WMOD00268

• Applicant: CWCB
• Sponsor Name: USBR
• Project Name: Final Report Weather Damage Mitigation Program
• Title: Numerical Simulations of Snowpack Augmentation for Drought Mitigation Studies in the Colorado Rocky Mountains
• Prepared For: USBR - WDMP
• Prepared By: Curt Hartzell, Dr. William Cotton, Joe Busto
• Date: 9/1/2005
• State: CO
• Weather Modification - Doc Type: Scientific Study

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2.6 Task 3.. Perform simulations of Lagrangian transport of seeding
materials on selected days covering a range of wind and
stability regimes

This task first involved selecting certain meteorological regimes that impact
the transport and dispersion of Agl cloud-seeding material, and then identify six
case study days that represent those regimes. The selection of case study days
was based primarily on observed wind direction, low-level stability, and the location
and amount of snowfall. The CSU Team then performed Lagrangian trajectory
analyses using RAMS model output data to examine the predicted trajectories and
the extent to which they interact with clouds in the target area. Findings from these
case studies are summarized in Subsection 3.8.

The selection of meteorological regimes included the identification of
precipitation observation sites. The research project team decided that the
NRCS SNOTEL (SNOpack TELemetry) network would provide the bulk of
precipitation data that would be used in project studies. This was due to the
network's reasonably large number of stations at representative higher elevation
sites over the entire study area, the reliability and generally high quality of its 24-
hr precipitation and SWE reports, and its uniform 0800 UTC (0100 MST)
reporting time. The 0100 MST observation time is convenient for evaluating
RAMS 24-hr simulated precipitation.

There were 94 SNOTEL sites within the state of Colorado, but only 63 of
these sites were on RAMS Grid 3. Appendix 2 gives location/IO information for
all 94 sites; the appendix figure shows the site locations within RAMS Grid 3.
Two of the 63 sites on Grid 3 had obviously bad data and were not used in
project studies. The SNOTEL sites used for statistical evaluations included 12
located within the target area and 18 non-target area sites. These 30 SNOTEL
sites are hilited with yellow in Appendix 2. The locations of SNOTEL sites within
and near the OW Program target area are shown in Figure 2.9. The numbers
identifying the sites correspond to SNOTEL site information listed in Appendix 2.

SNOTEL sites located to the west and southwest of the OW and Vall/BC
cloud-seeding operations may have been affected by other seeding programs
(see Figure 1.2); therefore, they were only used for the overall assessment of the
model's simulated precipitation across the Grid-3 domain. For the detailed
evaluation of control no-seed vs. seed simulations, the CSU team used the 30
sites indicated by yellow hilite in Appendix 2 plus 31 other non-target area sites
within Grid 3 (61 total). The final selection of sites included in the statistical
evaluation was done after quality control of the SNOTEL precipitation and SWE
data, aided by comparison with data collected by NWS climate stations, ski
areas, Community Collaborative Rain, Hail & Snow (CoCoRaHS) sites, and
NRCS snowcourse sites.

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