太白风格礼赞

太白风格礼赞大白县地处秦岭西部的中高山地带，境内山大林深，沟谷纵横，地域性小气候特别突出，大部分地方长冬无夏，春秋相连。春季回暖缓慢，时有寒潮出现，多大风天气；夏季雨水充沛，气候湿润；秋季降温迅速，初秋多连阴雨，日照条件极差；冬季漫长而寒冷，属典型的...     

华北地区旱-湿转变周期的动力研究

为研究我国华北地区降水旱涝变化的动力行为与规律，提出了利用气候层次理论，突变点数建模技术和子波分析技术结合来构建其在某一气候层次上的动力模式的方法，并应用该方法对我国华北多个站点降水资料分析和构建其年代层次变化的动力模式。最后应用所得的模式从动力学的角度揭示了我国华北地区的干湿特征。研究结果表明：我国华北地区大部分站点的降水湿润都明显短于旱期，干旱期要持续二十几年，而湿润期仅有几年左右。旱长湿短是华北地区降水的主要特征。     

不同下垫面条件下土壤含水量时空变化特征的对比分析

根据淮河三站1998-05-21－08-31逐日土壤水分6层观测资料和黑河1991-06-20－08-21、1990-12-17－1991-02-15逐日土壤水分4层观测资料，分析了邻近绿洲的沙漠区、河网区（湿润区）几种典型下垫面土壤水分含量的时空变化特征。结果表明，不同类型的下垫面条件下，夏季土壤水分在湿润研究区呈明显的单峰偏态分布，且以β分布拟合效果为最好；而在邻近绿洲的沙漠研究区则呈多峰分布，冬季呈Γ分布，且湿润的研究区域夏季土壤水分在时间上呈显著的10－25d的周期变化。     

中国地表热源的气候学特征

利用研制的地表热量平衡各分量的气候计算方法，结合全国６个热平衡站资料，计算并讨论了地表热源在全国的分布特征，分析了地面对大气加热的特点以及地表热源的参数化问题。指出季风气候背景、纬度、地形和地表湿润状况是决定地表热源特征的重要因素。就全年来说，在我国湿润、半湿润地区，潜热是地面加热大气的主要形式，西北干燥区则以感热加热为主。     

黑龙江省林业气候区划

使用84个观测站1961～1990年的气候资料阐述了黑龙江省热量资源、降水资源、光资源及风资源的分布状况。根据气候资源分布状况,针对林业生产的需求把黑龙江省分成七个林业气候区：温暖半干旱区、温暖半湿润区、温暖湿润区、温和湿润区、温凉湿润区、冷凉湿润区、寒冷湿润区；同时分析了各个林业气候区森林火灾的发生状况。为合理开发利用气候资源和森林资源提供了一定的依据。     

湿地生态系统与居地气候关系的研究

针对赤峰市半干旱区的达里诺尔湿地与兴安盟阿尔山湿润地区的湿地，利用湿地的小气候观测资料分别与其相邻的常规气象站的气象观测数据进行对比分析。初步得出以下结论：（1)湿地的“冷湿”效应显著，（2)湿地降水量主要受大气候的影响，与小气候效应无关。（3)位于湿润区的阿尔山湿地比位于半干旱区的达里诺尔湿地更能体现出“冷湿”小气候效应。（4)小气候效应对群落结构、物种分布等方面存在着重要的影响。位于湿润区的阿尔山湿地比位于干旱区的达里诺尔湿地中生、湿生植物偏多，但多样性指数、均匀性指数、物种丰富度低于干旱区的达里诺尔湿地，湿地植物群落的优势度指数要高于达里诺尔湿地，     

海北地区湿润度的变化特征分析

定义了一个能够表征干湿状况的物理量——湿润度(K=R/0.1×ΣT),据此把海北州以地理环境条件为背景划分为祁连山区南部(祁连、托勒、野牛沟)、门源盆地(门源)和青海湖北部(海晏、刚察)三个区,再按分区对海北6个气象站(门源、海晏、祁连、刚察、托勒、野牛沟)1961—2008年期间湿润度的时空变化以及湿润度与区域气候变化的联系进行了分析。结果表明:海北地区的湿润度0.02/10年趋势降低。但年际变化有明显的波动;在空间分布上积温间的湿润度东部高于西部。而主要生长季(6—9月份)的湿润度南部明显高于北部;湿润度与平均气温、最高气温、最低气温、蒸发、日照时数都存在明显的负相关。     

