WRF Large-eddy Simulations of chemical tracer deposition and seeding effect over complex terrain from ground- and aircraft-based AgI  generators

Xue, Lulin; Edwards, Ross; Huggins, Arlen W.; Lou, Xiaofeng; Rasmussen, Roy; Tessendorf, Sarah A.; Holbrook, Pat; Blestrud, D.; Kunkel, M. L.; Glenn, Brandal; Parkinson, Shaun

doi:10.1016/j.atmosres.2017.02.013

Cited by 17 publications

(15 citation statements)

References 34 publications

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“…Kang and Bryan () conducted idealized large‐eddy simulations (LESs) to investigate convection initiation due to heterogeneous surface fluxes and pointed out that increasing the model horizontal grid resolution is beneficial for forecasting convective initiation. The turbulence‐resolving LES mode of the Weather Research and Forecasting model (hereafter referred to as WRF‐LES) has been used for real case studies, and with positive results beneficial to the study of different topics such as wind energy (Liu et al, ), orographic cloud seeding (Chu et al, , ; Xue et al, , ), and deep convection (Heath et al, ; Parodi & Tanelli, ). These studies indicate that WRF‐LES is promising for fine‐scale weather forecasts.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms for a Record‐Breaking Rainfall in the Coastal Metropolitan City of Guangzhou, China: Observation Analysis and Nested Very Large Eddy Simulation With the WRF Model

Huang

Liu

Huai-yu³

et al. 2019

JGR Atmospheres

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Record‐breaking rainfall of 524.1 mm in 24 hr occurred in the coastal metropolitan city of Guangzhou, China, during 6–7 May 2017 and caused devastating flooding. Observation analysis and a nested very large eddy simulation (VLES) with Weather Research and Forecasting (WRF) model were conducted to investigate various factors that contributed to the heavy rainfall, including synoptic weather pattern, topographic effects, cold pool, and urban effects. First, the warm and moist southerly flow in the lower troposphere over the trumpet‐shaped topography of the Pearl River Delta continuously provided fuel for the development of the severe rainfall. Consequently, the southerly flow from the sea in the south strengthened with the development of the convection. Meanwhile, the precipitation‐produced weak cold pool supported a stationary outflow boundary, where new convective cells were continuously initiated and drifted downstream. The interaction between the cold outflows and the warm moist southerly flows in the lower troposphere formed a back‐building convective system, which produced local persistent heavy rainfall that lasted for more than 5 hr and reached record levels. Sensitivity experiments in which the urban area was removed from the model indicate that the urban forcing affected the timing and location of convective initiation and helped concentrate the maximum rain core. The nested WRF‐LES successfully simulated this heavy rainfall, and the model's advantages are noted for forecasting such local severe weather.

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Section: Introductionmentioning

confidence: 99%

Mechanisms for a Record‐Breaking Rainfall in the Coastal Metropolitan City of Guangzhou, China: Observation Analysis and Nested Very Large Eddy Simulation With the WRF Model

Huang

Liu

Huai-yu³

et al. 2019

JGR Atmospheres

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“…Determining the spatial and temporal distribution of AgI in snow has been especially useful in the past 5 years for validating and developing cloud seeding process models [8,9]. Two recent cloud seeding projects utilized snow chemistry data to inform statistical models or to parameterize weather model inputs: SNOWIE and the WWMPP [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Ground-Based and Aerial Cloud Seeding Using Trace Chemistry

Fisher

Lytle

Kunkel

et al. 2018

Advances in Meteorology

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Targeting seedable clouds with silver iodide in complex terrain adds considerable uncertainty in weather modification studies. This study explores the geographic and temporal distribution of silver iodide associated with an active cloud seeding program in central Idaho snowpack using trace chemistry. Over 4,000 snow samples were analyzed for the presence of a cloud seeding silver iodide (AgI) signature over two winter seasons. The results indicate the following. (1) At sites within 70 km of AgI sources, silver enrichments were detected at 88% of cases involving seeding efforts from ground generators, but none from aircraft seeded cases.(2) Real-time snow collection methods were replicable within 0.41 ppt and confirmed seeding signatures for the entire duration of a seeded storm ( = 3). (3) Sites sampled beyond 70 km of AgI sources ( = 13) lacked detectable seeding signatures in snow. The results of this study demonstrate some of the strengths and limitations of chemical tracers to evaluate cloud seeding operations and provide observational data that can inform numerical simulations of these processes. The results also indicate that this chemical approach can be used to help constrain the spatiotemporal distribution of silver from cloud seeding efforts.

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“…Different from idealized cases, the sensitivity of WRF‐LES to model resolution, forcing data, and turbulence resolving model needs to be assessed. Xue et al () simulated four cloud seeding events using WRF‐LES with a 667‐m resolution and found that WRF‐LES exhibits comparable increase in precipitation with observations. However, the WRF‐LES results may contradict the observations (e.g., Liu et al, ).…”

Section: Conclusion and Discussionmentioning

confidence: 97%

A High‐Resolution Simulation of Roll Convection Over the Yellow Sea During a Cold Air Outbreak

2019

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Horizontal convective rolls (HCRs) are significant for vertical transport of momentum, heat, and moisture, which is not fully understood partly due to lack of adequate observations. Previous high‐resolution modeling studies of roll convection mainly focused on idealized simulations. This study is one of the first simulations of HCRs with high‐resolution numerical weather prediction models in the real world, aiming to assess the modeling ability of realistic roll structure and investigate the characteristics of roll‐to‐cell transition. A real case of roll convection over the Yellow Sea during a cold air outbreak has been simulated, using the Weather Research and Forecasting (WRF) model at resolutions of 1 (WRF1) and 3 km (WRF3). Compared with the WRF3 simulation, the cloud water, vertical velocity, and the fine‐scale secondary circulations of HCRs are enhanced in WRF1 simulation, and the geometrical and physical parameters are consistent with the observations of satellite images (viewed as cloud streets) or previous studies. In this case, the 1‐km WRF simulation is able to reproduce the HCRs with a roll size of ~5 km. When the rolls transform to open cells downstream, the friction velocity and sensible heat flux gradually reduce following the prevailing wind, and the stability parameter –zi/L (the ratio of planetary boundary layer depth to Obukhov length) tends to increase with larger variances. During the roll‐to‐cell transition, the associated thermodynamic conditions are well simulated, with an average –zi/L ~ 22. In the future, reliable high‐resolution simulations can serve as an alternative to quantitatively investigate roll characteristics when observations are sparse or unavailable.

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WRF Large-eddy Simulations of chemical tracer deposition and seeding effect over complex terrain from ground- and aircraft-based AgI generators

Cited by 17 publications

References 34 publications

Mechanisms for a Record‐Breaking Rainfall in the Coastal Metropolitan City of Guangzhou, China: Observation Analysis and Nested Very Large Eddy Simulation With the WRF Model

Mechanisms for a Record‐Breaking Rainfall in the Coastal Metropolitan City of Guangzhou, China: Observation Analysis and Nested Very Large Eddy Simulation With the WRF Model

Assessment of Ground-Based and Aerial Cloud Seeding Using Trace Chemistry

A High‐Resolution Simulation of Roll Convection Over the Yellow Sea During a Cold Air Outbreak

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