地表热辐射方向性研究进展

地表热辐射方向性是基于多角度热红外遥感数据反演组分温度的基本问题 ,论文分析了国内外近来从等效比辐射率和热辐射模型两个角度研究非同温热辐射方向性所取得的进展和存在的问题 ,并指出今后应继续基本概念的探讨 ,加强遥感基础实验和热辐射理论模型简化和验证工作 ,进一步探讨基于热红外多角度遥感数据反演组分温度的新方法。     

KBr-K2SO4-H2O体系在318.15 K下的热力学性质和相平衡预测研究

本文采用电动势法对318.15 K下三元体系KBr-K₂SO₄-H₂O的热力学性质进行研究。首先,测定了KBr-H₂O溶液中KBr的电动势,线性回归出电极响应斜率κ和电极常数E⁰,结果表明实验所用离子选择性电极具有良好的能斯特响应。然后,对318.15 K下三元体系KBr-K₂SO₄-H₂O混合溶液中KBr的平均活度系数进行了研究,绘制了离子强度I及离子强度分数y_b与KBr的平均活度系数关系图,由图可得,当离子强度I一定,随着离子强度分数 y_b增大,KBr平均活度系数逐渐减小,且减小的趋势越来越大。当离子强度分数y_b是个定值时,KBr平均活度系数随着离子强度I的增大而减小。应用活度系数数据通过多元线性回归拟合出该温度条件下Pitzer模型混合离子作用参数θBr,SO₄和ψK,Br,SO₄,并计算了混合溶液中K₂SO₄的平均活度系数、渗透系数Φ,水活度a_w,超额吉布斯自由能GE。应用拟合的Pitzer混合离子相互作用参数和Pitzer模型计算了该三元体系在318.15 K下的溶解度数据,并对计算结果和其他温度下已经报道的KBr-K₂SO₄-H₂O三元体系的共饱和点处的溶解度数据进行比较,对比结果表明,溶解度计算结果可靠,拟合的离子相互作用参数具有较好的精度,可用于计算相关体系的热力学参数和相平衡的预测。     

Na+,K+,Rb+,Cs+//SO2-4-H2O体系固液相平衡热力学模拟

锂云母、铯榴石等矿物的硫酸盐焙烧浸出,是从中提取锂铷铯钾等碱金属元素的重要步骤,所得硫酸盐浸出液可近似看作Li⁺,Na⁺,K⁺,Rb⁺,Cs+ // SO₄2--H₂O六元水盐体系;其在浓缩过程呈现复杂的成盐特征,增加了各碱金属元素分离提取的难度,研究其相关水盐体系相图和相平衡性质对理解浸出液中碱金属的分离具有重要的理论指导意义。本文采用Pitzer-Simonson-Clegg超额Gibbs自由能方程和具有内在热力学一致性的CALPHAD方法,构建了Na⁺,K⁺,Rb⁺,Cs⁺//SO₄2--H₂O五元体系的多温固液相平衡热力学模型。借助该模型:1)实现了对Na₂SO₄₊Rb₂SO₄₊H₂O、Na₂SO₄₊Cs₂SO₄₊H₂O和K₂SO₄₊Cs₂SO₄₊H₂O三元体系的多温溶解度等温线的准确描述,并进一步构建了这些体系在240.15~380.15 K温度范围内的多温相图;2)实现了对K₂SO₄+Rb₂SO₄₊H₂O和Rb₂SO₄₊Cs₂SO₄₊H₂O体系中存在的固溶体相—水溶液平衡关系的准确描述,确认了(K,Rb)₂SO₄连续固溶体、以及(Rb,Cs)₂SO₄(α)和(Rb,Cs)₂SO₄(β)间断固溶体存在的合理性;3)预测了上述五元体系中所包含的全部4个四元子体系(Na₂SO₄₊ K₂SO₄₊ Rb₂SO₄+H₂O、Na₂SO₄ + K₂SO₄₊Cs₂SO₄₊ H₂O、Na₂SO₄₊ Rb₂SO₄₊Cs₂SO₄ + H₂O和K₂SO₄₊Rb₂SO₄₊Cs₂SO₄₊ H₂O)的相图,明确了四元相图中固溶体的类型及形成区域。然而,模型预测结果与现有四元体系实验数据间存在普遍的不一致性,尤其是固溶体形成区域,但模型预测结果从非实验角度给出了重要参考,对现有实验提出了挑战,未来对这些体系开展更为精细的实验研究非常必要。     

