Elevation-dependent warming(EDW),whereby warming rates are stratified by elevation,may increase the threat to the life-supporting solid water reservoir on the Tibetan Plateau.Previous studies have debated whether EDW ...Elevation-dependent warming(EDW),whereby warming rates are stratified by elevation,may increase the threat to the life-supporting solid water reservoir on the Tibetan Plateau.Previous studies have debated whether EDW exists and how it is driven.Using temperatures at 133 weather stations on the Tibetan Plateau during 17 different periods generated using a 30-year sliding window over 1973-2018,this study finds that the existence of EDW varies as the period moves forward,and critically it has become more severe over time.During the early part of the record with weaker regional warming,there were limited changes in snow depth and no EDW,but as time advances and regional warming intensifies,snow depth declines significantly at higher elevations,causing development of EDW.We conclude that enhanced regional warming has caused decreases in snow depth,largely controlling the pattern of EDW on the Tibetan Plateau.This may explain contrasting conclusions on EDW from previous studies which have used data for different periods,and our findings support enhanced EDW and more severe depletion of the Tibetan Plateau solid water reserves in a warmer future.展开更多
This paper proposes a systematic design method of overlap frequency domain equalization(FDE) for single carrier (SC) transmission without a guard interval (GI).Based on the analysis of signal-to-interference-plus-nois...This paper proposes a systematic design method of overlap frequency domain equalization(FDE) for single carrier (SC) transmission without a guard interval (GI).Based on the analysis of signal-to-interference-plus-noise ratio (SINR) of the equalizer output for each symbol,the authors adaptivelydetermine the block of the overlap FDE,where the block is defined as a set of symbols at the equalizeroutput with sufficiently low error rate,for a certain fixed sliding window size,which corresponds toa fast Fourier transform (FFT) window size.The proposed method takes advantage of the fact thatthe utility part of the equalized signal is localized around the center of the FFT window.In addition,the authors also propose to adjust the block size in order to control the computational complexity ofthe equalization per processed sample associating with the average bit error rate (BER) of the system.Simulation results show that the proposed scheme can achieve comparable BER performance to theconventional SC-FDE scheme with sufficient GI insertion for both the coded and uncoded cases withvarious modulation levels,while requiring lower computational complexity compared to the SC overlapFDE transmission with the fixed block.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK0102)the National Natural Science Foundation of China(41991281 and 41775076)Youth Innovation Promotion Association of Chinese Academy of Sciences(2018103)。
文摘Elevation-dependent warming(EDW),whereby warming rates are stratified by elevation,may increase the threat to the life-supporting solid water reservoir on the Tibetan Plateau.Previous studies have debated whether EDW exists and how it is driven.Using temperatures at 133 weather stations on the Tibetan Plateau during 17 different periods generated using a 30-year sliding window over 1973-2018,this study finds that the existence of EDW varies as the period moves forward,and critically it has become more severe over time.During the early part of the record with weaker regional warming,there were limited changes in snow depth and no EDW,but as time advances and regional warming intensifies,snow depth declines significantly at higher elevations,causing development of EDW.We conclude that enhanced regional warming has caused decreases in snow depth,largely controlling the pattern of EDW on the Tibetan Plateau.This may explain contrasting conclusions on EDW from previous studies which have used data for different periods,and our findings support enhanced EDW and more severe depletion of the Tibetan Plateau solid water reserves in a warmer future.
基金supported in part by Grant-in-Aid for Scientific Research No. 21760289 from the Ministry of Education, Science, Sport and Culture of Japanby the KMRC R&D Grant for Mobile Wireless from Kinki Mobile Radio Center, Foundation, Japan
文摘This paper proposes a systematic design method of overlap frequency domain equalization(FDE) for single carrier (SC) transmission without a guard interval (GI).Based on the analysis of signal-to-interference-plus-noise ratio (SINR) of the equalizer output for each symbol,the authors adaptivelydetermine the block of the overlap FDE,where the block is defined as a set of symbols at the equalizeroutput with sufficiently low error rate,for a certain fixed sliding window size,which corresponds toa fast Fourier transform (FFT) window size.The proposed method takes advantage of the fact thatthe utility part of the equalized signal is localized around the center of the FFT window.In addition,the authors also propose to adjust the block size in order to control the computational complexity ofthe equalization per processed sample associating with the average bit error rate (BER) of the system.Simulation results show that the proposed scheme can achieve comparable BER performance to theconventional SC-FDE scheme with sufficient GI insertion for both the coded and uncoded cases withvarious modulation levels,while requiring lower computational complexity compared to the SC overlapFDE transmission with the fixed block.
