Interest in intermediate soft-classified maps in land change model validation: suitability versus transition potential     

M. T. Camacho Olmedo  M. Paegelow  J. F. Mas 《International journal of geographical information science》2013,27(12):2343-2361

This study compares two types of intermediate soft-classified maps. The first type uses land use/cover suitability maps based on a multi-criteria evaluation (MCE). The second type focuses on the transition potential between land use/cover categories based on a multi-layer perceptron (MLP). The concepts and methodological approaches are illustrated in a comparable manner using a Corine data set from the Murcia region (2300 km², Spain) in combination with maps of drivers that were created with two stochastic, discretely operating, commonly used tools (MCE in CA_MARKOV and MLP in Land Change Modeler). The importance of the different approaches and techniques for the obtained results is illustrated by comparing the specific characteristics of both approaches by validating the suitability versus transition potential maps to each other using a Spearman correlation matrix and, between the Corine maps, using classical ROC (receiver operating characteristic) statistics. Then, we propose a new use of ROC statistics to compare these intermediate soft-classified maps with their respective hard-classified maps of the models for each category. The validation of these results can be beneficial in choosing a suitable model and provide a better understanding of the implications of the different modeling steps and the advantages and limitations of the modeling tools.  相似文献   

Age and growth of bluenose,Hyperoglyphe antarctica (Pisces: Stromateoidei) from the lower east coast,North Island,New Zealand     

Peter L. Horn 《新西兰海洋与淡水研究杂志》2013,47(3):369-378

Growth of the bluenose, Hyperoglyphe antarctica (Carmichael, 1818) from the lower east coast, North Island, was determined by counting growth check rings in otoliths. One growth check ring appeared to be laid down each year, so this technique is probably valid for aging bluenose. Female fish had a significantly higher growth rate than males. Comparisons of samples from three sites indicated no significant regional differences in growth. The von Bertalanffy parameters L8,K, and t0 fitted to back‐calculated fish lengths were, respectively, 81.1 cm, 0.308, ‐0.627 for males, and 86.1 cm, 0.308, ‐0.384 for females.  相似文献   

The GAVDOS Mean Sea Level and Altimeter Calibration Facility: Results for Jason-1     

ERRICOS C. PAVLIS  STELIOS P. MERTIKAS 《Marine Geodesy》2013,36(3-4):631-655

The location of the GAVDOS facility is under a crossing point of the original ground-tracks of TOPEX/Poseidon and the present ones for Jason-1, and adjacent to an ENVISAT pass, about 50 km south of Crete, Greece. Ground observations and altimetry comparisons over cycles 70 to 90, indicate that a preliminary estimate of the absolute measurement bias for the Jason-1 altimeter is 144.7 ± 15 mm. Comparison of Jason microwave radiometer data from cycles 37 and 62, with locally collected water vapor radiometer and solar spectrometer observations indicate a 1–2 mm agreement.  相似文献   

Multi-Model Validation of Currents in the Chesapeake Bay Region in June 2010     

Philip Y. Chu  Gregg A. Jacobs  M. Kemal Cambazoglu  Robert S. Linzell 《Marine Geodesy》2013,36(4):399-428

In this paper, we discuss the validation of water level and current predictions from three coastal hydrodynamic models and document the resource and operational requirements for each modeling system. The ADvanced CIRCulation Model (ADCIRC), the Navy Coastal Ocean Model (NCOM), and Delft3D have been configured and validated for the Chesapeake Bay region during a Navy exercise. Water level predictions are compared with a NOAA/NOS water level gauge at the Chesapeake Bay Bridge Tunnel location while current predictions are validated with Acoustic Doppler Profiler (ADP) measurement records at three locations in the lower Chesapeake Bay. Statistical metrics such as correlation coefficient and root mean square error (RMSE) are computed. Both the vertically-integrated currents and currents at varying water depths are compared as well. The model-data comparisons for surface elevation indicate all three models agreed well with water level gauge data. The two-dimensional version of ADCIRC, ADCIRC2D, and NCOM yield better statistics, in terms of correlation and RMSE, than Delft3D. For vertically-integrated currents, ADCIRC2D has the smallest RMSE at Thimble Shoal and Naval Station locations while NCOM has the smallest RMSE at Cape Henry. For the horizontal currents over the water column, the fully three-dimensional, baroclinic ADCIRC model, ADCIRC3D, and NCOM both showed better agreement with the ADP measurements.  相似文献   

The Harvest Experiment: Monitoring Jason-1 and TOPEX/POSEIDON from a California Offshore Platform Special Issue: Jason-1 Calibration/Validation     

《Marine Geodesy》2013,36(3-4):239-259

We present calibration results from Jason-1 (2001–) and TOPEX/POSEIDON (1992–) overflights of a California offshore oil platform (Harvest). Data from Harvest indicate that current Jason-1 sea-surface height (SSH) measurements are high by 138 ± 18 mm. Excepting the bias, the high accuracy of the Jason-1 measurements is in evidence from the overflights. In orbit for over 10 years, the T/P measurement system is well calibrated, and the SSH bias is statistically indistinguishable from zero. Also reviewed are over 10 years of geodetic results from the Harvest experiment.  相似文献   

The validation of HY-2 altimetermeasurements of a significant wave height based on buoy data     

