Essays on natural resources and labor economics

This dissertation consists of five empirical chapters spanning the areas of natural resource economics and labor economics. After a general introduction in chapter one, the next four chapters deal with how households respond to exogenous changes to economic opportunities such as shocks to employment or to life expectancy at birth. The fifth chapter investigates the linkage between agricultural management and ecosystem services. The dissertation makes extensive use of household survey data, both from the US and from a large number of cross-country surveys. The first two chapters show that unemployment during recessions may lower households’ recreation expenditure but increase households’ participation in local outdoor recreation activities. The findings from the third and fourth chapters suggest that rising life expectancy at birth increases years in school as well as lifetime earnings, which reinforces the role of health in economic development. The final chapter provides an estimate of the environmental benefits associated with the set of agricultural conservation practices identified in Iowa nutrient reduction Strategy 2013. The economic value from local recreation and aesthetics, drinking water purification, reduced soil erosion, and reduced greenhouse gas emissions are sizable and under some assumptions are of same order of magnitude as the estimated costs

Forecast of Total Electron Content over Europe for disturbed ionospheric Conditions

A general picture of the occurrence of ionospheric storms as function of local time, season and location is known from numerous studies over the past 50 years. Nevertheless, it is not yet possible to say how the ionosphere will actually respond to a given space weather event because the measurements of the onset time, location of maximum perturbation, amplitude and type of storm (positive or negative) deviate much from the climatology. However, statistical analyses of numerous storm events observed in the Total Electron Content (TEC) since 1995 enable to estimate and predict a most probable upcoming perturbed TEC over Europe based on forecasts of geomagnetic activity. A first approach will be presented here. The forecast of perturbed TEC is part of the Forecast System Ionosphere build under the umbrella of the FP7 project AFFECTS∗ (Advanced Forecast For Ensuring Communication Through Space). It aims to help users mitigating the impact on communication system

Ionospheric Propagation Effects on GNSS Signals and New Correction Approaches

The ionosphere is the ionized part of the earth’s atmosphere lying between about 50 km and several earth radii (Davies, 1990) whereas the upper part above about 1000 km height up to the plasmapause is usually called the plasmasphere. Solar extreme ultraviolet (EUV) radiation at wave lengths < 130 nm significantly ionizes the earth’s neutral gas. In addition to photoionisation by electromagnetic radiation also energetic particles from the solar wind and cosmic rays contribute to the ionization. The ionized plasma can affect radio wave propagation in various ways modifying characteristic wave parameters such as amplitude, phase or polarization (Budden, 1985; Davies, 1990). The interaction of the radio wave with the ionospheric plasma is one of the main reasons for the limited accuracy and vulnerability in satellite based positioning or time estimation. A trans-ionospheric radio wave propagating through the plasma experiences a propagation delay / phase advance of the signal causing a travel distance or time larger / smaller than the real one. The reason of the propagation delay can be realized considering the nature of the refractive index which depends on the density of the ionospheric plasma. The refractive index (n ≠ 1) of the ionosphere is not equal to that of free space (n = 1). This causes the propagation speed of radio signals to differ from that in free space. Additionally, spatial gradients in the refractive index cause a curvature of the propagation path. Both effects lead in sum to a delay / phase advance of satellite navigation signals in comparison to a free space propagation. The variability of the ionospheric impact is much larger compared to that of the troposphere. The ionospheric range error varies from a few meters to many tens of meters at the zenith, whereas the tropospheric range error varies between two to three meters at the zenith (Klobuchar, 1996). The daily variation of the ionospheric range error can be up to one order of magnitude (Klobuchar, 1996). After removal of the Selective Availability (SA, i.e., dithering of the satellite clock to deny full system accuracy) in 2000, ionosphere becomes the single largest error source for Global Navigation Satellite Systems (GNSS) users, especially for high-accuracy (centimeter - millimeter) applications like the Precise Point Positioning (PPP) and Real Time Kinematic (RTK) positioning. Fortunately, the ionosphere is a dispersive medium with respect to the radio wave; therefore, the magnitude of the ionospheric delay depends on the signal frequency. The advantage is that an elimination of the major part of the ionospheric refraction through a linear combination of dual-frequency observables is possible. However, inhomogeneous plasma distribution and anisotropy cause higher order nonlinear effects which are not removed in this linear approach. Mainly the second and third order ionospheric terms (in the expansion of the refractive index) and errors due to bending of the signal remain uncorrected. They can be several tens of centimeters of range error at low elevation angles and during high solar activity conditions. Brunner & Gu (1991) were pioneers to compute higher order ionospheric effects and developing correction for them. Since then higher order ionospheric effects have been studied by different authors during last decades, e.g., Bassiri & Hajj (1993), Jakowski et al. (1994), Strangeways & Ioannides (2002), Kedar et al. (2003), Fritsche et al. (2005), Hawarey et al. (2005), Hoque & Jakowski (2006, 2007, 2008, 2010b), Hernández-Pajares et al. (2007), Kim & Tinin (2007, 2011), Datta-Barua et al. (2008), Morton et al. (2009), Moore & Morton (2011). The above literature review shows that higher order ionospheric terms are less than 1% of the first order term at GNSS frequencies. Hernández-Pajares et al. (2007) found sub-millimeter level shifting in receiver positions along southward direction for low latitude receivers and northward direction for high latitude receivers due to the second order term correction. Fritsche et al. (2005) found centimeter level correction in GPS satellite positions considering higher order ionospheric terms. Elizabeth et al. (2010) investigated the impacts of the bending terms described by Hoque & Jakowski (2008) on a Global Positioning System (GPS) network of ground receivers. They found the bending correction for the dual-frequency linear GPS L1-L2 combination to exceed the 3 mm level in the equatorial region. Kim & Tinin (2011) found that the systematic residual ionospheric errors can be significantly reduced (under certain ionospheric conditions) through triple frequency combinations. All these studies were conducted to compute higher order ionospheric effects on GNSS signals for ground-based reception. Recently Hoque & Jakowski (2010b, 2011) investigated the ionospheric impact on GPS occultation signals received onboard Low Earth Orbiting (LEO) CHAMP (CHAllenging Minisatellite Payload) satellite. In this chapter, the first and higher order ionospheric propagation effects on GNSS signals are described and their estimates are given at different level of ionospheric ionization. Multi-frequency ionosphere-free and geometry-free solutions are studied and residual terms in the ionosphere-free solutions are computed. Different correction approaches are discussed for the second and third order terms, and ray path bending correction. Additionally, we have proposed new approaches for correcting straight line of sight (LoS) propagation assumption error, i.e., ray path bending error for ground based GNSS positioning. We have modelled the excess path length of the signal in addition to the LoS path length and the total electron content (TEC) difference between a curved and LoS paths as functions of signal frequency, ionospheric parameters such as TEC and TEC derivative with respect to the elevation angle. We have found that using the TEC derivative in addition to the TEC information we can improve the existing correction results

