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Commercial weather systems, data loggers, and weather databases

Ned Bair US Army Corps of Engineers Cold Regions Research and Engineering

LaboratoryEarth Research Institute, UC - Santa Barbara

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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 Scientific– Scientific applications, remote (no power)

installations– Campbell makes instruments, loggers, and

software• Andover – Facilities system– provides controllers– SQL Server interface

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CR3000

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Data loggers

• Record measurements from instruments into tables

• Often 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 Campbell

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Weather databases

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

spreadsheets?• When should one use a database versus a

spreadsheet?

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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 solutions• Campbell LNDB• Vista Datavision• Roll 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.

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Relational database systems

• Microsfot SQL Server• MySQL• PostegreSQL

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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

From http://edn.embarcadero.com/article/25209

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In practice

• Each table should contain as few columns as possible

• Converting 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.

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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 Young– Pros: Cheap– Cons: Rime and break easily, no heat.

• Cylindrical - Phil Taylor– Pros: can accurately measure very strong peak winds (220

mph); great heaters.– Cons: Spin-down time; expensive; phil will retire soon

• Sonic – Campbell, Lufft– Pros: No moving parts; not too expensive for 2d version– Cons: arms can rime up and break, but heated version is

offered

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Temperature/RH sensors

• usually combo probes• simple 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

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Tipping Buckets

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

– e.g. MetOne– Pros: accuracy, cost– Cons: clogging by ice; undercatch bias

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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, Sutron– Pros: accuracy, cost; – Cons: clogging by ice; undercatch bias; need to be

emptied, sometimes 2X or more a season.

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Undercatch

Goodison, B., Louie, P. Y. T., and Yang, D.: WMO Solid precipitation measurement intercomparison, World Meteorological Organization, 1998.

Undercatch at Mammoth

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Snow pillows

• Custom-made deals, e.g. CA DWR• Stainless 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 water– Pros – only decent measure of SWE on the ground– Cons – not very sensitive; expensive and hard to get– Custom rigs

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Radiometers

• Shortwave– Clear (200-1200nm) and nIR (1200-1500nm), e.g.

Eppley labs– Direct and diffuse (e.g. auto shadow band,

Sunshine pyranometer)• Longwave

– 3.5 µm

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Depth pingers

• Ultrasonic– Send a ultrasonic chirp down to snow surface,

then calculate depth based on its return time back to the sensor

– E.g. Judd, Campbell• Pros– cheap, accurate, durable

• Cons– Can 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 sensor– Pros: no moving parts– Cons: water kills signal, low SWE limit, expensive

• FMCW radar– Measures stratigraphy by scanning through radars frequencies – Pros: nondestructive stratigraphy– Cons: expensive and needs modeled grain sizes

• Lysimeters– Tipping buckets buried in the ground– Measure melt water– Pros: cheap, great way to measure when water 1st 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.