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- Author or Editor: Robert D. Elliott x
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Some general characteristics of synoptic developments in the 500 mb vorticity field are discussed with particular attention devoted to sudden injections of vorticity and to changes in circulation patterns downwind therefrom. Attention is then focused on vorticity injections generated at low latitudes, but not too low to interact in an important way with the middle latitude circulation. Composite maps based upon numerous cases are shown which reveal the development of large scale anomalous patterns in the westerlies during the 3 days subsequent to low latitude vorticity injection. The forecasting implications are discussed.
Some general characteristics of synoptic developments in the 500 mb vorticity field are discussed with particular attention devoted to sudden injections of vorticity and to changes in circulation patterns downwind therefrom. Attention is then focused on vorticity injections generated at low latitudes, but not too low to interact in an important way with the middle latitude circulation. Composite maps based upon numerous cases are shown which reveal the development of large scale anomalous patterns in the westerlies during the 3 days subsequent to low latitude vorticity injection. The forecasting implications are discussed.
An analysis of a series of cloud seeding projects conducted in three different Pacific-slope watershed areas, each during several seasons, is presented. Seven separate project-seasons are involved in each of which identical seeding procedures were used. Silver iodide smoke generators were operated at ground level for a total of well over 10,000 generator-hours during these operations.
Snowpack and other official precipitation records are examined and target-to-control-area comparisons made in order to bring out the effects of the seeding and apply statistical tests thereto.
It is concluded that this evaluation procedure, as applied to the available data, is capable of discerning the effectiveness of cloud seeding in increasing precipitation over a period of several seasons, but is not capable of bringing into focus the many details of interest to the cloud seeder.
An analysis of a series of cloud seeding projects conducted in three different Pacific-slope watershed areas, each during several seasons, is presented. Seven separate project-seasons are involved in each of which identical seeding procedures were used. Silver iodide smoke generators were operated at ground level for a total of well over 10,000 generator-hours during these operations.
Snowpack and other official precipitation records are examined and target-to-control-area comparisons made in order to bring out the effects of the seeding and apply statistical tests thereto.
It is concluded that this evaluation procedure, as applied to the available data, is capable of discerning the effectiveness of cloud seeding in increasing precipitation over a period of several seasons, but is not capable of bringing into focus the many details of interest to the cloud seeder.
Results of 1,460 replies to a questionnaire on the usefulness of various forecast aids are summarized. Figures are presented showing the forecast aids, charts and diagrams in the order of their indicated usefulness to forecasters. The analysis of the replies shows that differences between services are minor and mainly attributable to differences in requirements and data availability. Differences in experience and training are minor but indicate some small variations. For several forecast aids discrepancies are noted between a particular aid's usefulness and its use.
Results of 1,460 replies to a questionnaire on the usefulness of various forecast aids are summarized. Figures are presented showing the forecast aids, charts and diagrams in the order of their indicated usefulness to forecasters. The analysis of the replies shows that differences between services are minor and mainly attributable to differences in requirements and data availability. Differences in experience and training are minor but indicate some small variations. For several forecast aids discrepancies are noted between a particular aid's usefulness and its use.
