Building and End-to-end System for Long Term Soil Monitoring

Katalin Szlávecz, Alex Szalay, Andreas Terzis, Razvan Musaloiu-E., Sam Small, Josh Cogan,

Randal Burns

The Johns Hopkins University

Jim Gray, Stuart Ozer

Microsoft Research

Motivation for Building a Sensor Network

Monitoring: background data, trends =>

• Soil animal activity/metabolic processes depend on moisture, temperature

• Frequent visits disturb the sites

• Soil respiration, trace gas fluxes

• Better input for terrestrial hydrology models

• CS: Build and learn from a deployed system

Spatio-temporal Heterogeneity of the Soil Ecosystem

Heterogeneity

• Sampling problem

• Scaling problem

• Large scale estimates?

Capturing Heterogeneity at Mesoscale: Wireless Sensor Networks

• Small computers with radio transmitter

• Each connected to multiple sensors (moisture, air and soil temperature, light)

• Automatic data upload

Architecture

Network Design

• Ten mote network

• Each mote

– samples every min

– data stored in FLASH

– status every 2 min, wait for data request

• Single hop network

– Gateway connected to campus network 2m

8m

2m

From Raw Data to Useful Quantities

Temperature SensorCalibration

Temperature SensorCalibration

SoilTemperature

SoilTemperature

Water ContentVolumetric

Water ContentVolumetric

Soil Water Potential->Volumetric ConversionSoil Water Potential->Volumetric Conversion

VoltageVoltage

VoltageVoltage

VoltageVoltage

Moisture sensorA/D units

Moisture sensorA/D units

Reference voltageA/D units

Reference voltageA/D units

Temperature sensorA/D units

Temperature sensorA/D units

CPU clockCPU clock

Air TemperatureA/D units

Air TemperatureA/D units

Light IntensityA/D units

Light IntensityA/D units

TemperatureConversion

TemperatureConversion

Air TemperatureCelsius

Air TemperatureCelsiusUTC DateTimeUTC DateTime

ResistanceResistance

ResistanceResistance

Mote Resistor Calibration

Mote Resistor Calibration

Moisture SensorCalibration

Moisture SensorCalibration

Water PotentialWater Potential

Calibrationsin the Lab

Calibrationsin the Lab

Current Status Olin Deployment

• Operating since Sep 2005

• Over 8M data points

• Winding down

Database/Datacube

• SQL Server 2005 database

• Rich metadata stored in DB

• Adopted from astronomy: NVO

• Data access through web services

• Graphical interface

• DataCube under construction(multidimensional summary of data)

Online Data Access

Measurement

sensor hour

day

week

season

year

all

tenMinute

depth

categoryall

all

all Hour of Day

Day of Season

Week of Season

Season of Year

Patch

Site

all

Sensor Datacube Dimension Model

Lessons Learned: Wireless Sensor Networks

• Network lifetime is predictable • Nodes continue operate despite large

environmental fluctuations – Waterproofing is still an issue

Bathtub test

Lessons Learned: Wireless Sensor Networks II

• Single-hop network: transmission range is considerably shorter than in lab due to foliage– Relay node helps

• Low level programming is still required • Importance of sensor uniformity is essential

– Switch to Echo sensors

Lessons Learned: Data Systems

• We got real data, end-to-end ! • Sensors respond to environmental changes • Database from off-the-shelf components • Getting high level summaries : DataCube

• We need a fully automated pipeline: the current two manual steps are still too labor intensive

Additional Deployments ILeakin Park Urban forest, BES permanent plot

Since March 06

Additional Deployments II

Baltimore Polytechnic High SchoolTwo days ago

Integration of Sensor Data into Baltimore Ecosystem Study Projects

• Urban-rural gradient studies• Water and Carbon Cycling

– 200 node network at Cub Hill • Ecology of invasive species

– Less fluctuating? More refuges?– Light composition – onset of

reproduction• Spatio-temporal patterns of soil C and

N cycling– Attachment of additional gas sensors

Neighborhood Scale Heterogeneity: Cub Hill

• Many different land use /land management types

• Different soil conditions, soil communities

• Plan: to deploy 200 motes in summer 06

Maps by E. Ellis and D. Cilento, Dept. of Geography, UMBC

CO2 Flux tower

• Microsoft Research

• The Gordon and Betty Moore Foundation

• Seaver Foundation

• Gordon Bell

• Allison Smykel, Katy Juhaszova

Acknowledgement