scholarly journals Trends in OMI NO<sub>2</sub> observations over the United States: effects of emission control technology and the economic recession

2012 ◽  
Vol 12 (24) ◽  
pp. 12197-12209 ◽  
Author(s):  
A. R. Russell ◽  
L. C. Valin ◽  
R. C. Cohen
Keyword(s):  
United States ◽  
Power Plants ◽  
Economic Recession ◽  
The United States ◽  
Retrieval Algorithm ◽  
Vertical Column ◽  
Large Power ◽  
Mobile Sources ◽  
Light Duty Vehicle ◽  
The Impact

Abstract. Observations of tropospheric NO2 vertical column densities over the United States (US) for 2005–2011 are evaluated using the OMI Berkeley High Resolution (BEHR) retrieval algorithm. We assess changes in NO2 on day-of-week and interannual timescales to assess the impact of changes in emissions from mobile and non-mobile sources on the observed trends. We observe consistent decreases in cities across the US, with an average total reduction of 32 ± 7% across the 7 yr. Changes for large power plants have been more variable (−26 ± 12%) due to regionally-specific regulation policies. An increasing trend of 10–20% in background NO2 columns in the northwestern US is observed. We examine the impact of the economic recession on emissions and find that decreases in NO2 column densities over cities were moderate prior to the recession (−6 ± 5% yr−1), larger during the recession (−8 ± 5% yr−1), and then smaller after the recession (−3 ± 4% yr−1). Differences in the trends observed on weekdays and weekends indicate that prior to the economic recession, NO2 reductions were dominated by technological improvements to the light-duty vehicle fleet but that a decrease in diesel truck activity has contributed to emission reductions since the recession. We use the satellite observations to estimate a 34% decrease in NO2 from mobile sources in cities for 2005–2011 and use that value to infer changes in non-mobile sources. We find that reductions in NO2 from non-mobile sources in cities have been both more modest and more variable than NO2 reductions from mobile sources (−10 ± 13%).

scholarly journals Trends in OMI NO<sub>2</sub> observations over the US: effects of emission control technology and the economic recession

2012 ◽  
Vol 12 (6) ◽  
pp. 15419-15452 ◽  
Author(s):  
A. R. Russell ◽  
L. C. Valin ◽  
R. C. Cohen
Keyword(s):  
Power Plants ◽  
Economic Recession ◽  
The United States ◽  
Retrieval Algorithm ◽  
Vertical Column ◽  
Large Power ◽  
Mobile Sources ◽  
The Us ◽  
Light Duty Vehicle ◽  
The Impact

Abstract. Observations of tropospheric NO2 vertical column densities over the United States (US) for 2005–2011 are evaluated using the OMI Berkeley High Resolution (BEHR) retrieval algorithm. We assess changes in NO2 on day-of-week and interannual timescales to assess the impact of changes in emissions from mobile and non-mobile sources on the observed trends. We observe consistent decreases in cities across the US, with an average total reduction of 32 ± 7%. Changes for large power plants have been more variable (−26 ± 12%) due to regionally-specific regulation policies. An increasing trend of 10–20% in background NO2 columns in the Northwestern US is observed. We examine the impact of the economic recession on emissions and find that decreases in NO2 column densities over cities were moderate prior to the recession (−6 ± 5 % yr−1), larger during the recession (−8 ± 5 % yr−1), and then smaller after the recession (−3 ± 4 % yr−1). Differences in the trends observed on weekdays and weekends indicate that prior to the economic recession, NO2 reductions were dominated by technological improvements to the light-duty vehicle fleet but that a decrease in diesel truck activity has dominated emission reductions since the recession. We use the satellite observations to estimate a 34% decrease in NO2 from mobile sources in cities for 2005–2011 and use that value to infer changes in non-mobile sources. We find that reductions in NO2 from non-mobile sources in cities have been more variable than NO2 reductions from mobile sources (−10 ± 13%).

scholarly journals The Polarimetric Sensitivity of SMAP-Reflectometry Signals to Crop Growth in the U.S. Corn Belt

2020 ◽  
Vol 12 (6) ◽  
pp. 1007
Author(s):  
Nereida Rodriguez-Alvarez ◽  
Sidharth Misra ◽  
Mary Morris
Keyword(s):  
United States ◽  
Soil Moisture ◽  
The United States ◽  
Crop Growth ◽  
Corn Belt ◽  
Retrieval Algorithm ◽  
Agricultural Crop ◽  
Crop Height ◽  
Crop Type ◽  
The Impact

