A-Train Data Depot - Bringing Atmospheric Measurements Together

This paper describes the satellite data processing and services that constitute current functionalities of the A-Train Data Depot. We first provide a brief introduction to the original geometrical intricacies of the platforms and instruments of the A-Train constellation, and then proceed with description of our ATrain collocation processing algorithm that provides subsets that facilitate synergistic use of the various instruments. Finally, we present some sample image products from our web-based Giovanni tool which allows users to display, compare and download coregistered A-Train related data

A-Train Data Depot: Integrating and Exploring Data Along the A-Train Tracks

The immense potential for new science findings as a result of inter-instrument data analysis has led to the development of a new data portal at GSFC: the A-train Data Depot. The power and utility of this new service to the general public is amplified immensely when the archived data are used in conjunction with online data analysis services like Giovanni. This presentation details some of the challenges of data usage from multiple distinct missions and how the tool sets we have developed can help to overcome these challenges, considerably cut down on analysis overhead and promote science exploration in an otherwise very challenging arena

Contributions to the foundations of a safety case for the use of GNSS in railway environments

The use of GNSS in the railways for passenger information services and selective door opening is already commonplace but the advancement of this increasingly popular navigation technique into safety of life rail applications has been hindered by the unknown level of measurement error caused by the local rail environment, especially that due to multipath. Current state of the art receiver technologies are discussed along with the additional advantages of signal differencing using local base stations. Limiting factors for hardware in a kinematic environment are also discussed and specific examples to the rail environment highlighted. Safety critical analysis techniques such as FMEA, HAZOP and FTA are reviewed to illustrate the evaluation of safety integrity values and the possibility of system risk, leading to the formation of a structured safety case. Three main data sets from electrified, rural and urban rail environments have been collected using dual frequency geodetic receivers in order to enable analysis of multipath effects in normal railway operations. The code and phase data have been combined to compute fluctuations in multipath errors and these have been used to characterise this effect in both space and time. Where phase positioning is possible comparisons with standard code-based positions have been made to assess the overall quality of the type of GNSS positioning expected to be operationally-viable on the railways. Experiments have also been undertaken to evaluate the possible effects of electromagnetic radiation from overhead cables used to power the trains. Finally, the ways in which the results of these experiments can be used to help build a safety case for the use of GNSS on the railways are discussed. Overall it is concluded that it is unlikely that multipath errors or electromagnetic interference will be the limiting factors in utilising GNSS for safety-critical railway applications

Geographic and Seasonal Distributions of CO Transport Pathways and Their Roles in Determining CO Centers in the Upper Troposphere

Past studies have identified a variety of pathways by which carbon monoxide (CO) may be transported from the surface to the tropical upper troposphere (UT); however, the relative roles that these transport pathways play in determining the distribution and seasonality of CO in the tropical UT remain unclear. We have developed a method to automate the identification of two pathways ('local convection' and 'advection within the lower troposphere (LT) followed by convective vertical transport') involved in CO transport from the surface to the UT. This method is based on the joint application of instantaneous along-track, co-located, A-Train satellite measurements. Using this method, we find that the locations and seasonality of the UT CO maxima in the tropics were strongly correlated with the frequency of local convective transport during 2007. We also find that the 'local convection' pathway (convective transport that occurred within a fire region) typically transported significantly more CO to the UT than the 'LT advection -> convection' pathway (advection of CO within the LT from a fire region to a convective region prior to convective transport). To leading order, the seasonality of CO concentrations in the tropical UT reflected the seasonality of the 'local convection' transport pathway during 2007. The UT CO maxima occurred over Central Africa during boreal spring and over South America during austral spring. Occurrence of the 'local convection' transport pathway in these two regions also peaked during these seasons. During boreal winter and summer, surface CO emission and convection were located in opposite hemispheres, which limited the effectiveness of transport to the UT. During these seasons, CO transport from the surface to the UT typically occurred via the 'LT advection -> convection' pathway.NASA Aura Science Team NNX09AD85GJackson School of Geosciences at the University of Texas at AustinNASA Jet Propulsion Laboratory at the California Institute of TechnologyGeological Science

Improvements to the OMI Near-uv Aerosol Algorithm Using A-train CALIOP and AIRS Observations

