Quantifying artificial snowfall effects and accurately identifying microphysical changes remains a significant challenge due to background natural variability. This study analyzed two aircraft-based glaciogenic cloud seeding experiments conducted during the ICE-POP 2018 campaign on January 30 and March 21, 2018. To evaluate seeding effects, an integrated approach was utilized by linking numerical simulations, in situ airborne observations, and ground-based measurements. For the January 30 case, tracing the microphysical evolution along the Lagrangian advection path revealed a transition from ice initialization to dendritic growth, which was spatially aligned with the wind-driven transport of the seeded air mass. For the March 21 case, a distinct increase in ice particle concentrations and surface snowfall was recorded within the predicted seeding effect duration. The synchronization between the model-simulated seeding plume and the observed microphysical transitions provides a consistent physical basis for attributing these localized changes to the seeding experiment. By demonstrating a linked causal chain from plume dispersion to surface precipitation, this study underscores the capability of integrated observation–model frameworks to isolate seeding signals within complex orographic environments.

In this study, the effects of cloud seeding experiments were analyzed using ensemble numerical modeling. This study focuses on an aircraft seeding experiment conducted over the East Sea near the Yeongdong region of Gangwon Province on October 4, 2022. The weather research and forecasting (WRF) model was applied with parameterization to reflect the effects of hygroscopic seeding materials. The particle size distribution of domestically produced sodium chloride (NaCl) powder was measured and incorporated into the model. Fifty ensemble members (seeding start time legs) were constructed to calculate the probability of seeding-induced precipitation, which was then used to analyze the precipitation efficiency. The results showed that seeding materials were primarily dispersed to the Yeongdong and Yeongseo regions of Gangwon Province due to northeasterly winds. The 6-h (14:00–20:00 KST) cumulative simulated precipitation enhancement was 2.7, 4.4, and 0.9 mm at Bukgangneung (BGN), Gangneungseongsan (GNSS), and Daegwallyeong (DGY), respectively. Analysis of the precipitation ion components confirmed a distinct increase in seeding material-related ions at the BGN site, corresponding to 98

In an attempt to minimize the adverse impacts of rapid climate change, such as forest fires and droughts, the development of cloud seeding technologies has increasingly attracted attention. However, the effects of cloud seeding have not been verified directly. In the present study, chemical analysis of precipitation samples was explored as a method of confirming the case-by-case effects of cloud seeding experiments. Hourly precipitation samples were obtained using automatic precipitation collectors placed in seeded/nonseeded areas, which were calculated in advance by numerical methods. To directly confirm the effects of cloud seeding, analyses of ionic and heavy metal components (nonsea salt Ca 2+ and silver) of the samples were carried out. Three aviation experiments are presented (CaCl 2 , NaCl powder and CaCl 2 , AgI flare seedings). Each result demonstrated a noticeable increase in the main seeding materials at the rain sampling points within 1–3 h after the experiment, as confirmed by a numerical model. Although a small number of cases were considered in this study, our hourly analysis method highlights the potential for direct and rapid verification of cloud seeding experiments.

Cloud seeding has emerged as a promising strategy for artificially enhancing water availability in forest ecosystems, thereby supporting hydrological processes and promoting ecological function. While previous studies have reported improvements in hydrological indicators such as soil moisture and runoff following cloud seeding-induced precipitation, there remains a critical knowledge gap regarding the extent of these ecological effects including GPP and NPP across basins with differing forest characteristics—such as total area, forest coverage, and dominant tree species. This study addresses this gap by conducting a comparative assessment of the ecological benefits of cloud seeding across three basins in South Korea with varying forest properties. An ecohydrological model, RHESSys, is first calibrated for each basin to simulate both hydrological and ecological responses under different cloud seeding scenarios from 2020 to 2023. The results indicate that cloud seeding improves hydrological conditions—including runoff and soil moisture—proportional to the degree of precipitation enhancement, These hydrological improvements, in turn, lead to nonlinear yet consistent increases in GPP and NPP. Notably, the magnitude and persistence of these ecological benefits are more strongly influenced by forest characteristics than by basin size. Under cloud seeding scenarios simulating a 20% annual increase in precipitation, an expansion in forest cover from 78% to 84% results in a 3.1% to 4.2% increase in GPP. Moreover, basins dominated by broadleaf forests exhibit extended vegetation productivity responses, lasting approximately 20–30 days longer. These findings underscore the importance of incorporating basin-specific forest characteristics into the design and implementation of cloud seeding strategies aimed at ecological conservation and productivity enhancement.

