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EPA \ TAQMN \ Dust Storm \ Forecast

Forecast

In order to assess whether dust storm affect the air quality of Taiwan, the Environmental Protection Administration has accumulated related data such as the path of past dust storm that have invaded Taiwan, atmospheric information related to dust storm and others to establish a early warning process flow that describes the affect of dust storm on air quality.

Confirmation of Dust Storm in the East-Asia Region

The method of confirmation mainly rests in weather report analysis at regular intervals that are, according to the World Meteorological Organization (WMO) released by international weather stations every 3 or 6 hours (at 2 AM, 5 AM.......8 PM, and 11 PM). Therefore, with a complete forecast of the east-Asian region we can assess the strength and scale of occurring dust storm.

During dust storm season (November to May), Environmental Protection Administration personnel begin at 9 AM using the WINS system to retrieve 3 hour interval weather reports in the east-Asian region to confirm whether there are dust storm occurring in China's northwest, northern, and Mongolian regions starting from 5 AM the previous day to 8 AM the next day.

China has currently established a Chinese dust storm web page and with the convenience of the Internet, early warning personnel can log on this page to view observation, forecast, and reports related to dust storm. Recently China has also established air quality control centers in various areas; therefore, referencing the air quality information of various Chinese cities can also help in analyzing the strength, transportation, and effect of dust storm.

Assessing Possible Effect of Dust Storm on Taiwan

After dust storm have been confirmed in the China or Mongolia regions, the next step is to assess whether the weather will affect Taiwan. East-Asia dust storm mainly occur at 35 degree north latitude and 125 degrees east longitude in the northern, northeastern, and Mongolian regions of China and when they occur, micro particles of dust are lifted 3000 meters into the air and transported east by the west wind. Usually, the dust particles are sent east from Beijing to Korea or Japan and does not directly affect Taiwan. Therefore, when observing the weather we must take into consideration China's cold front system, which is advantageous in transporting dust to the east-west that can also be transported through the northeastern seasonal winds to in turn affect Taiwan, or possibly lower longitudes.

The EPA, using our dust storm early warning program, can handle a forecast from 5 days prior. When a dust storm that can potentially affect Taiwan occurs, the EPA personnel will reference the dust storm early warning programs of the United States and Japan to assess the strength and duration of the dust storm.

However if the dust storm is affected by the fronts in the rain cloud regions during transportation, it is beneficial for the settlement of the suspended micro particles. The EPA references the weather forecast programs of the central weather bureau, Japan, and the United States to analyze whether the route of the dust storm is affected by rain for a combined assessment of a dust storm affect on Taiwan.

Supplementary Assessment of Dust Storm Movement Position

Using the data collected by the MODIS satellite, the EPA analyzes graphical data based on full color, aerosol, and optical depth to triangulate the position of the dust storm. However, this method is restricted by the need to reposition the satellite and clouds. As there are many clouds in dust storm areas, the movement route of dust storm systems are often obstructed by clouds, making it hard to pinpoint the location of these storms. This leads to great difficulty in identifying these dust storm when they move out of their point of origin to the eastern sea, marking an obstacle that technology must conquer.

Confirmation of Air Quality Monitoring

From past reports monitoring Taiwan's air quality and related research studies, it is evident that dust storm move south from China's cold front into the northeastern seasonal winds which is why the EPA has established monitoring stations in the northeastern, northwestern, and eastern regions of Taiwan with even the Yang Ming monitoring station in the national park and the Matsu station established in '88 being capable of assessing the origin of foreign pollutants. The air quality around these monitoring stations is usually unaffected by local pollution with the density of suspended micro particles in the air at 50 micro-grams or lower per cubic meter. When foreign pollutants affect the air, the density of micro particles in the air increase to more than 100 micro-grams per cubic meter while showing signs of increased density from north to south, and from the coast to in-land.

The EPA personnel use the previous day's suspended micro particle data gathered from the air quality monitoring centers to assess whether Taiwan's air quality is affected by the dust storm of east Asia. Using the data gathered from these super monitoring stations, aside from being able to analyze the suspended particle density in the air (PM10 and PM2.5 ), it can simultaneously analyze the density of sulfate, nitrate, organic carbon, and inorganic carbon along with the amount and diameter of secondary micron-particles in suspension to grasp the characteristics of the micro particles in the dust storm.

Forecast

Confirmation of LIDAR Monitoring Data

When dust storm affect Taiwan, they cause an increase in the aerosol of our air which is why in 1992 the EPA instituted LIDAR in National Central University. This device can monitor the vertical plane of aerosol in the air, which can help us understand the dispersion and strength of the dust storm in a vertical space.

Confirmation of Post Content Analysis

According to the process above we can make preliminary confirmation that the dust storm of east Asia do affect Taiwan. However, that is an indirect affirmation which is why to further confirm the increase in density of micro particles in the air is in fact from east-Asian dust storm, micro particles gathered on filtered paper can be observed through qualitative methods. During dust storm, the PM10 samples from multiple monitoring stations show micro particles with a yellow-brown color, which is apparently different from the gray to gray-black gathered when there are no dust storms. This shows that the source of PM10 pollutants differs from normal.

During quantitative analysis of the EPA in a case dated to March 12th, 2005 PM10 micro particle samples were found to contain large amounts of Al and Ca during dust storm periods. The increase in ratio of basic gold and basic earth elements were similar to the characteristics of east-Asian dust storm; therefore, from content analysis we can further confirm that the rapid rise in PM10 density stems from dust storm in east Asia.

last update : 2017/07/31

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