The height of desert dust and carbonaceous aerosols layers and, to a lesser extent, the difficulty in assessing the predominant size mode of these absorbing aerosol types, are sources of uncertainty in the retrieval of aerosol properties from near UV satellite observations. The availability of independent, near-simultaneous measurements of aerosol layer height, and aerosol-type related parameters derived from observations by other A-train sensors, makes possible the direct use of these parameters as input to the OMI (Ozone Monitoring Instrument) near UV retrieval algorithm. A monthly climatology of aerosol layer height derived from observations by the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) sensor, and real-time AIRS (Atmospheric Infrared Sounder) CO observations are used in an upgraded version of the OMI near UV aerosol algorithm. AIRS CO measurements are used as a reliable tracer of carbonaceous aerosols, which allows the identification of smoke layers in areas and times of the year where the dust-smoke differentiation is difficult in the near-UV. The use of CO measurements also enables the identification of elevated levels of boundary layer pollution undetectable by near UV observations alone. In this paper we discuss the combined use of OMI, CALIOP and AIRS observations for the characterization of aerosol properties, and show a significant improvement in OMI aerosol retrieval capabilities

The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 1

These papers comprise a peer-review selection of presentations by authors from NASA, LPI industry, and academia at the Second Conference (April 1988) on Lunar Bases and Space Activities of the 21st Century, sponsored by the NASA Office of Exploration and the Lunar Planetary Institute. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics covered by this volume include (1) design and operation of transportation systems to, in orbit around, and on the Moon, (2) lunar base site selection, (3) design, architecture, construction, and operation of lunar bases and human habitats, and (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology

Climate change impacts and mitigation : reducing CO2 emissions from the freight transport sector : lessons for Mexico from the UK experience and future policy

The United Kingdom and Mexico have established goals to reduce CO2 emissions. With the publication of the Climate Change act in 2008 Britain acknowledges that is technologically ready to implement changes to bring important reductions of CO2 emissions. Mexico included Climate Change abatement in its 2007 development program. UK aims to achieve a reduction of 80% and Mexico a reduction of 50% in their CO2 emissions by the year 2050. To achieve these reductions both countries face the challenge of improving activities such as better use of fuels, for example natural gas for energy production or diesel used in road freight transport vehicles. Freight transport currently accounts 25% of global carbon emissions; with road freight as the fastest growing sector for both countries. The use of biofuels or clean energy powered vehicles is far from a 100% implementation in the fleet. Because of this improving the fuel efficiency in the current operation signifies an opportunity to reduce emissions. The United Kingdom is ahead in legislation through taxation, market incentives and research to encourage reductions from freight transport. Mexico is in its way to the creation of a Climate Change Law. This dissertation aims to determine which lessons Mexico can learn from the United Kingdom in its improvement of freight transport sector in two levels. The Macro level looks at legislation and private sector initiatives, and the Micro level simulating 11 scenarios using real data from operation of a food manufacturer provided by the StarFish Project. The scenarios simulate the implementation of a series of best practice recommendations to reduce emissions and improve operation. The results evidence that at a Macro level Mexico can implement legislation mechanisms to stimulate the reduction of CO2 emissions in the transport sector. At a Micro level the simulations show that even for developed countries like the United Kingdom there is a big potential to reduce carbon emissions from the freight transport sector. The outcome of the dissertation is that learn from experiences from other countries applies not only for Mexico and other developing countries but for every country aiming to improve the reduction of CO2 emissions

The OCO-2 oxygen A-band response to liquid marine cloud properties from CALIPSO and MODIS

Spectra of reflected sunlight in the oxygen A-band contain information about cloud properties such as cloud top pressure, optical depth, and pressure thickness. Here we show, for the first time, that high-spectral-resolution A-band Orbiting Carbon Observatory-2 (OCO-2) spectra respond largely as simulated to the optical properties of water clouds over ocean during November 2015 (N = 184,318) using input cloud properties from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua and the Cloud-Aerosol Lidar with Orthogonal Polarization on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). In A-band continuum channels the standard deviation of simulated minus observed radiance is ±37%. Selecting horizontally homogeneous clouds to mitigate three-dimensional cloud effects and collocation error with the other satellites, the standard deviation of the residuals is reduced to ±18%. Using a look-up table developed from simulations, OCO-2's estimated cloud top pressure for low clouds (Ptop > 680 hPa) has a standard deviation of ±61 hPa relative to CALIPSO retrievals, and bias is dependent on assumed cloud pressure thickness, with our smallest value being −5 hPa. Versus MODIS optical depth, the standard deviation is ±9.0 and the bias is −2.0, although these shrink for clouds of τ < 30. These values include collocation error between the different satellites, meaning that they place an upper bound on the OCO-2 retrieval uncertainty. The theoretical precision limit from OCO-2's instrumental uncertainty is shown to be ±2.4 hPa in above-cloud path and ±0.2% in optical depth for a two-channel retrieval. Options for retrieving cloud optical depth, cloud top pressure, and pressure thickness are discussed in the context of a formal OCO-2 cloud property retrieval