Differencing strategies for SLR observations at the Wettzell observatory

The precise estimation of geodetic parameters using single- and double-differenced SLR observations is investigated. While the differencing of observables is a standard approach for the GNSS processing, double differences of simultaneous SLR observations are practically impossible to obtain due to the SLR basic principle of observing one satellite at a time. Despite this, the availability of co-located SLR telescopes and the use of the alternative concept of quasi-simultaneity allow the forming of SLR differences under certain assumptions, thus enabling the use of these processing strategies. These differences are in principle almost free of both, satellite- and station-specific error sources, and are shown to be a valuable tool to obtain relative coordinates and range biases, and to validate local ties. Tested with the two co-located SLR telescopes at the Geodetic Observatory Wettzell (Germany) using SLR observations to GLONASS and LAGEOS, the developed differencing approach shows that it is possible to obtain single- and double-difference residuals at the millimetre level, and that it is possible to estimate parameters, such as range biases at the stations and the local baseline vector with a precision at the millimetre level and an accuracy comparable to traditional terrestrial survey methods. The presented SLR differences constitute a valuable alternative for the monitoring of the local baselines and the estimation of geodetic parameters.

GNSS Double Differences Used as Beacon Landing System for Aircraft Instrument Approach

When using GNSS navigation for final approach guidance of aircraft to a landing site, the only systems currently available are differential GNSS with additional integrity data called augmentation systems. These work well when the landing site is fixed in space and well surveyed. In all other cases, augmentation systems are difficult to use. Here, we propose relative navigation based on GNSS double difference measurement to accomplish the same task, but also onto moving landing platforms or at unsurveyed locations. We call this the Beacon Landing System. Furthermore, we show long term measurement data confirming the sub-meter accuracy and results from flight tests. During the flight test we successfully used the relative navigation for aircraft guidance.

Exploration of the data space via trans-dimensional sampling: the case study of seismic double difference data

Double differences (DD) seismic data are widely used to define elasticity distribution in the Earth's interior, and its variation in time. DD data are often pre-processed from earthquakes recordings through expert-opinion, where couples of earthquakes are selected based on some user-defined criteria, and DD data are computed from the selected couples. We develop a novel methodology for preparing DD seismic data based on a trans-dimensional algorithm, without imposing pre-defined criteria on the selection of couples of events. We apply it to a seismic database recorded on the flank of Katla volcano (Iceland), where elasticity variations in time has been indicated. Our approach quantitatively defines the presence of changepoints that separate the seismic events in time-windows. Within each time-window, the DD data are consistent with the hypothesis of time-invariant elasticity in the subsurface, and DD data can be safely used in subsequent analysis. Due to the parsimonious behavior of the trans-dimensional algorithm, only changepoints supported by the data are retrieved. Our results indicate that: (a) retrieved changepoints are consistent with first-order variations in the data (i.e. most striking changes in the DD data are correctly reproduced in the changepoint distribution in time); (b) changepoint locations in time do correlate neither with changes in seismicity rate, nor with changes in waveforms similarity (measured through the cross-correlation coefficients); and (c) noteworthy, the changepoint distribution in time seems to be insensitive to variations in the seismic network geometry during the experiment. Our results proofs that trans-dimensional algorithms can be positively applied to pre-processing of geophysical data before the application of standard routines (i.e. before using them to solve standard geophysical inverse problems) in the so called exploration of the data space.

Multi-GNSS Single-Difference Baseline Processing at NGS with newly developed M-PAGES software

<p>The U.S. National Geodetic Survey (NGS) has historically processed dual-frequency GPS observations in a double-differenced mode using the legacy software called the Program for the Adjustment of GPS Ephemerides (PAGES). As part of NGS’ modernization efforts, a new software suite named M-PAGES (i.e., Multi-GNSS PAGES) is being developed to replace PAGES. M-PAGES consists of a suite of C++ and Python libraries, programs, and scripts built to process observations from all GNSS constellations. The M-PAGES team has developed a single-difference baseline processing strategy that is suitable for multi-GNSS. This approach avoids the difficulty of forming double-differences across systems or frequencies, which may inhibit integer ambiguity resolution. The M-PAGES suite is expected to deploy to NGS’ Online Positioning User Service (OPUS) later this year. Here, we present the processing strategy being implemented along with a performance evaluation from sample baseline solutions obtained from data collected within the NOAA CORS Network.</p>

Can Credit Recipient Household Escape from Poverty?

