Convective outflow of South Asian pollution: A global CTM simulation compared with EOS MLS observations

A global 3-D chemical transport model is used to analyze observations of carbon monoxide (CO) and upper tropospheric clouds from the EOS Microwave Limb Sounder (MLS). MLS observations during 25 August–6 September 2004 reveal elevated CO and dense high clouds in the upper troposphere over the Tibetan plateau and southwest China, collocating with the upper level Tibetan anticyclone. Model simulations indicate the transport of boundary layer pollution by Asian summer monsoon (ASM) convection and orographic lifting to the upper troposphere over South Asia, where simulated distributions of CO resemble MLS observations. Model results also show elevated aerosols in the anticyclone region. Analysis of model simulated CO and aerosols indicate that the Tibetan anticyclone could ‘trap’ anthropogenic emissions lifted from northeast India and southwest China. These aerosols may be responsible for the formation of some of the dense high clouds.Engineering and Applied Science

Comparing the Structures and Photophysical Properties of Two Charge Transfer Co-crystals

In the search for molecular materials for next-generation optoelectronic devices, organic co-crystals have emerged as a promising class of semiconductors for their unique photophysical properties. This paper presents a joint experimental-theoretical study of ground and excited state charge transfer (CT) interactions in two CT co-crystals. Reported herein is a novel CT co-crystal Npe:TCNQ, formed from 4-(1-naphthylvinyl) pyridine (Npe) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules via molecular self-assembly. The electronic structure and photophysical properties of Npe:TCNQ are compared with those of the co-crystal composed of Npe and 1,2,4,5-tetracyanobenzene (TCNB) molecules, Npe:TCNB, reported here with a higher-symmetry (monoclinic) crystal structure than previously published. Npe:TCNB and Npe:TCNQ dimer clusters are used as theoretical model systems for the co-crystals and their electronic structure is compared to that of the extended solids via periodic boundary conditions density functional theory (PBC DFT). UV-Vis absorption spectra of the dimers are computed with time-dependent density functional theory (TD-DFT) and compared to experimental UV-Vis diffuse reflectance spectra. Both Npe:TCNB and Npe:TCNQ are found to exhibit neutral character in the S0 state and ionic character in the S1 state. The degree of CT in the S0 state of Npe:TCNB is found to be slightly smaller than that of Npe:TCNQ, as predicted from differences in electron affinities of the acceptors. Furthermore, the degree of CT in the S1 state of Npe:TCNB is found to be slightly higher than that of Npe:TCNQ, aligning with predictions employing a recently developed orbital similarity metric

Supporting Information for "Comparing the Structures and Photophysical Properties of Two Charge Transfer Co-crystals"

There are two main folders in this directory, named NpeTCNB and NpeTCNQ.Each folder of these two has three folders named Ground_State_Calculations, TDDFT_Calculations, and PBC_Calculation. These folders has the structures that are reported in the manuscript.The naming convention used is as follows:1) The conformers name start with Str and with a number, ex: Str1, Str2, etc...2) The functional is also included in the conformer name, ex: Str1-B3LYP, Str1-CAM-B3LYP3) The basis sets are labeled as:a) B0 for 6-31G(d,p)b) B1 for 6-31+G(d,p)c) B2 for 6-311+G(d,p)4) When empirical dispersion is used, the file name has "GD3" in the name, ex: Str1-CAM-B3LYP-B0-GD3.log</p

The Earth Observing System Microwave Limb Sounder (EOS MLS) on the Aura Satellite

The Earth Observing System Microwave Limb Sounder measures several atmospheric chemical species (OH, HO2, H2O, O3, HCl, ClO, HOCl, BrO, HNO3, N2O, CO, HCN, CH3CN, volcanic SO2), cloud ice, temperature, and geopotential height to improve our understanding of stratospheric ozone chemistry, the interaction of composition and climate, and pollution in the upper troposphere. All measurements are made simultaneously and continuously, during both day and night. The instrument uses heterodyne radiometers that observe thermal emission from the atmospheric limb in broad spectral regions centered near 118, 190, 240, and 640 GHz, and 2.5 THz. It was launched July 15, 2004 on the National Aeronautics and Space Administration's Aura satellite and started full-up science operations on August 13, 2004. An atmospheric limb scan and radiometric calibration for all bands are performed routinely every 25 s. Vertical profiles are retrieved every 165 km along the suborbital track, covering 82 S to 82 N latitudes on each orbit. Instrument performance to date has been excellent; data have been made publicly available; and initial science results have been obtained

Early Validation Analyses of Atmospheric Profiles from EOS MLS on the Aura Satellite

We present results of early validation studies using retrieved atmospheric profiles from the Earth Observing System Microwave Limb Sounder (MLS) instrument on the Aura satellite. 'Global' results are presented for MLS measurements of atmospheric temperature, ozone, water vapor, hydrogen chloride, nitrous oxide, nitric acid, and carbon monoxide, with a focus on the January-March 2005 time period. These global comparisons are made using long-standing global satellites and meteorological datasets, as well as some measurements from more recently launched satellites. Comparisons of MLS data with measurements from the Ft. Sumner, NM, September 2004 balloon flights are also presented. Overall, good agreeement is obtained, often within 5% to 10%, but we point out certain issues to resolve and some larger systematic differences; some artifacts in the first publicly released MLS (version 1.5) dataset are noted.We comment briefly on future plans for validation and software improvements