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  • 1
    Online-Ressource
    Online-Ressource
    Evaluation of Glaciogenic Cloud Seeding using Trace Chemistry
    Weather Modification Association ; 2016
    In:  The Journal of Weather Modification Vol. 48, No. 1 ( 2016-04-30), p. 24-42
    Details
    In: The Journal of Weather Modification, Weather Modification Association, Vol. 48, No. 1 ( 2016-04-30), p. 24-42
    Kurzfassung: Glaciogenic cloud seeding with silver iodide (AgI) has been used to enhance precipitation for over 60 years. Assessments of AgI impact and dispersion are often quantified using atmospheric processes models with impact assessed by comparing models with and without inclusion of cloud seeding modules.  However, there is inherent uncertainty in these aerosol models and physical validation of AgI distribution is of value to both validate and improve model performance. The purpose of this study is to demonstrate the capacity to physically validate the dispersion of AgI by measuring silver enrichments in snow.Field and laboratory methods were developed to detect trace seeding signatures in snowpack. Unique laboratory layout and protocols were developed to reduce contamination potential within a traditional ICP-MS laboratory setting (not housed in a Class 100 Clean Room). Using these methods, we sampled a series of snow profiles within the target area of active cloud seeding in the central mountains of Idaho. Our results demonstrate the ability the ability to reproduce distinct evidence of elevated Ag at concentrations at a hillslope (0.25 km2) and at the basin (2,400 km2) scale. The construction of 8 snow pits at one site (hillslope scale) and 6 sites along a 65 km transect (basin scale) reliably identified both of the seeded storm layers sampled. The location of the peaks in Ag concentration within the snow profiles generally corresponds in timing to known cloud seeding events. Distinct seeded storm layers were reliably identified seeding signatures more than 60 km from the AgI sources, where silver concentrations were only enhanced 1-3 parts per trillion. Ag enriched snow in these chemical profiles generally correspond to downwind target locations and AgI seeding times. 
    Materialart: Online-Ressource
    ISSN: 0739-1781 , 0739-1781
    URL: Article
    DOI: 10.54782/jwm.v48i1.548
    Sprache: Unbekannt
    Verlag: Weather Modification Association
    Publikationsdatum: 2016
    ZDB Id: 2928716-9
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  • 2
    Online-Ressource
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    Vertical Motions in Orographic Cloud Systems over the Payette River Basin. Part III: An Evaluation of the Impact of Transient Vertical Motions on Targeting during Orographic Cloud Seeding Operations
    American Meteorological Society ; 2022
    In:  Journal of Applied Meteorology and Climatology Vol. 61, No. 11 ( 2022-11), p. 1753-1777
    Details
    In: Journal of Applied Meteorology and Climatology, American Meteorological Society, Vol. 61, No. 11 ( 2022-11), p. 1753-1777
    Kurzfassung: In Part II, two classes of vertical motions, fixed (associated with vertically propagating gravity waves tied to flow over topography) and transient (associated primarily with vertical wind shear and conditional instability within passing weather systems), were diagnosed over the Payette River basin of Idaho during the Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE). This paper compares vertical motions retrieved from airborne Doppler radial velocity measurements with those from a 900-m-resolution model simulation to determine the impact of transient vertical motions on trajectories of ice particles initiated by airborne cloud seeding. An orographic forcing index, developed to compare vertical motion fields retrieved from the radar with the model, showed that fixed vertical motions were well resolved by the model while transient vertical motions were not. Particle trajectories were calculated for 75 cross-sectional pairs, each differing only by the observed and modeled vertical motion field. Wind fields and particle terminal velocities were otherwise identical in both trajectories so that the impact of transient vertical circulations on particle trajectories could be isolated. In 66.7% of flight-leg pairs, the distance traveled by particles in the model and observations differed by less than 5 km with transient features having minimal impact. In 9.3% of the pairs, model and observation trajectories landed within the ideal target seeding elevation range ( 〉 2000 m), whereas, in 77.3% of the pairs, both trajectories landed below the ideal target elevation. Particles in the observations and model descended into valleys on the mountains’ lee sides in 94.2% of cases in which particles traveled less than 37 km.
