Implementation Plan of Korea Monsoon Experiment

1. Introduction

The "Changma" brings a significant amount of rainfall during June and July and is a major supplier of the national water resource in Korea. Meanwhile, it causes natural disaster related to water supply by its large interannual variation. Hong (1996) reported that the most frequent severe weather event in Korea is ``heavy rainfalls'' during the Changma season, which occupies 30% of occurrence among all natural disasters. Property loss due to heavy rainfalls reaches up to 70% of all total property loss in Korea. Another disaster related to Changma is ``drought''. In the estimation of property loss due to natural disasters, the impact of the droughts is not included in Table 1 due to the difficulty of the loss it being counted quantitatively. If the loss due to drought is included, total loss will grow several times by heavy rainfall alone. In fact, the 1995 winter drought in the southern part of the Korean peninsula was directly related to the considerably less rainfall during the Changma season of 1994.

To abate casualties from the severe weather events it is absolutely necessary to monitor and forecast them properly. However, because of its high temporal and spatial variability, there is insufficient information about the details of local heavy rainfall associated with eastward moving meso- to synoptic-scale disturbances that develop frequently along the Changma front. Given this circumstance, a more accurate prediction of seasonal and temporal precipitation might be one of the most urgent tasks to be accomplished in the near future. In order to achieve this goal, it is important to monitor the extreme weather events precisely, to analyze the observed data properly, and to understand these events clearly.

Although the accurate prediction of the Changma is imperative to minimize casualties, it is not yet well understood how the evolution features of the Changma system - on-set, intensity, duration, and retreat. Many scientists of east Asia and other countries including USA and Australia have recognized the importance of understanding both the atmospheric circulation and the water cycles of the east Asian monsoon. Relevant is the role of the east Asian monsoon in the energy transfer and water cycle of the global climate system to predict either short- or long-term variations of rainfall. They have planned several collaborative experiments to monitor the east Asian monsoon at China. The major planned projects are GAME (GEWEX Asian Monsoon Experiment) and SCSMEX (South China Sea Monsoon Experiment).

The participation of Korea in the GAME and SCSMEX project may provide a unique opportunity to establish a reasonable Changma monitoring system and enhance the confidence of long-term precipitation forecasts. To do this, the Korea Monsoon Study Panel (KMSP) was organized in 1995 to include experts from KMA, universities, and research institutions. KMSP provided a science plan of KORMEX (Korea Monsoon Experiment) on March 1996. The practical purposes of KORMEX are to produce a data set of the Changma and heavy rainfall, to understand the mechanism of the Changma and heavy rainfall and to improve predictability. There are two main distinct tasks in KORMEX: The first is to provide a data archiving system for researches on the dynamical and physical mechanism of the Changma. The second is to enhance the prediction capability through the modelling studies on the Changma with the use of the data set above to validate the model simulations.

2. Scientific Objectives of KORMEX

• to identify the Changma in terms of the energy and water cycle as a part of the Asian summer monsoon,
• to improve the short-term and seasonal prediction of on-set, duration and retreat of the Changma through the enhancing of the treatment of water cycle in the global climate models and numerical forecasting models,
• to elucidate the life cycle of meso- and synoptic-scale disturbances developed along the Changma front and then, to improve the prediction of heavy rainfall phenomena,
• to assess the impact of intraseasonal and interannual variability of the Changma on the regional water resource management.

3. Strategy for KORMEX

a) Production of essential data sets for various scale of disturbances related to the Changma collaborating with other field experiments, such as GAME and SCSMEX

The intensive regional process experiments will be deployed based on three-dimensional field campaigns, which aim to integrate and disintegrate the energy transfer and water cycle processes in Korea. Since Korea is located in the way of the northward migration of monsoon front, the intensive field experiment in the Korean peninsula may contribute to understanding, developing, maintaining, and decaying of meso- and synoptic-scale disturbances along the Changma front over the East China sea.

The KORMEX region is well covered by operational observation networks of meteorological and hydrological services and these observational data will be obtained from existing networks. Special observational data sets will be added to the standard data for the Keumkang river basin.

The radiative forcing, which depends upon cloud and aerosol distribution and surface hydrological conditions (snow cover, soil moisture, vegetation), affects not only the regional but also the large-scale monsoon circulation directly. The long-term monitoring of the surface radiation is essential to estimate energy budgets over the Asian monsoon region since the monsoon circulation is a thermally driven circulation due to differential radiative forcing between the continents and the oceans. The monitoring of the surface radiation by KORMEX might contribute to the radiation monitoring activities of GAME, and furthermore to the Global Atmospheric Watching (GAW), the Baseline Surface Radiation Network (BSRN), and the satellite-based Surface Radiation Budget (SRB) projects.

