Pub Date : 2023-09-08DOI: 10.1175/jamc-d-23-0070.1
Amanda M. Murphy, C. Homeyer
Forecasting tornadogenesis remains a difficult problem in meteorology, especially for short-lived, predominantly non-supercellular tornadic storms embedded within mesoscale convective systems (MCSs). This study compares populations of tornadic non-supercellular MCS storm cells to their nontornadic counterparts, focusing on nontornadic storms that have similar radar characteristics to tornadic storms. Comparison of single-polarization radar variables during storm lifetimes show that median values of low-level, mid-level, and column-maximum azimuthal shear, as well as low-level radial divergence, enable the highest degree of separation between tornadic and nontornadic storms. Focusing on low-level azimuthal shear values, null storms were randomly selected such that the distribution of null low-level azimuthal shear values matches the distribution of tornadic values. After isolating the null cases from the nontornadic population, signatures emerge in single-polarization data that enable discrimination between nontornadic and tornadic storms. In comparison, dual-polarization variables show little deviation between storm types. Tornadic storms both at tornadogenesis and at 20-minute lead time show collocation of the primary storm updraft with enhanced near-surface rotation and convergence, facilitating the non-mesocyclonic tornadogenesis processes.
{"title":"Comparison of Radar-Observed Tornadic and Nontornadic MCS Cells using Probability Matched Means","authors":"Amanda M. Murphy, C. Homeyer","doi":"10.1175/jamc-d-23-0070.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0070.1","url":null,"abstract":"\u0000Forecasting tornadogenesis remains a difficult problem in meteorology, especially for short-lived, predominantly non-supercellular tornadic storms embedded within mesoscale convective systems (MCSs). This study compares populations of tornadic non-supercellular MCS storm cells to their nontornadic counterparts, focusing on nontornadic storms that have similar radar characteristics to tornadic storms. Comparison of single-polarization radar variables during storm lifetimes show that median values of low-level, mid-level, and column-maximum azimuthal shear, as well as low-level radial divergence, enable the highest degree of separation between tornadic and nontornadic storms. Focusing on low-level azimuthal shear values, null storms were randomly selected such that the distribution of null low-level azimuthal shear values matches the distribution of tornadic values. After isolating the null cases from the nontornadic population, signatures emerge in single-polarization data that enable discrimination between nontornadic and tornadic storms. In comparison, dual-polarization variables show little deviation between storm types. Tornadic storms both at tornadogenesis and at 20-minute lead time show collocation of the primary storm updraft with enhanced near-surface rotation and convergence, facilitating the non-mesocyclonic tornadogenesis processes.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47743857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-06DOI: 10.1175/jamc-d-22-0195.1
Francesco Battaglioli, Pieter Groenemeijer, T. Púčik, Mateusz Taszarek, Uwe Ulbrich, Henning Rust
We have developed additive logistic models for the occurrence of lightning, large (≥ 2 cm), and very large (≥ 5 cm) hail to investigate the evolution of these hazards in the past, in the future, and for forecasting applications. The models, trained with lightning observations, hail reports, and predictors from atmospheric reanalysis, assign an hourly probability to any location and time on a 0.25° × 0.25° × 1-hourly grid as a function of reanalysis-derived predictor parameters, selected following an ingredients-based approach. The resulting hail models outperform the Significant Hail Parameter and the simulated climatological spatial distributions and annual cycles of lightning and hail are consistent with observations from storm report databases, radar, and lightning detection data. As a corollary result, CAPE released above the -10°C isotherm was found to be a more universally skilful predictor for large hail than CAPE. In the period 1950–2021, the models applied to the ERA5 reanalysis indicate significant increases of lightning and hail across most of Europe, primarily due to rising low-level moisture. The strongest modelled hail increases occur in northern Italy with increasing rapidity after 2010. Here, very large hail has become 3 times more likely than it was in the 1950s. Across North America trends are comparatively small, apart from isolated significant increases in the direct lee of the Rocky Mountains and across the Canadian Plains. In the southern Plains, a period of enhanced storm activity occurred in the 1980s and 1990s.