    Materialart: Online-Ressource
    ISSN: 1558-8424 , 1558-8432
    URL: Article
    DOI: 10.1175/JAMC-D-21-0230.1
    RVK:
    UA 4547
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2022
    ZDB Id: 2227779-1
    ZDB Id: 2227759-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
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    Vertical Motions in Orographic Cloud Systems over the Payette River Basin. Part II: Fixed and Transient Updrafts and Their Relationship to Forcing
    American Meteorological Society ; 2022
    In:  Journal of Applied Meteorology and Climatology Vol. 61, No. 11 ( 2022-11), p. 1733-1751
    Details
    In: Journal of Applied Meteorology and Climatology, American Meteorological Society, Vol. 61, No. 11 ( 2022-11), p. 1733-1751
    Kurzfassung: Updrafts in wintertime cloud systems over mountainous regions can be described as fixed, mechanically driven by the terrain under a given ambient wind and stability profile (i.e., vertically propagating gravity waves tied to flow over topography), and transient, associated primarily with vertical wind shear and conditional instability within passing weather systems. This analysis quantifies the magnitude of fixed and transient updraft structures over the Payette River basin sampled during the Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE). Vertical motions were retrieved from Wyoming Cloud Radar measurements of radial velocity using the algorithm presented in Part I. Transient circulations were removed, and fixed orographic circulations were quantified by averaging vertical circulations along repeated cross sections over the same terrain during the campaign. Fixed orographic vertical circulations had magnitudes of 0.3–0.5 m s −1 . These fixed vertical circulations were composed of a background circulation in which transient circulations were embedded. Transient vertical circulations are shown to be associated with transient wave motions, cloud-top generating cells, convection, and turbulence. Representative transient vertical circulations are illustrated, and data from rawinsondes over the Payette River basin are used to infer the relationship of the vertical circulations to shear and instability. Maximum updrafts are shown to exceed 5 m s −1 within Kelvin–Helmholtz waves, 4 m s −1 associated with transient gravity waves, 3 m s −1 in generating cells, 6 m s −1 in elevated convection, 4 m s −1 in surface-based deep convection, 5 m s −1 in boundary layer turbulence, and 9 m s −1 in shear-induced turbulence.
    Materialart: Online-Ressource
    ISSN: 1558-8424 , 1558-8432
    URL: Article
    DOI: 10.1175/JAMC-D-21-0229.1
    RVK:
    UA 4547
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2022
    ZDB Id: 2227779-1
    ZDB Id: 2227759-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
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    A Transformational Approach to Winter Orographic Weather Modification Research: The SNOWIE Project
    American Meteorological Society ; 2019
    In:  Bulletin of the American Meteorological Society Vol. 100, No. 1 ( 2019-01), p. 71-92
    Details
    In: Bulletin of the American Meteorological Society, American Meteorological Society, Vol. 100, No. 1 ( 2019-01), p. 71-92
    Kurzfassung: The Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE) project aims to study the impacts of cloud seeding on winter orographic clouds. The field campaign took place in Idaho between 7 January and 17 March 2017 and employed a comprehensive suite of instrumentation, including ground-based radars and airborne sensors, to collect in situ and remotely sensed data in and around clouds containing supercooled liquid water before and after seeding with silver iodide aerosol particles. The seeding material was released primarily by an aircraft. It was hypothesized that the dispersal of the seeding material from aircraft would produce zigzag lines of silver iodide as it dispersed downwind. In several cases, unambiguous zigzag lines of reflectivity were detected by radar, and in situ measurements within these lines have been examined to determine the microphysical response of the cloud to seeding. The measurements from SNOWIE aim to address long-standing questions about the efficacy of cloud seeding, starting with documenting the physical chain of events following seeding. The data will also be used to evaluate and improve computer modeling parameterizations, including a new cloud-seeding parameterization designed to further evaluate and quantify the impacts of cloud seeding.
    Materialart: Online-Ressource
    ISSN: 0003-0007 , 1520-0477
    URL: Article
    DOI: 10.1175/BAMS-D-17-0152.1
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2019
    ZDB Id: 2029396-3
    ZDB Id: 419957-1
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Online-Ressource
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    Wintertime Orographic Cloud Seeding—A Review
    American Meteorological Society ; 2019
    In:  Journal of Applied Meteorology and Climatology Vol. 58, No. 10 ( 2019-10), p. 2117-2140
    Details
    In: Journal of Applied Meteorology and Climatology, American Meteorological Society, Vol. 58, No. 10 ( 2019-10), p. 2117-2140
    Kurzfassung: This paper reviews research conducted over the last six decades to understand and quantify the efficacy of wintertime orographic cloud seeding to increase winter snowpack and water supplies within a mountain basin. The fundamental hypothesis underlying cloud seeding as a method to enhance precipitation from wintertime orographic cloud systems is that a cloud’s natural precipitation efficiency can be enhanced by converting supercooled water to ice upstream and over a mountain range in such a manner that newly created ice particles can grow and fall to the ground as additional snow on a specified target area. The review summarizes the results of physical, statistical, and modeling studies aimed at evaluating this underlying hypothesis, with a focus on results from more recent experiments that take advantage of modern instrumentation and advanced computation capabilities. Recent advances in assessment and operations are also reviewed, and recommendations for future experiments, based on the successes and failures of experiments of the past, are given.