江苏省近50a气候干湿特征研究

根据江苏省1960—2009年54个气象台站常规气象观测资料,利用Penman-Monteith公式计算了全省各地区50 a的逐日潜在蒸散量,结合逐日降水量,推算出了相对湿润度指数值,并采用国家标准《气象干旱等级》(GB/T20481-2006)中的相对湿润度分级指标对全省干湿状况进行了评估,分析其时空变化特征。研究表明:1)就全年而言,江苏省半干旱区与湿润区各占50%左右的面积,其中淮北、江淮北部、苏北沿海的北部为半干旱区,江淮南部、苏北沿海的南部、沿江、苏南地区为湿润区;2)降水量和潜在蒸散量是影响相对湿润度指数的两个关键因子,降水量的变化对相对湿润度的时空分布起着主导作用,潜在蒸散量起着辅助作用。3)江苏省1 a中冬季的南北气候干湿反差最大、夏季最小,湿润区范围夏季最大、秋季最小,半干旱区范围秋季最大、夏季没有,干旱区范围春季最大、夏季和秋季没有。夏季气候最湿润、春季气候最干燥。4)淮北和苏北沿海地区的相对湿润度指数年变化呈"单峰型",江淮、沿江和苏南地区的年变化呈"双峰型",苏北沿海地区相对湿润度年内变化最大,沿江地区最小。     

前期晴暖少雨 后期阴冷多雨

1994年1～3月，我省受西太平洋副高和大陆冷高压的交替影响，前期晴暖干旱，后期阴冷湿润，春季低温阴雨明显，中南部出现倒春寒。1、前期暖融融后期冷飕飕1月至2月上旬，我省阳光普照，晴天时间长，气温高。平均气温比历年同期偏高3～4C，其中1月上旬和2月上旬的平均气温都比历年同期偏高4～6℃，为近几年少见。2月中旬～3月中旬，我省平均气温转而比历年同期偏低2”C左右。其中3月中旬平均气温比常年偏低3～5”C，相对较冷。2、前期于爽爽后期湿涯渡1月至2月上旬，我省雨水奇缺，海丰县滴雨未下。除韶关、汕头市分别降雨18mm和13mm外，…     

大面积地表湿润程度的间接表示方法和陆面蒸发量计算

本文指出,一个可用一般气象观测资料计算得出的量,即气温与小块湿润地表的温度的差值,可以用来反映同一地区大面积地表的湿润程度。并由此得到一种计算陆面实际蒸发量的方法。此概念对于遥感地表湿润程度也是有用的。 1.湿润地表温度的计算 在当地气候条件下,一小块充分湿润地表所具有的地表温度称为湿润地表温度。若当地地表已充     

Evaluation of an urban land surface scheme over a tropical suburban neighborhood

A two-step statistical downscaling method has been reviewed and adapted to simulate twenty-first-century climate projections for the Gulf of Fonseca (Central America, Pacific Coast) using Coupled Model Intercomparison Project (CMIP5) climate models. The downscaling methodology is adjusted after looking for good predictor fields for this area (where the geostrophic approximation fails and the real wind fields are the most applicable). The method’s performance for daily precipitation and maximum and minimum temperature is analysed and revealed suitable results for all variables. For instance, the method is able to simulate the characteristic cycle of the wet season for this area, which includes a mid-summer drought between two peaks. Future projections show a gradual temperature increase throughout the twenty-first century and a change in the features of the wet season (the first peak and mid-summer rainfall being reduced relative to the second peak, earlier onset of the wet season and a broader second peak).     

1961—2010年云南干湿气候变化

利用15个站点1961—2010年日照时数、降水量和平均温度等气候资料,计算云南5个区域各季节相对湿润度指数,分析云南干湿气候变化特征。结果表明,相对湿润度指数可定量、准确地表达云南各区域自然气候干湿程度,能客观反映云南干湿气候的波动变化和区域性差别。20世纪90年代中期以来,云南干季、雨季潜在蒸散量呈增大变化趋势,同期降水量有减小的趋势变化,从而在气候变暖背景下引发云南气候的干旱化趋势。干季各地相对湿润度指数年际波动变化大,年代际差异明显;雨季各地干湿状况年际波动相对较小,且呈现明显的周期性波动变化趋势。云南5个区域的干湿气候变化既有一致性也有差异性：滇中和滇西南比较一致,滇西北与滇东南差异明显,滇西北与滇东北雨季差异突出、干季较为相似。     