{"title":"Modelled multidecadal trends of lightning and (very) large hail in Europe and North America (1950–2021)","authors":"Francesco Battaglioli, Pieter Groenemeijer, T. Púčik, Mateusz Taszarek, Uwe Ulbrich, Henning Rust","doi":"10.1175/jamc-d-22-0195.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0195.1","url":null,"abstract":"\u0000We have developed additive logistic models for the occurrence of lightning, large (≥ 2 cm), and very large (≥ 5 cm) hail to investigate the evolution of these hazards in the past, in the future, and for forecasting applications. The models, trained with lightning observations, hail reports, and predictors from atmospheric reanalysis, assign an hourly probability to any location and time on a 0.25° × 0.25° × 1-hourly grid as a function of reanalysis-derived predictor parameters, selected following an ingredients-based approach. The resulting hail models outperform the Significant Hail Parameter and the simulated climatological spatial distributions and annual cycles of lightning and hail are consistent with observations from storm report databases, radar, and lightning detection data. As a corollary result, CAPE released above the -10°C isotherm was found to be a more universally skilful predictor for large hail than CAPE. In the period 1950–2021, the models applied to the ERA5 reanalysis indicate significant increases of lightning and hail across most of Europe, primarily due to rising low-level moisture. The strongest modelled hail increases occur in northern Italy with increasing rapidity after 2010. Here, very large hail has become 3 times more likely than it was in the 1950s. Across North America trends are comparatively small, apart from isolated significant increases in the direct lee of the Rocky Mountains and across the Canadian Plains. In the southern Plains, a period of enhanced storm activity occurred in the 1980s and 1990s.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49549926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-06DOI: 10.1175/jamc-d-23-0012.1
Sisi Chen, L. Xue, S. Tessendorf, Thomas H. Chubb, Andrew Peace, Luis Ackermann, Artur Gevorgyan, Yi Huang, S. Siems, Roy Rasmussen, Suzanne Kenyon, Johanna Speirs
This study presents the first numerical simulations of seeded clouds over the Snowy Mountains of Australia. WRF-WxMod®, a novel glaciogenic cloud seeding model, was utilized to simulate the cloud response to winter orographic seeding under various meteorological conditions. Three cases during the 2018 seeding periods were selected for model evaluation, coinciding with an intensive ground-based measurement campaign. The campaign data were used for model validation and evaluation. Comparisons between simulations and observations demonstrate that the model realistically represents cloud structures, liquid water path, and precipitation. Sensitivity tests were performed to pinpoint key uncertainties in simulating natural and seeded clouds and precipitation processes. They also shed light on the complex interplay between various physical parameters/processes and their interaction with large-scale meteorology. Our study found that in unseeded scenarios, the warm and cold biases in different initialization datasets can heavily influence the intensity and phase of natural precipitation. Secondary ice production via Hallett-Mossop processes exerts a secondary influence. On the other hand, the seeding impacts are primarily sensitive to aerosol conditions and the natural ice nucleation process. Both factors alter the supercooled liquid water availability and the precipitation phase, consequently impacting the AgI nucleation rate. Furthermore, model sensitivities were inconsistent across cases, indicating no single model configuration optimally represents all three cases. This highlights the necessity of employing an ensemble approach for a more comprehensive and accurate assessment of the seeding impact.
