Statistical adjoint sensitivity distributions of meteorological forecast errors of Asian dust transport events in Korea

Abstract

A B S T R A C TThe sensitivities of meteorological forecast errors associated with Asian dust transport events to changes in the initial state were evaluated for 46 occurrences that affected the Korean Peninsula from 2005 to 2010. Adjoint-based sensitivities were used to determine these sensitivities. Sensitive regions were located primarily over two regions upstream from the Korean Peninsula: the northern source region, including areas of Mongolia and northern China, and the Tibetan Plateau. Depending on transport trajectories, month, and year, the sensitive regions were located over either the northern source regions or the Tibetan Plateau. That is, the Asian dust forecast in Korea was found to be sensitive to the meteorological fields over the northern source regions, but also those over the Tibetan Plateau even though the latter is not a dust source region or an upstream area according to the transport trajectories. Employing additional observations at existing instrumentation sites or developing new observational sites in both sensitive regions could be beneficial in reducing the atmospheric circulation forecast errors in East Asia, thus improving the accuracy of transport forecasts of Asian dust events affecting the Korean Peninsula.

Effect of Observation Network Design on Meteorological Forecasts of Asian Dust Events

“…Asian dust events are an important spring phenomenon in East Asia. Recently, the importance of predicting Asian dust events on the Korean Peninsula has been increased because of the increasing number of events (Sugimoto et al 2003), the increasing occurrence frequency in fall and winter in South Korea (Kim et al 2013), and the longer duration of individual events. To mitigate the social and economic damage from Asian dust events, accurate forecasts of such events are essential.…”

“…In terms of the effect of meteorological forecasts on chemical transports, Sistla et al (1996), Biswas and Rao (2001), Zhang et al (2007), and Liu et al (2011) showed that small uncertainties in meteorological input to transport models result in large uncertainties in ozone and CO 2 predictions. In this sense, the uncertainties in the meteorological forecasts could cause large errors in Asian dust forecasts on the Korean Peninsula Kim and Kay 2010;Kim et al 2013).…”

“…The transport paths of Asian dust connecting the dust source regions to the Korean Peninsula are closely associated with extratropical pressure systems over East Asia (e.g., Chung and Park 1997;Uno et al 2001;Kim et al 2013). During Asian dust events on the Korean Peninsula, typically a high pressure system follows behind a surface frontal cyclone over the Korean Peninsula (e.g., Merrill and Kim 2004;Kim et al , 2013. showed that difficulties in forecasting the path of the dust and the location and speed of the high pressure system behind a surface frontal cyclone over the Korean Peninsula caused an incorrect forecast for the Asian dust event that occurred during 7-9 April 2006.…”

“…However, no studies have considered the effect of the observation network for meteorological forecast fields specifically during Asian dust events using a realistic modeling system. In addition, although the Korea Meteorological Administration (KMA) collects meteorological and dust [e.g., particulate matter 10 (PM10) concentration] data from surface observation sites operated by the KMA and the China Meteorological Administration (CMA) over the Asian dust source regions, these sites were determined subjectively, and the observational data are insufficient to produce accurate Asian dust predictions (Kim et al , 2013. Therefore, to determine an optimal observation network for meteorological forecasts during Asian dust events, the characteristics of observation networks were investigated for 11 Asian dust events that affected the Korean Peninsula from 2005 to 2010 by performing observing system simulation experiments (OSSEs) using the Weather Research and Forecasting (WRF) Model.…”

“…First, the characteristics of randomly fixed and adaptive observation networks were investigated for various observation densities and distances between observation sites. Adaptive observation strategies are used to design the observation network because they employ more objective criteria to decide observational sites, which improve meteorological transport forecasts associated with Asian dust events, as mentioned in Kim et al (2013). The adaptive observation networks were determined according to adjoint sensitivity analyses.…”