Student Support/Preparation

Scientific Justification

A data logger is an electronic device that automatically collects data at a predetermined sampling rate. This lets you collect valuable environmental measurements in remote locations. It also let’s you collect data continuously so that you can see changes during each day. With a data logger, you can collect data during weekends and school breaks up to a month in length without daily reading and resetting of the thermometer. Data is stored on a memory chip that should remember any data sent to it, even if the operating battery fails.

 Continuous soil temperature measurements such as these are not routinely collected except in a few research sites. You will add a significant additional site to the world-wide data set. Our view of climate is dominated by our easy access to air temperature data, but soil temperatures might be just as important. Until more soil temperature data are available, we just don’t know.

Synthesis Questions

• How do soil and air temperature vary throughout the day?
• How are soil temperature and air temperature related?
• How are soil temperatures at different depths related?
• How are changes in soil and air temperature affected by soil moisture?
• How does soil texture affect soil temperature?
• For influencing the timing of budburst and other phenologic changes in your area, are temperature averages or extremes more important?

Data Logger Preparation

Lab Guide

Task

Prepare and assemble the data logger and cables. Load the data logger software.

What You Need

Data Logger/Sensor Assembly

- H08-006-04 HOBO H8 4-Channel External
- TMC1-HA Wide-range temperature sensor, 0.3 m (1 ft) cable (1)
- TMC20-HA Wide-range temperature sensor, 6.1 m (20 ft) cable (3)
- Water tight box such as Rubbermaid #1 square sandwich box (~0.5 L volume)
- CaSO4 or other dehydrating agent (100 mL)
- Strain-relief connectors (4)

Computer interface

- BoxCar Pro® v.3.5+ or v.4.0 software
- PC or MAC computer interface cable

In the Lab

1. Use a permanent marker to mark BOTH ends of four sensor cables, about 1 cm from the reinforced plug tip. Use 1,2,3 or 4 lines drawn completely around each cable. Label the short cable #1.

2. Seal cables and data logger in a water-tight box

• Option A) Using strain relief connectors:
• Drill or punch-out four equally-spaced, 12 mm (1/2") holes in sidewall.
• Install strain relief connectors, using a bit of silicon sealant around the threads.
• Insert sensor cables through connectors and plug into appropriate data logger sockets.
• Note: a set of strain relief connectors can be obtained by sending your mailing address to: Dr. Jim Washburne, GLOBE Program, Dept. of Hydrology & Water Resources, University of Arizona, Tucson, AZ, 85721-0011 or emailing to: jwash@hwr.arizona.edu

OR

• Option B) Using wire ties and silicon sealant:
• Drill four equally-spaced, 5 mm (1/4") holes in sidewall.
• Insert sensor cables through the sidewall and plug into appropriate data logger sockets.
• Fasten a wire tie snug against inside wall.
• Fasten a wire tie snug against outside wall.
• Apply silicon sealant around wires and between wire tie and hole.
• Let dry/cure for 24 hrs.

3. Load the Boxcar Pro software on your computer. If you are using a MAC, you must download the software from: www.onsetcomp.com/Support/2543_MacBCP.html . Note: newer iMAC/G3/G4 computers with USB ports require additional cable adapters.

• Follow the software installation instructions on page 1 of the BoxCar Pro® User's Manual.
• Connect the serial cable to a PC (9-pin, D-type) COM port OR to a MAC (8-pin, O-type) modem port.
• Check  the date and time on your computer to ensure that they are correct.
• Run c:\Bxcrpro3\Bxcrpro.exe (default location) or double click on the BoxCar Pro® icon.

Calibration and Lab Tests

Lab Guide

Task

Verify that the data logger and sensors are operating normally.