This study quantitatively analyzes the effects of cloud seeding on precipitation and seasonal variations over the Boryeong Dam region,which has the lowest dam storage in South Korea,based on a one-year numerical simulation for 2021.The Morrison microphysics scheme in the WRF(Weather Research and Forecasting)model was modified to estimate differences in precipitation between simulations with seeding materials(AgI and CaCl2;SEED)and without them(UNSD).The effect of cloud seeding on increasing precipitation or artificial rainfall(AR)between the two simulations was highest in August(average:0.21 mm;31%of the SEED-simulated monthly mean)and lowest in January(average:0.003 mm;30%).This large AR may be attributable to a combination of abundant moisture from the summer monsoon climate and enhanced cloud droplet growth resulting from cloud seeding.In the analysis of seasonal representative cases,cloud seeding demonstrated more pronounced effects in spring and summer,with mean 180-min accumulated AR values of 0.46 and 0.43 mm,respectively,within the study area.In the spring,where an actual flight experiment was conducted,the simulated mean 180-min accumulated AR(1.41 mm)in the flight experiment area was close to the observed value(1.61 mm)for the same area.Additionally,cloud seeding promoted the hygroscopic growth of water vapor,thereby reducing the cloud water mixing ratio and increasing the rain water mixing ratio.Seasonal cross-sectional analysis further highlighted the impact of cloud seeding on changes in these two mixing ratios,with the most pronounced effects observed in spring and summer.

This study analyzes and compares the results of airborne snowfall enhancement experiments conducted on November 25 and 28, 2019, as part of the International Joint Cloud Observation and Weather Control Experiment (IJCO-WCE) 2019 campaign. The objective was to assess the effects of experimental interventions on cloud precipitation patterns. To address the challenges in verifying artificial snowfall enhancement, this study proposes an innovative approach, utilizing a post-experiment zigzag flight path for in-situ observations. This approach allowed for detailed comparisons between affected and unaffected cloud regions. Precipitation was observed in the target area on the leeward side on November 25, whereas no precipitation was recorded during the November 28 experiment. We concluded that airborne snowfall enhancement is more effective when the lower atmosphere is unstable at the rear of a trough, as confirmed by changes in the distribution of precipitation particles in the clouds and on the ground. Two identical flight experiments were conducted using the KMA/NIMS atmospheric research aircraft, allowing detailed observations. Data collected from onboard cloud observation instruments and six ground stations facilitated detailed analyses of changes in the concentration and size distribution of cloud particles (e.g., supercooled droplets, ice crystals, and snow particles). The method of comparing particle sizes between clouds affected and unaffected by the experiments is used to verify the effectiveness of artificial snowfall enhancement techniques. This methodology could be widely adopted in future studies to improve our understanding of weather modification strategies.

Abstract Rac1, a Rho GTPase family member, is dysregulated in a variety of tumor types including gastric adenocarcinoma, but little is known about its role in cancer stem-like cells (CSCs). Therefore, Rac1 activity and inhibition were examined in gastric adenocarcinoma cells and mouse xenograft models for epithelial-to-mesenchymal transition (EMT) and CSC phenotypes. Rac1 activity was significantly higher in spheroid-forming or CD44+ gastric adenocarcinoma CSCs compared with unselected cells. Rac1 inhibition using Rac1 shRNA or a Rac1 inhibitor (NSC23766) decreased expression of the self-renewal transcription factor, Sox-2, decreased spheroid formation by 78%–81%, and prevented tumor initiation in immunodeficient mice. Gastric adenocarcinoma CSCs had increased expression of the EMT transcription factor Slug, 4.4- to 8.3-fold greater migration, and 4.2- to 12.6-fold greater invasion than unselected cells, and these increases could be blocked completely with Rac1 inhibition. Gastric adenocarcinoma spheroid cells were resistant to 5-fluorouracil and cisplatin chemotherapy, and this chemotherapy resistance could be reversed with Rac1 shRNA or NSC23766. The PI3K/Akt pathway may be upstream of Rac1, and JNK may be downstream of Rac1. In the MKN-45 xenograft model, cisplatin inhibited tumor growth by 50%, Rac1 inhibition by 35%, and the combination by 77%. Higher Rac1 activity, in clinical specimens from gastric adenocarcinoma patients who underwent potentially curative surgery, correlated with significantly worse survival (P = 0.017). In conclusion, Rac1 promotes the EMT program in gastric adenocarcinoma and the acquisition of a CSC state. Rac1 inhibition in gastric adenocarcinoma cells blocks EMT and CSC phenotypes, and thus may prevent metastasis and augment chemotherapy. Implications: In gastric adenocarcinoma, therapeutic targeting of the Rac1 pathway may prevent or reverse EMT and CSC phenotypes that drive tumor progression, metastasis, and chemotherapy resistance. Mol Cancer Res; 15(8); 1106–16. ©2017 AACR.

