Monin–Obukhov Similarity Functions for the Structure Parameters of Temperature and Humidity     

Dan Li  Elie Bou-Zeid  Henk A. R. De Bruin 《Boundary-Layer Meteorology》2012,145(1):45-67

Monin–Obukhov similarity functions for the structure parameters of temperature and humidity are needed to derive surface heat and water vapour fluxes from scintillometer measurements and it is often assumed that the two functions are identical in the atmospheric surface layer. Nevertheless, this assumption has not yet been verified experimentally. This study investigates the dissimilarity between the turbulent transport of sensible heat and water vapour, with a specific focus on the difference between the Monin–Obukhov similarity functions for the structure parameters. Using two datasets collected over homogeneous surfaces where the surface sources of sensible heat and water vapour are well correlated, we observe that under stable and very unstable conditions, the two functions are similar. This similarity however breaks down under weakly unstable conditions; in that regime, the absolute values of the correlations between temperature and humidity are also observed to be low, most likely due to large-scale eddies that transport unsteadiness, advection or entrainment effects from the outer layer. We analyze and demonstrate how this reduction in the correlation leads to dissimilarity between the turbulent transport of these two scalars and the corresponding Monin–Obukhov similarity functions for their structure parameters. A model to derive sensible and latent heat fluxes from structure parameters without measuring the friction velocity is tested and found to work very well under moderately to strongly unstable conditions (−z/L > 0.5). Finally, we discuss the modelling of the cross-structure parameter over wet surfaces, which is crucial for correcting water vapour effects on optical scintillometer measurements and also for obtaining surface sensible and latent heat fluxes from the two-wavelength scintillometry.  相似文献   

Origin and Extent of Fresh Paleowaters on the Atlantic Continental Shelf, USA   总被引：3，自引：0，他引：3  

by Denis Cohen  Mark Person  Peng Wang  Carl W. Gable  Deborah Hutchinson  ee Marksamer  Brandon Dugan  Henk Kooi  Koos Groen  Daniel Lizarralde  Robert L. Evans  Frederick D. Day-Lewis  John W. Lane Jr. 《Ground water》2010,48(1):143-158

While the existence of relatively fresh groundwater sequestered within permeable, porous sediments beneath the Atlantic continental shelf of North and South America has been known for some time, these waters have never been assessed as a potential resource. This fresh water was likely emplaced during Pleistocene sea-level low stands when the shelf was exposed to meteoric recharge and by elevated recharge in areas overrun by the Laurentide ice sheet at high latitudes. To test this hypothesis, we present results from a high-resolution paleohydrologic model of groundwater flow, heat and solute transport, ice sheet loading, and sea level fluctuations for the continental shelf from New Jersey to Maine over the last 2 million years. Our analysis suggests that the presence of fresh to brackish water within shallow Miocene sands more than 100 km offshore of New Jersey was facilitated by discharge of submarine springs along Baltimore and Hudson Canyons where these shallow aquifers crop out. Recharge rates four times modern levels were computed for portions of New England's continental shelf that were overrun by the Laurentide ice sheet during the last glacial maximum. We estimate the volume of emplaced Pleistocene continental shelf fresh water (less than 1 ppt) to be 1300 km³ in New England. We also present estimates of continental shelf fresh water resources for the U.S. Atlantic eastern seaboard (10⁴ km³) and passive margins globally (3 × 10⁵ km³). The simulation results support the hypothesis that offshore fresh water is a potentially valuable, albeit nonrenewable resource for coastal megacities faced with growing water shortages.  相似文献   

Reading Groundwater in the 21st Century          下载免费PDF全文

Thad Plumley  Henk Haitjema 《Ground water》2015,53(4):507-507

  相似文献   

Impact Factor or Impact?          下载免费PDF全文

Henk Haitjema 《Ground water》2015,53(6):825-825

  相似文献   

Resonance properties of tidal channels with multiple retention basins: role of adjacent sea   总被引：1，自引：1，他引：0  

