Dynamic Coupling of the NMMB and CMAQ Models Through the U.S. National Unified Operational Prediction Capability (NUOPC)

Abstract

An earth system modeling framework (ESMF) that enables unprecedented insight into the various aspects of the geophysical sciences of Planet Earth in an integrated and holistic manner is needed to study the physical phenomena of weather and climate. The ESMF concept has recently been promoted and elevated by multiple governmental agencies and institutions in the U.S.A. to unify a standard engineering practice and coding protocol in building geophysical model interfaces towards efficient dynamic coupling of earth models and deployment of earth modeling systems for operational services. This new capability is called the National Unified Operational Prediction Capability (NUOPC) (available at http://www.nws.noaa.gov/nuopc/). This project demonstrates the efficacy of using NUOPC as the software package to efficiently in-line, or 2-way couple at every synchronization time-step, the dust prediction capability of the U.S. National Air Quality Forecasting Capability (NAQFC). The NAQFC in the National Centers for Environmental Prediction (NCEP) operations comprises of an off-line coupled National Weather Service (NWS) North American Mesoscale-model (NAM) and the U.S. EPA Community Air Quality Multiscale Model (CMAQ). The limitation of the off-line coupled NAM-CMAQ is that NAM gives meteorological prediction to CMAQ hourly and uni-directionally. This project attempted a new coupling paradigm allowing NAM and CMAQ communicate with one another per synchronization time-step at roughly 5 min intervals uni-directionally or bi-directionally. In this project, the NUOPC protocol was tightly followed and the in-line NAM-CMAQ ability tested to forecast fine mode particulates concentration with earth-crustal origin. A strong dust storm occurred in the South Western U.S. on May 11 2014 was used as a test case for the NUOPC in-line NAM-CMAQ forecasting capability. The forecast performance for the test case was evaluated against measured surface concentration of fine particulate smaller than 2.5 μm in diameter (PM_2.5).