Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3...

53
Eddy Flux Measurements turbulent fluxes eddy covariance method measurement techniqes Olaf Kolle IMPRS core course Atmosphere & Ocean 2016

Transcript of Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3...

Page 1: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

Eddy Flux Measurements

turbulent fluxes eddy covariance method measurement techniqes

Olaf Kolle IMPRS core course

Atmosphere & Ocean 2016

Page 2: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

2 Eddy-Covariance Instrumentation Index of contents

Index of Contents

1. Turbulent Fluxes and Eddy Covariance Method

2. History of Eddy-Covariance Measurements and Instrumentation

3. Modern Instruments and Data Acquisition

4. Power Supply Issues

5. Examples of Station Setups of MPI-BGC

6. Additional Sources of Information

Page 3: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

3 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Eddy Covariance Measurements Why is it widely used?

Biosphere-Atmosphere-Exchange Eddy Covariance (EC) as a meteorological tool

to determine energy, trace gas and momentum exchange between

ecosystems and the atmosphere for continuous flux measurements → long term observation to obtain fluxes with a high temporal resolution and without disturbance of the environment

Page 4: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

4 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Eddy Covariance Measurements Why is it widely used?

Some key questions and applications

how do ecosystems react on • global warming (e.g. permafrost areas) • increasing atmospheric CO2 concentrations (e.g. growth rates)

how are energy exchange, hydrological cycle, trace gas exchange modified by land use change

selective manipulation experiments comparison of adjacent ecosystems within same climate gain long term data for global databases gain data for model development and validation

Page 5: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

5 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Eddy Covariance Measurements Where to apply?

→ Atmospheric Boundary Layer (ABL) Definition: The part of the troposphere that is directly influenced by the presence of the

earth’s surface and which responds to surface forcings with a timescale of about 1 hour or less (Stull, 1988)

However: Given enough time or space, the entire atmosphere will adjust to surface

conditions (boundary conditions) But:

Surface conditions change too rapidly for the entire atmosphere to adjust. Changes arise from diurnal cycle of energy exchange at the surface.

Page 6: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

6 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Vertical integration:

Fzcwdz

tc hh

=∂

∂+

∂∂

∫∫00

'' Fcwcwdztc

h

h

=−+∂∂

⇒ ∫ 00

''''

cSzcw

tc

=∂

∂+

∂∂ ''

''cwFF S +=

total flux = storage flux + turbulent flux

Eddy Covariance Measurements Theory and equations

uc

vc

wc

Page 7: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

7 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Example for turbulent time series Vertical wind velocity and CO2 concentration

Page 8: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

8 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Example for turbulent time series Vertical wind velocity and CO2 concentration

( ) ( ) ''''11),cov(11

cwcwn

ccwwn

cwn

jjjj

n

jj ==−⋅−= ∑∑

==

Page 9: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

9 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Eddy Covariance Measurements Assumptions

Both variables must be measured at the same point in space and time (how?) Horizontal homogeneity (advection? → footprint analysis)

Steady state conditions (quality test)

Page 10: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

10 Eddy-Covariance Instrumentation Turbulent Fluxes

Turbulent Fluxes and Eddy Covariance Method

Eddy Covariance Measurements Instruments

All variables have to be measured fast enough to catch all flux contributing fluctuations within the entire frequency range For wind components and temperature: Sonic anemometer-thermometer For trace gases: Fast responding gas analyzer

Page 11: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

11 Eddy-Covariance Instrumentation History

History of Eddy-Covariance Measurements and Instrumentation

• First instruments to measure turbulent wind field in boundary layer appeared 1944 – Interest of military in flow patterns of missiles – Theoretical meteorologists interested in wind velocity spectra (Kolmogorov) – Similarity theory (Monin and Obukhov) – Assumption of constant flux in surface layer

• Advances in meteorology and the evolution of sonic anemometry • First instruments capable to measure trace gas concentrations virtually without delay

Radiation in the atmosphere Kondratyev Academic Press, 1969 - 911 Pages

Page 12: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

12 Eddy-Covariance Instrumentation History

The Kansas and Minnesota Experiments

From: Energy and Water Cycles in the Climate System Ehrhard Raschke, Daniela Jacob Springer Science & Business Media, 29.06.2013 - 467 Pages