{"title":"Simulating Wintertime Orographic Cloud Seeding over the Snowy Mountains of Australia","authors":"Sisi Chen, L. Xue, S. Tessendorf, Thomas H. Chubb, Andrew Peace, Luis Ackermann, Artur Gevorgyan, Yi Huang, S. Siems, Roy Rasmussen, Suzanne Kenyon, Johanna Speirs","doi":"10.1175/jamc-d-23-0012.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0012.1","url":null,"abstract":"\u0000This study presents the first numerical simulations of seeded clouds over the Snowy Mountains of Australia. WRF-WxMod®, a novel glaciogenic cloud seeding model, was utilized to simulate the cloud response to winter orographic seeding under various meteorological conditions. Three cases during the 2018 seeding periods were selected for model evaluation, coinciding with an intensive ground-based measurement campaign. The campaign data were used for model validation and evaluation.\u0000Comparisons between simulations and observations demonstrate that the model realistically represents cloud structures, liquid water path, and precipitation. Sensitivity tests were performed to pinpoint key uncertainties in simulating natural and seeded clouds and precipitation processes. They also shed light on the complex interplay between various physical parameters/processes and their interaction with large-scale meteorology.\u0000Our study found that in unseeded scenarios, the warm and cold biases in different initialization datasets can heavily influence the intensity and phase of natural precipitation. Secondary ice production via Hallett-Mossop processes exerts a secondary influence. On the other hand, the seeding impacts are primarily sensitive to aerosol conditions and the natural ice nucleation process. Both factors alter the supercooled liquid water availability and the precipitation phase, consequently impacting the AgI nucleation rate. Furthermore, model sensitivities were inconsistent across cases, indicating no single model configuration optimally represents all three cases. This highlights the necessity of employing an ensemble approach for a more comprehensive and accurate assessment of the seeding impact.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49410492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-06DOI: 10.1175/jamc-d-23-0024.1
C. Rozoff, David S. Nolan, George H. Bryan, Eric A. Hendricks, J. Knievel
Populated urban areas along many coastal regions are vulnerable to landfalling tropical cyclones (TCs). To the detriment of surface parameterizations in mesoscale models, the complexities of turbulence at high TC wind speeds in urban canopies are presently poorly understood. Thus, this study explores impacts of urban morphology on TC-strength winds and boundary layer turbulence in landfalling TCs. To better quantify how urban structures interact with TC winds, large-eddy simulations (LES) are conducted with the Cloud Model 1 (CM1). This implementation of CM1 includes immersed boundary conditions (IBCs) to represent buildings and eddy recycling to maintain realistic turbulent flow perturbations. Within the IBCs, an idealized coastal city with varying scales is introduced. TC winds impinge perpendicular to the urbanized coastline. The numerical experiments show that buildings generate distinct, intricate flow patterns that vary significantly as the city structure is varied. Urban IBCs produce much stronger turbulent kinetic energy than is produced by conventional surface parameterizations. Strong effective eddy viscosity due to resolved eddy mixing is displayed in the wake of buildings within the urban canopy, while deep and enhanced effective eddy viscosity is present downstream. Such effects are not seen in a comparison LES simulation using a simple surface parameterization with high roughness values. Wind tunneling effects in streamwise canyons enhance pedestrian-level winds well beyond what is possible without buildings. In the arena of regional mesoscale modeling, this type of LES framework with IBCs can be used to improve parameters in surface and boundary layer schemes to more accurately represent the drag coefficient and the eddy viscosity in landfalling TC boundary layers.