亚洲热带山地垂直植被带对晚第四纪气候变化的响应

过去一直认为热带低海拔地区晚更新世冰期的地表气温基本维持不变。孢粉分析、树线等研究结果证明,从南半球的新几内亚和赤道附近的苏门达腊,一直到我国的热带山地在末次盛冰期垂直植被带下降了500m～1600m不等。植被带的下降不仅仅与温度变化有关,其他的综合因素如高海拔紫外线辐射、大气CO₂浓度等都可能共同影响垂直植被带的分布。综合研究认为,整个亚洲地区年均温度平均下降约4℃的结果与热带非洲和美洲基本一致,并与近两年来热带海洋表层水温的研究结果和近期的气候模拟结果相吻合。     

城市不同下垫面的能量平衡及温度差异模拟

城市能量平衡是研究城市热岛效应的物理基础。利用北京市教学植物园2010年的实测数据,设置不同类型下垫面(植被覆盖类型:林地、草地和不透水层覆盖类型:道路、房屋),利用局地尺度城市气象参数化方案模拟并分析了相同气象条件和净辐射通量输入下,不同类型下垫面的显热、潜热通量及蒸散降温效应的差异。结果显示:(1)不同类型下垫面的各能量支出项有明显差异,植被覆盖区域和不透水层覆盖区域的波文比年均值分别为0.28和4.60,且在植被生长季差异较大;(2)城市扩展过程中道路、房屋替换林地、草地的过程,也是显热增加而潜热减少的过程。植被层向不透水层转换的过程中,显热通量年均增加32.74W/m²,潜热通量减少38.87W/m²,储热通量增加7.95W/m²;(3)理论上,植被蒸散的年降温效应使单位面积植被覆盖区域的气温比不透水层区域可低2.63℃。     

Rainfall interception by sand-stabilizing shrubs related to crown structure

On the edge of the Tengger Desert in northern China,revegetation has changed the landscape from moving dunes to stabilized dunes covered by shrubs,which further modifies the pattern of rainfall redistribution.To study rainfall interception loss by shrubs and its relationship to rainfall properties and crown structure,throughfalls passing through crowns of Artemisia ordosica Krash.and Caragana korshinskii Kom.were measured using nine PVC cups under the canopy of each of the two shrubs during 73 rain events over a three-year period,with total rainfall of 260.9 mm.Interception losses of gross rainfall by A.ordosica and C.korshinskii account for 15% and 27% of the total on a crown area basis,and 6% and 11% on a ground area basis,respectively.Individual throughfall(T) and interception(I) were significantly related to rainfall amount(Pg),duration(D),and intensity(R).Ratios of throughfall to rainfall(T/Pg) and interception to rainfall(I/Pg) were not only significantly related to Pg,D,and R,but also to shrub species,and interactions of species with crown volume(CV) and leaf area index(LAI).Under most rain events,interceptions by C.korshinskii with greater CV and LAI were significantly higher than those by A.ordosica,and more rainfall interception occurred at locations closer to the stems of the two shrubs.For C.korshinskii,I/Pg had a significant positive linear relation with CV and LAI,while T/Pg had a significant negative linear relation with them.CV has a greater influence on T/Pg and I/Pg than does LAI.Using a regression method,canopy water storage capacities are estimated to be 0.52 and 0.68 mm,and free throughfall coefficient to be 0.62 and 0.47 for A.ordosica and C.korshinskii,respectively.     

基于Landsat数据的2种地表温度空间降尺度算法比较研究

以2003年5月29日福州市LandsmETM＋影像为数据源,对2种地表温度空间降尺度算法——EM算法和HUTS算法进行实验、比较与分析,EM算法是利用高空间分辨率的地表比辐射率对低空间分辨率的亮度温度影像进行调节,从而达到提高热红外影像空间分辨率的目的;HUTS算法则是引入了归一化差异植被指数NDVI和地表反照率d,通过在低空间分辨率拟合二者与地表温度LST之间的关系,然后根据其尺度不变性,将该关系应用到高空间分辨率的影像上,从而达到提高热红外影像空间分辨率的目的．研究结果表明：1）2种算法所得结果影像都能在有效提高空间分辨率的同时较好地保持了原始地表温度影像的空间分布特征,达到了较好的降尺度效果;2）以RMSE为定量评价指标,HUTS算法要略优于EM算法,其中,EM算法的RMSE为1．2494,而HUTS算法仅为0．9869．     

NPP-VIIRS热红外数据地表温度反演方法研究

地表温度作为监测陆地表面与大气变化的重要参数,对于研究地表能量平衡和全球气候变化具有重要作用。可见光红外成像辐射仪套件（Visible Infrared Imaging Radiometer Suite,VIIRS）是搭载在新一代对地观测卫星NPP上的一个重要传感器。与其他传感器相比,VIIRS拥有更高的空间分辨率。分裂窗算法是反演地表温度最常用的方法,主要是利用两个热红外通道来反演地表温度,经过多年的研究和改进,发展了多种形式的分裂窗算法。由于过去很少有人利用VIIRS数据对多种分裂窗算法进行对比分析,因此利用VIIRS传感器上M15和M16两个热红外通道数据计算辐亮度和星上亮温,采用多种形式的分裂窗算法反演获得多组地表温度数据,再利用海拉尔野外观测站点的实测数据对结果进行验证,对比各算法精度,得到反演精度较高的算法。结果显示PR84算法的反演误差最大达到1.8 K,其余各算法反演地表温度的RMSE都在1.5 K以内,算法中加入二次项和水汽项可以提高算法精度,其中BL95的算法精度最高达到了1.23 K。研究结果表明,BL95算法更适用于VIIRS热红外数据地表温度反演。     

