retreat starting in the 1990s. Decadal estimates of changes in glacier area for a subset of 31 glaciers from 1900 to 2000 are used to test a snow water equivalent model that is subsequently employed to examine the effects of temperature and precipitation variability on annual glacier area changes for these glaciers. Model results indicate that both winter precipitation and winter temperature have been important climatic factors affecting the variability of glacier variability during the 20th Century. Most of the glaciers analyzed appear to be more sensitive to temperature variability than to precipitation variability. However, precipitation variability is important, especially for high elevation glaciers. Additionally, glaciers with areas greater than 1 km² are highly sensitive to variability in temperature.