Measuring surface wind direction by monostatic HF ground-wave radar at the eastern China Sea

The extraction of full wind vectors from data obtained by single-site (monostatic) high-frequency ground-wave radar (HFGWR) is an ongoing challenge because of the inherent directional ambiguities. Here, a new algorithm for resolving the ambiguity of wind direction from monostatic data is presented. The true wind direction is determined by minimizing the sum of the difference among three wind directions derived from three different radar look angles. The wind directions estimated by applying the algorithm to data obtained from the OSMAR2000 HFGWR situated at the Eastern China Sea are compared with values obtained from ship-borne instrumentation. The mean difference between the ground-truthed values and those obtained from the radar data is approximately 20/spl deg/. The distance limit for wind direction sensing using the OSMAR2000 is about 200 km, which is the range for which signal-to-noise ratios typically exceed about 23 dB in the relevant first-order portions of the backscatter spectra.     

A method to dynamically subdivide parcels in land use change models

Spatial simulation models have become a popular tool in studying land use/land cover (LULC) change. An important, yet largely overlooked process in such models is the land subdivision, which is known to govern LULC change and landscape restructuring to a large extent. To fill this gap, we propose an efficient and straightforward method to simulate dynamic land subdivision in LULC change models. Key features in the proposed method are implementing a hierarchical landscape where adjacent cells of the same LULC type form patches, patches form properties, and properties form the landscape and incorporating real subdivision layouts. Furthermore, we use a queue-based modified flood-fill algorithm to dynamically reset LULC patches following a subdivision. The proposed subdivision method is demonstrated in action using a prototype agent-based LULC model developed for an amenity landscape in Australia. Results show that it is computationally feasible to run the subdivision method even as spatial resolution is increased, thus providing a proven means for spatial simulation models to dynamically split parcel land.     

Masculinities, femininities and the geographies of public and private drinking landscapes

Geographers have been slow to address issues about abstinence, drinking and drunkenness, but the importance of alcohol on the social and political agenda has underpinned recent growth in this field. Explorations of the gendered geographies of drinking are one important strand in this emerging field, but there is currently a paucity of research on women and gender (as opposed to men), and a dearth of research which looks beyond a rather narrowly specified range of public drinking environments. This paper addressed these short-comings through a quantitative and qualitative examination of different men’s and women’s alcohol consumption in private as well as diverse public drinking environments in 21st Century Britain. The paper emphasises the importance of gendered moralities in shaping gender and intra-gender differences in drinking levels, locations and motivations, and explores the connections between apparently separate public and private drinking environments.     

Seasonal Rainfall Forecasts for the Yangtze River Basin in the Extreme Summer of 2020※

Seasonal forecasts for Yangtze River basin rainfall in June, May–June–July (MJJ), and June–July–August (JJA) 2020 are presented, based on the Met Office GloSea5 system. The three-month forecasts are based on dynamical predictions of an East Asian Summer Monsoon (EASM) index, which is transformed into regional-mean rainfall through linear regression. The June rainfall forecasts for the middle/lower Yangtze River basin are based on linear regression of precipitation. The forecasts verify well in terms of giving strong, consistent predictions of above-average rainfall at lead times of at least three months. However, the Yangtze region was subject to exceptionally heavy rainfall throughout the summer period, leading to observed values that lie outside the 95％ prediction intervals of the three-month forecasts. The forecasts presented here are consistent with other studies of the 2020 EASM rainfall, whereby the enhanced mei-yu front in early summer is skillfully forecast, but the impact of midlatitude drivers enhancing the rainfall in later summer is not captured. This case study demonstrates both the utility of probabilistic seasonal forecasts for the Yangtze region and the potential limitations in anticipating complex extreme events driven by a combination of coincident factors.     

Climate change and hydrology at the prairie margin: Historic and prospective future flows of Canada's Red Deer and other Rocky Mountain rivers

