On the (mis)use of statistical methods in hydro-climatological research

Abstract

This paper discusses four areas where, in the author's view, statistical methods are misused in reporting results of hydro-climatological research. They are: (i) the use of the same data set both to suggest a hypothesis (commonly of trend over time) and to test it; (ii) failure to use an appropriate significance level for tests in which a number of hypotheses are tested, even when the data sets used are mutually uncorrelated; (iii) failure to account for spatial correlations between variables, whether these are explanatory or response variables; and (iv) exaggerated importance given to statistical tests of significance, in particular to the 5% and 1% significance levels.

Citation Clarke, R. T. (2010) On the (mis)use of statistical methods in hydro-climatological research. Hydrol. Sci. J. 55(2), 139–144.     

Detecting the Nonlinearity of Fish Acoustic Signals

1Introduction Ithasbeenknownforsometimethatmanyfishesproducesoundstocommunicatewitheachother,andfishsoundsoftendemonstratecomplexityandvariety.Differentfishspeciesproducetotallydifferenttypesofsounds.Furthermore,eventhesamespeciesprobablyproducesdifferent…     

Pyramids and ceremonial centers in mesoamerica: Were they oriented using a magnetic compass?

Fuson (1969), see also Carlson (1975), claims that Olmécs and Maya knew and used a (lodestone) compass for the orientation of pyramids, ceremonial and other important buildings, thousand years before Chinese. This hypothesis is tested here with the aid of the new data, namely by comparison of paleomagnetic declinations for that time and area (Korte and Bőhnel, 2005), with orientation data of buildings based also on our measurements at many archaeological localities of México, Guatemala, and in Copán in Honduras by GPS and with a precise compass. After eliminating known astronomical and calendar orientation of some structures, we have found that there is majority of structures with an orientation that clearly deviates from geographic north (pole of rotation of the Earth). When trying to explain this, we can rule out pure chance, local topography, aesthetic, meteorological or defense reasons. Thus, the Fuson hypothesis can still explain the observed site layout and building orientations. But more accurate and extensive information mainly from paleomagnetism and archaeology is needed to reject or accept the hypothesis. A proof of knowledge of a compass in Mesoamerica prior to Chinese would be important for our understanding history of the ancient world. jklokocn@asu.cas.cz kost@fsv.cvut.cz ttc.praha@iol.cz     

相位单差残差评估北斗区域导航系统载波相位观测量质量

由于北斗区域导航系统采用混合星座设计,其不同类型卫星载波相位观测量的质量得到广泛关注。当基线较短且模糊度正确固定后,卫星残差信息可有效反映观测数据质量。本文采用优化的站际单差算法获取不同卫星单差残差序列,并对其进行统计分析与假设检验。结果表明,北斗GEO与IGSO卫星数据质量无系统性差异,其质量随卫星高度角的降低而明显变差。良好环境下,GEO与IGSO卫星相位单差残差基本服从正态分布,可依据卫星高度角等信号质量指标建立合适的随机模型。     

冰封河道综合糙率计算方法比较与分析

综合糙率是冰封河道水力计算的重要输入参数。根据水流连续性和力的平衡原理,分别推导得到冰封河道综合糙率的通用公式,并选取抛物线形、矩形和梯形作为典型断面,系统地总结Pavlovskiy、Einstein、Lotter、Sabaneev、Larsen、改进的Larsen等常见公式由通用公式基于何种假定（分区的湿周、流速或水力半径相等）简化得到。采用水槽实测数据和野外观测资料,对比上述公式的计算精度,结果表明改进的Larsen公式的计算结果与实测值吻合较好,推荐在工程设计中使用。前5种公式误差较大的原因在于分区的流速、水力半径相等对于冰封河道不具有普适性,尤其是Lotter公式和Pavlovskiy公式在冰盖和河床糙率差异较大时会明显低估冰封河道的综合糙率,在工程设计中应慎重采用。     

Mixing and transport near the shallow-crested Rumble III seamount and the implications for plankton distribution

Vessel-based observations of water column structure and flow near a shallow-crested seamount are used to quantify the physical disturbance induced by that seamount. The implications of this disturbance on the ‘feeding hole’ hypothesis are then examined based on data from moored thermistors and acoustic current profilers, as well as vessel-based acoustic sounding-derived biomass estimates, currents, and conductivity-temperature-depth profiles from a 55 km square grid of stations around the crest. Mean currents in the region of 0.2 m s^?1 are comparable to observations from surface drifters whereas the semidiurnal tidal flow amplitude was one third of this. Thorpe Scale-based estimates of energy dissipation rate were in the range 10^?9 to 2.10^?8 W kg^?1 and vertical diffusivities K_z were in the range 10^?4 to 10^?3 m² s^?1. Turbulence levels were higher upstream of the seamount–likely due to the influence of nearby seamounts Rumble IV and V. There was no evidence of a Taylor Cap in the Rumble III velocity field. The sounder data provide some evidence of a feeding hole and analysis based on diffusivities suggests that this might persist downstream of the seamount for as much as 7 days.     

Cranks, conventionalists and geomorphology

Hypotheses in geomorphology may be conventional or unconventional. It is argued that outrageous hypotheses produced by conventional thinkers with a streak of unconventionality occasionally shift paradigms and are invaluable alternatives to conventional hypotheses, which tend merely to shore up seemingly safe and secure ruling paradigms.     

Taylor’s hypothesis and two-point coherence measurements

Experimentally obtained time coherence has traditionally been interpreted as streamwise one-dimensional spatial coherence through Taylor’s hypothesis. We calculate corrections to the highwavenumber part of the coherence to account for the errors caused by the deviation from Taylor’s hypothesis in high-intensity turbulent flows. The small-scale turbulence is assumed to be frozen and convected by a fluctuating convection velocity. Both Lumley’s two-term approximation and the Gaussian approximation are used in the calculations. In general, we find that the coherence for crossstream separations is significantly overestimated by the direct use of Taylor’s hypothesis, the error increasing with wavenumber; that for streamwise separations is underestimated. The analyses are compared with cross-stream coherence measurements in the atmospheric surface layer. Our results indicate that predictions from Lumley’s approximation yield better agreement with experimental data for cross-stream separations than those from the Gaussian model. Our study suggests that reliable measurement of two-point spatial coherence can be achieved only for scales not too small compared to the sensor separation.     

大洋环流型式转换在冰期旋回中的作用及经典第四纪冰期理论质疑(续)

大洋环流型式转换在冰期旋回中的作用及经典第四纪冰期理论质疑(续)汉景泰Ｗ．Ｓ．Ｆｙｆｅ(加拿大西安大略大学地质系)４问题及讨论大洋环流－气候学说认为从冰期到间冰期海洋－大气系统全球性巨型再组合导致了末次冰期的终止。     

菲尔德斯形变监测网质量分析

从数理统计角度出发，对西南极菲尔德斯形变监测网进行综合质量评估。文中主要讨论了形变监测网粗差检验，形变监测网的可靠性及可监测性。同时结合菲尔德斯形变监测网实测数据进行分析。本文认为该形变监测网有利于监测菲尔德斯海峡断层的剪切运动。