Precipitation Measurement - Standard Gauge The Good: Simple Inexpensive The Bad: Maintenance Evaporation - No digital output - Spatial extent

Precipitation Measurement - Weighing Gauge The Good: Time series Simple (mostly) The Bad: Messy maintenance Moving parts - No digital output Spatial extent Pretty expensive

Precipitation Measurement - Tipping Bucket The Good: Digital time series Accurate The Bad: Snow? - Loss during tips

Precipitation Measurement - Piezoelectric The Good: Very accurate Digital data logger The Bad: Expensive - Spatial extent

Doppler Radar A standard rain gage will have a sample area of ~ ft2, but radar will sample ~ hundreds mi2

Stick gage - $400 Tipping bucket - $700 Weighing - $5,000+ Doppler - $5,000,000

Measurement Errors Placement (near structures) Wind Unequal distribution (rain is a spatial process) Placement:

Wind Error 1. Reduced effective catch area. 2. Rain gage will cause wind to lift and accelerate.

Wind

Double Alter Wind Shield

Dealing with Spatial Variability Arithmetic Mean Thiessen Polygon Interpolation

Cloud Drip Icacos , Puerto Rico 423 mm/yr Pico del Este, Puerto Rico Monteverde, Costa Rica 350 mm/yr Some tropical watershed research shows that cutting cloud forests actually reduces stream flow.

Hail and sleet are frozen rain, where as snow crystals form when water vapor condenses directly into ice. As much as 75 percent of water supplies in the western United States are derived from snowmelt . 300 inches of snow that the Lake Tahoe area receives is equivalent to about 30 inches of rain.

Snow Measurement Snow pack Core sampling Snow “Pillow”

Getting Rain Data http://fawn.ifas.ufl.edu http://data.cuahsi.org SJRWMD National Climate Data Center National Weather Service (NOAA)