The South Saskatchewan River Basin of southern Alberta drains the transboundary central Rocky Mountains region and provides the focus for irrigation agriculture in Canada. Following extensive development, two tributaries, the Oldman and Bow rivers, were closed for further water allocations, whereas the Red Deer River (RDR) remains open. The RDR basin is at the northern limit of the North American Great Plains and may be suitable for agricultural expansion with a warming climate. To consider irrigation development and ecological impacts, it is important to understand the regional hydrologic consequences of climate change. To analyse historic trends that could extend into the future, we developed century‐long discharge records for the RDR, by coordinating data across hydrometric gauges, estimating annual flows from seasonal records, and undertaking flow naturalization to compensate for river regulation. Analyses indicated some coordination with the Pacific decadal oscillation and slight decline in summer and annual flows from 1912 to 2016 (?0.13%/year, Sen's slope). Another forecasting approach involved regional downscaling from the global circulation models, CGCMI‐A, ECHAM4, HadCM3, and NCAR‐CCM3. These projected slight flow decreases from the mountain headwaters versus increases from the foothills and boreal regions, resulting in a slight increase in overall river flows (+0.1%/year). Prior projections from these and other global circulation models ranged from slight decrease to slight increase, and the average projection of ?0.05%/year approached the empirical trend. Assessments of other rivers draining the central and northern Rocky Mountains revealed a geographic transition in flow patterns over the past century. Flows from the rivers in Southern Alberta declined (around ?0.15%/year), in contrast to increasing flows in north‐eastern British Columbia and the Yukon. The RDR watershed approaches this transition, and this study thus revealed regional differentiation in the hydrological consequences from climate change.     

The Harvest Experiment: Monitoring Jason-1 and TOPEX/POSEIDON from a California Offshore Platform

We present calibration results from Jason-1 (2001-) and TOPEX/POSEIDON (1992-) overflights of a California offshore oil platform (Harvest). Data from Harvest indicate that current Jason-1 sea-surface height (SSH) measurements are high by 138 ± 18 mm. Excepting the bias, the high accuracy of the Jason-1 measurements is in evidence from the overflights. In orbit for over 10 years, the T/P measurement system is well calibrated, and the SSH bias is statistically indistinguishable from zero. Also reviewed are over 10 years of geodetic results from the Harvest experiment.     

Evaluation of Geochemical Reference Standards by X-Ray Fluorescence Analysis

Twenty five elements in twenty six geochemical reference standards analyzed by X-ray fluorescence spectrometry yield major and trace element concentrations close to consensus values. Ninety percent of our analyses agree with consensus values for standards to within pm 0.5 to 1.5 relative percent for major elements and pm 3 to 5 relative percent or pm 1-3 ppm, whichever is higher, for trace elements. Consistent divergences from consensus values of trace elements are noted.     

Benthic exchange of nutrients in Galveston Bay, Texas

Nutrient regeneration rates were determined at three sites increasing in distance from the Trinity River, the main freshwater input source, to Galveston Bay, Texas, from 1994 through 1996. Diffusive fluxes generally agreed in direction with directly measured benthic fluxes but underestimated the exchange of nutrients across the sediment-water interface. While the fluxes of ammonium and phosphate were directed from the sediment into the overlying waters, the fluxes of silicate and chloride changed in both magnitude and direction in response to changing Trinity River flow conditions. Oxygen fluxes showed benthic production during both summer 1995 and winter 1996, while light-dark deployments showed production-consumption, respectively. Benthic inputs of nutrients were higher at either the middle or outer Trinity Bay regions, most likely due to a higher quality and quantity of the autochthonous organic matter deposited. This feature is consistent with and gives evidence for previously observed non-conservative mixing behaviors reported for nutrients in this region of Galveston Bay. Calculated turnover times, between 7 to 135 d for phosphate, 4 to 56 d for silicate, and 0.3 to 10 d for ammonium were significantly shorter than the average Trinity Bay water residence time of 1.5 yr for the period September 1995 through October 1996. During periods of decreased Trinity River flow and increased residence times, benthic inputs of ammonium and phosphate were 1 to 2 orders of magnitude greater than Trinity River inputs and were the dominant input source of these nutrients to Trinity Bay. The sediments, a sink for silicate when overlying water column concentrations of silicate were elevated, became a source of silicate to the overlying waters of Trinity Bay under reduced flow, high salinity conditions.     

Using Wavelet Coherence to Characterize Surface Water Infiltration into a Low-Lying Karst Aquifer

Karstified carbonate aquifers may receive significant recharge contributions from losing streams, hence, the knowledge about surface water-groundwater (SW-GW) interactions is crucial with regard to water management (e.g., source protection zone delineation). The dynamics of SW-GW interactions may depend on factors such as the relative water levels between streams and aquifers, resulting in a temporal variation of exchange, which imposes complexity to the understanding of such dynamics. This study highlights the use of high-resolution time series and multiresolution analysis to help to gain insights into such complex dynamics. Wavelet coherence is applied on hourly time series of rainfall, stream, and spring discharges of a low-lying karstified spring catchment to yield a correlation in the time-frequency domain. This analysis provides comprehensive information on the overall impact of the river on the spring, which is supported by the cross-correlation function, as well as by more detailed information, including time-variant influences such as a threshold level of influence. Field observations of turbidity sampling at the spring appear to support this interpretation. This innovative approach relies on basic hydrological parameters, water level, or discharge, and is therefore applicable to many other systems with such existing time series.