Page 13: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

13 Eddy-Covariance Instrumentation History

Fast Hygrometers

• Lyman-α-Hygrometer

– Emission by hydrogen at 121.56nm – Absorption by water vapour in short open path – Model 220 Lyman-alpha Hygrometer by

Campbell Scientific (1978)

From: United States Geological Survey Water-supply Paper (1990)

Energy Balance Station (IMK, Karlsruhe, now KIT)

Page 14: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

14 Eddy-Covariance Instrumentation History

Fast Hygrometers

Summary

Commercial instruments in the early 1990s

Page 15: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

15 Eddy-Covariance Instrumentation History

Fast Gas Analyzers for CO2 or CO2 and H2O

• Closed path non-dispersive infrared gas analyzers by LICOR – LI-6251: only CO2, purely analog board (discontinued) – LI-6252: only CO2, analog/digital board (discontinued) – LI-6262: CO2 and H2O, analog/digital board (discontinued)

• Open path infrared gas analyzer by ADC – OP-2: only CO2 and H2O, analog/digital board (discontinued) OP-2 Instruction Manual

Page 16: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

16 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Sonic Anemometers

• CSAT3 (Campbell Scientific, USA)

– preferred direction – sampling rate up to 60 Hz – 4 analog outputs @ 12 Bit – no analog inputs – SDM interface – RS232 interface – no heating

• Gill R3/50, R3, HS (Gill, UK)

– omnidirectional (R3) or preferred direction (HS) – sampling rate up to 50/100 Hz – 8 analog outputs @ 14 Bit – 6 analog inputs @ 14 Bit, 50/100 Hz – RS422/RS232 interface – no heating

Page 17: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

17 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Sonic Anemometers

• Gill Windmaster and Windmaster Pro (Gill, UK)

– omnidirectional – sampling rate up to 20/32 Hz – 4 analog outputs @ 12/14 Bit – 2/4 analog inputs @ 12/14 Bit – RS422/RS485/RS232 interface – no heating

• Young Sonic Anemometer 81000V (Young, USA)

– omnidirectional – sampling rate up to 32 Hz – 4 analog outputs @ 12 Bit – 4 analog inputs @ 12 Bit – RS485/RS232 interface – no heating

Page 18: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

18 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Sonic Anemometers

• Metek USA-1 (Metek, Germany) – omnidirectional – sampling rate up to 50 Hz – 4 analog outputs @ 12 Bit – 6 analog inputs @ 16 Bit – RS422/RS232 interface – with heating – internal data processing possible – new versions available

• Ultrasonic Anemometer 3D (Thies, Germany)

– omnidirectional – sampling rate typ. 285 Hz, output rate up to 1000 Hz – 3 analog outputs @ 16 Bit – 3 analog inputs @ 16 Bit – RS485/RS422 interface – with heating – internal data processing possible

Page 19: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

19 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Sonic Anemometers

From: Practical Handbook of Tower Flux Observation

3D propeller anemometer (Young, USA)

other sonic anemometers

Page 20: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

20 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (closed path)

• LI-7000 (Licor, USA)

– closed path, IR for CO2 and H2O – sample cell volume: 10.86 cm3

– 4 analog outputs @ 14 Bit (300 Hz update) – output rate up to 20 Hz (max. frequency response) – RS232 – Power consumption: 15 W to 40 W

• EC155 (Campbell Scientific, USA) – closed path, IR for CO2 and H2O – sample cell volume: 5.9 cm3

– sampling rate 100 Hz, output rate up to 25 Hz – 2 analog outputs @ 16 Bit (150 Hz update) – RS485, SDM, USB

Page 21: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

21 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (closed path)

• G1301-f, G2301-f, G2311-f (Picarro, USA)

– Cavity Ring-Down Spectroscopy (CRDS) for CO2, CH4, H2O – sample cell volume: ? cm3

– 7 analog outputs @ ? Bit (? Hz update) – max. frequency response: 10 Hz (8 l/min to > 11 l/min) – RS232, Ethernet, USB – Power consumption: < 600 W (with pump)