{"title":"Large-eddy Simulations of the Tropical Cyclone Boundary Layer at Landfall in an Idealized Urban Environment","authors":"C. Rozoff, David S. Nolan, George H. Bryan, Eric A. Hendricks, J. Knievel","doi":"10.1175/jamc-d-23-0024.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0024.1","url":null,"abstract":"\u0000Populated urban areas along many coastal regions are vulnerable to landfalling tropical cyclones (TCs). To the detriment of surface parameterizations in mesoscale models, the complexities of turbulence at high TC wind speeds in urban canopies are presently poorly understood. Thus, this study explores impacts of urban morphology on TC-strength winds and boundary layer turbulence in landfalling TCs. To better quantify how urban structures interact with TC winds, large-eddy simulations (LES) are conducted with the Cloud Model 1 (CM1). This implementation of CM1 includes immersed boundary conditions (IBCs) to represent buildings and eddy recycling to maintain realistic turbulent flow perturbations. Within the IBCs, an idealized coastal city with varying scales is introduced. TC winds impinge perpendicular to the urbanized coastline. The numerical experiments show that buildings generate distinct, intricate flow patterns that vary significantly as the city structure is varied. Urban IBCs produce much stronger turbulent kinetic energy than is produced by conventional surface parameterizations. Strong effective eddy viscosity due to resolved eddy mixing is displayed in the wake of buildings within the urban canopy, while deep and enhanced effective eddy viscosity is present downstream. Such effects are not seen in a comparison LES simulation using a simple surface parameterization with high roughness values. Wind tunneling effects in streamwise canyons enhance pedestrian-level winds well beyond what is possible without buildings. In the arena of regional mesoscale modeling, this type of LES framework with IBCs can be used to improve parameters in surface and boundary layer schemes to more accurately represent the drag coefficient and the eddy viscosity in landfalling TC boundary layers.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44500207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study analyzed the macro- and microphysical response characteristics of a typical multicell hailstorm after seeding on 27 April 2019 in Weining, China, using X-band dual-polarization radar (YLD1-D) data. An improved X-pol hydrometeor identification algorithm was employed for hydrometeor identification. According to the diffusion of the seeding agents, the seeded hailstorm was graded into three study regions, and the evolution of the seeded hailstorm was divided into four periods. The response characteristics of the seeded hailstorm in each region and period were compared and analyzed. The results show that 1) macroscopically, the decrease in the reflectivity and the height of strong echo mainly occurred in the seeded period, whereas the decrease in the echo top and the height of the storm was mainly in the postseeded period; the echo height variation of the unseeded hailstorm is obviously different from that of the seeded hailstorm; and 2) from the microscopic perspective, the decrease in low-density graupel and supercooled water and the increase in ice crystals and aggregates in the seeded region mainly occurred in the seeded period, which was consistent with the time required for the “benefit competition” after the silver iodide completed nucleation. When compared with the seeded region, the hydrometeors in the unseeded region had an opposite trend (or an in-phase trend with an obviously lower changing rate), which further indicated the impact of the artificial ice nuclei on microphysical processes in the seeded region. For hailstorms with a high content of supercooled droplets and graupel, the key mechanisms of hail suppression are “cloud water glaciation,” “beneficial competition,” and “early rainout.”