WANG Jichao  ZHANG Jie  YANG Jungang 《海洋学报(英文版)》2013,32(11):87-90

HY-2 has been launched by China on August 16, 2011 which assembles multi-microwave remote sensing payloads in a body and has the ability of monitoring ocean dynamic environments. The HY-2 satellite data need to be calibrated and validated before being put into use. Based on the in-situ buoys from the Nation- al Data Buoy Center （NDBC）, Ku-band significant wave heights （SWH, hs） of HY-2 altimeter are validated. Eleven months of HY-2 altimeter Level 2 products data are chose from October 1, 2011 to August 29, 2012. Using NDBC 60 buoys yield 902 collocations for HY-2 by adopting collocation criteria of 30 min for tempo- ral window and 50 km for a spatial window. An overall RMS difference of the SWH between HY-2 and buoy data is 0.297 m. A correlation coefficient between these is 0.964. An ordinary least squares （OLS） regression is performed with the buoy data as an independent variable and the altimeter data as a dependent vari- able. The regression equation of hs is hs （HY-2）=0.891 × hs （NDBC）＋0.022. In addition, 2016 collocations are matched with temporal window of 30 rain at the crossing points of HY-2 and Jason-2 orbits. RMS difference of Ku-band SWH between the two data sets is 0.452 m.  相似文献   

The geographic distribution of Echiura from southern Africa     

《African Journal of Marine Science》2013,35(1):11-21

The echiuran fauna of southern Africa currently comprises two families, four genera and 16 species of which one has recently been described as new to science and four are new records for the region. The taxonomic characters distinguishing the genera are given. The zoogeographic distribution of the southern African species is outlined and discussed. Knowledge of the echiuran fauna is too scanty to throw any light on the division of the coastline into faunistic provinces.  相似文献   

Experimental and numerical analyses of vibrations induced by high-speed trains on the Córdoba–Málaga line     

P. Galvín  J. Domínguez 《Soil Dynamics and Earthquake Engineering》2009

This paper has two main purposes. One is to present and analyse soil and structural vibration data obtained experimentally during certification testing of the high-speed train line between Córdoba and Málaga (Spain) that was opened on December 2007. The second is to show the capabilities of a three-dimensional boundary element method (BEM)/finite element method (FEM) numerical approach for the analysis of train induced vibrations. The model can represent local soil conditions, discontinuities such as underpasses, as well as structures placed next to the rail track. Vibrations in those structures can be computed taking into account, in a rigorous way, dynamic soil–structure interaction and local soil properties. Experimental and numerical results at several points near the track are compared. Results for an overhead contact support structure are also evaluated. The comparison of numerically predicted and recorded results shows that the model is reliable for predicting the amplitude of vibrations produced in the soil and nearby structures by high-speed trains.  相似文献   

Testing global geopotential models through comparison of a local quasi-geoid model with GPS/leveling data     

Pavel Novák  Jan Kostelecký  Jaroslav Klokočník 《Studia Geophysica et Geodaetica》2009,53(1):39-60

The satellite missions CHAllenging Minisatellite Payload (CHAMP) and Gravity Recovery And Climate Experiment (GRACE) provide accurate data that are routinely inverted into spherical harmonic coefficients of the geopotential forming a global geopotential model (GGM). Mean square errors of these coefficients, in some cases even entire covariance matrices, are included in the GGM. Due to estimation procedures with a large redundancy and insufficiently propagated observation errors, they often do not represent the actual accuracy of the harmonic coefficients, thus also gravity field parameters synthesized from the respective GGM. Since in most cases standard methods validating the GGMs reached their limits, new procedures and independent data are being currently sought. This article discusses an alternative validation procedure based on comparison of the GGMs with independent data represented by a set of GPS/leveling stations. Due to a different spectral content of the height anomalies synthesized from the GGMs and of those derived by combination of GPS-based ellipsoidal and leveled normal heights, the GGM-based low frequency height anomaly is enhanced for a high frequency component computed from local ground gravity and elevation data. The methodology is applied on a set of selected points of the European Vertical Reference Network and Czech trigonometric stations. In accordance with similar tests based on entirely independent data of cross-over altimetry, obtained results seem to indicate low-frequency deficiencies in the current GGMs, namely in those estimated from data of single-satellite missions.  相似文献   

Comparison and validation of MODIS standard and new combination of Terra and Aqua snow cover products in northern Xinjiang,China   总被引：1，自引：0，他引：1  

Xianwei Wang  Hongjie Xie  Tiangang Liang  Xiaodong Huang 《水文研究》2009,23(3):419-429

Taking northern Xinjiang, China, as an example, this study first compares the standard MODIS Terra and Aqua snow cover classifications, and then compares the accuracy of the standard MODIS daily and 8‐day snow cover products with the new daily and multi‐day snow cover combination of MODIS Terra and Aqua observations using in situ measurements. Under clear sky in both products, the agreement of land classification from MODIS Terra and Aqua daily and 8‐day snow cover products is close to 100% for a entire water year. In contrast, the agreement of snow classification from MODIS Terra and Aqua is high only in the winter months, decreasing in the rest of the period. The high agreement mainly concentrates in land or snow‐dominated areas, and major disagreements take place in the transitions zones from snow to land. The disagreement (mainly snow–land) in the 8‐day products is higher than that in the daily products. In addition, both MODIS Terra and Aqua cloud masks tend to map more areas in the transition zones as cloud. Under clear sky conditions, the three daily products have similar accuracy of snow and land classification, and the 8‐day standard products and the multi‐day combination product also have similar accuracy of snow and land classification. This further suggests that the algorithm in the combination of Terra and Aqua snow cover products is valid. Moreover, in the actual weather/cloud conditions, the combination products from Terra and Aqua reduce cloud blockage and improve snow classification accuracy against either MODIS Terra or Aqua (51% against 44% and 34% for daily and 92% against 87% and 78% for 8‐day, respectively), although Terra snow product (daily or 8‐day) has slightly better accuracy than the Aqua snow product. The new combination products can provide better mapping of spatiotemporal variation of snow cover/glacier and for snow‐melting modeling. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献