CRDS principle

Page 22: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

22 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (closed path)

• Models 911-0010 and 911-0011 (Los Gatos, USA)

– Integrated-Cavity Output Spectroscopy (ICOS) for CO2, CH4, H2O – sample cell volume: 408 cm3

– 3 analog outputs @ ? Bit (? Hz update) – max. frequency response: 10 Hz to 20 Hz (> 20 l/min) – RS232, Ethernet, USB – Power consumption: 150 W (without pump)

LGR’s Off-Axis Integrated-Cavity Output Spectroscopy (Off-Axis ICOS)

Page 23: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

23 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (closed path)

• TGA200A (Campbell Scientific, USA)

– tunable-diode laser absorption spectroscopy (TDLAS) for CO2 isotopes, N2O, CH4 – sample cell volume: 200 cm3

– measurement rate: 500 Hz – max. frequency response: 10 Hz (15 l/min) – Ethernet, RS232, SDM – Power consumption: ~100 W (without pump)

Page 24: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

24 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (enclosed path)

• LI-7200 (Licor, USA)

– non-dispersive infrared gas analyzer for CO2 and H2O – sample cell volume: 16 cm3

– maximum bandwidth: 20 Hz (digital processing) – max. frequency response: 10 Hz (15 l/min) – 6 analog outputs @ 16 Bit – 4 analog inputs @ 16 Bit – Ethernet (in/out), RS232 (max. 20 Hz), SDM (max. 50 Hz) – USB storage possible – Power consumption: 12 W (30 W during warmup)

Page 25: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

25 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (open path)

• LI-7500, LI-7500A (Licor, USA)

– non-dispersive infrared gas analyzer for CO2 and H2O – maximum bandwidth: 20 Hz (digital processing) – 2 analog outputs @ 16 Bit, update rate 300 Hz – RS232 (max. 20 Hz), SDM (max. 40 Hz) – Power consumption: 10 W (30 W during warmup)

Page 26: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

26 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (open path)

• EC150 (Campbell Scientific, USA)

– non-dispersive infrared gas analyzer for CO2 and H2O – measurement rate: 100 Hz – maximum bandwidth: 25 Hz (digital processing) – 2 analog outputs @ 16 Bit, update rate 100 Hz – RS485 (max. 50 Hz), SDM , USB (max. 50 Hz) – Power consumption: 5 W

Page 27: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

27 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (open path)

• LI-7700 (Licor, USA) – Wavelength Modulation Spectroscopy (WMS) @ 1.6µm for CH4

– measurement rate: 1000 Hz – maximum bandwidth: 20 Hz (digital processing) – 4 analog inputs @ 16 Bit – 3 thermocouple inputs – Ethernet – Power consumption: 8 W

Laser beam makes 60 passes = 30 m

Page 28: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

28 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (comparison)

Closed Path Instruments

• Several peripheral devices (pump, chemicals or zero gas, tubing, filters)

• Signal drift due to contamination of sample cell (more in humid conditions)

• Loss of information in the high frequency range due to signal smearing inside tubing and insufficient response time of analyser → spectral correction

Page 29: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

29 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (comparison)

Closed Path Instruments

• Time lag between turbulence signals and concentration data

• Factory repairs (cell, source, detector) • Regular and intense maintenance

(calibration, filters, cleaning of hoses) • High power consumption of system • Rather high running costs

Page 30: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

30 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (comparison)

Open Path Instruments

• No peripheral devices required • Easy setup • Less maintenance • Small drift (calibration every 6 months) • Fast sensor response, no time lag • Lower power consumption of system • Lower running costs

--- but ---

Page 31: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

31 Eddy-Covariance Instrumentation Modern Instruments

Present-Day Gas Analyzers (comparison)

Open Path Instruments

• Very sensitive to rain, fog and dew • Large ‘correction’ of flux data required due to density

fluctuations: Webb-Pearman-Leuning (WPL) correction (Webb et al., 1980) Sensible heat flux corrects latent heat flux and both correct the CO2 flux.

