Asia-Pacific Remote Sensing最新文献

{"title":"The challenges of representing vertical motion in numerical models","authors":"S. C. van den Heever, L. Grant, G. Stephens, Z. Haddad, R. L. Storer, O. Sy, D. Posselt","doi":"10.1117/12.2501584","DOIUrl":"https://doi.org/10.1117/12.2501584","url":null,"abstract":"Even though vertical motion is resolved within convection-permitting models, recent studies have demonstrated significant departures in predicted storm updrafts and downdrafts when compared with Doppler observations of the same events. Several previous studies have attributed these departures to shortfalls in the representation of microphysical processes, in particular those pertaining to ice processes. Others have suggested that our inabilities to properly represent processes such as entrainment are responsible. Wrapped up in these issues are aspects such as the model grid resolution, as well as accuracy of models to correctly simulate the environmental conditions. Four primary terms comprise the vertical momentum equation: advection, pressure gradient forcing, thermodynamics and turbulence. Microphysical processes including their impacts on latent heating and their contributions to condensate loading strongly impact the thermodynamic term. The focus of this study is on the thermodynamic contributions to vertical motion, the shortfalls that arise when modeling this term, and the observations that might be made to improve the representation of those thermodynamical processes driving convective updrafts and downdrafts.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133677513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of turbulence on the transmission of partially coherent vortex beams in the ocean environment","authors":"Yongxu Li, Yiping Han","doi":"10.1117/12.2326390","DOIUrl":"https://doi.org/10.1117/12.2326390","url":null,"abstract":"The analytical expressions of mode probability density (MPD) and crosstalk probability density (CPD) for LaguerreGaussian correlated Schell-mode (LGCSM) beams propagating through oceanic turbulence are established based on the geometrical optics approximation. Using the derived formulae and numerical simulation, the propagation characteristics of a single LGCSM beam in turbulent ocean are quantificationally analyzed in detail. The numerical results for the effects of all kinds of parameters on the MPD and CPD curves of a LGCSM beam propagating in the ocean environment are presented and illustrated. This research is expected to provide a convenient way and useful guidance to describe and treat the propagation of laser beam in turbulent medium.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115283207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Initial investigation of the angular dependence of the NOAA-20 VIIRS solar diffuser BRDF change factor","authors":"N. Lei, X. Xiong","doi":"10.1117/12.2324530","DOIUrl":"https://doi.org/10.1117/12.2324530","url":null,"abstract":"The NOAA-20 (formerly the Joint Polar Satellite System-1) satellite was launched on November 18, 2017. One of the five scientific instruments aboard the NOAA-20 satellite (N20) is the Visible Infrared Imaging Radiometer Suite (VIIRS). The VIIRS scans the earth surface in 22 spectral bands, of which 14 are denoted as the reflective solar bands (RSBs) with design band central wavelengths from 412 to 2250 nm. The VIIRS regularly performs on-orbit radiometric calibration of its RSBs, primarily through observations of an onboard sunlit solar diffuser (SD). The on-orbit change of the SD bidirectional reflectance distribution function (BRDF) value, denoted as the H-factor, is determined by an onboard solar diffuser stability monitor (SDSM). We have shown that the H-factor for the SD on the VIIRS instrument on the Suomi National Polar-orbiting Partnership (SNPP) satellite is both incident and outgoing sunlight direction dependent. This angular dependence profoundly affects the on-orbit radiometric calibration process and results. Here, we give preliminary results for the angular dependence for the N20 VIIRS SD H-factor, and compare the dependence with that for the SNPP VIIRS.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122177415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison and research of group refractivity models and atmospheric delay to lidar","authors":"Jiuying Chen, Mei Zhou, Ge-Er Teng, Huijing Zhang, Jian Hu, Chuanrong Li","doi":"10.1117/12.2324253","DOIUrl":"https://doi.org/10.1117/12.2324253","url":null,"abstract":"Satellite laser range system measures the distance between the satellite and the surface of the earth by figuring out the transit time of laser pulse. The beam is refracted when it goes through the atmosphere. The atmosphere refraction effect causes laser propagation delay and path bending, which is one of the key factors to restrict the accuracy of laser ranging. In order to improve the accuracy of atmospheric refraction delay correction, it is necessary to strengthen the study of atmospheric group refractivity models and atmospheric refraction delay correction method. According to the data of Xuzhou upper air meteorological station, which are the monthly values of upper limit layers for 30 years (1981-2010) in China, three atmospheric group refractivity models were analyzed and compared. The atmospheric refraction delays to LiDAR were calculated by ray tracing method. The differences among the group refractivity models as a function of month or direction angle were given, which lay the foundation for the practical application and precision evaluation of LiDAR.