Search

Objectives: Since there is only nadir radiometer onboard for the wide-swath altimetry, the wet tropospheric delay can only be corrected by models inside the cross-swath or substituted by the nadir radiometer measured data, which lead to the lower accuracy.Methods: In order to improve the accuracy of wet tropospheric correction (WTC) inside the cross-swath, an optimum interpolation method to fuse the nadir radiometer WTC is proposed, and it is verified by taken the SWOT (surface water and ocean topography) wide-swath altimeter as example. Results: Inside the cross-swath, when the ERA5 (ECMWF reanalysis 5th generation) data are used, the residual of WTC after correction by optimum interpolation method can be reduced by 40% compared with the nadir radiometer WTC substituted. When the simulated WTCs from the spectrum of radiometer measured WTCs are used, the residual of WTC after correction by optimum in⁃ terpolation method can be reduced by 80% in all latitude areas compared with the nadir radiometer WTC substituted.Conclusions: The optimum interpolation method has much better accuracy than the nadir radiometer WTC substituted in the case of high water vapor variability. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The indoor simulation is adopted instead of field experiment to minimize the experimental frequency of the millimeter wave passive detector in field. In view of the process of millimeter wave radiometer in terminal-sensitive projectile detecting armor target, a mathematical model of indoor hardware-in-the-loop simulation system is established, an equivalent mathematic model of indoor simulation system and field detection is built, and a millimeter wave radiometer hardware-in-the-loop simulation system is designed. Finally, the hardware-in-the-loop simulation results are compared with the measured results on the tower. The results show the correctness of the millimeter wave radiometer hardware-in-the-loop simulation system and the equivalent relationship of the proposed model. It can be used for the hardware-in-the-loop simulation test for the development and production test of terminal sensitive projectiles. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Photosynthetically active radiation (PAR) is a key environmental factor affecting the change of net ecosystem exchange (NEE) during the daytime. However, the coordinate system of PAR measured by horizontal radiometers over sloping terrain does not match that of NEE after tilt-corrected of the ultrasonic anemometer. Using the temperate deciduous broad-leaved forest at the Maoershan site with an average slope of 9° and a azimuth of 296° as a case, we investigated the diurnal variations in NEE and its driving factors in the growing season (May to September) of 2016. We assessed the differences in estimating light response parameters and the explanations of NEE by other environmental factors between the PAR measured by horizontal and slope-parallel radiometers. The results showed that the diurnal change of NEE in each month of the growing season presented a morning-afternoon asymmetrically unimodal curve: the value was negative (net carbon absorption) about 2.5 h after sunrise, reached the peak around 12:00, then approached zero again at two hours before sunset. The daily net uptake maximized in July and minimized in May. During the whole growing season, the time-lag and difference in the PAR measured by the horizontal versus slope-parallel radiometers led to that the PAR values measured by the horizontal radiometer increased photosynthetic quantum yield (α) and daytime respiration rate (R d ) by 13.3% and 11.5%, respectively, and decreased the maximum photosynthetic efficiency (A max ) by 7.7%. The light response curves of NEE were asymmetrical in the morning and afternoon, with R d and A max in the afternoon being greater than that in the morning. Weather conditions affected light response parameters: on cloudy days, A max was higher than that in sunny days, the α and R d were lower versus those in sunny days for most conditions. However, the monthly A max and R d were generally higher for horizontally measured PAR than for slope-parallelly measured PAR, especially for A max in the cloudy afternoon. The radiometer-orientation affected the explanation of daytime NEE by air temperature (T a ) and vapor pressure deficit (VPD). The correlation of NEE residual based on the slope-parallel radiometer with T a and VPD (r ranged: 0.013 to 0.197, 0.098 to 0.224) was tighter than that based on the horizontal radiometer (r ranged: 0.082 to 0.219, 0.162 to 0.282) when the negative correlations with T a for September was excluded. Our results indicated that the measurements of PAR on the inclined terrains could cause errors in the environmental interpretations of NEE. Such findings had implications for the radiometric measurement of mountain vegetation and the reasonable interpretation of carbon exchange in terrestrial ecosystems.

Near-surface remote sensing is an important technique for in-situ monitoring of forest phenology and a robust tool for scaling of the phenology with a high temporal resolution and mode-rate spatial coverage. Here, we first reviewed the methods of near-surface remote sensing with three major optical sensors (i.e., radiometer, spectrometer, and digital camera) for monitoring forest phenology. Second, we analyzed sources of uncertainties from distinguishing the phenophases by using the data obtained at the Maoershan flux site in the temperate forest. We found that the error was mainly attributed to the extracting method. Third, we analyzed the linkage of near-surface remote sensing with other methods and its intrinsic problems. Finally, we proposed four priorities in the research of this field: 1) linking optical (or canopy structural) phenology with functional phenology (physiological and ecological processes); 2) integrating the regional networks of canopy phenology for global networking observation and data sharing of canopy phenology; 3) integrating multi-source and multi-scale phenological data with the help of near-surface remote sensing; 4) developing phenology models based on near-surface remote sensing in order to improve the phenology simulation in the dynamic global vegetation models.