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A precipitation system developed continuously along the western coastline of the Korean Peninsula and created considerable precipitation both along the coast and inland on 26 July 2011. In this study, the causes for this nearshore convective system are investigated from observations and the results of model experiments. Three-dimensional radar fields clearly show that a change of wind at the surface border played an important role in the development of the nearshore convection system. The simulation results, which are very similar to the observations, show that the surface border generated and maintained the convergence zone. The roughness change enhanced the convergence, and the interaction between the deepening cold pool and downward flow maintained the convergence zone. The surface mechanical discontinuity affected by the roughness change between sea and land formed the convergence (gradient of wind stress), which induced momentum transfer to the upper layer. The cold pool created a steep gradient of potential temperature and provided the reason for the propagated convergence zone with the downward flow. The maximum value of the surface change factor, which comprises the influencing factors for the long-lasting convective system, reflects the enhancement of the system at the coast.

This study explores the characteristics of drop size distribution (DSD) using PARticle SIze and VELocity (Parsivel) disdrometer at Jincheon (JC; 36.9 °N, 127.5 °E) and Miryang (MY; 35.5 °N, 128.6 °E) sites, during the period June 2015 to March 2016. Twelve cases were selected from Parsivel disdrometer data to compare the characteristics of DSDs between central and southeastern Korea. The average DSD at both sites shows a similar pattern; there is a slightly larger magnitude of small drops at JC. A comparison was undertaken on average raindrop spectra at JC and MY during three different rainfall systems; namely the Changma (CS), Localized low pressure (LS), and Typhoon (TS) system. Rainfall at JC tends to have more raindrops than MY especially over small diameter drops (0.31−0.81 mm). The differences in JC and MY may be attributed to the errors related to use of the Parsivel disdrometer, differences in the amounts of rainfall, or differences in the prevailing rainfall systems (CS, LS, and TS). Total monthly rainfall at JC and MY were 783.10 (726.92) and 781.80 (701.17) mm, respectively based on the rain gauge and Automatic Weather Stations (AWS). However, there was good agreement (within 7%−11%) between Parsivel disdrometer data and data obtained from the rain gauges or AWS. The average raindrop spectra at JC tends to have more raindrops than MY in different rainfall systems especially over small drops. During CS, the rainfall at JC is higher than MY across all the diameters on July 23, 2015. During LS at both sites there is a similar pattern, but with slightly larger diameter at JC as measured on August 16, 2015 (D> 6.5 mm). The rainfall at JC during TS tends to have more small drops compared to MY on July 12, 2015. The DSD characteristics are different across rainfall systems and climatic regions.

In this study, we propose a new methodology for analysis of the initial stage of localized convective precipitation. The developed algorithm was used to create three-dimensional constant-altitude plan-position-indicator (3D CAPPI) data, which are high-spatiotemporal-resolution volumetric data, using two X-band polarimetric radars that are located in the Kanto region of Japan. Advection vectors are estimated by applying the normalized cross-correlation method to observed successive precipitation echoes on the polar coordinate system at each antenna tilt angle. The estimated advection vectors are expressed by a linear regression model that depends on time and tilt angle. In addition, 3D CAPPI data utilize the mosaic method to obtain further precipitation information from radar observations. The algorithm produces the detailed 3D structure of rapidly developing convective cells and provides quantitative information on convective precipitation, such as the echo top height, maximum reflectivity, and appearance time and height of each cell. The 3D CAPPI mosaic also clearly shows the back-building process at the initial stage of convective precipitation.

This paper is concerned with the temporal variation characteristics of two meteorological factors (temperature and humidity) in four metropolitan cities (Seoul, Busan, Daegu, Daejeon) in South Korea. Data are extracted from seven years (2008 to 2014) of hourly time series data in meteorological offices of the Korea Meteorological Administration. Using the detrended cross-correlation analysis (DCCA) method, the DCCA coefficient of temperature is compared to that of humidity from daily time series data during four seasons in the four metropolitan cities. In particular, as window size s increases, the DCCA cross-correlation coefficient approaches 0.034 at a time lag of 14 days in the case of spring in Seoul. We find the weak cross-correlation between temperature and humidity at different time lags of 14, 21 and 28 days in spring in Seoul, and the errors E T in the ANN are relatively larger values than that of any other season in both the ANN and the MRM. Particularly, in the ANN model, there exist relatively a large error value of temperature as the characteristics of the non-stationary, deterministically chaotic and noisy meteorological data extracted for the short-term prediction rather than the long-term prediction.

