A comparison of cumulus parameterization schemes in a numerical weather prediction model for a monsoon rainfall event

In order to evaluate cumulus parameterization (CP) schemes for hydrological applications, the Pennsylvania State University–National Center for Atmospheric Research's fifth‐generation mesoscale model (MM5) was used to simulate a summer monsoon in east China. The performances of five CP schemes (Anthes–Kuo, Betts–Miller, Fritsch–Chappell, Kain–Fritsch, and Grell) were evaluated in terms of their ability to simulate amount of rainfall during the heavy, moderate, and light phases of the event. The Grell scheme was found to be the most robust, performing well at all rainfall intensity and spatial scales. The Betts–Miller scheme also performed well, particularly at larger scales, but its assumptions may make it inapplicable to non‐tropical environments and at smaller scales. The Kain–Fritsch scheme was the best at simulating moderate rainfall rates, and was found to be superior to the Fritsch–Chappell scheme on which it was based. The Anthes–Kuo scheme was found to underpredict precipitation consistently at the mesoscale. Simulation performance was found to improve when schemes that included downdrafts were used in conjunction with schemes that did not include downdrafts. Copyright © 2005 John Wiley & Sons, Ltd.     

Transient soft X-ray sources

A rocket observation of cosmic soft X-rays suggests the existence of transient, recurrent soft X-ray sources which are found variable during the flight time of the rocket. Some of the soft X-ray sources thus far reported are considered to be of this time. These sources are listed in Table I, and their positions are shown in Figure 2.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.     

Assessment of Nigeriasat-1 satellite data for urban land use/land cover analysis using object-based image analysis in Abuja,Nigeria

This study assesses the usefulness of Nigeriasat-1 satellite data for urban land cover analysis by comparing it with Landsat and SPOT data. The data-sets for Abuja were classified with pixel- and object-based methods. While the pixel-based method was classified with the spectral properties of the images, the object-based approach included an extra layer of land use cadastre data. The classification accuracy results for OBIA show that Landsat 7 ETM, Nigeriasat-1 SLIM and SPOT 5 HRG had overall accuracies of 92, 89 and 96%, respectively, while the classification accuracy for pixel-based classification were 88% for Landsat 7 ETM, 63% for Nigeriasat-1 SLIM and 89% for SPOT 5 HRG. The results indicate that given the right classification tools, the analysis of Nigeriasat-1 data can be compared with Landsat and SPOT data which are widely used for urban land use and land cover analysis.     

A numerical study of the effect of frozen soil on dust emission during an East Asian dust event in December 2009

There are few dust simulation studies for East Asian dust events that took place in the wintertime, when the surface conditions of the dust source region differ from those of the springtime. The soil water turns into ice when the temperature falls below freezing, and the ice might prohibit wind erosion by increasing the binding strength between soil particles. However, the contribution of frozen soil to reducing dust outbreaks remains unclear. This study investigates the effect of frozen soil on dust emission through a case study of a severe wintertime East Asian dust event that originated on 23 and 24 December 2009 in Southern Mongolia and Inner Mongolia and reached Korea on 25 and 26 December 2009 using WRF/Chem with a new dust emission scheme. Model simulations with and without the effect of frozen soil were conducted. A temperature below 0°C and relative soil saturation exceeding 40% were used for frozen soil criteria, and the frozen soil was prohibited from emitting dust. The dust concentrations derived from the simulation without the effect of frozen soil were about three times higher than the observed PM₁₀ concentrations, while the results from the simulation with the frozen-soil effect were quite similar to those of the observation data. The simulation of the wintertime East Asian dust event with the frozen-soil effect improved the model representation. The sensitivity tests for frozen soil indicate that the criteria of frozen soil used in this study are appropriate for this case study.     

Assessing regional groundwater quality and its health implications in the Lokpaukwu, Lekwesi and Ishiagu mining areas of southeastern Nigeria using factor analysis

Unusual occurrence of mental-related illnesses has been reported in the Ishiagu mining area of South Eastern Nigeria and this may be related to the long-term consumption of heavy metal-contaminated groundwater. Groundwater from 27 domestic water sources (mainly open hand dug wells and springs) was therefore sampled within two seasons and analyzed for both physical and chemical parameters. Results were compared with international standards for drinking water and also subjected to factor analysis. The analysis showed that iron has the highest concentration of heavy metals exceeding the WHO-permitted desirable limit of 0.3?mg/l in about 73% of cases. Manganese was ubiquitous in groundwater samples exceeding the EU-permitted limits in about 41% of cases. Zinc, although within acceptable international limits was also common in samples from the Ishiagu central area, the Ayaragu, and the Amaubiri-Lokpauku axis. Lead and cadmium occurred in 3 and 13% of cases, respectively, and was outside international regulatory standards for drinking water. Long-term exposure to manganese and cadmium may therefore be a significant cause of the prevalence of mental related illness in the study area. There is also the possibility of impacts from other elements previously undetected in the groundwater system of the study area (but revealed through factor analysis) including arsenic, vanadium, bromine and fluorite (ide) and this needs urgent investigation. Major factors affecting groundwater quality included mineral dissolution and polluted discharge/recharge from mining operations.     

