青海省太阳辐射强度时空变化特征分析

利用西宁、刚察、格尔木、玉树和玛沁5站的1971-2014年逐日总辐射资料和青海省50个气象台站的温度、降水和日照时数等气象资料,分析了太阳辐射量与气象要素的内在关系,建立了无辐射观测资料地区的太阳辐射推算方法,并根据推算出的各气象站点太阳辐射量,分析了青海省全境太阳辐射量变化规律及分布特征。研究结果表明：青海省年太阳总辐射量在5 668~7 091 MJ·m^-2之间,由西北向东南逐渐递减,全省年太阳总辐射量超过6 000 MJ·m^-2的有42个站点,占全省总站点的84%。太阳总辐射量在春、夏季自东南向西北部逐渐增加,在秋季自西北向东南部逐渐减小,冬季全省各地差异较小。青海省4-8月的太阳辐射量最强,旬太阳辐射量主要集中在3月上旬-10月上旬,周太阳辐射量主要集中在第12周-第43周。青海省太阳日辐射变化趋势均呈抛物线型,早晨和傍晚辐射值较低,日出后开始呈上升趋势,北京时间13：00左右达到最高值后开始下降。日辐射持续时间从3月开始增加,9月开始减少。     

藏北高原多年冻土区地表反照率时空变化特征

利用自动气象站数据和MODIS（MOD02）数据,对位于藏北高原多年冻土区的阿雅克气象站、卓乃湖气象站、唐古拉气象站和西大滩气象站四个观测站点的单点地表反照率的季节变化、日变化和站点所属区域（88°~95°E,32°~38°N）的区域地表反照率夏、冬季节的空间分布进行了分析研究,得出：2013年,四个研究站点地表反照率均是夏季最小,冬季最大,春季大于秋季,其他季节较夏季地表反照率峰值较多;当太阳高度角大于40°时各站点地表反照率日变化基本不变,地表冻融过程中地表反照率完全冻结阶段 ＞ 日冻融循环阶段 ＞ 完全融化阶段,且地表日冻融循环阶段地表反照率日变化的中间时刻有明显下降。研究区域夏、冬季地表反照率大部分在0.1~0.3范围内;冬季地表反照率大于0.3的区域明显多于夏季,夏季区域地表反照率自阿雅克到唐古拉呈带状递减。     

Multivariate geostatistical methods of mean annual and seasonal rainfall in southwest Saudi Arabia

A multivariate geostatistics (cokriging) is used for regional analysis and prediction of rainfall throughout the southwest region of Saudi Arabia. Elevation is intruded as a covariant factor in order to bring topographic influences into the methodology. Sixty-three representative weather stations are selected for a 21-year period covering different microclimate conditions. Results show that on an annual basis, there is no significant change using elevation. On the seasonal basis, the cokriging method gave more information about rainfall occurrence values, its accuracy related to the degree of correlation between elevation and rainfall by season. The prediction of spring and winter rainfall was improved owing to the importance of orographic processes, while the summer season was not affected within its monsoon climatology. In addition, fall season shows inverse and weak correlation of elevation with rainfall. Cross-validation and cokriging variances are also used for more accuracy of rainfall regional estimation. Moreover, even though the correlation is not significant, the isohyet values of cokriged estimates provided more information on rainfall changes with elevation. Finally, adding more secondary variables in addition to elevation could improve the accuracy of cokriging estimates.     

近40a来江河源区生态环境变化的气候特征分析

利用月气象资料,对过去40a江河源气候变化特征进行分析,并与全球、全国、青藏高原进行了比较.结果表明:江河源区气温具有增暖趋势,近40a两地年平均气温分别增加约0.8℃和0.7℃,为高原异常变暖区.黄河源区变暖的主要特征是最低气温变暖,日照时数增加;最低、最高气温的显著变暖,以及较黄河源区增加更长的日照时数是长江源区变暖的主要特征.长江源区冬季变暖的作用不是主要的,春季、夏季和秋季的变暖作用比冬季还要大;黄河源区的变暖也并不主要是冬季变暖造成的,秋季变暖的作用与其相当,其它季节的变暖作用也不能忽视.近40a来江河源区降水量略有增加,主要体现在20世纪80年代中后期以来春季与冬季降水量的明显增加,夏季降水量虽然总体上没有明显变化,且局地夏季降水量呈持续减少趋势.与全球、全国以及高原区对比显示,江河源区对全球气候变暖的响应最敏感,变暖首先从长江源和整个高原发端,之后15a.黄河源和全国才进入显著温暖期.黄河源与长江源北部降水量的增加表明,气候变暖有利于高原增加降水量.     