{"title":"The Macro- and Microphysical Response Characteristics of the Multicell Hailstorm Hail-Suppression Operation: Case Study","authors":"Yuan Lu, Yunjun Zhou, Shuping Zou, Zhe Yang, Yong Zeng","doi":"10.1175/jamc-d-22-0129.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0129.1","url":null,"abstract":"\u0000This study analyzed the macro- and microphysical response characteristics of a typical multicell hailstorm after seeding on 27 April 2019 in Weining, China, using X-band dual-polarization radar (YLD1-D) data. An improved X-pol hydrometeor identification algorithm was employed for hydrometeor identification. According to the diffusion of the seeding agents, the seeded hailstorm was graded into three study regions, and the evolution of the seeded hailstorm was divided into four periods. The response characteristics of the seeded hailstorm in each region and period were compared and analyzed. The results show that 1) macroscopically, the decrease in the reflectivity and the height of strong echo mainly occurred in the seeded period, whereas the decrease in the echo top and the height of the storm was mainly in the postseeded period; the echo height variation of the unseeded hailstorm is obviously different from that of the seeded hailstorm; and 2) from the microscopic perspective, the decrease in low-density graupel and supercooled water and the increase in ice crystals and aggregates in the seeded region mainly occurred in the seeded period, which was consistent with the time required for the “benefit competition” after the silver iodide completed nucleation. When compared with the seeded region, the hydrometeors in the unseeded region had an opposite trend (or an in-phase trend with an obviously lower changing rate), which further indicated the impact of the artificial ice nuclei on microphysical processes in the seeded region. For hailstorms with a high content of supercooled droplets and graupel, the key mechanisms of hail suppression are “cloud water glaciation,” “beneficial competition,” and “early rainout.”","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45001410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1175/jamc-d-23-0135.1
{"title":"Equity, Inclusion, and Justice: An Opportunity for Action for AMS Publications Stakeholders","authors":"","doi":"10.1175/jamc-d-23-0135.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0135.1","url":null,"abstract":"","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44882894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.1175/jamc-d-22-0162.1
Riku Shimizu, S. Shige, T. Iguchi, Cheng‐Ku Yu, Lin-Wen Cheng
The Dual-frequency Precipitation Radar (DPR), which consists of a Ku-band precipitation radar (KuPR) and a Ka-band precipitation radar (KaPR), onboard the GPM Core Observatory cannot observe precipitation at low altitudes near the ground contaminated by surface clutter. This near-surface region is called the blind zone. DPR estimates the clutter free bottom (CFB) which is the lowest altitude not included in the blind zone, and estimates precipitation at altitudes higher than the CFB. High CFBs, which are common over mountainous areas, represent obstacles to detection of shallow precipitation and estimation of low-level enhanced precipitation. We compared KuPR data with rain gauge data from the Da-Tun Mountain of northern Taiwan acquired from March 2014 to February 2020. A total of 12 cases were identified in which the KuPR missed some rainfall with intensity of >10 mm h−1 that was observed by rain gauges. Comparison of KuPR profile and ground-based radar profile revealed that shallow precipitation in the KuPR blind zone was missed because the CFB was estimated to be higher than the lower bound of the range free from surface echoes. In the original operational algorithm, CFB was estimated using only the received power data of the KuPR. In this study, the CFB was identified by the sharp increase in the difference between the received powers of the KuPR and the KaPR at altitude affected by surface clutter. By lowering the CFB, the KuPR succeeded in detection and estimation of shallow precipitation.
GPM核心天文台搭载的双频降水雷达(DPR)由ku波段降水雷达(KuPR)和ka波段降水雷达(KaPR)组成，无法观测受地表杂波污染的近地低空降水。这个近地表区域被称为盲区。DPR估计无杂波底(CFB)，即不包括在盲区内的最低高度，并估计高于CFB的高度的降水。山区常见的高cfb是探测浅层降水和估计低层增强降水的障碍。我们将KuPR数据与台湾北部大屯山2014年3月至2020年2月的雨量计数据进行了比较。共确定了12个案例，其中KuPR错过了雨量计观测到的一些强度为bbb10 mm h−1的降雨。对比KuPR廓线和地面雷达廓线发现，由于估计的CFB高于无地面回波距离的下界，因此遗漏了KuPR盲区的浅层降水。在最初的运算算法中，仅使用KuPR接收的功率数据估计CFB。在地面杂波的影响下，KuPR和KaPR的接收功率之差急剧增加，从而识别出CFB。通过降低循环流化床(CFB)， KuPR成功地探测和估计了浅层降水。