Direct effects and feedback of desert dust on the climate of the Arabian Peninsula during the wet season: a regional climate model study

We investigate the dust radiative forcing and its feedback on the Arabian Peninsula’s wet season climate using the International Centre for Theoretical Physics-Regional Climate Model (ICTP-RegCM4). We have found that the dust plumes exert a negative (positive) radiative forcing at the surface (top of the atmosphere) by reducing incoming solar radiation reaching the ground and locally heating up the atmosphere column. Consequently, the surface air temperature is cooler, hence indicating a decrease in the warm bias and an increase in the temperature gradient. This reduces the geopotential heights and enhances the low-level wind convergence, suggesting stronger upward motion. These changes increase evaporation, the difference between precipitation and evaporation in the atmosphere and rainfall over the Peninsula, indicating an intensification of the hydrologic cycle. The decrease in the precipitation dry bias and the large reduction in the temperature warm bias caused by the impact of dust over the entire Peninsula represent a significant success for the RegCM4 simulation. Therefore, the inclusion of dust in the simulation of the Arabian Peninsula’s climate for the wet season contributes to an improved performance of this regional climate model over the region.     

西安市霾天气与清洁天气变化特征及影响因素分析

利用2006-2012年西安市污染物质量浓度、气象站逐时地面风场、相对湿度和能见度等资料,依据霾天气的定义统计理论霾日数,对比人工观测霾日与判据统计理论霾日的合理性,通过对霾天气与清洁天气过程的气象条件分析,分析西安市霾天气与清洁天气过程的变化特征及影响因素。结果表明：2006-2012年西安市霾天气过程在干季发生频率较高,湿季发生较少。地面风场对霾天气过程影响较大,绝大部分霾天气过程的日平均风速＜1.5 m·s^-1;干季大部分霾天气过程日平均风速≤1.0 m·s^-1,极端个例甚至在0.5 m·s^-1以下。清洁天气过程在干季发生次数多于湿季,主要与干季风速较大和湿度较小相关。     

Climate change in Central America and Mexico: regional climate model validation and climate change projections

Central America has high biodiversity, it harbors high-value ecosystems and it??s important to provide regional climate change information to assist in adaptation and mitigation work in the region. Here we study climate change projections for Central America and Mexico using a regional climate model. The model evaluation shows its success in simulating spatial and temporal variability of temperature and precipitation and also in capturing regional climate features such as the bimodal annual cycle of precipitation and the Caribbean low-level jet. A variety of climate regimes within the model domain are also better identified in the regional model simulation due to improved resolution of topographic features. Although, the model suffers from large precipitation biases, it shows improvements over the coarse-resolution driving model in simulating precipitation amounts. The model shows a dry bias in the wet season and a wet bias in the dry season suggesting that it??s unable to capture the full range of precipitation variability. Projected warming under the A2 scenario is higher in the wet season than that in the dry season with the Yucatan Peninsula experiencing highest warming. A large reduction in precipitation in the wet season is projected for the region, whereas parts of Central America that receive a considerable amount of moisture in the form of orographic precipitation show significant decreases in precipitation in the dry season. Projected climatic changes can have detrimental impacts on biodiversity as they are spatially similar, but far greater in magnitude, than those observed during the El Ni?o events in recent decades that adversely affected species in the region.     

高黎贡山复杂地形下局地环流的数值模拟研究

本文利用中尺度模式WRF(weather research and forecasting)模拟了2016年干季和湿季高黎贡山南段(腾冲—保山地区)山谷风环流,分析YSU、MYJ、MYNN3、ACM2和BouLac五种边界层参数化方案在高黎贡山复杂下垫面的适用性.研究结果表明YSU方案对温度模拟的效果最好;ACM2模拟...     

青藏高原雨季特征及其对气候增暖的响应

利用青藏高原气象台站逐日观测资料,采用候雨量稳定通过临界阈值的方法对高原雨季起讫期进行客观定量划分,在此基础上,进一步分析增暖背景下雨季起讫期和雨季降水演变特征,并对比增暖前后高原雨季起讫期及不同等级降水的响应特征.结果表明:青藏高原雨季平均开始期为5月第3候、结束期为9月第6候、共持续28候;青藏高原雨季降水集中期为...     