Synoptic analysis of dust storm over Arabian Peninsula: a case study on February 28, 2009

Sand and dust storms are causing hazards and problems in aviation as well as the dangers and distresses they cause on living things. The low meteorological visibility, the presence of strong winds with gust, and the transport of dust and sand particles by the wind are dangerous on landing and departure of aircrafts, and even on planes that are parked. The main aim of the study is to examine the meteorological conditions causing the dust storm that took place in the Arabian Peninsula on February 28, 2009, and to determine the source of dust caused dust storm, sand storm, blown sand, and blown dust at the airports. Within the scope of the study, aviation routine weather report (METAR) and aviation selected special weather report (SPECI) reports have been assessed at many airports over Arabian Peninsula (AP), the northern part of the AP and North Africa. As model outputs; NCEP–DOE Reanalysis 2 data, BSC–DREAM8B, and HYSPLIT model were used. In the satellite images; METEOSAT MSG dust RGB images, MODIS, and Kalpana-1 data were used. According to obtained results, dust storms were detected in Bahrain, Kuwait, Saudi Arabia, and United Arab Emirates (UAE). At Al-Ahsa Airport in Saudi Arabia, the lowest visibility measured on February 28, 2009, dropping to 200 m, which was dominated by blowing sand. The source region of the dust observed at Dubai Airport in UAE is the eastern regions of the Rub’al Khali Desert located between Saudi Arabia, Oman, and UAE.     

典型岩溶区潜在蒸散发变化及其影响因素

蒸散发过程是联系大气过程和陆面水文过程的关键环节,对区域/流域水循环过程和水量平衡具有重要影响。岩溶区,地表生态环境脆弱,对气候变化响应敏感,蒸散发可能是联系大气、水、热交换和碳循环的关键生态水文过程。准确地估算蒸散发对于深入研究岩溶水循环响应气候变化、碳循环、生态修复等具有重要作用。本文选择典型岩溶区桂林市为研究对象,基于1951~2015年桂林市气象站逐日气象数据,采用Penman- Monterith方法计算了潜在蒸散发量,利用Mann- Kendall非参数检验法和相关性分析研究桂林市潜在蒸散发的变化趋势及其影响因素。研究结果表明,桂林市潜在蒸散发具有明显的年、年际和季节尺度变化特征。1951~2015年桂林市潜在蒸散发呈显著的减小趋势,变化速率为-8. 02 mm/10a;夏季、秋季和冬季潜在蒸散发呈下降趋势,而春季呈微弱的上升趋势;夏季潜在蒸散发的显著减小是影响年蒸散发下降的主要原因;桂林市潜在蒸散发在1967和2003年左右发生突变;通过Mann- Kendall趋势检验和相关性分析得出,桂林市平均气温、最高、最低气温呈显著的上升趋势,而风速、相对湿度、日照时数呈显著的下降趋势;日照时数是影响桂林市潜在蒸散发变化的主要因素,其次是风速。     

Sedimentation on a wave-dominated, open-coast tidal flat, south-western Korea: summer tidal flat – winter shoreface