b) 4DDA for various scale processes in the energy transfer and water cycle

The various kinds of data sets will be obtained and collected through field observations. Based upon the meteorological and hydrological data sets obtained through the observations and monitoring related to KORMEX and special field experiments, the four-dimensional data assimilation will be performed by using the regional meso-scale as well as storm-scale models with a resolution of 40 km and 10 km, respectively. At the initial stage of 4DDA, the intensified in situ operational data together with the Keumkang river basin field observation data would be compiled as densely as possible, to conform to the resolution of the assimilation system. Finally, the satellite data and GAME re-analysis data will be utilized to produce highly qualified re-analysis data sets for the energy and water cycle involved in the Changma.

c) Understanding of heavy rainfall mechanism in Korea and then, seeking methodology to forecast floods precisely

The Keumkang river basin, a vulnerable region from heavy rainfall phenomenon in Korea, is selected for the site of intensive field observations of cloud processes, planetary-boundary layer, meso-scale atmospheric circulations and surface hydrological processes. The major goal of this intensive field observation might be the understanding of the dynamical and physical mechanisms of heavy rainfall phenomena. The assimilated data of this field experiment is essential for the meso-scale atmospheric modelling and local- or macro-scale hydrological modelling.

d) Conducting process studies for better representation of physical process modelling for better predictions of the Changma and associated heavy rainfalls

Process studies are essential to overcome the shortage of our knowledge on the processes and details governing the energy and water cycle. It is very hard to expect the improvement of numerical predictions without better representation of physical interactions among small scale processes. Including is the cloud-radiation and soil-vegetation-atmosphere, and the scale linkage between heavy rainfalls and large scale motions. The field observation experiment should also be designed to address the questions of process studies.

Modelling, particularly coupled modelling, is the means by which the knowledge of physical processes will be synthesized and tested. This work will be based on process studies and data collection activities. Optimal use will be made of previous modelling experiences and is strongly encouraged. These observational studies and numerical experiments will improve the understanding of the energy and water cycles.

e) Seeking a reasonable seasonal forecast on monsoon for better management of water resources

Understanding the local water cycle is the first thing to do in managing water resources properly. One major goal is to improve the prediction of monsoon and local floods. The intensive Kuemkang river basin field experiment is essential in the development and improvement of hydrological models. In the coupling of high resolution hydrological models with atmospheric models, the process studies are necessary including soil-vegetation-atmosphere interactions. This improvement of macro- and local-scale hydrological models for the major river basins will provide a better understanding of the regional water cycle and enhance the managing of water resource variations.

4. Achievement of KORMEX

a) Improvement in the Prediction of the Changma and related heavy rainfall events

The Changma is not only the major water supplier but the cause of numerous casualties. However, it is not an easy task to predict the Changma properly because the disturbances associated with the Changma front have a character to move rapidly toward Korea from the eastern edge of the Tibetan Plateau along the Changma front. One of the aims of the KORMEX program is improving the atmospheric models developed through coupling with hydrological models. Such models will improve the accuracy of operational weather forecasts as well as seasonal monsoon predictions in Korea.

b) Better Water Resource Management

Improved models for distributed and physically based descriptions of the hydrological cycle and the coupling with hydrological and atmospheric models in particular, will be of major importance in regard to aspects of water resource management. It will be possible to make an assessment of the impact of climate change on water resources, including hydraulic power production, agriculture, forestry, water supply, ground water recharge, and the occurrence of droughts and floods. These issues are very important considering the potential shortage of water resources as a result of industrialization in Korea. The coupled atmospheric-hydrological models have the potential to open new fields of practical applications.

c) Asian Monsoon Monitoring and Impact

The role of cloud systems and cumulus convections should be understood to reduce the uncertainties in seasonal predictions of the Asian monsoon in the climate models. To understand the monsoon multi-scale variability, it is also important to investigate the role of land surface processes over the Eurasian continent and that of water surfaces over the South China Sea. The KORMEX programme will collaborate to other programs, for example GAME and SCSMEX, to increase the understanding of energy and water fluxes over the Asia monsoon.

5. Elements of the KORMEX Program

a) Intensification of in situ observations

Existing operational observation networks of the Korea Meteorological Administration (KMA) will provide the bulk of the meteorological and hydrological data needed for physical initialization and validation of models and for diagnostic studies. Korea is one region in which a dense network of meteorological and hydrological stations exists including 400 AWS stations, 4 radiosonde stations, two mibile radars, two NEXRADs, five C-band weather radars. KMA will enhance its monitoring capability on the upper atmospheric motion, atmospheric moisture movement, and surface radiation monitoring. The satellite monitoring will be conducted by the remote sensing group with the data of GMS-5, TRMM and ADEOS-1 in collaboration with GAME.

b) The Kuemkang river basin field experiment with process studiess

A regional intensive field observation experiment has been planned at the catchment of the Kuemkang river basin in the mid-west part of the Korea peninsula. This site is not only one of the regions with heavy rainfall but also one of the covered regions with comprehensive network of weather radar stations and hydrological stations. Thus, this Kuemkang river basin field experiment may provide essential data to the development and improvement of atmospheric and hydrological models through various process studies.

c) Data assimilation

A climate data center will be set up to produce, collect, verify, and distribute KORMEX archives to data users. Four dimensional data assimilation systems will be developed by several groups based on high resolution models. The verified data and 4-DDA data will be distributed to the researchers and operational personnel to assist the estimation of mass circulation, energy and water distribution and variations near the Korea peninsula. This KORMEX data center will coordinate with neighboring countries to study the east Asian monsoon.

d) Numerical experiments

The numerical experiments including the coupling with atmospheric models and hydrological models is an important aspect of the KORMEX research. Many different scales of models will address specific scientific issues of KORMEX.

