Current state of the global operational aerosol multi-model ensemble: An update from the International Cooperative for Aerosol Prediction (ICAP)
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
Authors: Xian, Peng; Reid, Jeffrey S.; Hyer, Edward J.; Sampson, Charles R.; Rubin, Juli, I; Ades, Melanie; Asencio, Nicole; Basart, Sara; Benedetti, Angela; Bhattacharjee, Partha S.; Brooks, Malcolm E.; Colarco, Peter R.; da Silva, Arlindo M.; Eck, Tom F.; Guth, Jonathan; Jorba, Oriol; Kouznetsov, Rostislav; Kipling, Zak; Sofiev, Mikhail; Perez Garcia-Pando, Carlos; Pradhan, Yaswant; Tanaka, Taichu; Wang, Jun; Westphal, Douglas L.; Yumimoto, Keiya; Zhang, Jianglong
Abstract
Since the first International Cooperative for Aerosol Prediction (ICAP) multi-model ensemble (MME) study, the number of ICAP global operational aerosol models has increased from five to nine. An update of the current ICAP status is provided, along with an evaluation of the performance of ICAP-MME over 2012-2017, with a focus on June 2016-May 2017. Evaluated with ground-based Aerosol Robotic Network (AERONET) aerosol optical depth (AOD) and data assimilation quality MODerate-resolution Imaging Spectroradiometer (MODIS) retrieval products, the ICAP-MME AOD consensus remains the overall top-scoring and most consistent performer among all models in terms of root-mean-square error (RMSE), bias and correlation for total, fine- and coarse-mode AODs as well as dust AOD; this is similar to the first ICAP-MME study. Further, over the years, the performance of ICAP-MME is relatively stable and reliable compared to more variability in the individual models. The extent to which the AOD forecast error of ICAP-MME can be predicted is also examined. Leading predictors are found to be the consensus mean and spread. Regression models of absolute forecast errors were built for AOD forecasts of different lengths for potential applications. ICAP-MME performance in terms of modal AOD RMSEs of the 21 regionally representative sites over 2012-2017 suggests a general tendency for model improvements in fine-mode AOD, especially over Asia. No significant improvement in coarse-mode AOD is found overall for this time period.
Experimental investigation on mahua methyl ester blended with diesel fuel in a compression ignition diesel engine
INTERNATIONAL JOURNAL OF AMBIENT ENERGY
Authors: Kumar, M. Vijay; Babu, A. Veeresh; Kumar, P. Ravi
Abstract
In this article, the mahua tree's high importance in the present-day plantations is described and the preparation of mahua methyl ester (MME) from the raw mahua seed oil by the two methods of the transesterification process is described. The tested physical properties were compared with the requirement of ASTM D-6751. The obtained MME and its blends of B20, B40, B60, and B80 were investigated in an unmodified diesel engine. From the results of the performance, it has been observed that brake-specific fuel consumption and brake thermal efficiency are slightly improved (B20 and B40) at part-load conditions and approach diesel at full-load conditions. From combustion analysis, it was seen that ignition delay was shorter for biodiesel and its blends compared with the diesel fuel. The emission characteristics of carbon monoxide, hydrocarbons, and smoke opacity were reduced for all the fuel blends, but at high temperatures they undergo an endothermic reaction and produced various oxides of nitrogen.