{"title":"Narrowing the Blind Zone of the GPM Dual-Frequency Precipitation Radar to Improve Shallow Precipitation Detection in Mountainous Areas","authors":"Riku Shimizu, S. Shige, T. Iguchi, Cheng‐Ku Yu, Lin-Wen Cheng","doi":"10.1175/jamc-d-22-0162.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0162.1","url":null,"abstract":"\u0000The Dual-frequency Precipitation Radar (DPR), which consists of a Ku-band precipitation radar (KuPR) and a Ka-band precipitation radar (KaPR), onboard the GPM Core Observatory cannot observe precipitation at low altitudes near the ground contaminated by surface clutter. This near-surface region is called the blind zone. DPR estimates the clutter free bottom (CFB) which is the lowest altitude not included in the blind zone, and estimates precipitation at altitudes higher than the CFB. High CFBs, which are common over mountainous areas, represent obstacles to detection of shallow precipitation and estimation of low-level enhanced precipitation. We compared KuPR data with rain gauge data from the Da-Tun Mountain of northern Taiwan acquired from March 2014 to February 2020. A total of 12 cases were identified in which the KuPR missed some rainfall with intensity of >10 mm h−1 that was observed by rain gauges. Comparison of KuPR profile and ground-based radar profile revealed that shallow precipitation in the KuPR blind zone was missed because the CFB was estimated to be higher than the lower bound of the range free from surface echoes. In the original operational algorithm, CFB was estimated using only the received power data of the KuPR. In this study, the CFB was identified by the sharp increase in the difference between the received powers of the KuPR and the KaPR at altitude affected by surface clutter. By lowering the CFB, the KuPR succeeded in detection and estimation of shallow precipitation.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43825858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-22DOI: 10.1175/jamc-d-23-0061.1
Junjie Cao, Fu Guan, Xiang Zhang, Won-Ho Nam, G. Leng, Haoran Gao, Qingqing Ye, Xihui Gu, J. Zeng, Xu Zhang, Tailai Huang, D. Niyogi
Predicting drought severity is essential for drought management and early warning systems. Although numerous physical model-based and data-driven methods have been put forward for drought prediction, their abilities are largely constrained by data requirements and modeling complexity. There remains a challenging task to efficiently predict categorial drought, especially for the United States Drought Monitor (USDM). Aiming at this issue, multiple Markov chains for USDM based categorial drought prediction are successfully proposed and evaluated in this paper. In particular, this study concentrated on how the Markov order, step size, and training set length affected prediction accuracy (PA). According to the experiments from 2000 to 2021, it was found the one-step and first-order Markov models had the best accuracy in predicting droughts up to 4 weeks ahead. The PA steadily dropped with increasing step scale, and the average accuracy at monthly scale was 88%. In terms of seasonal variability, summer (July-August) had the lowest PA while winter had the highest (January-February). In comparison to the western region, the PA in the eastern US is 25% higher. Moreover, the length of the training set had obvious impact on the PA of the model. The PA in one-step prediction was 87% and 78% under 20-year and 5-year training sets respectively. The results of the study showed that Markov models predicted categorical drought with high accuracy in the short term and showed different performances on time and space scales. Proper use of Markov models would help disaster managers and policymakers to put mitigation policies and measures into practice.
{"title":"Multiple Markov Chains for Categorial Drought Prediction on United States Drought Monitor at Weekly Scale","authors":"Junjie Cao, Fu Guan, Xiang Zhang, Won-Ho Nam, G. Leng, Haoran Gao, Qingqing Ye, Xihui Gu, J. Zeng, Xu Zhang, Tailai Huang, D. Niyogi","doi":"10.1175/jamc-d-23-0061.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0061.1","url":null,"abstract":"\u0000Predicting drought severity is essential for drought management and early warning systems. Although numerous physical model-based and data-driven methods have been put forward for drought prediction, their abilities are largely constrained by data requirements and modeling complexity. There remains a challenging task to efficiently predict categorial drought, especially for the United States Drought Monitor (USDM). Aiming at this issue, multiple Markov chains for USDM based categorial drought prediction are successfully proposed and evaluated in this paper. In particular, this study concentrated on how the Markov order, step size, and training set length affected prediction accuracy (PA). According to the experiments from 2000 to 2021, it was found the one-step and first-order Markov models had the best accuracy in predicting droughts up to 4 weeks ahead. The PA steadily dropped with increasing step scale, and the average accuracy at monthly scale was 88%. In terms of seasonal variability, summer (July-August) had the lowest PA while winter had the highest (January-February). In comparison to the western region, the PA in the eastern US is 25% higher. Moreover, the length of the training set had obvious impact on the PA of the model. The PA in one-step prediction was 87% and 78% under 20-year and 5-year training sets respectively. The results of the study showed that Markov models predicted categorical drought with high accuracy in the short term and showed different performances on time and space scales. Proper use of Markov models would help disaster managers and policymakers to put mitigation policies and measures into practice.