Page 32: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

32 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

• on site system

1. pure data collection 2. data collection and processing 3. data collection, processing and visualization

4. data archiving 5. data transmission

Page 33: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

1. pure data collection data collection can be done with data-loggers, computers or special systems

• suitable data-loggers from Campbell Scientific: CR1000, CR3000, CR5000, CR6

• computers should be selected according to power supply situation and environmental conditions (laptops, industrial computers, desktop computers)

• an example for a special system is

the LI-7550 interface box with USB-stick data storage

33 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

Page 34: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

2. data collection and on site processing

– customized data-logger programs with on line flux calculation from Campbell Scientific support of CSAT3, open or closed path gas analyzer and meteorological sensors – EddyMeas (MPI-BGC) running on WINDOWS® (tested up to WIN7) support of various Gill sonics, Metek USA-1, Young 81000V, CSAT3 (only when linked to datalogger) support of most gas analyzers (CH4 only partly) – SmartFlux™ (Licor Biosciences)

34 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

Page 35: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

3. data collection and on site processing and visualization

– EddyMeas (MPI-BGC)

– Campbell Scientific data-logger and EC-system connected to computer running RTMC software

35 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

Page 36: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

36 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

• Typical measurement and data acquisition setups

analog

digital

air inlet line

Page 37: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

37 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

• Typical measurement and data acquisition setups

digital digital

anal

og

analog

Page 38: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

38 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

• Typical measurement and data acquisition setups

Can be used with SmartFlux integrated

Page 39: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

39 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

• Typical measurement and data acquisition setups

digital

digital (SDM) digital (SDM)

analog

air inlet line

Page 40: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

40 Eddy-Covariance Instrumentation Data Acquisition

Data Acquisition

• Typical measurement and data acquisition setups

digital (SDM)

IRGASON

Page 41: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

41 Eddy-Covariance Instrumentation Power Supply Issues

Power Supply Issues

• wide range of power requirements – data-logger with sonic and open path analyzer: ~ 6 W

– data-logger with sonic and closed path analyzer: ~ 12 W

– computer with sonic and enclosed path analyzer: ~ 75 W

– computer with sonic and closed path analyzer (e.g. LI-7000): ~ 120 W

– computer with sonic and closed path analyzer (e.g. Picarro): ~ 500 W

– typical setup with computer, sonic, LI-7200, vertical profile of CO2 and H2O (valve switching unit and data-logger), meteorological sensors on a data-logger, fans: ~ 180 W to 250 W

Page 42: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

42 Eddy-Covariance Instrumentation Power Supply Issues

Power Supply Issues

• power supply systems – line power: UPS always recommended

– solar energy • Tanguro (Brasil): 1 kW & batteries (800 Ah) sufficient

• Hainich (Germany): 2.5 kW & batteries not sufficient ® generator

– fuel cell running on methanol or propane: 50 W to 100 W (lifetime ~ 5000 h)

– wind energy: not really common

– generator only (diesel, gasoline, propane): lifetime of engine 1000 h to 2000 h

– batteries only: possible for very low power consumption, regular exchange

Page 43: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

43 Eddy-Covariance Instrumentation Power Supply Issues

Power Supply Issues

• lightning protection – very important at least for voltage spikes through power line

– instrument protection by ‘outer lightning protection’ • lightning rod: cone ® of protection

• isolated conductor must be well earthed

• isolated mounting of instruments and grounding

• tower construction as conductor also possible but not recommended

– protection of data acquisition (data-logger, computer etc.) by ‘inner lightning protection’ • each single wire protected by surge arresters (overvoltage protectors): expensive

• excellent grounding where provided (chassis of devices, shields of cables)

Page 44: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

44 Eddy-Covariance Instrumentation Examples of Station Setups

Examples of Station Setups

Wetzstein, Thuringia, Germany • spruce forest • line power • 30 m tower • Gill R3, LI-7000, laptop • profile system • meteorology

Page 45: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

45 Eddy-Covariance Instrumentation

Examples of Station Setups

Gebesee, Thuringia, Germany • agricultural field • line power • 3 m to 6 m telescopic tower • Gill R3, LI-7000, laptop • profile system • meteorology

