[1] This study developed an algorithm for estimating solar radiation from space using a neural network (NN) with an improved learning algorithm to approximate radiative transfer code. The NN solver for the solar radiation budget is based on radiative transfer calculations. All data sets for testing and training the NN were generated from radiative transfer code. Thus the NN traces the radiative transfer calculation that is approximated by a learning algorithm. To demonstrate the effectiveness of the NN approach for high-speed estimation and multiparameter problems, the NN was applied to data from a geostationary satellite and a Sun-synchronous subrecurrent orbit satellite. The developed algorithm was applied to data from the Multi-functional Transport Satellite-1 Replacement (MTSAT-1R) geostationary satellite, and estimations were validated against in situ observations for March 2006 at four SKYNET sites. Byproducts of the algorithm include UVA, UVB, and photosynthetically active radiation (PAR) fluxes as well as direct and diffuse components. The NN approach enables semi-real-time analysis of these products by high-speed calculation. In addition, the NN allows for consideration of detailed particle optical parameters in the solar radiation budget without the need for a massive database. The method was also applied to observations from the Advanced Earth Observing Satellite-II/Global Imager (ADEOS-II/GLI) for May 2003. The results showed trends in the direct and diffuse components of downward solar radiation over the North Pacific Ocean. This report outlines the construction of the NN for radiation budget estimation and demonstrates the effectiveness of the NN approach.
Cloud systems over the Maritime Continent and the tropical western Pacific defined by the Geostationary Meteorological Satellite (GMS) were tracked, and their evolution was compared with cloud parameters [e.g., minimum blackbody brightness temperature (TBB), cloud area size, TBB gradient at cloud edges]. In addition, cloud systems observed by the Tropical Rainfall Measuring Mission (TRMM) were examined, and the relationship with precipitation was investigated. Analysis areas were divided into four regions: open ocean, coastal sea, coasts, and land.Cloud systems that did not split from or merge with other systems (28% of a total of 290 717 cloud systems) showed common features on cloud parameters in spite of different lifetimes or their locations. While the minimum TBB appeared in the beginning of their lifetimes, the cloud area was still expanding. At the time of first detection, the TBB gradient at the edge of the cloud system was the maximum and decreased with time. The rain rate was maximized when the TBB was at a minimum or earlier. For example, a system with the lifetime of 5 h over the ocean has a minimum TBB 2 h after the occurrence, a maximum area at 3 h, a maximum TBB gradient at 1 h, and a maximum rain rate at 1 h. Vertical development was significant in coasts, while remarkable horizontal expansion appeared over land. In particular, precipitation ice and storm height profiles showed differences among regions.
Abstract:The eddy covariance and energy balance method was employed to determine evapotranspiration (LE ) over a wet temperate C3-C4 co-existing grassland in Japan. After sensible heat flux (H) was estimated via the eddy covariance technique, LE was calculated as the residual of the energy budget with calibration against the direct measurements of LE by a lysimeter. Daily mean LE varied from 0Ð8 to 10Ð5 MJ d 1 , with a peak at 16Ð5 MJ d 1 in late July to early August. Day-to-day and seasonal variability in LE was affected appreciably by net radiation (R n ), atmospheric vapour pressure deficit (VPD), canopy surface conductance (g c ) and leaf area index (LAI). Before the canopy closure, LE responded to LAI in a linear manner. However, LE decreased with increasing LAI later in summer. Daytime variation in the decoupling coefficient ( ) demonstrates that the canopy decoupled from the atmosphere in the morning and LE was primarily driven by the available energy, while in the afternoon the canopy partially coupled to the atmosphere so that LE was sensitive to VPD and g c . Throughout the whole measurement period, was generally larger than 0Ð5, suggesting that the available energy contributes more to LE than VPD.
Tropical Rainfall Measuring Mission (TRMM) data during June-August 1998 are used to investigate diurnal variations of rain and cloud systems over the tropics and midlatitudes. The peak time of the coldest minimum brightness temperature derived from the Visible and Infrared Scanner (VIRS) and the maximum rain rate derived from the Precipitation Radar (PR) and the TRMM Microwave Imager (TMI) are compared. Time distributions are generally consistent with previous studies. However, it is found that systematic shifts in peak time relative to each sensor appeared over land, notably over western North America, the Tibetan Plateau, and oceanic regions such as the Gulf of Mexico. The peak time shift among PR, TMI, and VIRS is a few hours.The relationships among the amplitude of diurnal variation, convective frequency, storm height, and rain amount are further investigated and compared to the systematic peak time shifts. The regions where the systematic shift appears correspond to large amplitude of diurnal variation, high convective frequency, and high storm height. Over land and over ocean near the coast, the relationships are rather clear, but not over open ocean.The sensors likely detect different stages in the evolution of convective precipitation, which would explain the time shift. The PR directly detects near-surface rain. The TMI observes deep convection and solid hydrometeors, sensing heavy rain during the mature stage. VIRS detects deep convective clouds in mature and decaying stages. The shift in peak time particularly between PR (TMI) and VIRS varies by region.
Multiple renal artery grafts procured by open nephrectomy can be transplanted as successfully as those with single arteries, by using meticulous suturing techniques.
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