Observations of Greenhouse Gas Isotopologues with ACE-FTS and WACCM

Increases in greenhouse gas concentrations in the atmosphere are the major driver of climate change. Quantifying the sources and sinks of these gases is a major focus of research. Measuring isotopologues, or molecules that differ in isotopic composition, is one useful way of constraining the budget of a molecule as they are highly sensitive to different sources and sinks. However, measurements above the surface have been restricted to a few locations and have only reached the lower stratosphere. Satellite-based remote sensing can achieve nearly global measurement coverage, but so far no satellites have measured isotopologues. Presented here are measurements of isotopologues of CH4, CO, CO2, and N2O in the stratosphere and mesosphere collected using the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS). These measurements are complemented by model runs using the Whole Atmosphere Community Climate Model (WACCM). Both data sets show the strong influence of transport in the upper atmosphere on the isotopic distribution of these molecules. In addition, WACCM accurately calculates the abundances of isotopologues previously measured via balloon and aircraft. These data sets show the usefulness of satellite-based measurements of isotopologues in the upper atmosphere

ATMOSPHERIC ISOTOPOLOGUES OBSERVED WITH ACE-FTS AND MODELED WITH WACCM

Atmospheric isotopologues are useful tracers of dynamics and chemistry and can be used to constrain budgets of gases in the atmosphere. The Atmospheric Chemistry Experiment (ACE) routinely measures vertical profiles of over 35 molecules and 20 isotopologues via solar occultation from a satellite in low Earth orbit. The primary instrument is an infrared Fourier transform spectrometer with a spectral range of 750 – 4400 wn and a resolution of 0.02 wn. ACE began taking measurements in 2004 and is still active today. This talk focuses on isotopic measurements of CH$_{4}$, CO, CO$_{2}$, and N$_{2}$O from ACE-FTS. To complement ACE-FTS data, modeling using the Whole Atmosphere Community Climate Model (WACCM) was performed for each molecule._x000d

A Near-Global Atmospheric Distribution of N2O Isotopologues

The distributions of the four most abundant isotopologues and isotopomers (N2O, 15NNO, N15NO, and NN18O of nitrous oxide have been measured in the Earth\u27s stratosphere by infrared remote sensing with the Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer. These satellite observations have provided a near-global picture of N2O isotopic fractionation. The relative abundances of the heavier species increase with altitude and with latitude in the stratosphere as the air becomes older. The heavy isotopologues are enriched by 20-30% in the upper stratosphere and even more over the poles. These observations are in general agreement with model predictions made with the Whole Atmosphere Community Climate Model (WACCM). A detailed 3-D chemical transport model is needed to account for the global isotopic distributions of N2O and to infer sources and sinks

Global Stratospheric Measurements of the Isotopologues of Methane From the Atmospheric Chemistry Experiment Fourier Transform Spectrometer

This paper presents an analysis of observations of methane and its two major isotopologues, CH3D and 13CH4, from the Atmospheric Chemistry Experiment (ACE) satellite between 2004 and 2013. Additionally, atmospheric methane chemistry is modeled using the Whole Atmospheric Community Climate Model (WACCM). ACE retrievals of methane extend from 6 km for all isotopologues to 75 km for 12CH4, 35 km for CH3D, and 50 km for 13CH4. While total methane concentrations retrieved from ACE agree well with the model, values of δD-CH4 and δ13C-CH4 show a bias toward higher δ compared to the model and balloon-based measurements. Errors in spectroscopic constants used during the retrieval process are the primary source of this disagreement. Calibrating δD and δ13C from ACE using WACCM in the troposphere gives improved agreement in δD in the stratosphere with the balloon measurements, but values of δ13C still disagree. A model analysis of methane\u27s atmospheric sinks is also performed

Causation, complexity, and the concert: the pragmatics of causal explanation in international relations

A causal explanation provides information about the causal history of whatever is being explained. However, most causal histories extend back almost infinitely and can be described in almost infinite detail. Causal explanations therefore involve choices about which elements of causal histories to pick out. These choices are pragmatic: they reflect our explanatory interests. When adjudicating between competing causal explanations, we must therefore consider not only questions of epistemic adequacy (whether we have good grounds for identifying certain factors as causes) but also questions of pragmatic adequacy (whether the aspects of the causal history picked out are salient to our explanatory interests). Recognizing that causal explanations differ pragmatically as well as epistemically is crucial for identifying what is at stake in competing explanations of the relative peacefulness of the nineteenth-century Concert system. It is also crucial for understanding how explanations of past events can inform policy prescription

The Power of Social Intelligence: Sepuluh Cara jadi Orang Yang Pandai Bergaul

The Power of Social Intelligence mengupas tuntas hal-hal efektif, sederhana, dan praktis untuk meraih Kecerdasan Sosial pembaca. Di dalamnya terdapat cara-cara yang membantu pembaca untuk: meningkatkan semua aspek kemampuan sosial pembaca, baik dalam pergaulan maupun pekerjaan, menjadi lebih percaya diri, mempunyai kehidupan sosial yang lebih aktif dan sukse, s dapat berkomunikasi dengan lebih baik