Examples of Station Setups

Page 46: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

46 Eddy-Covariance Instrumentation

Examples of Station Setups

Majadas, Extremadura, Spain • holm oak grove • line power • 2 x 15 m tower, 1 subcanopy tower • Gill R3, LI-7200, industrial computer • profile system • meteorology

Examples of Station Setups

Page 47: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

47 Eddy-Covariance Instrumentation

Examples of Station Setups

Tanguro, Mato Grosso, Brasil • rain forest (control and burnt) • solar energy system • 2 x 36 m tower • Metek USA-1, LI-7200, laptop computer • meteorology

Examples of Station Setups

Page 48: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

48 Eddy-Covariance Instrumentation

Examples of Station Setups

Tanguro, Mato Grosso, Brasil • soy field • solar energy system • 6 m tower • Metek USA-1, LI-7200, industrial computer • meteorology

Examples of Station Setups

Page 49: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

49 Eddy-Covariance Instrumentation

Examples of Station Setups

Tanguro, Mato Grosso, Brasil • soy field • solar energy system • 6 m tower • Metek USA-1, LI-7200, industrial computer • meteorology

Examples of Station Setups

Page 50: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

50 Eddy-Covariance Instrumentation

Examples of Station Setups

ZOTTO, Central Siberia, Russia • pine forest, bog • generator • 1 x 30 m tower, 1 x 10 m tower • Metek USA-1, LI-7200, Picarro,

laptop computer • profile system • meteorology

Examples of Station Setups

Page 51: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

51 Eddy-Covariance Instrumentation

Examples of Station Setups

Cherskii, North East Siberia, Russia • tussok tundra • generator • 2 x 6 m tower (control, drained) • Metek USA-1, LI-7200, Los Gatos,

industrial computer • meteorology

Examples of Station Setups

Page 52: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

52 Eddy-Covariance Instrumentation Communication Standards

Communication Standards

wired communication between instruments, data-loggers and computers • RS232

− old standard for serial data transmission − max. distance: 15 m to 50 m − 300 baud up to 115200 baud (baud=symbols/second): ~ 1 Mbit/s

• RS422 − longer distances: 1200 m − 10 bus sharing units − 10 Mbit/s

• RS485 − longer distances: 1200 m − 32 bus sharing units − 12 Mbit/s

• SDM (synchronous device for measurement (addressable) − max. distance: 7 m − 15 bus sharing units − > 10 Mbit/s

• SDI-12 (synchronous digital interface) − max. distance: 70 m − 1200 baud

• Ethernet − 10, 100 Mbit/s, 1, 10, 100 Gbit/s − 1 m to 50 km, copper and optical fiber

• USB (1.0, 2.0, 3.0) since 1996 − universal serial bus − 1.5 Mbit/s to 5 Gbit/s − max. distance: 5 m

Page 53: Eddy Flux Measurements · 2016-03-17 · Eddy-Covariance Instrumentation Turbulent Fluxes 3 Turbulent Fluxes and Eddy Covariance Method Eddy Covariance Measurements Why is it widely

53 Eddy-Covariance Instrumentation Additional Sources of Information

Additional Sources of Information

Field intercomparison of four methane gas analyzers suitable for eddy covariance flux measurements O. Peltola1, I. Mammarella1, S. Haapanala1, G. Burba2, and T. Vesala1

1Department of Physics, University of Helsinki, P.O. Box 48, Helsinki 00014, Finland 2LI-COR Biosciences, 4421 Superior Street, Lincoln, NE 68504, USA Biogeosciences, 10, 3749–3765, 2013

Practical Handbook of Tower Flux Observation The Forest Meteorology Research Group of the Forestry and Forest Products Research Institute (FFPRI) runs FFPRI FluxNet. The network carries out research on the exchange of energy, water and carbon dioxide between the atmosphere and Japanese forest ecosystems.

A Brief Practical Guide to Eddy Covariance Flux Measurements George Burba, Dan Anderson

Eddy Covariance A Practical Guide to Measurement and Data Analysis Editors: Marc Aubinet, Timo Vesala, Dario Papale

Eddy Covariance Method George Burba (Licor Biosciences)