基于现场观测资料的卫星海表盐度网格化产品误差分析与质量评估

自欧洲土壤湿度和盐度卫星SMOS和美国宝瓶座盐度卫星Aquarius相继发射之后,多个数据中心发布了两颗卫星的海表盐度网格化产品,其中包括法国海洋研究院SMOS卫星数据小组发布SMOS Locean L3盐度产品、西班牙巴塞罗那专家中心发布SMOS BEC L4盐度产品和美国宇航局喷气动力实验室发布AquariusV3.0 CAP L3盐度产品。本文利用精确盐度现场观测资料从产品精度和模拟海洋现象能力两个方面对以上3种产品质量进行了评估。研究表明:(1) 在精度方面,与盐度现场资料相比,Aquarius CAP 产品质量最高,产品盐度偏差和均方根误差全年稳定且偏差较小,部分海域达到了设计精度;SMOS两种卫星产品在全球海域偏差较不稳定,个别月份出现异常偏差值;SMOS产品在低纬和开阔海域的数据质量相对较高,但在高纬海域仍存在较大误差,需要进一步提升;(2) 在刻画海洋现象方面,Aquarius产品在热带太平洋较好刻画了淡池东缘盐度锋,SMOS BEC产品的刻画能力次之,SMOS Locean产品在热带太平洋充满了小尺度噪音,描述物理现象方面表现偏差。     

Fitness‐related consequences shed light on the mechanisms of covering and sheltering behaviors in the sea urchin Glyptocidaris crenularis

We know of no comparative assessment on the benefits and costs of long‐term covering and sheltering behaviors in sea urchins. The present study investigated the long‐term effects of conditions suitable for sheltering and covering behaviors on fitness‐related traits of sea urchins Glyptocidaris crenularis. In general, conditions suitable for covering and sheltering behaviors significantly affected the fitness‐related traits of G. crenularis in a long‐term laboratory study of 31 months. Glyptocidaris crenularis kept in conditions suitable for sheltering behavior (bricks with openings) showed significantly lower test size, body weight, organ (test, lantern, gonad and gut) weights, gonad index and slower gonad development than those kept in conditions suitable for covering behavior (presence of shells) and the control conditions (without conditions for covering and sheltering). However, the index of maximum pressure resistance of the test was significantly higher in G. crenularis kept in the sheltering conditions than those in the covering and control conditions. The present study provides new insight into the mechanisms of covering and sheltering behaviors and has implications for the conservation and aquaculture of sea urchins.     

Standard-sample bracketing calibration method combined with Mg as an internal standard for silicon isotopic compositions using multi-collector inductively coupled plasma mass spectrometry

Silicon isotope analysis traditionally uses a standard-sample bracketing (SSB) method that relies upon greater instrument stability than can be consistently expected. The following proposed method reduces the level of instrumental stability required for the analysis process and provides a valid solution for high-precision and accurate studies of Si isotopic compositions. Rock samples were dissolved by using alkali fusion and acidification. Silicon isotopes were purified with an ion exchange resin. Interfering peaks for isotopes were separated by using a Nu Plasma 1700 multi-collector inductively coupled plasma mass spectrometry (MS) system in high-resolution mode (M/ΔM > 8000 RP). Two magnesium isotopes (²⁵Mg and ²⁶Mg) and three silicon isotopes (²⁸Si, ²⁹Si, and ³⁰Si) were analyzed in the same data collection cycle. Mg isotopes were used as an internal standard to calibrate the mass discrimination effects in MS analysis of Si isotopes in combination with the SSB method in order to reduce the effects of MS interference and instrumental mass discrimination on the accuracy of measurements. The conventional SSB method without the Mg internal standard and the proposed SSB method with Mg calibration delivered consistent results within two standard deviations. When Mg was used as an internal standard for calibration, the analysis precision was better than 0.05 ‰ amu.     

商洛市水源涵养服务功能空间格局与影响因素

以商洛市为例,利用InVEST产水量模型和多年平均涵养水量模型,以参数本地化、实地率定和结果验证,对该区水源涵养功能的空间格局分异规律及其影响因素进行分析。结果表明：① 商洛市水源涵养总量为27.48×10⁸m3/a,水源涵养能力为324.85 mm。五大流域水源涵养功能依次为旬河>乾佑河>金钱河>丹江>洛河。② 气候因素对产水能力空间格局影响最大,10 a土地利用变化和下垫面植被、土壤因素则对水源涵养空间异质性影响显著。③ 子流域单元产水能力相关性强的因子为多年平均降水、实际蒸散发和植物可利用水,水源涵养功能关键驱动因子是潜在蒸散量、土壤饱和导水率与森林覆盖率。     

Improving the extreme rainfall forecast of Typhoon Morakot (2009) by assimilating radar data from Taiwan Island and mainland China

This study examined the impact of an improved initial field through assimilating ground-based radar data from mainland China and Taiwan Island to simulate the long-lasting and extreme rainfall caused by Morakot (2009). The vortex location and the subsequent track analyzed through the radial velocity data assimilation (VDA) are generally consistent with the best track. The initial humidity within the radar detecting region and Morakot’s northward translation speed can be significantly improved by the radar reflectivity data assimilation (ZDA). As a result, the heavy rainfall on both sides of Taiwan Strait can be reproduced with the joint application of VDA and ZDA. Based on sensitivity experiments, it was found that, without ZDA, the simulated storm underwent an unrealistic inward contraction after 12-h integration, due to underestimation of humidity in the global reanalysis, leading to underestimation of rainfall amount and coverage. Without the vortex relocation via VDA, the moister (drier) initial field with (without) ZDA will produce a more southward (northward) track, so that the rainfall location on both sides of Taiwan Strait will be affected. It was further found that the improvement in the humidity field of Morakot is mainly due to assimilation of high-value reflectivity (strong convection) observed by the radars in Taiwan Island, especially at Kenting station. By analysis of parcel trajectories and calculation of water vapor flux divergence, it was also found that the improved typhoon circulation through assimilating radar data can draw more water vapor from the environment during the subsequent simulation, eventually contributing to the extreme rainfall on both sides of Taiwan Strait.     

The Effects of Spatial Scale and Aggregation on Food Access Assessment: A Case Study of Tucson,Arizona

Adequate access to healthy food has become a social issue due to the recent Great Recession and heightened levels of unemployment. Geographers have focused their attention on how to accurately evaluate food access and how to identify and delineate food deserts; that is, low-income neighborhoods where affordable and healthy food is lacking or limited. Findings of recent food access studies are, however, dramatically inconsistent. We argue that spatial scale and the level of aggregation used in constructing food access measures could account for a major portion of the varying results. We draw on an empirical study in the Tucson, Arizona, metropolitan area, to examine how varying geographic scales and aggregation methods affect food access assessment. We also provide an analysis to show how spatial scale and aggregation practices lead to inconsistent conclusions about food access and designation of food deserts.     

辽河口海区悬浮体运移扩散动力特征

控制着辽河口海区悬浮体运移的主要动力是河流迳流、潮流和余流．它们对最大浑浊带中河水与海水的混合，密度流循环以及悬浮物的沉降和运移共同起作用．悬浮物向海运移与河口区最大浑浊带有关，即与河流迳流、潮流和余流作用所控制的悬浮物数量有关。悬浮物向海运移似乎遵循两个周期：１．小潮—大湖周期；２．河流迳流丰枯周期．最大运移发生在大潮期和河流迳流丰水期。