Wet snow may cause significant damage to humans and property, and thus, it is necessary to estimate the corresponding liquid fraction (FL). Consequently, the FL of wet snow was estimated using a novel technique; specifically, the particle shape irregularity (Ir) was estimated through the particle coordinate information obtained using 2-D video disdrometer (2DVD) measurements. Moreover, the possibility of quantitively estimating FL via Ir, based on the temperature (T), was examined. Eight snowfall cases from 2014 to 2016 were observed through a 2DVD installed in Jincheon, South Korea, to analyze the dominant properties of physical variables of snowflakes (i.e., the terminal velocity (VT), particle density (ρs), Ir, and FL) and the corresponding relationships according to the T ranges (−4.5 < T (°C) < 2.5) in which wet snow can occur. It was clarified that the volume-equivalent particle diameter (D)–FL and D–Ir relationships depended on T, and a relationship existed between Ir and FL. The analysis results were verified using the Yong-In Testbed (YIT) S-band weather radar and T-matrix scattering simulation. The D–FL relationship was implemented in the scattering simulation, and the results indicated that the simulated reflectivity (ZS) was highly correlated with the observed reflectivity (ZO) under all T classes. These features can provide a basis for radar analysis and quantitative snowfall estimation for wet snow with various FL values.

Typhoon Khanun caused over 226 mm of accumulated rainfall for 6 h (0700 to 1300 UTC), localized around the summit of Mt. Halla (height 1950 m), with a slanted rainfall pattern to the northeast. In this study, we investigated the enhancement mechanism for precipitation near the mountains as the typhoon passed over Jeju Island via dual-Doppler radar analysis and simple trajectory of passive tracers using a retrieved wind field. The analysis of vertical profiles of the mountain region show marked features matching the geophysical conditions. In the central mountain region, a strong wind (≥ 7 m s− 1) helps to lift low-level air up the mountain. The time taken for lifting is longer than the theoretical time required for raindrop growth via condensation. The falling particles (seeder) from the upper cloud were also one of the reasons for an increase in rainfall via the accretion process from uplifted cloud water (feeder). The lifted air and falling particles both contributed to the heavy rainfall in the central region. In contrast, on the leeward side, the seeder-feeder mechanism was important in the formation of strong radar reflectivity. The snow particles (above 5 km) were accelerated by strong downward winds (≤−6 m s− 1). Meanwhile, the nonlinear jumping flow (hydraulic jump) raised feeders (shifted from the windward side) to the upper level where particles fall. To support these development processes, a numerical simulation using cloud-resolving model theoretically carried out. The accreting of hydrometeors may be one of the key reasons why the lee side has strong radar reflectivity, and a lee side weighted rainfall pattern even though lee side includes no strong upward air motion.

We study the temporal and spatial variation characteristics of meteorological factors (temperature, humidity, and wind velocity) at a meteorological tower located on Bosung-gun of South Korea. We employ the detrended cross-correlation analysis (DCCA) method to extract the overall tendency of the hourly variation from data of meteorological factors. The relationships between meteorological factors are identified and quantified by using DCCA coefficients. From our results, we ascertain that the DCCA coefficient between temperature and humidity at time lag m = 24 has the smallest value at the height of 10 m of the measuring tower. Particularly, the DCCA coefficient between temperature and wind speed at time lag m = 24 has the largest value at a height of 10 m of the measuring tower