Economic Valuation of Ecosystem Benefits from Conservation Practices Targeted in Iowa Nutrient Reduction Strategy 2013: A Non Market Valuation Approach

With the aim of improving water quality, the Iowa Nutrient Reduction Strategy 2014 sets a goal of reducing agricultural non-point-source generated nitrogen load by 41 percent and phosphorus load by 29 percent in Iowa’s waterways. The “strategy” describes several land use that could achieve those reductions, such as widespread adoption of conservation practices in farming, land retirement, and wetland restoration that can meet the specified target reduction. The goal of the current study is to identify the range of ecosystem benefits resulting from the conservation practices associated with each of these scenarios and apply a nonmarket valuation method to monetize as many of these co-benefits as possible. The results will inform policymakers and stakeholders regarding the efficiency of the program

Agricultural Trade Liberalization and Downstream Market Power: The Ad Valorem Case

Exports of agricultural commodities to developed countries play a significant role in the economies of many developing countries. The elimination of import tariffs has the potential to benefit producers in the developing countries, but estimates of the extent of the gains from trade liberalization typically assume perfect competition. Significant concentration in the food processing and retailing sectors of the U.S. and the EU undermine the plausibility of this assumption in the case of agricultural trade, however. Sexton, Sheldon, McCorriston, and Wang (2007) develop a model of the effects of trade liberalization that accounts for the vertically-linked and concentrated characteristics of the developed countries’ food markets. Their analysis is limited to the case of a constant per unit tariff, however. In this paper, we extend the analysis of the effects of trade liberalization in the presence of downstream market power to the case of an ad alorem tariff, and we find important qualitative differences from the results for the unit tariff case

Transionospheric Microwave Propagation: Higher-Order Effects up to 100 GHz

Ionospheric refraction is considered as one of the major accuracy limiting factors in microwave space-based geodetic techniques such as the Global Positioning System (GPS), Satellite Laser Ranging (SLR), very-long-baseline interferometry (VLBI), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and satellite altimetry. Similarly, a high-performance ground-to-space and space-to-ground microwave link is considered to be very important for synchronizing clocks in global networks. Moreover, precise time and frequency transfer may lead to new applications in navigation, Earth observation, solar system science, and telecommunications. However, all transionospheric microwave signals are subject to ionospheric refraction and subsequent delays in the travel time. Since the ionosphere is a dispersive medium for radio signals, the first-order propagation effect can be removed by combining signals at two or more frequencies. Anyway, higher-order ionospheric effects remain uncorrected in such combinations. The residuals can significantly affect the accuracy of precise positioning, navigation, as well as the performance of time and frequency transfer. Here, we studied ionospheric propagation effects including higher-order terms for microwave signals up to 100 GHz frequencies. The possible combination between the L, S, C, X, Ku, and Ka band frequencies is studied for the first-order ionosphere-free solutions. We estimated the higher-order propagation effects such as the second- and third-order terms and ray-path bending effects in the dual-frequency group delay and phase advance computation. Moreover, the correction formulas originally developed for global navigation satellite systems (GNSS) L-band frequencies are tested for mitigating residual errors at higher frequencies up to 100 GHz