Vascular endothelial growth factor A (VEGF-A) inhibition with pazopanib is an approved therapy for sarcomas, but likely results in compensatory pathways such as upregulation of hypoxia inducible factor 1α (HIF-1α). In addition, cancer stem-like cells can preferentially reside in hypoxic regions of tumors and be resistant to standard chemotherapies. In this study, we hypothesized that the combination of VEGF-A inhibition, HIF-1α inhibition, and hypoxia-activated chemotherapy with evofosfamide would be an effective multimodal strategy. Multimodal therapy was examined in one genetically engineered and two xenograft mouse models of sarcoma. In all three models, multimodal therapy showed greater efficacy than any single agent therapy or bimodality therapy in blocking tumor growth. Even after cessation of therapy, tumors treated with multimodal therapy remained relatively dormant for up to 2 months. Compared to the next best bimodality therapy, multimodal therapy caused 2.8-3.3 fold more DNA damage, 1.5-2.7 fold more overall apoptosis, and 2.3-3.6 fold more endothelial cell-specific apoptosis. Multimodal therapy also decreased microvessel density and HIF-1α activity by 85-90% and 79-89%, respectively, compared to controls. Sarcomas treated with multimodal therapy had 95-96% depletion of CD133(+) cancer stem-like ells compared to control tumors. Sarcoma cells grown as spheroids to enrich for CD133(+) cancer stem-like cells were more sensitive than monolayer cells to multimodal therapy in terms of DNA damage and apoptosis, especially under hypoxic conditions. Thus multimodal therapy of sarcomas with VEGF-A inhibition, HIF-1α inhibition, and hypoxia-activated chemotherapy effectively blocks sarcoma growth through inhibition of tumor vasculature and cancer stem-like cells.

Cloud seeding is generally used to secure additional water resources, which is not an easy goal to achieve, as the spatial variability of rainfall is high. Instead, the increased rain may moisten the neighboring forest. This study focuses on this situation and estimates the possible increase in the net primary production (NPP) due to cloud seeding. This study considers the Boryeong Dam basin in Korea as a study area and uses the Carnegie-Ames-Stanford Approach (CASA) model to estimate the NPP at 8-day intervals. As a result, first, the increase of the current 8-day NPP is greater when the rainfall amount during the last 16-day period is 50 mm or more. The mean increase of the 8-day NPP is estimated at about 1.873 g/m(2) of carbon. Second, the increase of the NPP with the target 16-day rainfall of 50 mm is estimated at about 3%, which is about 4% with the target 16-day rainfall of 100 mm. Simply extrapolating the derived result to the entire forest in Korea, the increased carbon accumulation can be extended to about 0.6 and 0.8% of the total carbon emission in 2018, respectively. These amounts correspond to about 1.2 and 1.5% of the target amount of carbon reduction by 2030 in Korea.