Tools to identify and classify stratiform and convective rains at various times of the 12 days from June 2015 to March 2016 in Jincheon, Korea, were developed by using a Parsivel disdrometer and S-band polarimetric (S-POL) radar data. Stratiform and convective rains were identified using three different methods (vertical profile of reflectivity (VPR), the method proposed by Bringi et al. (BR03), and a combination of the two (BR03-VPR)) by using a Parsivel disdrometer for its applications to radar as a reference. BR03-VPR exhibits a better classification scheme than the VPR and BR03 methods. The rain types were compared using the drop size distribution (DSD) retrieved from polarimetric variables and reflectivity only. By using the DSD variables, a new convective/stratiform classification line of the log-normalized droplet number concentration ( log 10 N w ) − median volume diameter ( D 0 ) was derived for this area to classify the rainfall types using DSD variables retrieved from the polarimetric radar. For the radar variables, the method by Steiner et al. (SHY95) was found to be the best method, with 0.00% misclassification of the stratiform rains. For the convective rains, the DSD retrieval method performed better. However, for both stratiform and convective rains, the fuzzy method performed better than the SHY95 and DSD retrieval methods.

To investigate the impact of rainfall type on rainfall estimation using polarimetric variables, rainfall relations such as those between rain rate (R) and specific differential phase (KDP), between R and KDP/differential reflectivity (ZDR), and between R and reflectivity (Z)/ZDR, were examined with respect to the precipitation type classified using drop size distributions (DSDs) measured by a disdrometer. The classification of rainfall type was assessed using four different methods: temporal rainfall variation, and the relations between intercept parameter (N0) and R, normalized intercept parameter (Nw) and median diameter (D0), and slope parameter (&Lambda, ) and R. The logN0&ndash, R relation discriminated between convective and stratiform rain with less standard deviation than the other methods as shown by the Z&ndash, ZDR scatter with respect to the rainfall types. The transition type from convective to stratiform and vice versa occurred in the stratiform rain region for all methods. To apply the classified rainfall relations to radar rainfall estimation, logNw and D0 were retrieved from polarimetric variables to discriminate the rainfall types in the radar domain. The DSD classification was verified with the vertical profile of reflectivity extracted at two positions corresponding to gage sites. Statistical analysis of four different rainfall events showed that rainfall estimation using the relations with precipitation type were better than those obtained without classification. The R(KDP,ZDR) relation with classification performed best on rainfall estimation for all rainfall events. The greatest improvement in rainfall estimation was obtained from R(Z,ZDR) with classification. We conclude that the classification of rainfall type leads to more accurate rainfall estimation. The different relations R(KDP), R(KDP,ZDR), and R(Z,ZDR) with respect to the rain types using polarimetric radar show improvement compared to estimation without consideration of rainfall type, in Korea.

During the 2012 Changma season of June and July, we conducted an intensive field observation to investigate the microphysical characteristics of orographic precipitation that passed around Mt. Halla (oriented west–east; height: 1950 m; width: 78 km; length: 35 km) in South Korea's Jeju Island. On July 04, 2012, Jeju Island experienced a convective precipitation system that developed in the southern part of a stationary front. With the goal of understanding the microphysical process of this system (precipitation intensity: 70 mm h−1), we collected detailed data using 7 Parsivel disdrometers, a ground-based dual S-band Doppler radar, and GPS sounding. The convective precipitation developed in a considerably warm and moist environment (near-surface relative humidity: 94%) with dominant southwesterly winds of 4.7 m s−1 at low altitudes. The convective region was formed by a combination of coastal ascending air and considerably warm and moist low-level marine inflow. The coastal warm and moist ascending air activates the warm rain process of moisture uptaken from sea surface, increasing the concentration of large-sized raindrops (diameter: ≥ 5 mm). The continuous development of a convective region extending from the foothill to the upslope highlights that the convective updrafts continuously supply low-level moisture to the convective region. This influx of moisture and the condensation of small-, middle-, and large-sized raindrops combine to create a significant concentration of large-sized raindrops along the upslope of the mountain. Around the mountaintop, the fall of precipitation drives the breakup process aided by convective ascending airs, increasing the concentrations of small-sized raindrops. On the leeward side, the existence of orographically generated stationary wind convergences is notable. As a result and the marine inflow along the southeastern gentle slope, i.e., the convective region, continues to develop, thereby activating cold rain processes. This study sheds light on the variety of raindrop size distributions and moisture processes at locations relative to a single-peak mountain leading to localized heavy precipitation during the passage of an isolated convective precipitation event.

