College of Behavioral & Social Sciences

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Author: search.filters.author.Jiang, Bo

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    Surface Shortwave Net Radiation Estimation from FengYun-3 MERSI Data
    (MDPI, 2015-05-19) Wang, Dongdong; Liang, Shunlin; He, Tao; Cao, Yunfeng; Jiang, Bo
    The Medium-Resolution Spectral Imager (MERSI) is one of the major payloads of China’s second-generation polar-orbiting meteorological satellite, FengYun-3 (FY-3), and it is similar to the Moderate-Resolution Imaging Spectroradiometer (MODIS). The MERSI data are suitable for mapping terrestrial, atmospheric and oceanographic variables at continental to global scales. This study presents a direct-estimation method to retrieve surface shortwave net radiation (SSNR) data from MERSI top-of-atmosphere (TOA) reflectance and cloud mask products. This study is the first attempt to use the MERSI to retrieve SSNR data. Several critical issues concerning remote sensing of SSNR were investigated, including scale effects in validating SSNR data, impacts of the MERSI calibration update on the estimation of SSNR and the dependency of the retrieval accuracy of SSNR data on view geometry. We also incorporated data from twin MODIS sensors to assess how time and the number of satellite overpasses affect the retrieval of SSNR data. Validation against one-year data over seven Surface Radiation Budget Network (SURFRAD) stations showed that the presented algorithm estimated daily SSNR at the original resolution of the MERSI with a root mean square error (RMSE) of 41.9 W/m2 and a bias of −1.6 W/m2. Aggregated to a spatial resolution of 161 km, the RMSE of MERSI retrievals can be reduced by approximately 10 W/m2. Combined with MODIS data, the RMSE of daily SSNR estimation can be further reduced to 22.2 W/m2. Compared with that of daily SSNR, estimation of monthly SSNR is less affected by the number of satellite overpasses per day. The RMSE of monthly SSNR from a single MERSI sensor is as small as 13.5 W/m2.
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    Land Surface Albedo Estimation from Chinese HJ Satellite Data Based on the Direct Estimation Approach
    (MDPI, 2015-05-04) He, Tao; Liang, Shunlin; Wang, Dongdong; Chen, Xiaona; Song, Dan-Xia; Jiang, Bo
    Monitoring surface albedo at medium-to-fine resolution (<100 m) has become increasingly important for medium-to-fine scale applications and coarse-resolution data evaluation. This paper presents a method for estimating surface albedo directly using top-of-atmosphere reflectance. This is the first attempt to derive surface albedo for both snow-free and snow-covered conditions from medium-resolution data with a single approach. We applied this method to the multispectral data from the wide-swath Chinese HuanJing (HJ) satellites at a spatial resolution of 30 m to demonstrate the feasibility of this data for surface albedo monitoring over rapidly changing surfaces. Validation against ground measurements shows that the method is capable of accurately estimating surface albedo over both snow-free and snow-covered surfaces with an overall root mean square error (RMSE) of 0.030 and r-square (R2) of 0.947. The comparison between HJ albedo estimates and the Moderate Resolution Imaging Spectral Radiometer (MODIS) albedo product suggests that the HJ data and proposed algorithm can generate robust albedo estimates over various land cover types with an RMSE of 0.011–0.014. The accuracy of HJ albedo estimation improves with the increase in view zenith angles, which further demonstrates the unique advantage of wide-swath satellite data in albedo estimation.
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    Does Homicide Decrease with Globalization
    (2020-02-28) LaFree, Gary; Jiang, Bo
    Research is strongly divided on whether globalization increases or decreases homicide and interpersonal violence. Elias argued that as Western societies opened up to commerce over the past 500 years they gradually “civilized,” resulting in decreasing levels of criminal violence. By contrast, Marx famously reasoned that the capitalist spread of commerce corroded traditional values and institutions, widened the gulf between the rich and poor and increased levels of interpersonal crime. Somewhat surprisingly, we could find few direct tests of the connection between globalization and cross-national violent crime. Based on a comprehensive cross-national database on homicide and a robust set of controls, we find strong evidence that globalization over the past half century is associated with declining homicide rates.
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    Situational Perspectives of Maritime Piracy
    (2019) Jiang, Bo; LaFree, Gary D; Criminology and Criminal Justice; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The emergence of maritime piracy has caused a great deal of concerns among various dimensions of our society. However, with few exceptions prior research has been hampered by a lack of theoretical underpinning and access to the most appropriate statistical methods. While there are nuances of piracy that can be considered quite unique, in general it can be situated within a broader framework of offending based on outcomes that seemingly share many of the same qualities. My dissertation attempts to improve our understanding of the crime by testing three core tenets of situational perspectives in the context of piracy. Three research questions motivated by LaFree and Birbeck (1991)’s conceptualization of a situation are examined – 1) To what extent does the study of maritime piracy support the central tenets of environmental criminology and crime and harm concentration at places; 2) How do offender motivation, target suitability and the absence of capable guardians and their convergence impact the instantaneous risk of piracy in South East Asia; and 3) To what extent do economic conditions of fishermen impact the instantaneous risk of piracy in East Africa and South East Asia. I rely on the IMO-GISIS database from 1995 to 2014, as well as auxiliary data from various organizations to tackle these questions. First, exploiting spatial econometrics methods, I find that there is statistically significant spatiotemporal patterns of concentration of hot spots and harm spots. Second, results from survival analyses indicate that the hazard ratios of the measures of high motivation, absence of capable guardians, suitable targets and their convergence are greater than 1 and significant in both the Malacca Strait and South China Sea. The series of robustness tests based on both frequentist and Bayesian statistics provide similar conclusions. Third, using a two-stage semiparametric approach, I find that there is statistically significant evidence to show that economic conditions of the fisherman-pirate adversely impact the instantaneous risk of ships being attacked in East Africa and the Malacca Strait and South China Sea. A robustness check based on an alternative specification supports the finding. I conclude with the implications of the research for theory, social policy and future research.
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    Land Surface Albedo Estimation from Chinese HJ Satellite Data Based on the Direct Estimation Approach
    (Multidisciplinary Digital Publishing Institute (MDPI), 2015-05-04) He, Tao; Liang, Shunlin; Wang, Dongdong; Chen, Xiaona; Song, Dan-Xia; Jiang, Bo
    Monitoring surface albedo at medium-to-fine resolution (<100 m) has become increasingly important for medium-to-fine scale applications and coarse-resolution data evaluation. This paper presents a method for estimating surface albedo directly using top-of-atmosphere reflectance. This is the first attempt to derive surface albedo for both snow-free and snow-covered conditions from medium-resolution data with a single approach. We applied this method to the multispectral data from the wide-swath Chinese HuanJing (HJ) satellites at a spatial resolution of 30 m to demonstrate the feasibility of this data for surface albedo monitoring over rapidly changing surfaces. Validation against ground measurements shows that the method is capable of accurately estimating surface albedo over both snow-free and snow-covered surfaces with an overall root mean square error (RMSE) of 0.030 and r-square (R2) of 0.947. The comparison between HJ albedo estimates and the Moderate Resolution Imaging Spectral Radiometer (MODIS) albedo product suggests that the HJ data and proposed algorithm can generate robust albedo estimates over various land cover types with an RMSE of 0.011–0.014. The accuracy of HJ albedo estimation improves with the increase in view zenith angles, which further demonstrates the unique advantage of wide-swath satellite data in albedo estimation.