scholarly journals The impact of ground-based glaciogenic seeding on a shallow stratiform cloud over the Sierra Madre in Wyoming: A multi-sensor study of the 3 March 2012 case

2018 ◽  
Vol 214 ◽  
pp. 74-90 ◽  
Author(s):  
Binod Pokharel ◽  
Bart Geerts ◽  
Xiaoqin Jing
Keyword(s):  
Stratiform Cloud ◽  
Sierra Madre ◽  
Glaciogenic Seeding ◽  
The Impact

Dual-Polarization Radar Data Analysis of the Impact of Ground-Based Glaciogenic Seeding on Winter Orographic Clouds. Part I: Mostly Stratiform Clouds

2015 ◽  
Vol 54 (9) ◽  
pp. 1944-1969 ◽  
Author(s):  
Xiaoqin Jing ◽  
Bart Geerts ◽  
Katja Friedrich ◽  
Binod Pokharel
Keyword(s):  
Radar Data ◽  
Control Area ◽  
Target Area ◽  
Dual Polarization ◽  
Stratiform Clouds ◽  
Orographic Clouds ◽  
Close Range ◽  
Glaciogenic Seeding ◽  
Differential Reflectivity ◽  
The Impact

AbstractThe impact of ground-based glaciogenic seeding on wintertime orographic, mostly stratiform clouds is analyzed by means of data from an X-band dual-polarization radar, the Doppler-on-Wheels (DOW) radar, positioned on a mountain pass. This study focuses on six intensive observation periods (IOPs) during the 2012 AgI Seeding Cloud Impact Investigation (ASCII) project in Wyoming. In all six storms, the bulk upstream Froude number below mountaintop exceeded 1 (suggesting unblocked flow), the clouds were relatively shallow (with bases below freezing), some liquid water was present, and orographic flow conditions were mostly steady. To examine the silver iodide (AgI) seeding effect, three study areas are defined (a control area, a target area upwind of the crest, and a lee target area), and comparisons are made between measurements from a treated period and those from an untreated period. Changes in reflectivity and differential reflectivity observed by the DOW at low levels during seeding are consistent with enhanced snow growth, by vapor diffusion and/or aggregation, for a case study and for the composite analysis of all six IOPs, especially at close range upwind of the mountain crest. These low-level changes may have been affected by natural changes aloft, however, as evident from differences in the evolution of the echo-top height in the control and target areas. Even though precipitation in the target region is strongly correlated with that in the control region, the authors cannot definitively attribute the change to seeding because there is a lack of knowledge about natural variability, nor can the outcome be generalized, because the sample size is small.

The impact of ground-based glaciogenic seeding on clouds and precipitation over mountains: A multi-sensor case study of shallow precipitating orographic cumuli

2014 ◽  
Vol 147-148 ◽  
pp. 162-182 ◽  
Author(s):  
Binod Pokharel ◽  
Bart Geerts ◽  
Xiaoqin Jing ◽  
Katja Friedrich ◽  
Joshua Aikins ◽  
...  
Keyword(s):  
Glaciogenic Seeding ◽  
The Impact

A Case Study on the Impact of Ground-based Glaciogenic Seeding on Winter Orographic Clouds at Daegwallyeong

2015 ◽  
Vol 36 (4) ◽  
pp. 301-314 ◽  
Author(s):  
Ha-Young Yang ◽  
◽  
Sanghee Chae ◽  
Jin-Yim Jeong ◽  
Seong-Kyu Seo ◽  
...  
Keyword(s):  
Orographic Clouds ◽  
Glaciogenic Seeding ◽  
The Impact

An Airborne Profiling Radar Study of the Impact of Glaciogenic Cloud Seeding on Snowfall from Winter Orographic Clouds

2010 ◽  
Vol 67 (10) ◽  
pp. 3286-3302 ◽  
Author(s):  
Bart Geerts ◽  
Qun Miao ◽  
Yang Yang ◽  
Roy Rasmussen ◽  
Daniel Breed
Keyword(s):  
Doppler Radar ◽  
Weather Conditions ◽  
Cold Season ◽  
Near Surface ◽  
Medicine Bow Mountains ◽  
Orographic Clouds ◽  
Surface Reflectivity ◽  
Glaciogenic Seeding ◽  
The Impact ◽  
Composite Data

Abstract Data from an airborne vertically pointing millimeter-wave Doppler radar are used to study the cloud microphysical effect of glaciogenic seeding of cold-season orographic clouds. Fixed flight tracks were flown downstream of ground-based silver iodide (AgI) generators in the Medicine Bow Mountains of Wyoming. Composite data from seven flights, each with a no-seeding period followed by a seeding period, indicate that radar reflectivity was higher near the ground during the seeding periods. Several physical considerations argue in favor of the hypothesis that the increase in near-surface reflectivity is attributed to AgI seeding. While the increase in near-surface reflectivity and thus snowfall rate are statistically significant, caution is warranted in view of the large natural variability of weather conditions and the small size of the dataset.

scholarly journals A multi-sensor study of the impact of ground-based glaciogenic seeding on clouds and precipitation over mountains in Wyoming. Part II: Seeding impact analysis

2017 ◽  
Vol 183 ◽  
pp. 42-57 ◽  
Author(s):  
Binod Pokharel ◽  
Bart Geerts ◽  
Xiaoqin Jing ◽  
Katja Friedrich ◽  
Kyoko Ikeda ◽  
...  
Keyword(s):  
Impact Analysis ◽  
Glaciogenic Seeding ◽  
The Impact