The impact of climate change on the Niger River Basin hydroclimatology, West Africa

Climate change has the potential to reduce water availability in West Africa. This study aims to quantify the expected impact of increased greenhouse gases (GHGs) on hydroclimatology of Niger River Basin (NRB). Boundary data from a general circulation model are used to force a regional climate model, to produce dynamically downscaled hydroclimatic variables of NRB under present-day (PRS) and future climate scenarios. The data were further analyzed to detect changes in atmospheric and surface water balance components and moisture recycling ratio (β). The results show that elevated GHGs (under A1B scenario) would produce a drier climate during the rainy season and a wetter climate during the dry season. A warmer climate over NRB in all months was projected. Highest temperature increase of 3 °C occurs about 14°N in May and June, and the smallest increase of 0.5 °C occurs below 8°N in wet-dry transition period. Evaporation reduces during wet season and increases during the dry periods. Humidity increases by 2 % in the dry season, but decreases by 2–4 % in the wet season. Maximum change in moisture influx of 20.7 % and outflux of 20.6 % occur in June and July, respectively. β is projected to decrease in 75 % of the months with biggest relative change of ?18.4 % in June. The projected decrease in precipitation efficiency (ρ) during the wet season reaches ?20.3 % in June. For PRS run, about 66 % of the available atmospheric moisture in NRB precipitates between June and September, of which around 21 % originates from local evaporation. The result suggests that under enhanced GHGs, local evaporation will contribute less to atmospheric moisture and precipitation over the basin. Projected changes in rainfall and streamflow for Upper Niger and Benue sub-basin are significantly different during the wet season.     

沙尘暴垂直输运的两相流理论Ⅰ:气块模式

沙尘暴是风蚀荒漠化中的一种天气现象,其形成受到两方面因素的共同影响:(1)自然因素,包括大风、降水减少及沙源;(2)人类活动因素,人类活动因素是指人类在发展经济过程中对植被的破坏以后,导致沙尘暴爆发频率数增加.沙尘暴已经成为中国西北、华北地区严重的气候灾害,而对沙尘的研究主要集中在起沙问题与沙尘沉降的问题,在理论上对前者研究较多,而对后者的研究则比较缺乏.假设空气块中带有沙尘,沙尘颗粒很小,随空气一起运动,可不计沙尘Stockes末速度,这样由空气和沙尘组成两相流.在两相流情况下,分析了均匀环境和非均匀环境条件下沙尘沉降的条件和速率.通过分析得到在均匀背景场下有利于沙尘沉降的条件为大的初始沙尘浓度扰动与小的初始温度扰动.进一步考虑更为真实的环境场,模式给出3种特征沉降区域:(1)速降区,沉降速率较快;(2)缓降区,沙尘先上升后下降,沉降时间较长;(3)波动区,沙尘在空气中不断地上下波动,此时很难判断沙尘何时沉降,取决于地面状况.同时也分析了沙尘不断上扬的背景条件.     

Influence of irrigated agriculture on diurnal surface energy and water fluxes, surface climate, and atmospheric circulation in California

The impact of land use change on regional climate can be substantial but also is variable in space and time. Past observational and modeling work suggests that in a ‘Mediterranean’ climate such as in California’s Central Valley, the impact of irrigated agriculture can be large in the dry season but negligible in the wet season due to seasonal variation in surface energy partitioning. Here we report further analysis of regional climate model simulations showing that diurnal variation in the impact of irrigated agriculture on climate similarly reflects variation in surface energy partitioning, as well as smaller changes in net radiation. With conversion of natural vegetation to irrigated agriculture, statistically significant decreases of 4–8?K at 2?m occurred at midday June–September, and small decreases of ~1?K occurred in winter months only in relatively dry years. This corresponded to reduced sensible heat flux of 100–350?W?m^?2 and increased latent heat fluxes of 200–450?W?m^?2 at the same times and in the same months. We also observed decreases of up to 1,500?m in boundary layer height at midday in summer months, and marginally significant reductions in surface zonal wind speed in July and August at 19:00 PST. The large decrease in daytime temperature due to shifts in energy partitioning overwhelmed any temperature increase related to the reduced zonal sea breeze. Such changes in climate and atmospheric dynamics from conversion to (or away from) irrigated agriculture could have important implications for regional air quality in California’s Central Valley.