WMOD00263 ‎(2)‎

• Applicant: CWCB
• Sponsor Name: USBR
• Project Name: Response to RFP
• Title: Numerical Simulations of Snowpack Augmentation for Drought Mitigation Studies in the Colorado Rocky Mountains
• Prepared For: USBR
• Prepared By: Joe Busto, CWCB
• Date: 8/20/2003
• Weather Modification - Doc Type: Application

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The seeding contractor will provide the CSU team with information on their cloud
seeding operations, including locations of generators used and seeding rates. The CSU
team proposes to evaluate simulated non-seeded vs. seeded precipitation accumulations
on monthly and seasonal time scales. For more rigorous statistical evaluation of
simulated precipitation by RAMS, CSU will apply Multivariate Randomized Block
Permutation (MRBP) analysis for a selected one-month period. This evaluation is
important to determine if the model-forecast skill is sufficient to discriminate seeding
responses. CSU then plans to perform Lagrangian transport and diffusion calculations of
seeding materials on selected days to determine the extent to which ground-based
generated seeding material is entering the supercooled clouds.

Modeling studies in the past have been limited to single case studies or used very
simplified models (i.e. parcel models). In this proposal we intend to perform daily
forecasts or simulations throughout a winter season. Post analysis for each forecast
period will include model simulations of transport and diffusion of seeding material, its
activation if and when it enters clouds, the effect of the seeding on explicitly represented
precipitation processes, and then sedimentation of precipitation to the ground. This
should provide a unique physical evaluation of the effects of seeding supercooled
orographic clouds in Colorado.

The main deliverables include: (1) real-time forecasts of winds and natural (non-seeded)
precipitation to aid in seeding operation decision-making; (2) post analysis of simulated
seeding effects on monthly and seasonal accumulated precipitation; (3) evaluations of
transport and dispersion of seeding material for selected weather regimes; and (4)
rigorous statistical evaluations of model performance in predicting natural vs. seeded
orographic precipitation for a selected month. This will benefit the program by providing
a physical evaluation of the seeding operations, which should help determine if the
seeding operations have a cost-effective benefit.

In addition to the basic research study proposal we have added the option to extend the
evaluations of model performance using MRBP statistics from one month to five months
of winter seeding operations. Funding of this option would increase the confidence in the
evaluation of the model's performance.

Although it is not included in our proposal, we urge the Reclamation to find support for
the construction of a new continuous-flow diffusion chamber (CFDC) for measuring ice
nuclei concentrations. The CFDC is important for the proposed modeling studies since
background concentrations of ice nuclei are required. It also can provide further evidence
that the seeding material is getting into the regions of the target clouds. This device can
also be used to support other cloud seeding programs funded by the Weather Damage
Modification Program.

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