Cloud seeding is well known to address water shortage problems caused by droughts by adding more precipitation and consequent runoff. Unlike previous studies, this study investigates another positive effect of cloud seeding on the activation of vegetation by integrating numerical cloud seeding simulations and processed-based modeling of various ecohydrological components. As the carbon cycle is closely related to the hydrological processes in ecosystems, we adopt the RHESSys ecohydrological modeling to synthetically simulate runoff and soil moisture along with primary productivity and vegetation respiration. Numerical simulations with and without cloud seeding are generated by the WRF-ARW model for the Boryeong Dam basin, one of the basins vulnerable to droughts, in 2021. The cloud seeding simulations of two cases are input into the RHESSys model to examine changes in hydrological and ecological components due to the added amount of precipitation. The results exhibit significant increases in annual precipitation (18 %) and runoff (22 %), and enhanced soil moisture stimulating the ecological components such as GPP and NPP, especially in spring. Cloud seeding can be considered to create optimal conditions for vegetation to absorb or sequester carbon from the atmosphere, thereby boosting vegetation growth. Additionally, the time-lagged correlations between cloud seeding and soil moisture, GPP, NPP, and respiration suggest that vegetation activity is highly dependent on antecedent 1-2 months occurrences of cloud seeding. This study implies that the cloud seeding effect on additional NPP can be

The National Institute of Meteorological Sciences in Korea has developed the Weather Modification Hybrid Rocket (WMHR), an advanced system that offers enhanced stability and cost-effectiveness over conventional solid -fuel rockets. Designed for precise operation, the WMHR enables accurate control over the ejection altitude of pyrotechnics by modulating the quantity of oxidizer, facilitating specific cloud seeding at various atmospheric layers. Furthermore, the rate of descent for pyrotechnic devices can be adjusted by modifying parachute sizes, allowing for controlled dispersion time and concentration of seeding agents. The rocket's configuration also supports adjustments in the pyrotechnic device's capacity, permitting tailored seeding agent deployment. This innovation reflects significant technical progression and collaborations with local manufacturers, in addition to efforts to secure testing sites and address hybrid rocket production challenges. Notable outcomes of this project include the creation of a national framework for weather modification technology utilizing hybrid rockets, enhanced cloud seeding methods, and the potential for broader meteorological application of hybrid rockets beyond precipitation augmentation. An illustrative case study confirmed the WMHR's operational effectiveness, although the impact on cloud seeding was limited by unfavorable weather conditions. This experience has provided valuable insights and affirmed the system's potential for varied uses, such as weather modification and deploying high -altitude meteorological sensors. Nevertheless, the expansion of civilian weather rocket experiments in Korea faces challenges due to inadequate infrastructure and regulatory limitations, underscoring the urgent need for advancements in these areas.

The microphysical properties of ice pellets (IP) are analyzed, and associated relevant thermodynamic conditions are investigated using rawinsonde soundings and model reanalysis data in the Yeongdong region of Korea. During the intensive observation campaign of snowfall, two distinctive IP events of 1 March 2021 (IP1) and 15 March 2018 (IP2) were observed when strong cold advection was prevalent below about 2 km as accompanied by distinctive inversion strength (4.7 ~ 9.3 ℃) above the cold layers. Cold air intrusion along the eastern side of Taebaek mountains appeared to abruptly decrease low level (850 hPa) temperature up to -4.7 ~ -3.4 ℃, but warmer than 8-year average (-9.5 ℃), respectively. Both episodes had smaller maximum size (1.8 mm in average) of ice pellets with greater fallspeed (4.2 m s −1 ) in comparison to general snow crystals. Ice pellets occurred in the synoptic condition of the High in the north and the Low passing by the south, which resulted in cold northeasterly over the Yeongdong region. Rawinsonde soundings show a melting layer between 800 and 700 hPa just above the freezing layer of 900 ~ 800 hPa existed, such as a reversed S temperature profile, which is also consistent with the model reanalysis. The IPs’ life time was short within a couple of hours since it occurred along with low-level strong cold advection (IP1) or rapidly-moving squall line (IP2).

This study investigates the changes caused by forest fires and the following recovery processes, targeting four forest fire sites in Korea. The time series of two vegetation indices, leaf area index (LAI) and normalized difference vegetation index (NDVI) are investigated along with evapotranspiration (ET) time series for the study objectives. The analysis results show that LAI is most sensitive to burn severity and burned area with its change ranging from 40 % to 70 %, while the changes of NDVI and ET remain 30 % and 20 %, respectively, regardless of forest fire sites. The recovery time from forest fire also varies according to indices: the recovery time is estimated to be about 15 years when considering LAI and NDVI, while just 5 years when considering ET. Overall, LAI seems better to analyze the change in vegetation before and after forest fires. Different vegetation shift patterns after the forest fire are also noticed, mostly from evergreen needleleaf trees to deciduous broadleaf trees. However, it is also found that bad soil fertility condition and artificial afforestation help to maintain the evergreen needleleaf trees after the forest fire.