Sedimentation on the open-coast tidal flats of south-western Korea is controlled by seasonal variation in the intensity of onshore-directed winds and waves. As a result, an environmental oscillation takes place between tide-dominated conditions in summer and wave-dominated conditions in winter. In summer, thick muddy deposits, including sporadic storm deposits, accumulate in response to low wave energy, weak currents, and intense solar insolation that promotes consolidation of the mud at low tide. Bioturbation is minimal because of rapid sedimentation and soft substrate. During the autumn, the summer mud deposits experience erosion due to increasingly strong onshore winds and waves, until only small mud patches and mud pebbles remain. The concentration of ebb runoff between the mud patches produces small, ephemeral tidal creeks. In winter, storm waves occur frequently (ca 10 days a month) and dominate sedimentation in the intertidal zone, producing extensive wave-generated parallel lamination and short-wavelength (0·3–2 m) hummocky cross-stratification. The prevalence of strong onshore winds decreases in spring, allowing longer and more frequent intervals of calm weather, during which time muddy sediments are deposited by tidal processes. Over the long term, winter storm waves dominate sedimentation and the preserved deposits consist of amalgamated storm beds that resemble those generally associated with shorefaces. This raises the question of how many ancient ‘shorefaces’ are, in fact, open-coast tidal flats.     

Impact of dust events on aerosol optical properties over Iraq

The spatial and temporal characteristics of aerosol optical properties (AOP) were analyzed in order to find out the hotspot aerosol sources over Iraq and surrounding regions. The correlation of AOP with the frequency of dust events (dust storm (DS), rising dust (RD), suspended dust (SD)) over 12 Iraqi stations is evaluated during the study period (January 2005–December 2014). The AOP: aerosol absorption optical depth (AAOD), aerosol extinction optical depth (AOD), and aerosol single scattering albedo (SSA) at 388 and 500 nm and aerosol index (AI), are derived from the Ozone Monitoring Instrument (OMI) on board the Aura satellite. Three well-known spatial interpolation techniques: inverse distance weighting, radial basis function with three sub-types, and kriging with three sub-types, are examined in ArcGIS software. Statistical analysis is applied to compute the station probability of dust events and its correlation with AOP. Results showed that the spline with the lowest RMSE and MPE near zero is the optimum method for estimating AOP. The spatial mean of AAOD, AOD, and AI (SSA) have the same pattern with high (low) mean values over the south and northwest of Iraq, Kuwait, and the northeast of Saudi Arabia. The seasonal variability of AAOD and AOD over the Iraqi stations showed that high (low) values occurred during spring and summer (winter) and concluded that AAOD is a responsible component for variation in AOD. DS and RD probability is higher over stations in the middle and south of Iraq than the stations in the north. High SD probability is over Mosul, Baghdad, and Nasiriya stations. The correlation of AOP with dust events suggests that the AAOD component is more important in the study of DS than SSA and AI while AI is a good index for the study of RD and SD in the study region.     

Physical control of primary productivity on a seasonal scale in central and eastern Arabian Sea

Usingin situ data collected during 1992–1997, under the Indian programme of Joint Global Ocean Flux Study (JGOFS), we show that the biological productivity of the Arabian Sea is tightly coupled to the physical forcing mediated through nutrient availability. The Arabian Sea becomes productive in summer not only along the coastal regions of Somalia, Arabia and southern parts of the west coast of India due to coastal upwelling but also in the open waters of the central region. The open waters in the north are fertilized by a combination of divergence driven by cyclonic wind stress curl to the north of the Findlater Jet and lateral advection of nutrient-rich upwelled waters from Arabia. Productivity in the southern part of the central Arabian Sea, on the other hand, is driven by advection from the Somalia upwelling. Surface cooling and convection resulting from reduced solar radiation and increased evaporation make the northern region productive in winter. During both spring and fall inter-monsoons, this sea remains warm and stratified with low production as surface waters are oligotrophic. Inter-annual variability in physical forcing during winter resulted in one-and-a-half times higher production in 1997 than in 1995.     

Estimation of climatic transition in Riyadh (Saudi Arabia) in global warming perspectives

The present exercise is a study to enquire into the recent climatic transition, if any in Riyadh, Saudi Arabia. Conventional climatic indicators such as rainfall distribution, temperature regime, relative humidity, sunshine duration, wind velocity and evaporation characteristics were examined over a period of twenty six years of available meteorological data. The analyses showed a remarkable mutual resemblance and unidirectional trend in all the temperature parameters like absolute monthly maximum, absolute monthly minimum, mean monthly maximum, mean monthly minimum and mean monthly temperatures and the mean monthly maximum and mean monthly minimum relative humidities. Similarly, the trends in sunshine duration, wind velocity and pan evaporation were also supportingly in accordance to the general trends of climatic transition. The analysis based on a smaller period climatic data shows a good deal of agreement with the trends of studies on global warming projections made by simulated models on the basis of CO₂ concentration changes in the atmosphere.     

