The advent of new data sets describing soil texture and associated soil properties offers the promise of improved hydrological simulation. Here we describe the composition of a new soil texture data set and its implementation into a specific land surface modeling system, namely, the Catchment land surface model (LSM) of the NASA Goddard Earth Observing System version 5 (GEOS-5) modeling and assimilation framework. First, global soil texture composites are generated using data from the Harmonized World Soil Database version 1.21 (HWSD1.21) and the State Soil Geographic (STATSGO2) project, with explicit consideration of different levels of organic material. Then, the LSM's soil parameters are upgraded using the new texture data, with hydraulic parameters derived for the more extensive set of texture classes using pedotransfer functions. Other changes to the LSM parameters are included to further support simulations at increasingly fine resolutions. A suite of simulations with the original and new parameter versions shows modest yet significant improvements in the Catchment LSM's simulation of soil moisture and surface hydrological fluxes. The revised LSM parameters will be used for the forthcoming Soil Moisture Active Passive (SMAP) soil moisture assimilation product.
The Soil Moisture Active Passive (SMAP) mission Level-4 Soil Moisture (L4_SM) product provides 3-hourly, 9-km resolution, global estimates of surface (0–5 cm) and root-zone (0–100 cm) soil moisture and related land surface variables from 31 March 2015 to present with ~2.5-day latency. The ensemble-based L4_SM algorithm assimilates SMAP brightness temperature (Tb) observations into the Catchment land surface model. This study describes the spatially distributed L4_SM analysis and assesses the observation-minus-forecast (O − F) Tb residuals and the soil moisture and temperature analysis increments. Owing to the climatological rescaling of the Tb observations prior to assimilation, the analysis is essentially unbiased, with global mean values of ~0.37 K for the O − F Tb residuals and practically zero for the soil moisture and temperature increments. There are, however, modest regional (absolute) biases in the O − F residuals (under ~3 K), the soil moisture increments (under ~0.01 m3 m−3), and the surface soil temperature increments (under ~1 K). Typical instantaneous values are ~6 K for O − F residuals, ~0.01 (~0.003) m3 m−3 for surface (root zone) soil moisture increments, and ~0.6 K for surface soil temperature increments. The O − F diagnostics indicate that the actual errors in the system are overestimated in deserts and densely vegetated regions and underestimated in agricultural regions and transition zones between dry and wet climates. The O − F autocorrelations suggest that the SMAP observations are used efficiently in western North America, the Sahel, and Australia, but not in many forested regions and the high northern latitudes. A case study in Australia demonstrates that assimilating SMAP observations successfully corrects short-term errors in the L4_SM rainfall forcing.
In this paper, we have investigated under what conditions positive geopotential height anomalies can be interpreted as blocking structures. Furthermore, we have studied the persistence of blocking. The data used here are the observed daily 500 hPa geopotential heights for 10 winter seasons from 1982/83 to 1991/92. The objective blocking criteria of Dole (1978) have been compared with the subjective blocking criteria established by Rex (1950a, b). Our study indicates that if we want to relate positive geopotential height anomalies to blocking as defined by Rex, not only the amplitude, but also the latitudinal position of the anomalies is important. Positive anomalies centered at about 45°N represent a northward extension of the subtropical anticyclone. Large positive anomalies centered at about 60°N are accompanied with negative anomalies at low latitudes and blocking anticyclones centered at about 50°N. We found that blocking and strong zonal flow have the same anomaly pattern but with opposite sign. The day‐to‐day changes in geopotential height associated with blocking are computed and the relevance of these day‐to‐day changes to the persistence of the blocking pattern is examined. We find that the day‐to‐day changes are smaller than normal over the blocking area, but larger than normal north of it. The anomalous day‐to‐day changes are mainly caused by the northward shift of the jet stream and the corresponding shift in the track of the transient weather disturbances. The strength of the day‐to‐day changes depends very much on the exact latitudinal location where the changes are computed. These results indicate that the day‐to‐day changes in geopotential height do not contain information about the persistence of the blocking pattern itself, but merely about the shift of the transient eddies caused by the blocking pattern. Hence, we can not simply interpret the persistence of blocking in terms of the day‐to‐day changes in positive anomalies. The persistence of blocking and strong zonal flow has been examined. As blocking and strong zonal flow are associated with approximately the same anomaly pattern but with opposite sign, the persistence of blocking and strong zonal flow can be expressed in terms of the duration of the corresponding anomaly patterns. We have shown that the average duration of the blocking and strong zonal flow patterns is approximately the same. This leads us to conclude that although the daily changes in geopotential height are small near the center of the blocking high, the blocking regime itself is not more persistent than the strong zonal flow regime. The persistence of blocking and strong zonal flow has also been compared with a first‐order Markov process. Generally speaking, we find no significant differences in persistence between the blocking and strong zonal flow regimes and the first‐order Markov process. This leads us to conclude that blocking is not more persistent than other atmospheric anomalies of the same geographical scale. This is in agreement with Lindzen (1986).
Advanced triboelectric nanogenerator techniques provide a massive opportunity for the development of new generation wearable electronics, which toward multi-function and self-powering. Textiles have been refreshed with the requirement of flexible electronics in recent decades. In particular, knitted-textiles have exhibited enormous and prominent potential possibilities for smart wearable devices, which are based on the merits of high stretchability, excellent elasticity, comfortability as well as compatibility. Combined knitted textiles with nanogenerator techniques will promote the knitted textile triboelectric nanogenerators (KNGs) emerging, endowing conventional textiles with biomechanical energy harvesting and sensing energy supplied abilities. However, the design of KNGs and the construction of KNGs are based on features of human motions symbolizing considerable challenges in both high efficiency and excellent comfort. Currently, this review is concerned with KNGs construction account of triboelectric effects referring to knitted-textile classifications, structural features, human motion energy traits, working mechanisms, and practical applications. Moreover, the remaining challenges of industrial production and the future prospects of knitted-textile triboelectric nanogenerators of harvesting biomechanical energy are presented.
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