Supplemental Figure S1. A. Western blot for putative CSC markers in AGS, MKN-45, and NCI-N87 cells grown as monolayers or as spheroids. Supplemental Figure S2. A. Western blot of CD44(-) and CD44(+) AGS, MKN-45 and NCI-N87 spheroid cells for CD44, Sox2, Oct-4, Nanog, and c-Myc. Supplemental Figure S3. A. Western blot of AGS and NCI-N87 monolayer and spheroid cells for total and phosphorylated MAPK proteins. Supplemental Figure S4. A. Migration and invasion assays of GA monolayer and spheroid cells. Supplemental Figure S5. A. Western blot of AGS and NCI-N87 spheroid cells for total and phosphorylated JNK, active Rac1, N-cadherin, Slug, Snail, and Zeb1. Supplemental Figure S6. Proliferation assays for GA monolayer cells (A) and spheroid cells (B) following treatment with the Rac1 inhibitor NSC23766, 5-fluorouracil (5-FU), cisplatin, and/or carrier (DMSO). Supplemental Figure S7. A. Western blot of MKN-45 cells for total Rac1 following transduction with Rac1 shRNA (sh.Rac1) or scrambled control shRNA (sh.Scr).

In this study, a method for verifying the effect of cloud seeding in the case of a mixture of natural and artificial rainfall bands was proposed, and its applicability to each experimental case was evaluated. Water resources that could be secured through cloud seeding were also quantified for the experiments on forest fire prevention, drought mitigation, and dust reduction in 2020. Data on numerical simulations, radar-derived rainfall, rain gauge-derived rainfall, and weather conditions were applied. Areas with seeding and nonseeding effects were classified according to the numerical simulation results and wind system, and enhanced rainfall was determined by comparing the changes in rainfall between the two areas. The amount of water resources was determined by considering the area of the seeding effect and rainfall density. As a result, 1.74 mm (4.75 million tons) of rainfall increased from the experiment on forest fire prevention, 0.84 mm (1.30 million tons) on drought mitigation, and 2.78 mm (24.44 million tons) on dust reduction. Thus, an average rainfall of 1.0 mm could be achieved through the experiment. These results helped verify the pure seeding effect and achieve the experimental purpose.

In this study, the rainfall measurement characteristics of an optical particle size velocity (Parsivel) disdrometer, tipping-bucket rain gauge (TBG), and Pluvio weighing precipitation gauge (WPG) were analyzed and compared. Correlation analysis was performed between the 10-min and 1-h rainfall data observed with the Parsivel, TBG, and Pluvio from 2010 to 2019 at the Cloud Physics Observation Site which is located in northeast area of South Korea (N37.6869, E128.7586). At higher rainfall intensities, the Parsivel observed more rainfall; however, the TBG lost more rainfall during observation. The correlation between the Pluvio and Parsivel data was higher than that between the TBG and Parsivel data. Additionally, the Pluvio showed reduced loss in the rainfall observation than that by the TBG. The correlation between the Pluvio and TBG data was the highest, and the coefficient of determination increased by a maximum of 42.08% for 1-h rainfall compared to that for 10-min rainfall. Therefore, the Pluvio can generate relatively accurate rainfall data for water resource utilization.

The Dual Tipping Bucket Gauge (DTBG) is newly developed to improve the accuracy of rainfall measurements. DTBG includes two tipping buckets (TBs) in a gauge cylinder, named TB01 and TB05. The measurement resolution of TB01 and TB05 are 0.1 mm and 0.5 mm, respectively. Rainfall measurements by DTBG are made simultaneously by the two TBs. The higher amount of rainfall from either TB01 or TB05 is then taken as the rainfall amount by DTBG, which constitutes a major advantage of DTBG compared to a single TB rain gauge. For 14 rainfall events, the accuracy of DTBG was assessed by inter-comparisons of rainfall amounts by DTBG and Pluvio2 (reference gauge). The rainfall intensities by DTBG were fairly consistent with those by Pluvio2, with an average fractional bias of 0.07%. The present study demonstrates that DTBG is more accurate and reliable compared to a single TB rain gauge.