Spatiotemporal variations in rainfall–topographic relationships in southwestern Saudi Arabia

Spatial variations in the relationship between topography and mean annual and seasonal rainfalls in southwestern Saudi Arabia are examined using Kruskal–Wallis one-way analysis of variance. The topographic factors include physiographic features (topography), altitude, slope, proximity to a ridge or crest of mountains, and proximity to the Red Sea. There is a statistically significant effect of topographic factors on the mean annual rainfall, but the results are more significant for the mean seasonal rainfall. The largest amount of mean rainfall in the study area occurs during spring, when rainfall displays a significant relationship with topographic factors, in which more orographic rainfall patterns are associated with higher altitude, greater proximity to a ridge and steeper slopes. Higher altitudes do not necessarily receive more rain; some low altitude locations (i.e., the southern part of the study area) receive more rain during summer and fall because they are located on the windward side of the Asir Mountains and are exposed to the moist air masses brought by the southwest monsoonal system in summer and by the northwest air flow from the Mediterranean and Red Sea in the fall in addition to local convective rainfall patterns. Rainfall in winter increases in the foothills of the Asir Mountains above the coastal plain of the Red Sea. The steep western slopes (windward side) receive more rainfall than the gentle eastern slopes (leeward side): this may be due to the Asir Mountains forcing moist air masses carried by the westerly and northwest winds to rise and cool before they descend and warm on the leeward side.     

天山南坡科其喀尔冰川表碛区小气候特征研究

利用天山南坡科其喀尔冰川3号观测站2009年全年的气象观测资料,分析研究了科其喀尔冰川表碛区的小气候特征. 结果表明：总辐射和净辐射夏秋季较高、冬春季较低;反射辐射和地表反照率反之. 与其他地区不同,该区主要受积雪物理性质和下垫面状况的影响,冬春季地表反照率日变化表现为由大到小的变化过程,夏秋季表现为倒U型. 温度年变化表现为夏秋季高、冬春季低,最高月均值出现在8月,为9.4℃,最低月均值出现在1月,为-9.6℃. 受山谷风和冰川风的影响,全年的风向以西北风和西北偏西风为主,风向的日变化以11：00为界发生转向. 受降水和冰川消融等的影响,比湿夏秋季月均值较大,冬春季月均值较小.     

Development of storm hyetographs for flood forecasting in the Kingdom of Saudi Arabia

This paper presents the derivation of the design storm hyetograph patterns for the Kingdom of Saudi Arabia based on real rainfall events from meteorological stations distributed throughout the Kingdom. Two thousand twenty-seven rainfall storms for a 20–28-year period were collected and analyzed covering 13 regions of the Kingdom. Four distinct dimensionless rainfall hyetograph patterns have been obtained over the Kingdom, while two patterns have been obtained for each individual region because of the lack of data for long-duration storms in individual regions. The resulting dimensionless rainfall patterns for each region can be used to develop storm hyetographs for any design duration, total rainfall depth and return period. It has been shown that the developed storm hyetographs have different features from other storm patterns that are commonly used in arid zones. The study recommends using these curves for the design of hydraulic structures in Kingdom of Saudi Arabia and regions alike.     

