# Presentation: 171034

## Installation and Use of Meteorological Tower Systems

- Melanie A. Wetzel
***Desert Research Institute***
*and*
***University of Nevada, Reno***

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

**Notes:**
Networks of towers and other standardized installation options are becoming 
more ubiquitous.   As each agency develops locations and sensor suites which
meet the specific needs of their observing, maintenance and research programs,
it is important to have continuity, consistency and accuracy in the datasets, so
that the investment can support continued assessment of environmental change 
and promote interdisciplinary applications.

## Objectives

- Approach the use of instrumented tower systems as a process
- Present technical options for sensor and tower characteristics
- Describe factors and decisions critical to installation
- Provide examples of tower system applications

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

**Notes:**
I would like to address the topic of instrumented systems as a process which 
begins with project design and attention to quality assurance (QA) aspects, 
which will make both the initial setup and the subsequent use of the instrumentation
more economical and useful.

## Why Use Towers ?

- Standardization (generally to 10 m height) with respect to vertical profiles of wind, temperature and other boundary layer parameters
- Ability to apply parameterizations for other heights such as the logarithmic wind speed (S) *vs.* height (H) equation,  					Sa = Sb (Ha/Hb)***p***				 	Exponent ***p*** is typically in the range  0.14 for smooth terrain to 	  0.25 for rough terrain
- Reduction in blockage and shadowing from obstructions
- Increased availability of solar power; improved communications

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

## Examples of Existing Networks

- AWOS and ASOS
- Oklahoma MesoNet
- MesoWest
- SNOTEL
- Highway Networks  (DOT, States)
- Air Quality Networks
- DOE / ARM

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

## System Design Factors

*Sensor characteristics*
*Tower access*
*Transport, construction and maintenance*
*Data communications options*
*Power source*
*System expandability*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Process-Oriented Approach to System Design

*1.*    *Select sensors*
* **2.    Specify data acquisition*
*  **3.    Design power system*
*   **4.    Program the datalogger*
*    **5.    Install equipment*
*     **6.    Plan heights for equipment installation*
*       **7.    Design tower setup and installation procedures*
*        **8.    Orient instruments*
*         **9.    Install and initialize software*
*          **10.  Maintain data collection and data quality*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Steps for Specifying Instrumentation

*Determine scope of project and potential applications*
*Identify needs for simultaneous auxiliary data*
*Select types of instrumentation (parameters, resolution, range)*
*Determine sampling rates and length of study*
*Acquire specific instruments (cost, availability, etc)*
*Conduct analysis of extreme conditions (heat, cold, icing, wind)*

***Example of time averaging***
***measurements from a sensor ***
***with low resolution***

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

## Criteria for Sensor Selection 

*Sensor range, resolution, precision*
*Ruggedness and suitability for local environmental conditions*
*Cost of acquisition, operation and maintenance*
*Availability (lead time, access to replacement parts)*
*Manufacturer history *
*Software ease of use and compatibility*
*Technical support*
*Calibration requirements*
*Time response and sampling frequency*
*Compatibility with other sensors*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Data Acquisition Guidelines

*Determine data channel types and **	**number*
*Calculate memory requirements*
*Select data storage, access, editing and **	**merging methods*
*Define protocol for missing data*
*Determine procedures for identifying **	**drift or calibration errors*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Options for System Power

*Calculate power needed*
*Instruments*
*Datalogger*
*Communications*
*Heaters*
*Evaluate power sources*
*Direct power                                                                                                 (capacity, reliability)*
*Fueled generators                         *
*Wind and solar energy*
*Battery reserve (temperature                                                                                                                                                             effects and minimum capacity )*
*Provide adequate monitoring of power supply and interruptions*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Example of System Power Chart

*Communications power drain is larger than sensor operation or data storage functions.*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Programming for Data Acquisition

- Set up the datalogger program prior to field deployment
- Develop data capture protocol                    (dial-in, site visit, etc)
- Design data archival and documentation procedures

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Installation of Equipment at Site

- Assess possible hazards -- lightning, vandalism, animals, accidents
- Select location most appropriate to project objectives and longevity
- Avoid locales which are unrepresentative (fog, valley inversions)
- Identify and map potential obstructions or conditions
- dust
- wind
- temperature
- solar illumination
- precipitation

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Proper Heights for Equipment Installation

*Wind velocity standard height **	**vs. wind turbine height*
*Solar panel location for site **	**power vs solar energy **	**survey*
*Need for multiple or non-**	**	**standard heights*
*Access to control panel and **	**communications*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

## Considerations for Tower Setup

- Sensor placement
- Sensor orientation
- Shadowing
- Wind blockage
- Spatial representativeness

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

## Tower Types

- Poles with guy lines
- Tripod
- Triangular
- Sectioned
- Pivoting
- Use of structures

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  Orienting Instruments

- Wind Vane
- Radiative Sensors
- azimuth angle
- elevation angle
- Reducing shadowing of precipitation, wind and other parameters

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

##  On-site Software Installation

*Test communications to and from **	**tower*
*Download program to site **	**	**datalogger*
*Select and set time/date *
*Record local site parameters *
*latitude/longitude*
*elevation*
*location on map*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

## Quality Control and Data Management

- Prescribe schedule to routinely check data quality
- Monitor power supply
- Assess need to relocate sensors
- Evaluate benefits of sensor upgrade
- Prepare documentation for operations and training:
*Standard Operating Procedures*
*Site photos and diagrams*
*Log sheets for maintenance *
*Data format and archival schedule*
*Sensor calibration history *

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems

## References

*Daley, R., 1991:  Atmospheric Data Analysis.  Cambridge University Press, 457 pp.*
*DeFelice, T.P., 1998:  An Introduction to Meteorological Instrumentation and Measurement, Prentice Hall, New Jersey, 229 pp.*
*Webster, J.G., ed., 1999:  The Measurement, Instrumentation and Sensors Handbook.  CRC Press, 916 pp.*

- January 2001  --  AMS Short Course on Instrumentation

- Tower Systems