The internal structure and microphysical properties of a rainband of Typhoon Kong-Rey (TY), which occurred in 2018, and of the rainfall system indirectly affected by the typhoon (IA) that passed through the southern part of the Korean Peninsula in October 2018, were analyzed by operational S-band weather radars and particle size and velocity (PARSIVEL) disdrometers. The height of maximum intensity (Hc in km) of the IA was located at an elevation of ~ 7.5 km; moreover, in the TY regime, the column maximum (Cmax in dBZ) continuously increased up to 45 dBZ at all observation sites, while Hc decreased to 5 km. The IA showed hardly any increase in temperature during precipitation, differently from the TY. In the TY, the maximum fall velocity (Vmax) of raindrops with maximum diameters (Dmax) comprised between 2 and 3 mm was about 1 m s−1 lower than that of drops during precipitation derived from the typhoon's indirect impact. Convective precipitation in the IA presented the following raindrop size distribution (DSD) characteristics within an interval of 18 h (from 21:00 local standard time (LST) on 4 October to 15:00 LST on 5 October): the mass-weighted mean diameter (Dm) and the logarithmic normalized intercept parameter (logNw) were comprised between 1.3 and 1.5 mm and 3.8–4.3, respectively. However, TY showed large temporal variation within an interval of 15 h: Dm and logNw ranged between 1.2 and 2.9 mm and 2.9–4.6, respectively. Additionally, at rainfall rates (R) of 5–15 mm h−1, the shape parameter (μ) of the IA varied between 4 and 7, while that of the TY between 2 and 10.

To classify precipitation types as either convective or stratiform, drop size distributions (DSDs) measured by the Parsivel (PARticle size VELocity) instrument, and DSD parameters including median volume diameter (D 0 ) and normalized number concentration (Nw) retrieved by S-band polarimetric radar (BSL), were analyzed for a heavy rainfall event that occurred in southern Korea on 25 August 2014. The rainfall system was clearly identified as stratiform or convective rain at various times of day, at measurement sites at Changwon and Busan. New rainfall classification lines were derived from the Parsivel and BSL data, and were compared with existing classification methods based on climatological rainfall data. The classification methods using logNw-D 0 , logN 0 -rainrate, and slope-rainrate domain proposed in previous two studies performed well when applied to the new data if the slope and/or intercept values were changed. Another method using logN 0 -slope domain was not possible to classify the precipitation types well in the study area, as the best-fit line could not be obtained. The average measured D 0 and Nw values obtained from polarimetric radar were compared with climatological precipitation data, measured in both the tropics and mid-latitudes. And new separation line was obtained for the rainfall at the southern part of Korea.

In this paper, we study the multifractal structure and its property from the number of end stones, which means the number of stones on the board at the end of a game, in the Baduk game. We mainly estimate the generalized Hurst exponent, the Renyi exponent, and the singularity spectrum for the time-series data of the number of end stones via multifractal detrended fluctuation analysis. For three segments, we mainly simulate and analyze the multifractal strength in Baduk games with four players. Particularly, the results obtained for games with four players are compared to each other and analyzed in detail.

Three methods for determining the reflectivity bias of single polarization radar using dual polarization radar reflectivity and disdrometer data (i.e., the equidistance line, overlapping area, and disdrometer methods) are proposed and evaluated for two low-pressure rainfall events that occurred over the Korean Peninsula on 25 August 2014 and 8 September 2012. Single polarization radar reflectivity was underestimated by more than 12 dB and 7 dB in the two rain events, respectively. All methods improved the accuracy of rainfall estimation, except for one case where DSDs were not observed, as the precipitation system did not pass through the disdrometer location. The use of these bias correction methods reduced the RMSE by as much as 50%. Overall, the most accurate rainfall estimates were obtained using the overlapping area method to correct radar reflectivity. A combination of all three methods would produce more accurate rainfall estimates, provided optimal values are determined for the domain size for the overlapping area method, the sample number threshold for the equidistance line method, and the reflectivity threshold for the disdrometer method.