Consistent seasonal snow cover depth and duration variability over the Western Himalayas (WH)

Precipitation in solid form, i.e., snow, during winter season over the Western Himalayas (WH) leads to the build-up of seasonal snow cover. Seasonal snow cover build-up (snow cover depth and duration) largely depends on atmospheric variables such as temperature, precipitation, radiation, wind, etc. Integrated (combined) influence of atmospheric variables on seasonal snow cover gets reflected in terms of spatial and temporal variability in seasonal snow cover build-up pattern. Hence spatial and temporal variability of seasonal snow cover build-up can serve as a good indicator of climate change in high altitude mountainous regions like the WH. Consistent seasonal snow cover depth and duration, delay days and early melt days of consistent seasonal snow cover at 11 stations spread across different mountain ranges over the WH were analyzed. Mean, maximum and percentiles (25th, 50th, 75th, 90th and 95th) of consistent seasonal snow cover depth and duration show decline over the WH in the recent past 2–3 decades. Consistent seasonal snow cover is found to melt early and snow cover build-up pattern is found to show changes over the WH. Decline in consistent seasonal snow cover depth, duration and changing snow cover build-up pattern over the WH in recent decades indicate that WH has undergone considerable climate change and winter weather patterns are changing in the WH.     

北京上空大气臭氧垂直分布的特征

利用我国自行研制的探空仪和地面接收设备首次较系统地获得了北京地区连续一年（2001年 3月至2002年 2月）的大气臭氧垂直分布资料。结果分析表明：①北京地区上空臭氧浓度极大值的季节均值的变化范围为15．1～16．7 mPa,其高度位于20．7～25．1km之间,极小值的季节均值的变化范围为 2．0～2．8 mPa,其高度在对流层顶附近。②边界层和平流层下部是臭氧浓度变化的活跃区域,并具有明显的季节变化,在边界层内夏季臭氧积分浓度高于冬季相应值的 1．7倍之多,而在平流层下部,冬季臭氧积分浓度则高于夏季的相应值。夏季边界层中臭氧浓度偏高,表明臭氧是北京地区夏季重要的污染气体之一。③北京上空臭氧垂直廓线的形态呈多样性,夏秋季节以单峰为主,冬春季节经常出现双峰和多峰结构;次峰出现的区域一般在10～18km高度范围内。     

气候系统模式FGOALS_gI模拟的小冰期气候

利用1650～1750年逐年变化的太阳辐照度等外强迫资料,驱动中国科学院大气物理研究所LASG发展的快速气候系统模式FGOALS_gl,模拟了小冰期(LIA)气候.把模拟的LIA表面温度变化与重建资料进行对比,结果表明FGOALS_gl对LIA气候具有较强的模拟能力,说明太阳辐照度的自然变化是导致小冰期气候的重要成因.模拟结果显示,LIA时期纬向平均温度变化表现为整个对流层降温,低纬度地Ⅸ的降温中心位于对流层中层,北半球降温幅度大于南半球,高纬地区的降温幅度大于低纬地区.分析发现,中高纬地区的局地温度变化主要与环流异常相对应的冷暖平流有关;低纬地区的降温主要与赤道东风加强有关,东风增强通过增大蒸发和引起次表层冷海水上翻而令表层温度降低.LIA时期的降水变化丰要位于中低纬地区,表现为日界线东(西)侧降水的负(正)异常.与降水异常相对应.Walker环流加强,东太平洋对流活动减弱,它与低纬地区对流层中层冷异常相联系.与大气层顶净短波辐射异常的季节变化相对应,南、北半球夏季平均表面温度异常较之冬季低0.28℃左右.     

黄土高原和南海陆架古季风演变的生物记录与Heinrich事件

宝鸡黄土中０．１５Ｍａ以来植物硅酸体研究表明,年均温度、１月份和年均降水量的变化与深海氧同位素变化有很好的一致性,而７月份降水量的变化与印度洋反映季风强弱的粒度变化相类似。南海陆架孢粉研究发现,１４７００—１３９００ａＢ．Ｐ．和２２９００一２０６００ａＢ．Ｐ．气候变冷期与北大西洋沉积物中Ｈ１、Ｈ２变冷事件存在成因上的联系。全球冰量通过冬季风等因素在“轨道尺度”上可能影响了夏季风对特定地区的控制时间,从而控制了黄土区气候的年均状况,但没有影响夏季风固有的变化周期和振幅。由低纬夏季太阳辐射控制的夏季风以其准２００００ａ周期叠加在冬季风所具有的准０．１Ｍａ周期上。冬、夏季风的演化行为具有较强的相对独立性,冬、夏季风同时减弱或增强的情况是存在的。Ｈｅｉｎｒｉｃｈ事件在东亚地区不仅影响了冬季风而且影响了夏季风。     