    Materialart: Online-Ressource
    ISSN: 1558-8424 , 1558-8432
    URL: Article
    DOI: 10.1175/JAMC-D-18-0341.1
    RVK:
    UA 4547
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2019
    ZDB Id: 2227779-1
    ZDB Id: 2227759-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    Vertical Motions in Orographic Cloud Systems over the Payette River Basin. Part I: Recovery of Vertical Motions and Their Uncertainty from Airborne Doppler Radial Velocity Measurements
    American Meteorological Society ; 2022
    In:  Journal of Applied Meteorology and Climatology Vol. 61, No. 11 ( 2022-11), p. 1713-1731
    Details
    In: Journal of Applied Meteorology and Climatology, American Meteorological Society, Vol. 61, No. 11 ( 2022-11), p. 1713-1731
    Kurzfassung: Vertical motions over the complex terrain of Idaho’s Payette River basin were observed by the Wyoming Cloud Radar (WCR) during 23 flights of the Wyoming King Air during the Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE) field campaign. The WCR measured radial velocity V r , which includes the reflectivity-weighted terminal velocity of hydrometeors V t , vertical air velocity w , horizontal wind contributions as a result of aircraft attitude deviations, and aircraft motion. Aircraft motion was removed through standard processing. To retrieve vertical radial velocity W , V r was corrected using rawinsonde data and aircraft attitude measurements; w was then calculated by subtracting the mean W ( ) at a given height along a flight leg long enough for to equal the mean reflectivity-weighted terminal velocity at that height. The accuracy of the w and retrievals were dependent on satisfying assumptions along a given flight leg that the winds at a given altitude above/below the aircraft did not vary, the vertical air motions at a given altitude sum to 0 m s −1 , and at a given altitude did not vary. The uncertainty in the w retrieval associated with each assumption is evaluated. Case studies and a projectwide summary show that this methodology can provide estimates of w that closely match gust probe measurements of w at the aircraft level. Flight legs with little variation in equivalent reflectivity factor at a given height and large horizontal echo extent were associated with the least retrieval uncertainty. The greatest uncertainty occurred in regions with isolated convective turrets or at altitudes where split cloud layers were present.
    Materialart: Online-Ressource
    ISSN: 1558-8424 , 1558-8432
    URL: Article
    DOI: 10.1175/JAMC-D-21-0228.1
    RVK:
    UA 4547
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2022
    ZDB Id: 2227779-1
    ZDB Id: 2227759-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
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    Vertical Motions in Orographic Cloud Systems over the Payette River Basin. Part 4: Controls on Supercooled Liquid Water Content and Cloud Droplet Number Concentrations
    American Meteorological Society ; 2023
    In:  Journal of Applied Meteorology and Climatology ( 2023-08-10)
    Details
    In: Journal of Applied Meteorology and Climatology, American Meteorological Society, ( 2023-08-10)
    Kurzfassung: This paper examines the controls on supercooled liquid water content ( SLWC ) and drop number concentrations ( N t ,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 N t,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 N t,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 N t,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 N t ,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 N t,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.
    Materialart: Online-Ressource
    ISSN: 1558-8424 , 1558-8432
    URL: Article
    DOI: 10.1175/JAMC-D-23-0080.1
    RVK:
    UA 4547
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2023
    ZDB Id: 2227779-1
    ZDB Id: 2227759-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
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    Microphysical Characteristics and Evolution of Seeded Orographic Clouds
    American Meteorological Society ; 2021
    In:  Journal of Applied Meteorology and Climatology Vol. 60, No. 7 ( 2021-07), p. 909-934
    Details
    In: Journal of Applied Meteorology and Climatology, American Meteorological Society, Vol. 60, No. 7 ( 2021-07), p. 909-934
    Kurzfassung: The spatial distribution and magnitude of snowfall resulting from cloud seeding with silver iodide (AgI) is closely linked to atmospheric conditions, seeding operations, and dynamical, thermodynamical, and microphysical processes. Here, microphysical processes leading to ice and snow production are analyzed in orographic clouds for three cloud-seeding events, each with light or no natural precipitation and well-defined, traceable seeding lines. Airborne and ground-based radar observations are linked to in situ cloud and precipitation measurements to determine the spatiotemporal evolution of ice initiation, particle growth, and snow fallout in seeded clouds. These processes and surface snow amounts are explored as particle plumes evolve from varying amounts of AgI released, and within changing environmental conditions, including changes in liquid water content (LWC) along and downwind of the seeding track, wind speed, and shear. More AgI did not necessarily produce more liquid equivalent snowfall (LESnow). The greatest amount of LESnow, largest area covered by snowfall, and highest peak snowfall produced through seeding occurred on the day with the largest and most widespread occurrence of supercooled drizzle, highest wind shear, and greater LWC along and downwind of the seeding track. The day with the least supercooled drizzle and the lowest LWC downwind of the seeding track produced the smallest amount of LESnow through seeding. The stronger the wind was, the farther away the snowfall occurred from the seeding track.
    Materialart: Online-Ressource
    ISSN: 1558-8424 , 1558-8432
    URL: Article
    URL: Article
    DOI: 10.1175/JAMC-D-20-0206.1
    DOI: 10.1175/JAMC-D-20-0206s1
    RVK:
    UA 4547
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2021
    ZDB Id: 2227779-1
    ZDB Id: 2227759-6
    Standort Signatur Einschränkungen Verfügbarkeit
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