In this paper, the utility and the correlation technique of the detrended cross-correlation analysis and the combined detrended cross-correlation analysis methods are treated for the stochastic properties of the random walk and the Levy flight via nucleotide sequence data. Data are extracted definitely from twelve genomic DNA sequences (HUMHBB 1-6, Amazonmolly, Bushbaby, Cow, Dolphin, Elephant, and Tarsier) of the GenBank databank. We mainly simulate and analyze scaling exponents for three methods in 1D and 2D random walks and Levy flights. To compare each other between one gene and the other gene in the twelve genomic DNA sequences, the value of the detrended cross-correlation coefficient ρ D C C A in {HUMHBB3} and {Dolphin} genes is shown the largest value 0.214 in the 1D Levy flight with μ = 1 . 5 compared to other sets. The detrended cross-correlation coefficient ρ D C C A in {HUMHBB4} and {HUMHBB6} genes is shown the smallest value -0.231 in the 1D Levy flight with μ =1.5. We particularly find that the combined detrended cross-correlation coefficient ρ C D C C A in the two cases of {HUMHBB3}+{Bushbaby} and {HUMHBB6}+{Dolphin} has the largest value 0.331 in the 1D random walk compared to other sets, while that in {HUMHBB3}+{Tarsier} and {HUMHBB4}+{Elephant} has the smallest value -0.295 in the 1D Levy flight with μ = 1 . 5 .

The empirical relationships used to estimate rainfall amounts from polarimetric radar observations were developed and tested by using long-period drop size distribution (DSD) data and monitoring of rainfall events prior to operational use in Korea. Rainfall associated with Typhoon Meari in 2011 was selected to assess the performance of these relationships for point and areal rainfall amounts. Data quality was checked in regions of light rain to enable the quantitative use of polarimetric variables. The distributions of the cross-correlation co-efficient and standard deviation of the differential phase shift agreed with those established in a previous study, but the absolute average deviation of differential reflectivity (ZDR) was a little distorted. Biases in reflectivity (Z) and differential reflectivity were calculated following established methods and found to be –0.18 and 0.47 dB, respectively. The accuracy of rainfall amounts calculated from R(KDP) and R(KDP, ZDR) was poor. The best estimates of rainfall were obtained using R(Z, ZDR) based on DSDs from Oklahoma (OKC) in the USA and Busan (BSC) for both the point and areal mean cases. Correlation co-efficients of R(Z, ZDR) using the BSC DSDs were better than those using the OKC DSDs for areal mean rainfall amounts. Rainfall amounts in this particular case in Korea were estimated more accurately using the Brandes drop shape for R(Z, ZDR) than the equilibrium drop shape.

In countries with frequent aerial military exercises, chaff particles that are routinely spread by military aircraft represent significant noise sources for ground-based weather radar observation. In this study, a cost-effective procedure is proposed for identifying and removing chaff echoes from single-polarization Doppler radar readings in order to enhance the reliability of observed meteorological data. The proposed quality control procedure is based on three steps: 1) spatial and temporal clustering of decomposed radar image elements, 2) extraction of the clusters’ static and time-evolution characteristics, and 3) real-time identification and removal (or censoring) of target echoes from radar data. Simulation experiments based on this procedure were conducted on site-specific ground-echo-removed weather radar data provided by the Korea Meteorological Administration (KMA), from which three-dimensional (3D) reflectivity echoes covering hundreds of thousands of square kilometers of South Korean territory within an altitude range of 0.25–10 km were retrieved. The algorithm identified and removed chaff clutter from the South Korean data with a novel decision support system at an 81% accuracy level under typical cases in which chaff and weather clusters were isolated from one another with no overlapping areas.

In order to improve the accuracy of quantitative precipitation estimates, we correct radar reflectivity measurements by a “sorting and moving average” (SMA) method and with a POSS (precipitation occurrence sensing system) disdrometer. The correction procedure, optimized by a polynomial least-square fit of the data, greatly reduces errors in rainfall estimates. The Zc–R relationships for different cloud types are calculated using a classification algorithm. A VPR threshold algorithm is used to investigate the accuracy of rainfall estimates depending on the cloud type. For stratiform and convective cloud types, rainfall estimates were more accurate when the correction was taken into account, with statistical errors substantially reduced. The developed algorithm successfully reduced errors in the rainfall estimates and improved their accuracy. This new quantitative precipitation estimate (QPE) algorithm will improve the reliability of radar-based quantitative rainfall measurements and the accuracy of weather forecasts.

