Precipitation distribution analysis Flashcards
What is a basic rain gauge?
Is a simple funnel that transports water into a graduated cylinder, need to go out and measure it, downsides- water can evaporate out
What is a tipping bucket?
automated version of the simple rain gauge.
It knows how much volume it takes to flip the bucket back and forth.
Each time the bucket flips down, it toggles a switch which ways the ppt remotely.
- downsides- short rainfall can evaporate before it funnels into bucket, intense water can also cause it to fall out
What is an optical rain gauge?
is a point measurement of ppt where rain falls through the laser, interrupts it and the laser counts the ppt size and velocity, it can also account for the types of ppt
What are the biases associated with point measurements? Which apply to which instrument?
Evaporation loss- applies to tipping bucket and basic rain guage
Wetting loss- tipping buckets and basic rain gauge
Splash- tipping buckets and basic rain guage
Turbulence- can happen when trying to avoid splash- updraft will effect rain gauge and tipping bucket
Response rate- effects optical rain gauge
What are siting concerns?
Are when things obstruct the rain measurer, want the measurer to be 2x the heigh of the nearest obstruction and should be 2x the distance of the obstruction height
How is occult ppt an issue when it comes to point measurements?
Occult ppt can be missed the the gauge and it doesn’t actually flow from atmosphere (for ex fog drip)
How is does measuring a canopy lead to issues in point measurements?
you can get interception, water that never hits ground and miss that or you mght want to get accurate measurement, some intercepted water can flow in through stemflow so you might wanna account for that
Canopy drip might direct ppt to a certain spot, want to account for that
Point measurements types and pros and cons?
look at slide 11
How do you calculate ppt of an area?
can find weight of area (area of station/total area) and then * by ppt, and them sum up all ppt.
What is surface fitting (isohyetal techniques)?
A technique in which point measurements of ppt are taken, and then lines of simalar ppt are connected and those ar eused to build polygons, only works if rainfall is proportional to area
What is a hypsometric method (DEM)?
In which elevation and ppt are graphed together to see relationship, still includes a lot extrapolation as this elevation and ppt relationship can have issues with slope, aspect, attack of wind etc
If your missing guage data, what are the three things you can do?
average it, do a regression to find it, do a weighted average to find it