Pieter C. Roos  Henk M. Schuttelaars 《Ocean Dynamics》2015,65(3):311-324

  相似文献   

Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries   总被引：1，自引：0，他引：1  

George P. Schramkowski  Huib E. de Swart  Henk M. Schuttelaars 《Ocean Dynamics》2010,60(2):205-218

A three-dimensional numerical model with a prognostic salinity field is used to investigate the effect of a partial slip bottom boundary condition on lateral flow and sediment distribution in a transect of a tidally dominated channel. The transect has a symmetrical Gaussian cross-channel bottom profile. For a deep, well-mixed, tidally dominated channel, partial slip decreases the relative importance of Coriolis deflection on the generation of cross-channel flow patterns. This has profound implications for the lateral distribution of residual salinity that drives the cross-channel residual circulation pattern. Transverse sediment transport, however, is always found to be governed by a balance between advection of residual sediment concentration by residual lateral flow on the one hand and cross-channel diffusion on the other hand. Hence, the changes in the cross-channel distribution of residual salinity modify the lateral sediment distribution. For no slip, a single turbidity maximum occurs. In contrast, partial slip gives a gradual transition to a symmetrical density distribution with a turbidity maximum near each bank. For a more shallow, partially mixed tidal channel that represents the James River, a single turbidity maximum at the left bank is found irrespective of the near-bed slip condition. In this case, semi-diurnal contributions to sediment distribution and lateral flow play an important role in cross-channel sediment transport. As vertical viscosity and diffusivity are increased, a second maximum at the right bank again exists for partial slip.  相似文献   

Extreme storm surge modelling in the North Sea     

Nina Ridder  Hylke de Vries  Sybren Drijfhout  Henk van den Brink  Erik van Meijgaard  Hans de Vries 《Ocean Dynamics》2018,68(2):255-272

This study shows that storm surge model performance in the North Sea is mostly unaffected by the application of temporal variations of surface drag due to changes in sea state provided the choice of a suitable constant Charnock parameter in the sea-state-independent case. Including essential meteorological features on smaller scales and minimising interpolation errors by increasing forcing data resolution are shown to be more important for the improvement of model performance particularly at the high tail of the probability distribution. This is found in a modelling study using WAQUA/DCSMv5 by evaluating the influence of a realistic air-sea momentum transfer parameterization and comparing it to the influence of changes in the spatial and temporal resolution of the applied forcing fields in an effort to support the improvement of impact and climate analysis studies. Particular attention is given to the representation of extreme water levels over the past decades based on the example of the Netherlands. For this, WAQUA/DCSMv5 is forced with ERA-Interim reanalysis data. Model results are obtained from a set of different forcing fields, which either (i) include a wave-state-dependent Charnock parameter or (ii) apply a constant Charnock parameter (α _{C h} =?0.032) tuned for young sea states in the North Sea, but differ in their spatial and/or temporal resolution. Increasing forcing field resolution from roughly 79 to 12 km through dynamically downscaling can reduce the modelled low bias, depending on coastal station, by up to 0.25 m for the modelled extreme water levels with a 1-year return period and between 0.1 m and 0.5 m for extreme surge heights.  相似文献   

Can the Scheldt River Estuary become hyperturbid?     

Dijkstra  Yoeri M.  Schuttelaars  Henk M.  Schramkowski  George P. 《Ocean Dynamics》2019,69(7):809-827

Ocean Dynamics - We investigate the hypothesis by Winterwerp and Wang (Ocean Dyn 63:1279–1292, 2013) that channel deepening in the Scheldt River Estuary could lead to a large increase in...  相似文献   

Evaluation of WaPOR V2 evapotranspiration products across Africa     

Megan L. Blatchford  Chris M. Mannaerts  Sammy M. Njuki  Hamideh Nouri  Yijian Zeng  Henk Pelgrum  Steven Wonink  Poolad Karimi 《水文研究》2020,34(15):3200-3221