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45638414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-10DOI: 10.1175/jamc-d-23-0080.1
T. J. Zaremba, R. Rauber, B. Geerts, J. French, S. Tessendorf, L. Xue, K. Friedrich, C. Weeks, R. Rasmussen, M. Kunkel, D. Blestrud
This paper examines the controls on supercooled liquid water content (SLWC) and drop number concentrations (Nt,CDP) over the Payette River Basin during the SNOWIE campaign. During SNOWIE, 27.4% of 1 Hz in situ cloud droplet probe samples were in an environment containing supercooled liquid water (SLW). The interquartile range of SLWC, when present, was found to be 0.02-0.18 g m−3, and 13.3−37.2 cm−3 for Nt,CDP, with the most extreme values reaching 0.40−1.75 g m−3 and 150−320 cm−3 in isolated regions of convection and strong shear-induced turbulence. SLWC and Nt,CDP distributions are shown to be directly related to cloud top temperature and ice particle concentrations, consistent with past research over other mountain ranges. Two classes of vertical motions were analyzed as potential controls on SLWC and Nt,CDP, the first forced by the orography and fixed in space relative to the topography (stationary waves), and the second transient, triggered by vertical shear and instability within passing synoptic-scale cyclones. SLWC occurrence and magnitudes, and Nt,CDP associated with fixed updrafts were found to be normally distributed about ridgelines when SLW was present. SLW was more likely to form at low altitudes near the terrain slope associated with fixed waves due to higher mixing ratios and larger vertical air parcel displacements at low altitudes. When considering transient updrafts, SLWC and Nt,CDP appear more uniformly distributed over the flight track with little discernable terrain dependence as a result of time and spatially varying updrafts associated with passing weather systems. The implications for cloud seeding over the basin are discussed.
本文研究了雪威战役期间帕耶特河流域过冷液态水含量(SLWC)和滴数浓度(Nt,CDP)的控制。在SNOWIE期间，27.4%的1 Hz原位云滴探针样品处于含有过冷液态水(SLW)的环境中。当SLWC存在时，发现Nt,CDP的四分位数范围为0.02 ~ 0.18 g m−3和13.3 ~ 37.2 cm−3，在对流和强剪切诱导湍流的孤立区域，最极端的值达到0.40 ~ 1.75 g m−3和150 ~ 320 cm−3。SLWC和Nt、CDP的分布与云顶温度和冰粒子浓度直接相关，这与过去对其他山脉的研究结果一致。分析了两类垂直运动作为SLWC和Nt,CDP的潜在控制因素，第一类垂直运动是地形强迫的，相对于地形固定在空间上(平稳波)，第二类是瞬态的，由经过的天气尺度气旋的垂直切变和不稳定触发。SLWC的发生和震级以及与固定上升气流相关的Nt、CDP在SLW存在时沿脊线呈正态分布。在低海拔地区，靠近固定波相关的地形斜坡处，由于混合比较高，垂直气团位移较大，SLW更容易形成。当考虑瞬态上升气流、SLWC和Nt时，由于与过往天气系统相关的上升气流在时间和空间上的变化，CDP在飞行轨迹上的分布更加均匀，与地形的依赖性很小。讨论了在盆地上空播云的意义。
{"title":"Vertical Motions in Orographic Cloud Systems over the Payette River Basin. Part 4: Controls on Supercooled Liquid Water Content and Cloud Droplet Number Concentrations","authors":"T. J. Zaremba, R. Rauber, B. Geerts, J. French, S. Tessendorf, L. Xue, K. Friedrich, C. Weeks, R. Rasmussen, M. Kunkel, D. Blestrud","doi":"10.1175/jamc-d-23-0080.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0080.1","url":null,"abstract":"\u0000This paper examines the controls on supercooled liquid water content (SLWC) and drop number concentrations (Nt,CDP) over the Payette River Basin during the SNOWIE campaign. During SNOWIE, 27.4% of 1 Hz in situ cloud droplet probe samples were in an environment containing supercooled liquid water (SLW). The interquartile range of SLWC, when present, was found to be 0.02-0.18 g m−3, and 13.3−37.2 cm−3 for Nt,CDP, with the most extreme values reaching 0.40−1.75 g m−3 and 150−320 cm−3 in isolated regions of convection and strong shear-induced turbulence. SLWC and Nt,CDP distributions are shown to be directly related to cloud top temperature and ice particle concentrations, consistent with past research over other mountain ranges. Two classes of vertical motions were analyzed as potential controls on SLWC and Nt,CDP, the first forced by the orography and fixed in space relative to the topography (stationary waves), and the second transient, triggered by vertical shear and instability within passing synoptic-scale cyclones. SLWC occurrence and magnitudes, and Nt,CDP associated with fixed updrafts were found to be normally distributed about ridgelines when SLW was present. SLW was more likely to form at low altitudes near the terrain slope associated with fixed waves due to higher mixing ratios and larger vertical air parcel displacements at low altitudes. When considering transient updrafts, SLWC and Nt,CDP appear more uniformly distributed over the flight track with little discernable terrain dependence as a result of time and spatially varying updrafts associated with passing weather systems. The implications for cloud seeding over the basin are discussed.