Crop growth is an important parameter to monitor in order to obtain accurate remotely sensed estimates of soil moisture, as well as assessments of crop health, productivity, and quality commonly used in the agricultural industry. The Soil Moisture Active Passive (SMAP) mission has been collecting Global Positioning System (GPS) signals as they reflect off the Earth’s surface since August 2015. The L-band dual-polarization reflection measurements enable studies of the evolution of geophysical parameters during seasonal transitions. In this paper, we examine the sensitivity of SMAP-reflectometry signals to agricultural crop growth related characteristics: crop type, vegetation water content (VWC), crop height, and vegetation opacity (VOP). The study presented here focuses on the United States “Corn Belt,” where an extensive area is planted every year with mostly corn, soybean, and wheat. We explore the potential to generate regularly an alternate source of crop growth information independent of the data currently used in the soil moisture (SM) products developed with the SMAP mission. Our analysis explores the variability of the polarimetric ratio (PR), computed from the peak signals at V- and H-polarization, during the United States Corn Belt crop growing season in 2017. The approach facilitates the understanding of the evolution of the observed surfaces from bare soil to peak growth and the maturation of the crops until harvesting. We investigate the impact of SM on PR for low roughness scenes with low variability and considering each crop type independently. We analyze the sensitivity of PR to the selected crop height, VWC, VOP, and Normalized Differential Vegetation Index (NDVI) reference datasets. Finally, we discuss a possible path towards a retrieval algorithm based on Global Navigation Satellite System-Reflectometry (GNSS-R) measurements that could be used in combination with passive SMAP soil moisture algorithms to correct simultaneously for the VWC and SM effects on the electromagnetic signals.

The impact of shadow evacuation on evacuation time estimates for nuclear power plants

2015 ◽  
Vol 13 (2) ◽  
pp. 145 ◽  
Author(s):  
Kevin Weinisch, PE ◽  
Paul Brueckner, BA
Keyword(s):  
United States ◽  
Nuclear Power ◽  
Power Plants ◽  
The United States ◽  
Guidance Document ◽  
Shadow Region ◽  
Evacuation Time ◽  
Permanent Resident ◽  
The Us ◽  
The Impact

A shadow evacuation is the voluntary evacuation of people from areas outside a declared evacuation area. Shadow evacuees can congest roadways and inhibit the egress of those evacuating from an area at risk. Federal regulations stipulate that nuclear power plant (NPP) licensees in the United States must conduct an Evacuation Time Estimate (ETE) study after each decennial census. The US Nuclear Regulatory Commission (NRC) published federal guidance for conducting ETE studies in November 2011. This guidance document recommends the consideration of a Shadow Region which extends 5 miles radially beyond the existing 10-mile Emergency Planning Zone (EPZ) for NPPs. The federal guidance also suggests the consideration of the evacuation of 20 percent of the permanent resident population in the Shadow Region in addition to 100 percent of the declared evacuation region within the EPZ when conducting ETE studies. The 20 percent recommendation was questioned in a March 2013 report prepared by the US Government Accountability Office. This article discusses the effects on ETE of increasing the shadow evacuation from 20 to 60 percent for 48 NPPs in the United States. Only five (10 percent) of the 48 sites show a significant increase (30 minutes or greater) in 90th percentile ETE (time to evacuate 90 percent of the population in the EPZ), while seven (15 percent) of the 48 sites show a significant increase in 100th percentile ETE (time to evacuate all population in the EPZ). Study areas that are prone to a significant increase in ETE due to shadow evacuation are classified as one of four types; case studies are presented for one plant of each type to explain why the shadow evacuation significantly affects ETE. A matrix of the four case types can be used by emergency management personnel to predict during planning stages whether the evacuated area is prone to a significant increase in ETE due to shadow evacuation. Potential mitigation tactics that reduce demand (public information) or increase capacity (contraflow, traffic control points, specialized intersection treatments) to offset the impact of shadow evacuation are discussed.

Wrestling with 9/11: Immigrant Perceptions and Perceptions of Immigrants

2006 ◽  
Vol 3 (2) ◽  
pp. 107-124 ◽  
Author(s):  
Caroline Brettell
Keyword(s):  
United States ◽  
Immigration Policy ◽  
Asian Indians ◽  
World Trade Center ◽  
The United States ◽  
Fort Worth ◽  
Foreign Born ◽  
Immigrant Populations ◽  
Trade Center ◽  
The Impact

Soon after 9/11 a research project to study new immigration into the Dallas Fort Worth metropolitan area got under way. In the questionnaire that was administered to 600 immigrants across five different immigrant populations (Asian Indians, Vietnamese, Mexicans, Salvadorans, and Nigerians) between 2003 and 2005 we decided to include a question about the impact of 9/11 on their lives. We asked: “How has the attack on the World Trade Center on September 11, 2001 affected your position as an immigrant in the United States?” This article analyzes the responses to this question, looking at similarities and differences across different immigrant populations. It also addresses the broader issue of how 9/11 has affected both immigration policy and attitudes toward the foreign-born in the United States. 

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