气候系统模式FGOALS_gl模拟的小冰期气候

利用1650～1750年逐年变化的太阳辐照度等外强迫资料,驱动中国科学院大气物理研究所LASG发展的快速气候系统模式FGOALS_gl,模拟了小冰期(LIA)气候。把模拟的LIA表面温度变化与重建资料进行对比,结果表明FGOALS_gl对LIA气候具有较强的模拟能力,说明太阳辐照度的自然变化是导致小冰期气候的重要成因。模拟结果显示,LIA时期纬向平均温度变化表现为整个对流层降温,低纬度地区的降温中心位于对流层中层,北半球降温幅度大于南半球,高纬地区的降温幅度大于低纬地区。分析发现,中高纬地区的局地温度变化主要与环流异常相对应的冷暖平流有关; 低纬地区的降温主要与赤道东风加强有关,东风增强通过增大蒸发和引起次表层冷海水上翻而令表层温度降低。LIA时期的降水变化主要位于中低纬地区,表现为日界线东(西)侧降水的负(正)异常。与降水异常相对应,Walker环流加强,东太平洋对流活动减弱,它与低纬地区对流层中层冷异常相联系。与大气层顶净短波辐射异常的季节变化相对应,南、北半球夏季平均表面温度异常较之冬季低0.28℃左右。     

Assessing the impacts of rainfall intensity and urbanization on storm runoff in an arid catchment

In the past few decades, rapid urbanization has occurred in many regions of the Kingdom of Saudi Arabia due to increasing population and urban development. Additionally, the effects of global warming on rainfall characteristics have been observed. This rapid change in urbanization and climate change has cause significant changes in the nature of land surfaces and rainfall patterns, which affect the runoff process and the amount of surface runoff during floods. This study investigated the effect of urbanization and rainfall intensity for Hafr Al-Batin watershed located in Saudi Arabia. For this purpose, a hydrologic model, HEC-HMS, was adopted to simulate the flow of different rainfall intesities and urbanization levels. Simulated results showed that for a 100-year storm, a 24-h duration, and an urbanization level of 80%, the peak flow was 213% higher than the estimated current peak and the runoff volume was 112% higher than the current runoff volume. These results show a strong linear correlation between the level of urbanization and both peak discharge and runoff volume. Furthermore, the results indicate that for short return periods, the peak flow is more sensitive to the level of urbanization compared to long periods.     

Dynamics of sea-ice biogeochemistry in the coastal Antarctica during transition from summer to winter

The seasonality of carbon dioxide partial pressure(pCO_2).air-sea CO_2 fluxes and associated environmental parameters were investigated in the Antarctic coastal waters.The in-situ survey was carried out from the austral summer till the onset of winter[January 2012,February 2010 and March 2009) in the Enderby Basin.Rapid decrease in pCO_2 was evident under the sea-ice cover in January,when both water column and sea-ice algal activity resulted in the removal of nutrients and dissolved inorganic carbon(DIC) and increase in pH.The major highlight of this study is the shift in the dominant biogeochemical factors from summer to early winter.Nutrient limitation(low Si/N),sea-ice cover,low photosynthetically active radiation(PAR),deep mixed layer and high upwelling velocity contributed towards higher pCO_2during March(early winter).CO_2 fluxes suggest that the Enderby Basin acts as a strong CO_2 sink during January(-81 mmol m~2 d~(-1)),however it acts as a weak sink of CO_2 with-2.4 and-1.7 mmol m~(-2) d~(-1)during February and March,respectively.The present work,concludes that sea ice plays a dual role towards climate change,by decreasing sea surface PCO_2 in summer and enhancing in early winter.Our observations emphasize the need to address seasonal sea-ice driven CO_2 flux dynamics in assessing Antarctic contributions to the global oceanic CO_2 budget.