Commercial weather systems, data loggers, and weather datab - PowerPoint Presentation

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Commercial weather systems, data loggers, and weather databases

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Ned Bair US Army Corps of Engineers Cold Regions Research and Engineering LaboratoryEarth Research Institute, UC - Santa BarbaraSlide2

Weather systems

Some companies offer “one stop” shopping, e.g. Campbell offers instruments, logger, and software packages.

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Two US companies that offer commercial systems

Campbell ScientificScientific applications, remote (no power) installations

Campbell makes instruments, loggers, and softwareAndover Facilities systemprovides controllersSQL Server interface

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CR3000

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Data loggers

Record measurements from instruments into tablesOften convert a voltage into a physical quantity using a linear equation

Also can use serial protocols Use a simple high level programming language, e.g. Edlog for Campbell10Slide11

Weather databases

What is a relational database?What is the difference between databases and spreadsheets?

When should one use a database versus a spreadsheet?11Slide12

Spreadsheet/delimited flat file

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Table in a database

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Getting logger data into a database

This is the hard part!Commercial solutionsCampbell LNDB

Vista DatavisionRoll your own (e.g. UNIX shell scripting or Python)

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What is UNIX/LINUX

A plain text operating system. Linux (1991) is based on UNIX, developed in 1969 by Bell Labs.Tons of text tools, makes it great for processing scientific data

Cygwin is unix emulator for PCs.15Slide16

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Relational database systems

Microsfot SQL ServerMySQL

PostegreSQL18Slide19

SQL

Structured query language

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Primary keys

A unique identifier for a row

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Foreign keys

a field that links to a row in another table

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Normalization, first normal form

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From http://edn.embarcadero.com

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In practice

Each table should contain as few columns as possibleConverting a table from more columns to more rows usually results in a more normalized form

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CUES_CR3K_1_WS600Weather

CUES_CR3K_2_SNOW_DEPTH_2012rev

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Normalized form, transaction table

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Logger table

Transaction table

Mappings

List of tables

Instruments

Measurements

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How much time should I spend dealing with database issues?

It depends on the scale of your system. If you only have a few instruments, then a basic system that spits out logger tables, e.g. Campbell is fine.

If you have lots of instruments and things change frequently, then you need a database system, e.g. Andover.27Slide28

Why spend the effort of normalizing?

For more complex systems you will spend much less time overall with an efficient and normalized DB.

E.g. adding deleting columns in a flat file sucks. It’s not an issue with a transaction table.For the bigger systems I suggest becoming good friends with a DBA, preferably one who works for the same employer and likes patrol/avalanche work/etc.

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Wind heads

“Birds” - RM YoungPros: Cheap

Cons: Rime and break easily, no heat.Cylindrical - Phil TaylorPros: can accurately measure very strong peak winds (220 mph); great heaters.Cons: Spin-down time; expensive; phil will retire soonSonic – Campbell,

LufftPros: No moving parts; not too expensive for 2d versionCons: arms can rime up and break, but heated version is offered

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Temperature/RH sensors

usually combo probessimple install, but MUST be shielded from radiation.

Mammoth’s super signs, bank signs, and high school signs are often not shielded.e.g. Campbell HMP45C 30Slide31

Tipping Buckets

Work by filling a small bucket with melted precip until it tips, tips are counted by the gauge.

e.g. MetOnePros: accuracy, costCons: clogging by ice; undercatch

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Weighing gauges

Precip falls into an antifreeze/water mixture on top of a pressure transducer.

Increases in transducer weight correspond to precip increases.e.g Noah, SutronPros: accuracy, cost;

Cons: clogging by ice; undercatch bias; need to be emptied, sometimes 2X or more a season.

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Undercatch

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Goodison, B., Louie, P. Y. T., and Yang, D.: WMO Solid precipitation measurement

intercomparison, World Meteorological Organization, 1998.Slide34

Undercatch at MammothSlide35

Snow pillows

Custom-made deals, e.g. CA DWRStainless steel, usually 2 x 2 filled with antifreeze (ethylene glycol)

Antifreeze is piped to a pressure transducer, e.g. GE Druck that outputs a voltage, eg. 0-5 V, 0-100 in waterPros – only decent measure of SWE on the groundCons – not very sensitive; expensive and hard to get

Custom rigs35Slide36

Radiometers

ShortwaveClear (200-1200nm) and nIR

(1200-1500nm), e.g. Eppley labsDirect and diffuse (e.g. auto shadow band, Sunshine pyranometer)Longwave

– 3.5 µm36Slide37

Depth pingers

UltrasonicSend a ultrasonic chirp down to snow surface, then calculate depth based on its return time back to the sensor

E.g. Judd, CampbellProscheap, accurate, durableConsCan give null readings during heavy snow

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Cool shit

Gamma ray SWE detectors

Measure SWE via attenuation of gamma radiation emitted from earth’s core.Campbell makes a commercial sensorPros: no moving partsCons: water kills signal, low SWE limit, expensiveFMCW radarMeasures stratigraphy by scanning through radars frequencies

Pros: nondestructive stratigraphyCons: expensive and needs modeled grain sizesLysimetersTipping buckets buried in the groundMeasure melt water

Pros: cheap, great way to measure when water 1

st

gets through pack

Cons: not commercial systems available, get silted up.

Capacitance probes

Measure SWE via dielectric constant

Pros: very accurate

Cons: water kills signal

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Instrument calibration

All instruments require maintenance and calibration.Some instruments are more robust than others, e.g. Phil Taylor wind heads versus sonic anemometers.

This is an integral part of your budget that you can’t skimp on.Cap-Ex’s are usually easier sells than other budget items like pay raises.39