Estimation of GPS Differential Code Biases Based on Independent Reference Station and Recursive Filter

The differential code bias (DCB) of the Global Navigation Satellite Systems (GNSS) receiver should be precisely corrected when conducting ionospheric remote sensing and precise point positioning. The DCBs can usually be estimated by the ground GNSS network based on the parameterization of the global ionosphere together with the global ionospheric map (GIM). In order to reduce the spatial-temporal complexities, various algorithms based on GIM and local ionospheric modeling are conducted, but rely on station selection. In this paper, we present a recursive method to estimate the DCBs of Global Positioning System (GPS) satellites based on a recursive filter and independent reference station selection procedure. The satellite and receiver DCBs are estimated once per local day and aligned with the DCB product provided by the Center for Orbit Determination in Europe (CODE). From the statistical analysis with CODE DCB products, the results show that the accuracy of GPS satellite DCB estimates obtained by the recursive method can reach about 0.10 ns under solar quiet condition. The influence of stations with bad performances on DCB estimation can be reduced through the independent iterative reference selection. The accuracy of local ionospheric modeling based on recursive filter is less than 2 Total Electron Content Unit (TECU) in the monthly median sense. The performance of the recursive method is also evaluated under different solar conditions and the results show that the local ionospheric modeling is sensitive to solar conditions. Moreover, the recursive method has the potential to be implemented in the near real-time DCB estimation and GNSS data quality chec

Distributional impact of political violence : evidence from differential impacts on commodity price

The economic cost of political violence is well documented, studying its effect on a myriad of economic indicators such as manufacturing productivity, export performance, comparative advantage, cost of production, etc. While these are very important issues capturing largely long run effect of the political violence, short run welfare loss of the citizen due to political instability is mostly absent from the literature. One salient channel through which political instability impacts welfare is the price of essential food items. Our study uses political strikes of Bangladesh to examine its impact on rice price. We particularly use three types of rice – fine, medium and coarse to capture how the impact varies with the quality of rice and thus different income groups of buyers. We use daily retail and weekly wholesale price data of each district from Department of Agricultural Marketing (DAM) for the period 2010-2016 and pair them up with the incidence of strike data compiled by Ahsan and Iqbal (2016). The richness of this high frequency data allows us to control for all types of time and district invariant confounders using fixed effects. The results show that on the day of strike, rice price increases and this increase is higher for coarse rice. It indicates that the political strikes is costly for the ordinary citizen and the cost is disproportionately large on the poor more, who are the consumers of lower quality rice

Political instability and stock market returns : evidence from firm-level panel data of securities in Bangladesh

Conflict, political uncertainty and its impact on stock market has been a subject of interest in the literature. However, no study has yet explored the impact of political strikes on stock market outcomes. Political strike -- locally known as Hartal in Bangladesh -- is a different form of conflict than war or street protest, which is recurrent in nature. Using Dhaka Stock Exchange daily trading data of firms for the period 2005-2015 and controlling for a host of variables such as day, month, year, day-of-year trend and firm fixed effects, we find that political strike has a negative and statistically significant impact on stock market return. Our results show that, on the day of a political strike, stock market return drops about 0.14% which is economically sizable. This effect gets pronounced as the frequency of strike increases, based on week, month or year count of occurrences. Impact heterogeneity reveals that large firms are affected more from hartals compared to smaller firms

Ionospheric scintillations studies using Spire and COSMIC-2 radio occultation and GOLD satellite data

Low-earth orbits (LEO) satellites have been harnessing the concept of GNSS radio occultation (RO) for several atmospheric applications. With the advent of CubeSat technology, many space companies are now extending the GNSS-RO for ionospheric and space weather studies. This study demonstrates the capabilities of Spire’s constellation of CubeSats in detecting ionospheric scintillations. High rate 50 Hz GNSS measurements received by the STRATOS receivers onboard Spires’s CubeSats are used to detect scintillations over low latitude African sector. Spire’s GNSS-RO atmPhs files are accessed from University Corporation for Atmospheric Research (UCAR) data repository along with COSMIC-2 conPhs files. The amplitude scintillation index (S4) is computed for each COSMIC-2 and Spire RO profiles. While COSMIC-2 conPhs files are restricted to tangent point altitudes up to 130 km, the scintillation detection algorithm onboard Spire receivers enable to downlink the associated 50 Hz phase and pseudorange data of the extended RO profiles (up to zenith). Spire’s extended RO profiles enable to detect F-layer amplitude scintillations often occurring in post-sunset hours. The occurrences of scintillations are corroborated by equatorial plasma bubble (EPB) structures observed from NASA’s Global‐scale Observations of the Limb and Disk (GOLD) satellite. This study indicates the potential of Spire GNSS-RO data in augmenting and complementing ionospheric scintillation studies available from COSMIC-2 and other similar RO missions. This apability can provide an important contribution to scintillation monitoring and can further be extended to space weather nowcasts and forecasts