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"2139 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130006066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Landsat-8 on-orbit and Landsat-9 pre-launch sensor radiometric characterization","authors":"B. Markham, J. Barsi, M. Montanaro, J. McCorkel, A. Gerace, J. Pedelty, S. Hook, N. Raqueno, C. Anderson, Md. Obaidul Haque","doi":"10.1117/12.2324715","DOIUrl":"https://doi.org/10.1117/12.2324715","url":null,"abstract":"Landsat-8 has been operating on-orbit for 5+ years. Its two sensors, the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS), are continuing to produce high quality data. The OLI has been radiometrically stable at the better than 0.3% level on a band average basis for all but the shortest wavelength (443 nm) band, which has degraded about 1.3% since launch. All on-board calibration devices continue to perform well and consistently. No gaps in across track coverage exist as 100% operability of the detectors is maintained. The variability over time of detector responsivity within a band relative to the average is better than 0.05% (1 sigma), though there are occasional detectors that jump up to 1.5% in response in the Short-Wave InfraRed (SWIR) bands. Signal-to-Noise performance continues at 2-3x better than requirements, with a small degradation in the 443 nm band commensurate with the loss in sensitivity. Pre-launch error analysis, combined with the stability of the OLI indicates that the absolute reflectance calibration uncertainty is better than 3%; comparisons to ground measurements and comparisons to other sensors are consistent with this. The Landsat-8 TIRS is similarly radiometrically stable, showing changes of at most 0.3% over the mission. The uncertainty in the absolute calibration as well as the detector to detector variability are largely driven by the stray light response of TIRS. The current processing corrects most of the stray light effects, resulting in absolute uncertainties of ~1% and reduced striping. Efforts continue to further reduce the striping. Noise equivalent delta temperature is about 50 mK at typical temperatures and 100% detector operability is maintained. Landsat-9 is currently under development with a launch no earlier than December 2020. The nearly identical OLI-2 and upgraded TIRS-2 sensors have completed integration and are in the process of instrument level performance characterization including spectral, spatial, radiometric and geometric testing. Component and assembly level measurements of the OLI-2, which include spectral response, radiometric response and stray light indicate comparable performance to OLI. The first functional tests occurred in July 2018 and spatial performance testing in vacuum is scheduled for August 2018. Similarly, for TIRS-2, partially integrated instrument level testing indicated spectral and spatial responses comparable to TIRS, with stray light reduced by approximately an order of magnitude from TIRS.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134269927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new urban river network extraction method and spatial scale analysis","authors":"Jiawei Yang, Chengyu Liu, R. Shu, Feng Xie, Jianyu Wang, Chunlai Li","doi":"10.1117/12.2324650","DOIUrl":"https://doi.org/10.1117/12.2324650","url":null,"abstract":"In view of the confusing problem of urban river network water and building shadows in hyperspectral images, we analyzed typical shadow and water spectrum in AISA hyperspectral image. On the basis of Normalized Difference Vegetation Index (NDVI), the 588 nm height factor was introduced to constitute an anti-shadow water extraction method (ASWEM). Compared with NDVI extraction results, this method can effectively suppress shadows, especially those cast in buildings, improve water extraction accuracy and reduce water body commission error. The commission error is reduced from 45% to 10.4%, and Kappa coefficient is increased from 0.664 to 0.863. The change of spatial scale has a significant impact on the water extraction results. The lower the image resolution, the more serious the water leakage is, and some small rivers will not be able to extract. However, due to the influence of the mixed pixels, the spectral characteristics of the shadows are weakened to some extent, and the commission error is reduced. As the resolution decreases further, the number and mixing of mixed pixels increases, and the commission error increases.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134585565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"JPSS-2 VIIRS polarization sensitivity comparison with Heritage VIIRS sensors","authors":"D. Moyer, J. Mcintire, H. Oudrari, F. D. De Luccia","doi":"10.1117/12.2324801","DOIUrl":"https://doi.org/10.1117/12.2324801","url":null,"abstract":"The Joint Polar Satellite System 2 (JPSS-2) is the follow-on for the Suomi-National Polar-orbiting Partnership (S-NPP) and JPSS-1 missions. These spacecrafts provide critical weather and global climate products to the user community. A primary sensor on both JPSS and S-NPP is the Visible-Infrared Imaging Radiometer Suite (VIIRS) with Earth observations covering the Reflective Solar Band (RSB), Thermal Emissive Band (TEB) and Day Night Band (DNB) spectral regions. The VIIRS Sensor Data Records (SDRs) contain the calibrated Earth observations that are used to generate numerous Environmental Data Record (EDR) products such as Ocean Color/Chlorophyll (OCC), Global Land Cover, Aerosol and Land/Sea Surface Temperature (LST/SST). This SDR calibration is performed using unpolarized sources such as the Solar Diffuser (SD) for the RSBs and an On-Board Calibrator BlackBody (OBCBB) for the TEBs. Therefore, polarized Earth scenes will have radiometric bias errors within the SDRs based on how sensitive VIIRS is to polarized illumination and is corrected in some EDR algorithms. In addition to VIIRS polarization characterization methodology, this paper will discuss the JPSS-2 polarization sensitivity results and compare its performance to its predecessors S-NPP and JPSS-1 VIIRS. Optical modifications to the JPSS-2 VIIRS sensor to address heritage polarization sensitivity issues will be discussed.