This study aims to answer whether or notfinancial distribution can play a role in development and poverty alleviation in Indonesia. Households who receive credit are treated as the analysis level and research object. Credit is an instrument to help households escaping from poverty. Some opinions believe that by being given credit, households will be able to boost their economic capacity both in terms of purchasing power or business development capacity. However, to prove this opinion as well as to answer the question, using panel data from the Indonesian Family Live Survey (IFLS) in 2007 and 2014 will attempt to estimate the effect of the probability of households receiving credit on their poverty status. The probability of a credit recipient householdwill be calculated using Propensity Score Matching so that a similarity score of household characteristics will be obtained between those who get credit and those who do not. Using Double Differences, this study will address the description of changes in household poverty status after receiving credit from financial institutions. The PSM calculations results show that there are four variables as credit recipient household’s characteristics, namely collateral ownership, the status of property ownership, history of natural disasters, and gender. Meanwhile, the estimation results on poverty status indicate that credit recipient households have a greater probability of escaping poverty than those who do not receive credit. Therefore, the anti-poverty policy through the transmission of financial institutions is relevant to be prepared. The anti-poverty policy is related to low credit interest rates through government subsidies, public fund placement with low cost of fund, increasing financial literacyand knowledge of the society, and adjusting credit approval based on regional economic conditions.

Farmer field schools for improving economic sustainability performance of Indonesian vegetable production

PurposeA research and development project disseminated ecological technologies to approximately 3,250 vegetable farmers through farmer field schools (FFS) in four districts of Bali and East Java provinces of Indonesia. This article aims to assess the economic sustainability of vegetable production after FFS participation.Design/methodology/approachA survey randomly sampled 500 farmers, comprised of FFS participants (50%) and non-FFS participants (50%). Based on 1,000 farm operations, this analysis employed input-saving technology as the fundamental model examined using the double-difference method. Simultaneous reduction of agrochemicals and improvement of productivity represent indicators of economic sustainability.FindingsResults indicate that pesticide use decreased without jeopardising farm productivity; moreover, vegetable production increased. These findings indicate that the ecological technologies transferred through FFS significantly improved economic sustainability performance.Research limitations/implicationsThis study purposively selected farmers who grew tomato and chilli. Thus, the outcomes are not generalisable to other crops.Practical implicationsFFS continues to be an effective method for transferring agricultural technologies to farmer communities. Policymakers are recommended to use FFS for disseminating beneficial and sustainable technologies to broader agricultural communities.Social implicationsThe adoption of ecological technologies provides positive economic and ecological milieus.Originality/valueThis study employs a double-differences approach to verify input-saving technological progress. Therefore, the performance of economic sustainability attributable to the project intervention is theoretically justified.

Present-day deformation in the Upper Rhine Graben from GNSS data

ABSTRACT The Upper Rhine Graben (URG) undergoes continuous microseismicity recorded by seismic monitoring networks and moderate-magnitude earthquakes, such as in the zone north of the Alpine front, which includes the Jura thrust front, the Vosges, the Black Forest, the Swabian Jura and the Alsace plain. The surface velocity field is a good indication of the occurrence and location of strain gradients likely associated with seismogenic structures. To explore that possibility, we use long time-series of displacements measured from 2002 to 2018 with the dense GURN network (GNSS URG Network). The processing based on double differences of phase measurements offers an up-to-date surface velocity field of the URG and surrounding areas. The surface velocity field relative to the Eurasia reference frame (ITR2014) points out some areas where coherent movements are present for groups of stations. The heterogeneous velocity field across the Rhine Graben (Vosges, URG, Black Forest and Swabian Jura) displays velocity values below 0.2 mm yr−1. We compute a deformation field from the GNSS velocities to link the deformation to the spatial distribution of earthquakes in the Rhine Graben. The earthquakes are concentrated south of an east–west line passing through Strasbourg to the Alpine front. Instrumental and historical seismicity presents spatial similarities in the Vosges and Swabian Jura. Considering the consistent northward movement observed in the Alpine front, we suggest that the strong seismicity in the south of the URG is caused by the shortening of the Alps. North of the URG, the seismicity is more dispersed where the velocity field does not show coherent movements.

The Rupture of the Hub -Spoke Effect of Bilateral Trade Flows when Rules of Origin are Relaxed: The Case of Agadir Agreement Countries.

This paper aims at shedding light on the extent to which the Agadir Association agreement has fostered inter regional trade between the EU_26 and the Agadir_4. It analyzes the remarkable variation in the spatial/sectoral structure of exports, and the extent to which it has been induced by the Agadir agreement itself or due to the adoption of RoO PANEURO diagonal cumulative scheme. The dataset covers a timeframe from [2000 - 2014] designed to account for sector specific final and intermediate exports through a bilateral gravity model and through tbe Poisson Pseudo Maximum Likelihood Estimator PPML. The methodological approach is considered to be a two-fold one which starts by screening final export and intermediate flows through conducting a ‘Hierarchal Cluster Analysis’. Second step proceeds by exposing the export flows of the 3 clusters to treatment with diagonal RoO through ‘The Double Differences Approach’ DID benchmarked to equally comparable control groups. Across all scenarios applied a remarkable significance of the interaction term combining both treatment effects and time, for the coefficients of 11 out of the 13 sectors were detected and it further asserted that treatment with diagonal RoO contributed to increasing intra-Agadir’s_4 final and intermediate exports and exports to E.U._26.