6. Implementation Schedule of KORMEX

1. Preparing stage (1995-1997)
   (a) to set up the observation schedule and investigate implementation potential,
   (b) to establish KMSP,
   (c) to organize the KORMEX Project Office and Study Group,
   (d) to establish the Steering System of the International Project in KORMEX,
   (e) to arrange the cooperation with the domestic and oversea,
   
   1995. 3.: the 1st international workshop on the Changma,
   1996. 9.: the 2nd international workshop on the Changma,
   1997. 3.: the 3rd international study conference of GAME,
   
   (f) to execute field experiment and improve AWS for KAIN.
   

2. Pre-IOP stage (1997)
   (a) to prepare each observation and preliminary experiment,
   (b) to verify and develop the data procedure and satellite image analysis algorithm,
   (c) to install the initial stage of the KAIN,
   (d) to develop the 4DDA method of KMA and METRI (after 1997).
   

3. IOP stage (1998-2000)
   (a) to work the field observation and experiment,
   (b) to analyse the satellite data,
   (c) to execute the intensive observation (Summer, 1998),
   (d) to verify the model adaptability and continue updating,
   (e) to process 4-dimensional assimilation data,
   

4. Post-IOP and longterm monitoring stage (1996-2005)
   (a) to install KAIN
   (b) longterm monitoring of KAIN (at least until 2005)
   (c) to execute high resolution 4-dimensional data assimilation for the regional observations and experiments.
   

7. Data Management

The ultimate goal of KAIN is to manipulate various data from the field observations. Included are KAIN, synoptic observations, satellite and radar observations, four-dimensional data assimilation, and climate data. Then the data will be disseminated to the operational and research centers for the understanding of hydro-meteorological processes, meso-scale structures of the Changma front, and associated water and energy balances over the Korean Peninsula and surrounding regions. The major activities of KAIN include data acquisition, quality control, analysis, data assimilation, and distribution. The main objectives of the data management in KORMEX are:

• to establish a data bank for the easy access to the hydro-meteorological data during monsoon period,
• to process the data through quality control and data assimilation,
• to collect relevant information from domestics and overseas, and
• to disseminate various data to research centers and/or operational organizations.

a) KORMEX Data Center

The aim of the KORMEX Data Center is to collect data, to check quality, to archive, and to maintain a database for retrieval and application. KMA or METRI are appropriate candidates for the data center, since those organizations already have appropriate facilities and expertise on the real-time data communication and 4-dimensional data assimilation.

The data centers will be established in the research institutes and universities. The main data center is responsible for both real-time database and climatological database for routine observations. The data produced from the IOP observations and other data in KORMEX are also archived as a backup in the main center. Supplementary data centers will supply special observations and other data which need particular treatment, including data classified as level 2. The data service unit will be established in the center to support the application from the users.

b) Archive

A database system will be implemented for the optimal utilization of KORMEX data. There are several benefits of using a well-designed database.

• Savings in management and maintenance of data
• Promptness in the development of application programs
• Flexibility in the various data processing
• On-line access and data processing

The factors to be considered for the configuration of database are stability, compactness, fast retrieval, convenience, transparency, and safetyness. The data will be stored in Optical disk, HDD, and CD-ROM along with other media like micro film and micro fiche. Part of the data will be stored in distributed database, which is linked with high speed data network.

c) Data Management Policy

Most of the data collected in KORMEX will be open for the research purpose. The guideline will be also applied to the data exchanged through an international program. The data will be distributed to the users with the minimum cost. Large volumes of data from model simulation output, satellite imagery and weather charts will be stored in CD-ROM for distribution. Small volumes of data can be accessed by anonymous ftp or websites through the internet. The data obtained from international programs can be supplied through various media such as magnetic tapes, cartridges, and diskettes, depending on the user's requirement.

The data produced in KORMEX will be primarily distributed to the participating agencies and researchers. Other users can also access the data through the KORMEX Data Center. The request of the data from foreign users will be forwarded to, and processed through the KORMEX joint steering committee.

It is a prerequisite for the success of KORMEX to have an open approach to the exchange of all relevant information concerning the project. In particular, all data obtained from field experiments, as well as the codes and algorithms developed during KORMEX and the results of numerical experiments, should be available as freely as possible for non-commercial research purposes within the KORMEX community.

The KORMEX Data center will cooperate with the GAME data center of MRI in Japan, HUBEX data center in China, SCSMEX, TIPEX, and HUAMEX for the mutual exchange of the meteorological data.

8. References