Organic Agriculture and Globalization: A Maya Associative Corporation in Chiapas, Mexico

1997 ◽  
Vol 56 (4) ◽  
pp. 427-436 ◽  
Author(s):  
Ronald Nigh
Keyword(s):  
Social Organization ◽  
Organic Agriculture ◽  
Value Added ◽  
Organizational Form ◽  
Direct Access ◽  
Multiple Goals ◽  
Sierra Madre ◽  
Political Challenge ◽  
The Impact

Indigenas de la Sierra Madre de Motozintla (ISMAM), the world's foremost producer of organic gourmet coffee, is a prominent example of an associative corporation, an organizational form combining aspects of traditional Indian social organization and modern capitalist enterprises. The development of ISMAM's organic strategy is analyzed as acheiving multiple goals, including improving soils and improving marketing conditions by permitting greater value-added to growers through direct access to high-value markets. The role of external brokers and the impact of organic marketing on organizational structure are analyzed. Though not typical, ISMAM is an encouraging example of a viable small-farmer strategy for meeting the economic and political challenge of globalization.

scholarly journals A Case Study of Radar Observations and WRF LES Simulations of the Impact of Ground-Based Glaciogenic Seeding on Orographic Clouds and Precipitation. Part II: AgI Dispersion and Seeding Signals Simulated by WRF

2016 ◽  
Vol 55 (2) ◽  
pp. 445-464 ◽  
Author(s):  
Lulin Xue ◽  
Xia Chu ◽  
Roy Rasmussen ◽  
Daniel Breed ◽  
Bart Geerts
Keyword(s):  
Nucleation Rate ◽  
Wrf Model ◽  
Grid Spacing ◽  
Medicine Bow Mountains ◽  
Eddy Simulation ◽  
Cloud Dynamics ◽  
Vertical Dispersion ◽  
Orographic Clouds ◽  
Glaciogenic Seeding ◽  
The Impact

AbstractSeveral Weather Research and Forecasting (WRF) Model simulations of natural and seeded clouds have been conducted in non-LES and LES (large-eddy simulation) modes to investigate the seeding impact on wintertime orographic clouds for an actual seeding case on 18 February 2009 in the Medicine Bow Mountains of Wyoming. Part I of this two-part series has shown the capability of WRF LES with 100-m grid spacing to capture the essential environmental conditions by comparing the model results with measurements from a variety of instruments. In this paper, the silver iodide (AgI) dispersion features, the AgI impacts on the turbulent kinetic energy (TKE), the microphysics, and the precipitation are examined in detail using the model data, which leads to five main results. 1) The vertical dispersion of AgI particles is more efficient in cloudy conditions than in clear conditions. 2) The wind shear and the buoyancy are both important TKE production mechanisms in the wintertime PBL over complex terrain in cloudy conditions. The buoyancy-induced eddies are more responsible for the AgI vertical dispersion than the shear-induced eddies are. 3) Seeding has insignificant effects on the cloud dynamics. 4) AgI particles released from the ground-based generators affect the cloud within the boundary layer below 1 km AGL through nucleating extra ice crystals, converting liquid water into ice, depleting more vapor, and generating more precipitation on the ground. The AgI nucleation rate is inversely related to the natural ice nucleation rate. 5) The seeding effects on the ground precipitation are confined within narrow areas. The relative seeding effect ranges between 5% and 20% for the simulations with different grid spacing.

scholarly journals Dual-Polarization Radar Data Analysis of the Impact of Ground-Based Glaciogenic Seeding on Winter Orographic Clouds. Part II: Convective Clouds

2015 ◽  
Vol 54 (10) ◽  
pp. 2099-2117 ◽  
Author(s):  
Xiaoqin Jing ◽  
Bart Geerts
Keyword(s):  
Cloud Base ◽  
Base Temperature ◽  
Target Area ◽  
Dual Polarization ◽  
Low Level ◽  
Convective Clouds ◽  
Orographic Clouds ◽  
Orographic Convection ◽  
Glaciogenic Seeding ◽  
The Impact

AbstractThis second paper of a two-part series aims to explore the ground-based glaciogenic seeding impact on wintertime orographic clouds using an X-band dual-polarization radar. It focuses on three cases with shallow to moderately deep orographic convection that were observed in January–February of 2012 as part of the AgI Seeding Cloud Impact Investigation (ASCII) project over the Sierra Madre in Wyoming. In each of the storms the bulk upstream Froude number exceeded 1, suggesting unblocked flow. Low-level potential instability was present, explaining orographic convection. The clouds contained little supercooled liquid water on account of the low cloud-base temperature. Ice-crystal photography shows that snow mainly grew by diffusion and aggregation. To examine the seeding effect of silver iodide (AgI), five study areas are defined: two target areas and three control areas. Comparisons are made between the control and target areas as well as between a treated, or seeded, period and an untreated period. Low-level reflectivity tends to increase in the target areas relative to the control. This increase is larger in the lee target area than in the upwind target area, suggesting that precipitation enhancement is delayed in the presence of convection. The echo tops of the convective cells are not higher during seeding, relative to simultaneous changes in the control regions. This result suggests that the dynamic-seeding mechanism does not apply for the cold-base convective clouds that are studied here. An analysis of differential reflectivity and snow photography suggests that static seeding is the more likely snow-enhancement mechanism in these clouds.

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