Availability of an equation to evaluate error by optical path discretization in radiative transfer computation based on the successive order of scattering method

The availability of an equation to evaluate the influence of multiple scattering in the single scattering process corresponding to a layer of arbitrary optical thickness was established. In order to confirm the validity of this equation, the radiance distribution in this layer was computed using a plane–parallel layer model based on the successive order of scattering method. The relative errors in a radiance distribution computed were evaluated as a function of optical thickness by the derived equation. It was shown that this equation provides a theoretical background for determining layer thickness using the plane–parallel layer model.     

A Note on Seasonal Variation in Radiolarian Abundance

A statistical analysis of two consecutive sequences of observations on radiolarian abundances in the western North Pacific, by methods appropriate to data on the simplex (i.e., compositional data), show that although the overall graphical presentations of the frequencies appear similar, there are substantial differences in the earlier part of each of the series. The results of the multivariate analyses are used for identifying those species that contribute most to the analysis. A brief guide to the mathematical properties of compositional data is given.     

Laboratory experiments and thermal calculations for the development of a next-generation glacier-ice exploration system: Development of an electro-thermal drilling device

A next-generation drilling system, equipped with a thermal drilling device, is proposed for glacier ice. The system is designed to penetrate glacier ice via melting of the ice and continuously analyze melt-water in a contamination-free sonde. This new type of drilling system is expected to provide analysis data in less time and at less cost than existing systems. Because of the limited number of parameters that can be measured, the proposed system will not take the place of conventional drilling systems that are used to obtain ice cores; however, it will provide a useful method for quickly and simply investigating glacier ice.An electro-thermal drilling device is one of the most important elements needed to develop the proposed system. To estimate the thermal supply required to reach a target depth in a reasonable time, laboratory experiments were conducted using ice blocks and a small sonde equipped solely with heaters. Thermal calculations were then performed under a limited range of conditions. The experiments were undertaken to investigate the effects of the shape and material of the drill head and heater temperature on the rate of penetration into the ice. Additional thermal calculations were then performed based on the experimental results.According to the simple thermal calculations, if the thermal loss that occurs while heat is transferred from the heater to ice (in melting the ice) is assumed to be 50%, the total thermal supply required for heaters in the sonde and cable is as follows: (i) 4.8 kW (sonde) plus 0 W (cable) to penetrate to 300 m depth over 10 days into temperate glacier ice for which the temperature is 0 °C at all depths and to maintain a water layer along 300 m of cable; (ii) 10 kW (sonde) plus 19–32 kW (cable) to penetrate to 1000 m depth over 1 month into cold glacier ice for which the temperature is −25 °C at the surface and 0 °C at 1000 m depth and to maintain a water layer along 1000 m of cable; and (iii) 19 kW (sonde) plus 140–235 kW (cable) to penetrate to 3000 m depth over 2 months into an ice sheet for which the temperature is −55 °C at the surface and 0 °C at 3000 m depth and to maintain a water layer along 3000 m of cable. The thermal supply required for the cable is strongly affected by the thickness of the water layer, cable diameter, and the horizontal distance from the ice wall at which the ice temperature was maintained at its initial temperature. A large thermal supply is required to heat 3000 m of cable in an ice sheet (scenario (iii) above), but penetration into glacier ice (scenarios (i) and (ii) above) could be realistic with the use of a currently employed generator.     

Generalized Lyzenga's Predictor of Shallow Water Depth for Multispectral Satellite Imagery

Multispectral satellite remote sensing can predict shallow-water depth distribution inexpensively and exhaustively, but it requires many in situ measurements for calibration. To extend its feasibility, we improved a recently developed technique, for the first time, to obtain a generalized predictor of depth. We used six WorldView-2 images and obtained a predictor that yielded a 0.648 m root-mean-square error against a dataset with a 5.544 m standard deviation of depth. The predictor can be used with as few as two pixels with known depth per image, or with no depth data, if only relative depth is needed.