劈窗算法中Planck方程展开式参数模型的拟合研究

地表温度是地球生态环境的重要指标,劈窗算法是目前利用遥感反演地表温度最为成熟的算法。为求解两个通道参数组成的热辐射方程组,需将Planck辐射方程线性展开以使各通道辐射值与亮温Ti直接相关,可通过引入中间参数Li与亮温Ti以不同的数学关系模型进行拟合。以MODIS数据源为例,对4种不同拟合关系进行分析比较,发现线性和幂函数模型具有较高的精度和稳定性,估计Li的误差范围为0.019~0.197。进一步分析这两个模型在地表温度反演中的误差及对参数的敏感性,结果显示幂函数模型在各种情况下都优于传统的线性模型劈窗算法。     

Responses of photosynthesis and water relations to rainfall in the desert shrub creosote bush (Larrea tridentata) as influenced by municipal biosolids

Responses of photosynthesis (P_n), stomatal conductance (g_s), pre-dawn leaf water potential (Ψ_lp) and leaf water content (ω_l) of creosote bush to 10 rainfall events in the Chihuahuan Desert were investigated. Infiltration of rainwater was manipulated by applying municipal biosolids. The responses of P_nand water relation parameters to rainfall (>10 mm) were mainly dependent upon drought severity: (1) following a moderate drought, P_n, g_s, Ψ_lpand ω_lrecovered to corresponding values of irrigated plants within 2 days after a 23-mm rainfall; (2) Ψ_lpand g_sresponded to a 15-mm rainfall within 2 days, following a 25-day drought, whereas responses of P_nand ω_lwere delayed for several days; (3) responses of P_n, g_s, Ψ_lpand ω_lto a 14·7-mm rainfall were all delayed for several weeks following a 110-day drought, but the delay was longer in P_n, g_sand ω_lthan in Ψ_lp. Creosote bush responded to small rainfall events (approximately 6 to 8 mm) with an increase in Ψ_lp, but without noticeable changes in g_sand P_n, suggesting a strong stomatal control of water loss even though xylem embolism was reduced. Biosolids applied at high rates (3·4 and 9 kgm⁻²) decreased the soil water by 2 to 4 mm following rainfall events, and this in turn delayed and decreased the responses of P_nand water relation parameters to rainfall.P_nand g_swere linearly related to ω_land exponentially related to Ψ_lp. With the generally coincidental responses of P_nor g_sand ω_lto rainfall, we concluded that the responses of P_nand g_sto rainfall were dependent on leaf rehydration which resulted from restored hydraulic conductance following drought.     

利用ASTER遥感数据反演陆面温度的算法及应用研究

陆面温度是地气交换过程的一个重要参数,在生态环境研究中应用很广。传统方法只能进行点上的观测和计算,遥感的出现则使得计算区域陆面温度成为可能。ASTER遥感数据具有较高的空间分辨率和光谱分辨率,能够提供比NOAA/AVHRR和Landsat等遥感数据更丰富的陆面信息,有助于提高反演陆面温度的精度。本文以新疆自治区阿瓦提县典型研究区域为例,根据ASTER遥感数据的特点,基于温度/比辐射率分离算法的思想,运用ADE(AlphaDerivedEmissivity)、比值法和MMD(Maximum-MinimumDiffer-ence)三个模块计算陆面温度,并简要分析了模型的主要误差来源。分析结果表明本文所采用的算法是可行的,ASTER遥感数据用于反演陆面温度可以取得比较理想的结果,具有良好的应用前景。     

利用ASTER资料估算黑河中游沙漠和绿洲地区夏季地表温度

利用美国宇航局地球观测系统EOS-Terra卫星所搭载高级空基热发射反射辐射计(ASTER)5个热红外通道遥感资料,并结合三种地表温度反演算法和可见近红外信息,估算2003年夏季黑河中游地区沙漠和绿洲景观下地表温度空间分布。分析发现三种方法估算的地表温度比较接近,且反演值与地面观测值较为一致,能够作为陆面过程研究输入数据。其中,估算的水体温度主要介于19.0~21.0℃,绿洲内农田温度分布于27.0~29.0℃,荒漠戈壁地表温度分布于40.0~60.0℃;在绿洲内,由植被覆盖度参数化比辐射率方法（Pv方法）所估算地表温度值最低,Alpha导出比辐射率方法(ADE方法)估算值最高,由温度比辐射率分离方法(TES方法)估算值介于二者之间;荒漠戈壁区域Pv方法地表温度估算值最高,ADE方法估算值最低,TES方法估算值仍然介于前两者之间;绿洲和荒漠戈壁均具有较大地表温度空间变率。利用有关比辐射率光谱库地物观测数据拟合出一个经验公式以获取地物宽通道比辐射率。分析计算表明,地物目标在较大地表环境温度变化范围内,利用地物宽通道比辐射率计算地表长波辐射最大绝对误差不超过8.0 W·m-2。     