The temporal variations in raindrop size distributions (RSDs) observed during the East-Asian summer monsoon have been considered for the statistical procedure called the principal component analysis (PCA). This statistical examination reveals the most important factors in the RSD's variations and helps to critically re-evaluate the known RSD-parameterization models. Based on the results of the PCA applied to the medium-size dataset, it has been concluded that the most frequently used parametric shapes of RSDs present significant simplifications of the experimentally observed RSD variance. The simplifications are seen in the type and number of the parameters employed for the typical parameterization models. As a result of this study, four principal factors are revealed which might be used for a new RSD-parameterization model covering more than 80% of the observed RSD variance.

We study the multifractal property of the rainfall in seven cities of Korea. We mainly estimate the generalized Hurst exponent, the Renyi exponent, and the singularity spectrum for tick data of the rainfall. In particular, we discuss the recent findings that suggest the scaling exponents characterizing the rainfall multifractality. After analyzing the multifractality of rainfalls, we compare the multifractal property of seven different cities and discuss the behavior of each city.

To examine the fluctuations of aerosol number concentration with different size in the boundary layer of marine area during summer season, aerosol particles were assayed in the Ieodo Ocean Research Station, which is located 419 km southwest of Marado, the southernmost island of Korea, from 24 June to 4 July, 2008. The Laser Particle Counter (LPC) was used to measure the size of aerosol particles and NCEP/NCAR reanalysis data and sounding data were used to analyze the synoptic condition. The distribution of aerosol number concentration had a large variation from bigger particles more than 3 in diameter to smaller particles more than 1 in diameter with wind direction during precipitation. The aerosol number concentration decreased with increasing temperature. An increase (decrease) of small size of aerosol (0.30.5 in diameter) number concentration was induced by convergence (divergence) of the wind fields. The aerosol number concentration of bigger size more than 3 in diameter after precipitation was removed as much as 8994% compared with aerosol number concentration before precipitation. It is considered that the larger aerosol particles would be more efficient for scavenging at marine boundary layer. In addition, the aerosol number concentration with divergence and convergence could be related with the occurrence and mechanism of aerosol in marine boundary layer.

A two-phase phenomenon in three financial exchange prices is studied. To understand the underlying mechanism for the formation of market prices, we perform the multifractal analysis and the detrended fluctuation analysis in terms of time series of market prices. We also examine higher order temporal correlations for the market price. Although the multifractal properties of market prices are obtained, it cannot be reproduced the binomial multiplicative process through that was used to understand fully developed turbulence.

To understand the development mechanism of the aerosols in the surface boundary layer, the variation in the aerosol number concentration due to the divergence and convergence of the wind fields was investigated. The aerosol number concentration was measured in the size ranges of using a laser particle counter(LPC) from 0000 LST on 03 Feb. to 0600 LST on 07 Feb. 2004 at Mokpo in Korea during snowfall. The Velocity Azimuth Display(VAD) technique was used to retrieve the radar wind fields such as the horizontal wind field, divergence, and deformations including the vertical air velocity from a single Doppler radar. As a result, the distribution of the aerosol number concentration is apparently different for particles larger than during snowfall, and it has a tendency to increase at the beginning of the snowfall. The increase and decrease in the aerosol concentration due to the convergence and divergence of the wind fields corresponded to the particles with diameters greater than . It is found that the fluctuations in the aerosol number concentration are well correlated with the development and dissipation of snowfall radar echoes due to the convergence and divergence of horizontal wind fields near the surface boundary layer in the inland during the snowfall.

To improve the accuracy of polarimetric rainfall relations for heavy rainfall, an extreme rainfall case was analysed and some methods were examined. The observed differential reflectivity (ZDR) quality check was theoretically investigated using the relation between the standard deviation of differential reflectivity and cross correlation, and the light rain method for ZDR bias was also applied to the rainfall estimation. The best performance for this heavy rainfall case was obtained when the moving average of ZDR over a window size of 9 gates was applied to the rainfall estimation using horizontal reflectivity (ZH) and ZDR and to the calculation of ZH bias. The differential reflectivity calculated by disdrometer data may be an alternative to the vertical pointing scan for calculating ZDR bias. The accuracy of the combined rainfall relation, R(Z,ZDR,KDP,AH) was relatively insensitive to ZDR and ZH biases in both observations and simulations.