The Food and Agricultural Organization of the United Nations (FAO) portal to monitor water productivity through open-access of remotely sensed derived data (WaPOR) offers continuous actual evapotranspiration and interception (ETIa-WPR) data at a 10-day basis across Africa and the Middle East from 2009 onwards at three spatial resolutions. The continental level (250 m) covers Africa and the Middle East (L1). The national level (100 m) covers 21 countries and 4 river basins (L2). The third level (30 m) covers eight irrigation areas (L3). To quantify the uncertainty of WaPOR version 2 (V2.0) ETIa-WPR in Africa, we used a number of validation methods. We checked the physical consistency against water availability and the long-term water balance and then verify the continental spatial and temporal trends for the major climates in Africa. We directly validated ETIa-WPR against in situ data of 14 eddy covariance stations (EC). Finally, we checked the level consistency between the different spatial resolutions. Our findings indicate that ETIa-WPR is performing well, but with some noticeable overestimation. The ETIa-WPR is showing expected spatial and temporal consistency with respect to climate classes. ETIa-WPR shows mixed results at point scale as compared to EC flux towers with an overall correlation of 0.71, and a root mean square error of 1.2 mm/day. The level consistency is very high between L1 and L2. However, the consistency between L1 and L3 varies significantly between irrigation areas. In rainfed areas, the ETIa-WPR is overestimating at low ETIa-WPR and underestimating when ETIa is high. In irrigated areas, ETIa-WPR values appear to be consistently overestimating ETa. The relative soil moisture content (SMC), the input of quality layers and local advection effects were some of the identified causes. The quality assessment of ETIa-WPR product is enhanced by combining multiple evaluation methods. Based on the results, the ETIa-WPR dataset is of enough quality to contribute to the understanding and monitoring of local and continental water processes and water management.  相似文献   

The CM carbonaceous chondrite regolith Diepenveen     

Marco Langbroek  Peter Jenniskens  Leo M. Kriegsman  Henk Nieuwenhuis  Niek De Kort  Jacob Kuiper  Wim Van Westrenen  Michael E. Zolensky  Karen Ziegler  Qing‐Zhu Yin  Matthew E. Sanborn  Josh Wimpenny  Akane Yamakawa  Sebastiaan J. De Vet  Matthias M. M. Meier  Kees C. Welten  Kunihiko Nishiizumi  Marc W. Caffee  Aaron S. Burton  Jason P. Dworkin  Daniel P. Glavin  Qinghao Wu  Richard N. Zare  Alexander Ruf  Mourad Harir  Philippe Schmitt‐Kopplin   《Meteoritics & planetary science》2019,54(7):1431-1461

A carbonaceous chondrite was recovered immediately after the fall near the village of Diepenveen in the Netherlands on October 27, 1873, but came to light only in 2012. Analysis of sodium and poly‐aromatic hydrocarbon content suggests little contamination from handling. Diepenveen is a regolith breccia with an overall petrology consistent with a CM classification. Unlike most other CM chondrites, the bulk oxygen isotopes are extremely ¹⁶O rich, apparently dominated by the signature of anhydrous minerals, distributed on a steep slope pointing to the domain of intrinsic CM water. A small subset plots closer to the normal CM regime, on a parallel line 2 ‰ lower in δ¹⁷O. Different lithologies in Diepenveen experienced varying levels of aqueous alteration processing, being less aqueously altered at places rather than more heated. The presence of an agglutinate grain and the properties of methanol‐soluble organic compounds point to active impact processing of some of the clasts. Diepenveen belongs to a CM clan with ~5 Ma CRE age, longer than most other CM chondrites, and has a relatively young K‐Ar resetting age of ~1.5 Ga. As a CM chondrite, Diepenveen may be representative of samples soon to be returned from the surface of asteroid (162173) Ryugu by the Hayabusa2 spacecraft.  相似文献