1960-2007年中国地表潜在蒸散发敏感性的时空变化(英文)

Potential evapotranspiration (E0), as an estimate of the evaporative demand of the atmosphere, has been widely studied in the fields of irrigation management, crop water demand and predictions in ungauged basins (PUBs). Analysis of the sensitivity of E0 to meteorological factors is a basic research on the impact of climate change on water resources, and also is important to the optimal allocation of agricultural water resources. This paper dealt with sensitivity of E0 over China, which was divided into ten drainage systems, including Songhua River basin, Liaohe River basin, Haihe River basin, Yellow River basin, Yangtze River basin, Pearl River basin, Huaihe River drainage system, Southeast river drainage system, Northwest river drainage system and Southwest river drainage system. In addition, the calculation method of global radiation in Penman-Monteith formula was improved by optimization, and the sensitivities of Penman-Monteith potential evapotranspiration to the daily maximum temperature (STmax), daily minimum temperature (STmin), wind speed (SU2), global radiation (SRs) and vapor pressure (SVP) were calculated and analyzed based on the long-term meteorological data from 653 meteorological stations in China during the period 1960-2007. Results show that: (1) the correlation coefficient between E0 and pan evaporation increased from 0.61 to 0.75. E0 had the decline trends in eight of ten drainage systems in China, which indicates that "pan evaporation paradox" commonly exists in China from 1960 to 2007. (2) Spatially, Tmax was the most sensitive factor in Haihe River basin, Yellow River basin, Huaihe River drainage system, Yangtze River basin, Pearl River basin and Southeast river drainage system, and VP was the most sensitive factor in Songhua River Basin, Liaohe River basin, Northwest river drainage system while Rs was the most sensitive factor in Southwest river drainage system. For the nation-wide average, the most sensitive factor was VP, followed by Tmax, Rs, U2 and Tmin. In addition, the changes in sensitivity coefficients had a certain correlation with elevation. (3) Temporally, the maximum values of STmax and SRs occurred in July, while the maximum values of STmin, SVP and SU2 occurred in January. Moreover, trend analysis indicates that STmax had decline trends, while STmin, SU2, SRs and SVP had increasing trends.     

Thermal and exhumation histories of the northern subalpine chains (Bauges and Bornes—France): Evidence from forward thermal modeling coupling clay mineral diagenesis,organic maturity and carbonate clumped isotope (Δ47) data

Assessing the thermal evolution of sedimentary basins over time is a major aspect of modern integrated basin analysis. While the behavior of clay minerals and organic matter with increasing burial is well documented in different geological and thermal settings, these methods are often limited by the temperature ranges over which they can be precisely applied and by the available material. Here, we explore the emergent Δ₄₇ clumped isotope geospeedometry (based on the diffusional redistribution of carbon and oxygen isotopes in the carbonate lattice at elevated temperatures) to refine time‐temperature paths of carbonate rocks during their burial evolution. This study provides a reconstruction of the thermal and exhumation history of the Upper Cretaceous thrust belt series in the western subalpine massifs (Bauges and Bornes, French Alps) by a new approach combining for the first time available data from three independent geothermometers. The investigated area presents two zones affected by contrasting thermal histories. The most external zone has undergone a relatively mild thermal history (T < 70°C) and does not record any significant clay mineral diagenetic transformation. By contrast, the internal zone has experienced tectonic burial (prealpine nappes) in response to thrusting, resulting in overheating (T > 160–180°C) that induced widespread clay mineral diagenetic transformations (progressive illitization from R0 to R1 and R3 illite‐smectite mixed‐layers), organic matter maturation (oil window) and Δ₄₇ thermal resetting with apparent equilibrium temperatures above 160°C. The three employed geothermal indicators conjointly reveal that the investigated Upper Cretaceous rocks have suffered a wide range of burial temperatures since their deposition, with a thermal maximum locally up to 160–180°C. High temperatures are associated with the tectonic emplacement of up to 4 km of prealpine nappes in the northern part of the studied area. Finally, a forward thermal modeling using Δ₄₇, vitrinite reflectance and clay mineral data, is attempted to precisely refine the burial and exhumation histories of this area.