In this study, to get an optimum rainfall estimation using polarimetric variables observed from Bislsan radar which is the first polarimetric radar in Korea, rainfall cases for 84 hours caused by different conditions, which are Changma front and typhoon, Changma front only, and typhoon only, occurred in 2011, were analyzed. And rainfall algorithms were developed by using long period drop size distributions with six different raindrop axis ratio relations. The combination of the relations betweenRandZ,ZDR,RandKDP,ZDR, andRandKDPwith different rainfall intensity would be an optimum rainfall algorithm if the reference of rainfall would be defined correctly. In the case the reference is not defined adequately, the relation betweenRandZ,ZDR,KDP,AHandRandZ,KDP,AHcan be used as a representative rainfall relation. Particularly if the qualifiedZDRis not available, the relation betweenRandZ,KDP,AHcan be used as an optimum rainfall relation in Korea.

To assess the performance of rainfall estimation using specific differential phase observed by Bislsan radar, the first polarimetric radar in Korea, three rainfall cases occurring in 2011 were selected, each caused by different conditions: the first is the Changma front and typhoon, the second is only the Changma front, and the third is only a typhoon. For quantitative use of specific differential phase (KDP), a data quality algorithm was developed for differential phase shift (ΦDP), composed of two steps; the first involves removal of scattered noise and the second is unfolding ofΦDP. This order of the algorithm is necessary so as not to remove unfolded areas, which are the real meteorological target. All noise was removed and the foldedΦDPwere unfolded successfully for this study.RKDPrelations for S-band radar were calculated for 84,754 samples of observed drop size distribution (DSD) using different drop shape assumptions. The relation for the Bringi drop shape showed the best statistics: 0.28 for normalized error, and 6.7 mm for root mean square error for rainfall heavier than 10 mm h-1. Because the drop shape assumption affects the accuracy of rainfall estimation differently for different rainfall types, such characteristics should be taken into account to estimate rainfall more accurately using polarimetric variables.

Doppler radar analysis and a cloud-resolving storm simulator (CReSS) are used to investigate the enhancement mechanism of a localized intense precipitation system that occurred over Jeju Island, Korea, on 30 June 2006. Rain gauge data revealed intensive rainfall (> 80 mm in 100 min) over northwest of Jeju Island, and relatively low rainfall (≤ 20 mm) over the northeast of the island. The environment of the precipitation system consisted of near-saturated air (relative humidity (RH): ∼ 95%) from the surface to 700 hPa and a low lifting condensation level of 951 hPa. Doppler radar analysis revealed enhancement of the precipitation system on the northwestern lateral side (in this study, the term ‘lateral side’ refers to the sides of the mountain other than the lee-side and windward side) of Mt. Halla, the central mountain on the island (1950 m). In the region of enhancement, low-level convergence (7 × 10 − 4 s − 1 ) induced by orographic blocking with a relatively low Froude number (0.55) was observed. These observations were well simulated by a control run (CNTL) using CReSS. The simulated precipitation system was enhanced over the northwestern part of the island due to wind passing around Jeju Island, low-level convergence (1.6 × 10 − 3 s − 1 ) due to orographic blocking, and high RH (∼ 95%). In order to clarify the influence of topography and the low-level moist environment on enhancement of the precipitation system, numerical sensitivity experiments were conducted. The NOTR (no terrain) experiment produced straightforward wind without low-level convergence over the topography. Associated with these features, the CNTL rainfall amount on the northwestern lateral side of the island was 30.6% more than that produced in NOTR. A comparison of RH-controlled experiments and CNTL revealed that increasing moisture in the low-level environment resulted in greater intensity of the precipitation system. A reduction in low-level RH by as little as 2% could result in a 20.8% reduction in rainfall amount. Therefore, land areas with small, narrow, but steep topographic features, such as Jeju Island, could determine the intensity and location of the precipitation system under a moist environment during the rainy season.