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43487705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-09DOI: 10.1175/jamc-d-23-0050.1
Mikell Warms, K. Friedrich, L. Xue, S. Tessendorf, K. Ikeda
The Western United States, an economic and agricultural powerhouse, is highly dependent on winter snowpack from the Mountain West. Coupled with increasing water and renewable electricity demands, the predictability and viability of snowpack resources in a changing climate is becoming increasingly important. In Idaho, specifically, up to 75% of the state’s electricity production comes from hydropower, which is dependent on the timing and volume of Spring snowmelt. While we know that April 1 snowpack is declining from SNOTEL observations and is expected to continue to decline from GCM predictions, our ability to understand the variability of snowfall accumulation and distribution at the regional level is less robust. In this paper, we analyze snowfall events using 0.9 km-resolution WRF simulations to understand the variability of snowfall accumulation and distribution in the mountains of Idaho between 1 October 2016 – 31 April 2017. Various characteristics of snowfall events throughout the season are evaluated, including the spatial coverage, event durations and snowfall rates, and the relationship between cloud microphysical variables—particularly liquid and ice water content—on snowfall amounts. Our findings suggest that efficient snowfall conditions—e.g., higher levels of elevated supercooled liquid water—can exist throughout the winter season but are more impactful when surface temperatures are near or below freezing. Inefficient snowfall events are common, exceeding 50% of the total snowfall events for the year, with some of those occurring in peak winter. For such events, glaciogenic cloud-seeding could make a significant impact on snowpack development and viability in the region.
{"title":"Drivers of Snowfall Accumulation in the Central Idaho Mountains using Long-Term High-Resolution WRF Simulations","authors":"Mikell Warms, K. Friedrich, L. Xue, S. Tessendorf, K. Ikeda","doi":"10.1175/jamc-d-23-0050.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0050.1","url":null,"abstract":"\u0000The Western United States, an economic and agricultural powerhouse, is highly dependent on winter snowpack from the Mountain West. Coupled with increasing water and renewable electricity demands, the predictability and viability of snowpack resources in a changing climate is becoming increasingly important. In Idaho, specifically, up to 75% of the state’s electricity production comes from hydropower, which is dependent on the timing and volume of Spring snowmelt. While we know that April 1 snowpack is declining from SNOTEL observations and is expected to continue to decline from GCM predictions, our ability to understand the variability of snowfall accumulation and distribution at the regional level is less robust. In this paper, we analyze snowfall events using 0.9 km-resolution WRF simulations to understand the variability of snowfall accumulation and distribution in the mountains of Idaho between 1 October 2016 – 31 April 2017. Various characteristics of snowfall events throughout the season are evaluated, including the spatial coverage, event durations and snowfall rates, and the relationship between cloud microphysical variables—particularly liquid and ice water content—on snowfall amounts. Our findings suggest that efficient snowfall conditions—e.g., higher levels of elevated supercooled liquid water—can exist throughout the winter season but are more impactful when surface temperatures are near or below freezing. Inefficient snowfall events are common, exceeding 50% of the total snowfall events for the year, with some of those occurring in peak winter. For such events, glaciogenic cloud-seeding could make a significant impact on snowpack development and viability in the region.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44753370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：