The Channel ecosystem,a cross-roads of anthropogenic pressures and scientific studies: Lessons learned from the European INTERREG IV projects (2009–2015)

The English Channel hosts a high density of human activities, which result in strong pressures and impacts on its marine ecosystem. The European Union's INTERREG programme funds projects to promote sustainable development through ecosystem-based management and the development of socio-economic services in the Channel region. An analysis of the themes studied during INTERREG IVA projects to date reveals both gaps that should be addressed in the future, as well as good practices that should be maintained and promoted. This analysis was used to provide advice and recommendations on knowledge gaps which may form the foundation of future projects for European programmes such as those in the next INTERREG project call (2015–2020).     

Global air-sea surface carbon-dioxide transfer velocity and flux estimated using ERS-2 data and a new parametric formula

Using data from the European remote sensing scatterometer（ERS-2） from July 1997 to August 1998,global distributions of the air-sea CO₂ transfer velocity and flux are retrieved.A new model of the air-sea CO₂ transfer velocity with surface wind speed and wave steepness is proposed.The wave steepness（5） is retrieved using a neural network（NN） model from ERS-2 scatterometer data,while the wind speed is directly derived by the ERS-2 scatterometer.The new model agrees well with the formulations based on the wind speed and the variation in the wind speed dependent relationships presented in many previous studies can be explained by this proposed relation with variation in wave steepness effect.Seasonally global maps of gas transfer velocity and llux are shown on the basis of the new model and the seasonal variations of the transfer velocity and llux during the 1 a period.The global mean gas transfer velocity is 30 cm/h after area-weighting and Schmidt number correction and its accuracy remains calculation with in situ data.The highest transfer velocity occurs around 60°N and 60°S,while the lowest on the equator.The total air to sea CO₂ llux（calculated by carbon） in that year is 1.77 Pg.The strongest source of CO₂ is in the equatorial east Pacific Ocean, while the strongest sink is in the 68°N.Full exploration of the uncertainty of this estimate awaits further data.An effectual method is provided to calculate the effect of waves on the determination of air-sea CO₂ transfer velocity and fluxes with ERS-2 scatterometer data.     

Improved regional scale processes reflected in projected hydrological changes over large European catchments

For the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC), the recent version of the coupled atmosphere/ocean general circulation model (GCM) of the Max Planck Institute for Meteorology has been used to conduct an ensemble of transient climate simulations These simulations comprise three control simulations for the past century covering the period 1860–2000, and nine simulations for the future climate (2001–2100) using greenhouse gas (GHG) and aerosol concentrations according to the three IPCC scenarios B1, A1B and A2. For each scenario three simulations were performed. The global simulations were dynamically downscaled over Europe using the regional climate model (RCM) REMO at 0.44° horizontal resolution (about 50 km), whereas the physics packages of the GCM and RCM largely agree. The regional simulations comprise the three control simulations (1950–2000), the three A1B simulations and one simulation for B1 as well as for A2 (2001–2100). In our study we concentrate on the climate change signals in the hydrological cycle and the 2 m temperature by comparing the mean projected climate at the end of the twenty-first century (2071–2100) to a control period representing current climate (1961–1990). The robustness of the climate change signal projected by the GCM and RCM is analysed focussing on the large European catchments of Baltic Sea (land only), Danube and Rhine. In this respect, a robust climate change signal designates a projected change that sticks out of the noise of natural climate variability. Catchments and seasons are identified where the climate change signal in the components of the hydrological cycle is robust, and where this signal has a larger uncertainty. Notable differences in the robustness of the climate change signals between the GCM and RCM simulations are related to a stronger warming projected by the GCM in the winter over the Baltic Sea catchment and in the summer over the Danube and Rhine catchments. Our results indicate that the main explanation for these differences is that the finer resolution of the RCM leads to a better representation of local scale processes at the surface that feed back to the atmosphere, i.e. an improved representation of the land sea contrast and related moisture transport processes over the Baltic Sea catchment, and an improved representation of soil moisture feedbacks to the atmosphere over the Danube and Rhine catchments.     

中国区域多种数值模式资料的地面气象要素评估

利用中国气象局国家级自动站(2421个站)的观测资料,分别对2010年7月1日至2013年6月30日的欧洲中期数值预报中心(ECMWF)、日本气象厅(JMA)和美国国家海洋大气局的全球预测系统(GFS)数值模式资料的地面气温、相对湿度和风速在中国区域的适用性进行了比较研究。结果表明,3种数值模式资料都能在一定程度上反映观测资料所具有的时间和空间分布特征,东部地区的适用性要高于西部地区。不同的地面气象要素,差异较大:对于地面气温和地面相对湿度,ECMWF比JMA和GFS更接近实际观测,ECMWF和JMA的分析场数据质量要好于预报场;ECMWF和JMA地面气温在冬季与观测差异最大,GFS地面气温在夏季与观测差异最大;3种数值模式资料的地面相对湿度在秋季和冬季与观测差异最大;对于地面风速,在江淮流域和华南等东部区域JMA与实际观测差异最小,在北部和西部区域ECMWF最好,JMA和GFS地面风速在冬季与实际观测差异最大。     