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133542646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parameter comparison for linear spectral unmixing in field hyperspectral sampling of rocky desertification","authors":"Miao Jiang, Yi Lin","doi":"10.1117/12.2324391","DOIUrl":"https://doi.org/10.1117/12.2324391","url":null,"abstract":"Rocky desertification is one of the most serious problems in environmental deterioration, and its accurate mapping is of many implications for maintaining Earth’s sustainability. Compared to traditional field surveying approaches, remote sensing (RS), particularly hyperspectral RS, has proved to be a more efficient solution plan. Yet, hyperspectral RS also suffers from the problem of spectral mixing, since rocky desertification may correspond to various fractions of vegetation, bare soil, and exposed rock. Although linear spectral unmixing (LSU) is an effective method for resolving their ratios, different constraint conditions involving the selections of pure objects and end-member spectra may influence the result. To better overcome this basic problem, the key point of parameter comparison for LSU in field hyperspectral sampling of rocky desertification was investigated. In the typical rocky desertification areas in southwest China, an experiment of field hyperspectral RS sampling various scenarios of ground object mixing was conducted. Then, LSU was operated, by firstly classifying the digital photos of the sample plots to derive the proportion of each object. The specific LSU operations were classified into four types. The selection of end-member spectra were classified into three kinds of cases. With the 12 combination cases of the above-listed scenarios compared, we found that the results under the conditions of ANC and full constraint were better than the ASC and unconstrained conditions, and the performance for the end-member selection scenarios from case A to case C was dropping but could handle more complex situations. These inferences can supply a more solid theoretical basis for better implementing spectral unmixing in hyperspectral RS of rocky desertification.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114866480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of winter wheat recognition ability based on multiphase Sentinel-2A data","authors":"Fanchen Peng, Shuhe Zhao, Wenting Cai, Yamei Wang, Zhaohua Zhang","doi":"10.1117/12.2324724","DOIUrl":"https://doi.org/10.1117/12.2324724","url":null,"abstract":"Effective and dynamic recognition of winter wheat has important implications for the development of agriculture in In this paper, we proposed a method for winter wheat identification using particle swarm optimization-support vector machine (PSO-SVM) model and multi-temporal Sentinel-2A image. The eigenvector combination based on spectral information and the eigenvector combination based on texture information were constructed by using different phenological periods of winter wheat. The winter wheat was identified and extracted by PSO-SVM. The extraction accuracy under different feature band combinations was compared and analyzed. The results showed that PSO-SVM had higher accuracy than traditional SVM. Using PSO-SVM, the optimal combination was multi-temporal spectral and mean texture information combination and its classification accuracy was 91.25%. This paper provides a theoretical basis for the future use of Sentinel-2A data to extract other crop information.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123490277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Traceability and consistency of COSMIC radio occultation in comparison with NOAA-20 CrIS infrared sounder observations","authors":"C. Cao, E. Lynch, Bin Zhang","doi":"10.1117/12.2324331","DOIUrl":"https://doi.org/10.1117/12.2324331","url":null,"abstract":"The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite system for the Radio Occultation (RO) mission provides advances in meteorology, ionospheric research, climatology, and space weather by utilizing the readily available Global Navigation Satellite System (GNSS) signals in conjunction with GNSS receivers in low Earth orbiting (LEO) satellites. COSMIC was launched in 2006 with six satellites in a constellation known as FORMOSAT-3 in low inclination orbits to provide global coverage. RO relies on the calculation of GNSS signal time delay in carrier phase due to the atmosphere in the L1 and L2 signals transmitted between the GNSS and receiving satellites in the LEO orbit, from which the bending angle, refractivity, and atmospheric profiles can be retrieved. Since the Atomic Frequency Standard (AFS) based GNSS signal is International System of Units (SI) traceable, is actively maintained, and the precise orbit of both the GNSS and the LEO satellites can be determined accurately, RO data from COSMIC have been recognized as stable references for data assimilation (DA) in Numerical Weather Prediction (NWP) models. Currently, NWP customers are eager to obtain similar data from COSMIC2 which will be launched in the next few months to mitigate the aging COSMIC constellation and diminishing number of ROs. Meanwhile, the calibration of the hyperspectral sounders such as Cross-track Infrared Sounder (CrIS) on NOAA-20 relies on a high quality onboard blackbody which is also traceable to SI through prelaunch characterization relating to the laboratory blackbody with traceable calibration to NIST, and hyperspectral sounders have been recognized as onorbit calibration references for other broad- or narrow-band infrared (IR) observations. In this paper we analyze the traceability of both systems in their raw measurements as well as retrieved geophysical variables. Comparisons are also made in spectral radiance/brightness temperature derived from the two systems. The objective is to gain a better understanding of the different paths of traceability to SI and ensure the consistency of the products for numerical weather prediction and other applications. This study directly supports the COSMIC2 verification and validation, as well as postlaunch calibration/validation of NOAA-20 CrIS.","PeriodicalId":370971,"journal":{"name":"Asia-Pacific Remote Sensing","volume":"150 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128872733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}