GPT/2模型用于GPS大气可降水汽反演的精度分析

水汽是大气的重要组成成分之一,其时空变化受气温、气压等多种气象因素的影响。因此,研究水汽反演影响因素对获取高精度水汽信息具有重要意义。以中国区域为例,研究利用全球导航卫星系统(global navigation satellite system,GNSS)和非实测气象数据（气温和气压）探测大气可降水量（precipitable water vapor, PWV）的方法。首先,对欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasting, ECMWF)第5代气候再分析数据集(ECMWF reanalysis v5, ERA5)提供的气温、气压和GNSS反演的天顶对流层延迟进行评估;其次,大气加权平均温度T_m是PWV反演的关键参数,对不同的T_m计算模型进行分析,确定中国区域最优T_m计算模型;最后,根据误差传播理论推导PWV的理论误差,利用非实测数据计算小时分辨率的PWV并进行精度评估。结果表明,利用GNSS获取的中国区域PWV与无线电探空/ERA5 PWV均有较好的时空一致性,降雨期间PWV的误差较非降雨期间稍大。所提方法获取的PWV理论误差为2.0 mm,实际误差为2.1 mm。因此,基于GNSS和非实测气象参数反演的PWV具有较高精度,对于研究中国区域水汽时空变化与分布具有重要意义。

     

Reconstructing basal ice flow patterns of the Last Glacial Maximum Rhine glacier (northern Alpine foreland) based on streamlined subglacial landforms

Based on high-resolution (sub)glacial geomorphological mapping, we present a first digital inventory of streamlined bedforms within the footprint of a Last Glacial Maximum (LGM) Alpine piedmont glacier. A total of 2460 drumlins were mapped across the Rhine glacier foreland. Glacial lineations and one field of subglacial ribs (ribbed/Rogen moraines) — the first record of this type of subglacial landform on the Alpine foreland—were identified. Two flowsets, associated with (i) the Rhine glacier's LGM maximum advance (Schaffhausen stadial) and (ii) a late LGM readvance (Stein am Rhein stadial), are differentiated. The vast majority of streamlined bedforms occur in fields aligned in a 16- to 30-km-wide swath upstream of the Stein am Rhein frontal moraines. Orientation and elongation of drumlins and glacial lineations set the basis for the reconstruction of paleo-ice flow. Basal flow paths of the LGM maximum advance are visually interpreted and restricted to the zone proximal to the former ice front. The flow field reconstructed for the late LGM glacier readvance (Stein am Rhein stadial) extends tens of kilometres upstream and is modelled implementing a recently published kriging routine. The derived basal flow patterns paired with information on ice surface levels from lateral and frontal moraines and combined with relative ice velocity differences inferred from spatial changes in bedform elongation reveal detailed insights on ice flow geometries, particularly during the glacier readvance. Reconstructed flowlines highlight basal flow under shallow ice that is strongly controlled by local topography evidenced by diverging around basal bumps and converging in (narrow) valley sections and troughs, where basal flow velocities, steered by topography, are high. Gained paleo-ice basal flow patterns offer new insights on landscape evolution of the northern Alpine foreland and provide evidence-based flow data to validate future physical modelling results.     

欧洲地质公园的基本特征及其地学基础

在联合国教科文组织和欧盟的支持下,欧洲地质公园建立起来了,含10个成员。各个地质公园有不同的地质科学意义,完全取决于所在地区的地质构造演化历史。欧洲地质构造分区对该区地质遗迹类型、分布和组合有明显的控制作用。在地质公园的调查、评价、规划、建设过程中,地球科学的支撑是极其重要的。     

Accelerated sediment delivery to continental margins during post-orogenic rebound of mountain ranges

Changes in sediment flux to continental margins are commonly interpreted in terms of tectonic growth of topography or climatic change. Here, we show that variations in sediment yield from orogenic systems, previously considered as resulting from climate change, drainage reorganisation or mantle processes can be explained by intrinsic mechanisms of mountain belt/foreland basin systems naturally evolving during post-orogenic decay. Numerical modelling indicates an increase of sediment flux leaving the orogenic system synchronous with the cessation of deposition in the foreland basin and the transition from late syn- to post-orogenesis. Experiments highlight the importance of lithospheric flexure that causes the post-orogenic isostatic rebound of the foreland basin. Erosion of the rebounding foreland basin combined with continued sediment flux from the thrust wedge drives an acceleration in sediment outflux towards continental margins. Sediment budget records in natural settings such as the Northern Pyrenees or Western European Alps also indicate accelerated post-orogenic sediment delivery to the Bay of Biscay and Rhône Delta respectively. These intrinsic processes that determine sediment yield to continental margins must be accounted for prior to consideration of additional external tectonic or climatic controls.