What You Need

- Data logger assembly and cables
- Warm water (~50 oC), Un-insulated cup, Ice
- Calibration thermometer

In the Lab

1. Record Sensor Bias – This test verifies that all four channels are recording the same approximate temperature by collecting data for a few minutes with all four sensors grouped together measuring air temperature. The bias or difference between each sensor should be less than 1o C.

a.       Plug each sensor into the appropriate socket and place all four sensor tips together and away from any sources of heat (like a sunny spot).

b.      Connect the logger to the serial cable.

c.       Confirm that your computer's clock is showing the current local time.

d.      Double click on the Boxcar® icon to run this software.

e.       Select “Launch” (Crtl L) under the “Logger” button on the main menu bar.

f.        Change the file "Description" from "TEST" to "Day1bias".

g.       Change the "Interval" to "6 sec"

h.       Select the "Start" button, message should indicate the "program" is being loaded.

i.         Wait 3 min. The data logger should be working!

j.        Select “Readout” (Crtl R) under the “Logger” button on the main menu bar.

k.      Screen should indicate the data is being "Downloaded", then prompt you for a filename. The default should be Day1bias.dtf

l.         Use View, Display Options to look at each temperature channel separately.

m.     Record the average value from each channel in your GLOBE Science Log , they should be within 1o C of each other.

n.       Make sure that you understand the time axis scale and that it is showing the correct time and date and how to save the data to an Excel file.

2. Full Range Calibration

a.       Place the four temperature sensors in a half-full, non-insulated cup of warm water (~50 oC).

b.      Connect the logger to the serial cable.

c.       Confirm that your computer's clock is showing the current local time.

d.      Select “Launch” under the “Logger” button on the main menu bar.

e.       Set the file "Description"  to "CAyymmdd", where yymmdd is today’s year, month and day.

f.        Set the "Interval" to "5 min" and launch the logger with a delayed start at the next regular 5 minute time mark (example: its now 10:17:00. So set the delayed start for 10:20:00).

g.       Record the calibration thermometer temperature every 5 min in conjunction with the loggers sampling time. 

h.       After the temperature change slows to 1o C/5 min, add ice cubes and continue until the water approaches freezing.

Data Logger & Sensor Field Installation

Field Guide

Task

Install the data logger and sensors at your atmosphere study site.

What You Need

- Meter stick
- digging tools
- 120 cm x 2.5 cm PVC tube
- Data logger assembly and cables
- Drill with 12 mm spade bit
- Wire or brackets to secure PVC tube to post
- String or wire tie
- Desiccant

In the Field

1.      Plan the installation. Make sure that the distance between your box and deepest sensor is less than 5.5 meters and that it is safe to dig a 50 cm deep hole.

2.      Drill a 12 mm hole, if needed, through the bottom of your shelter, near the back.

3.      Place the Data logger box inside the instrument shelter.

4.      Use string or a wire tie to secure the air temperature sensor (#1) inside the instrument shelter.

5.      Feed your 3 long cables through the 12mm hole and pull them through the PVC tube (which protects the cables from excessive UV and animal bites). Plan on keeping any excess wire inside the shelter.

6.      Secure the PVC tube to the shelter post.

7.      Dig a hole 50 cm deep on the sunny (equatorward) side of the shelter post.

8.      Push sensors horizontally into the side of the hole  at 50 cm (#4), 10 cm (#3), and 5 cm (#2) depths, respectively. Use a nail or steel pin with a slightly smaller diameter to pilot these holes if the soil is hard.

9.      Open the bag of desiccant in the up-right position inside the watertight box or pour it into a light cotton bag (breathable – like a child’s sock) so the air inside the box will be kept dry.

10.  Seal the water tight box containing the data logger.

Data Logger Launching

Lab or Field Guide

Task

To launch your data logger for collecting  diurnal soil and air temperature measurements.

What You Need

- Data logger disconnected from the four sensor cables
- Computer: 386 or better, 4 Mb RAM, Windows 3.1 or later, 1 available COM (serial) port
- Data logger data sheet

In the Lab or Field

1. Make sure that your computer's clock is reading the correct local time.
2. Run the BoxCar® software
3. Connect the HOBO® 4-Channel External logger to the serial cable using the large jack.
4. Select “Launch”(Ctrl L) under “Logger” button on the main menu bar.
5. You should see or select the following:

i.                     Interval (duration) = 15 minutes (84 Days),
(more frequent observations will not be accepted).

ii.                   Measurement: Channels 1-4 recording Temperature (both oF and oC). Without the sensors connected, the values will be different but should be relatively constant.

iii.                  Battery Level: full (replace the battery when level falls below 30%)

6. Select “Advanced Options”.
7. You should see or select the following:

i.                     Wrap-around when full (unchecked)

ii.                   Delayed Start (checked) Set to expected start time; Use this feature to start sampling times on the quarter hour, example: XX:00:00, XX:15:00, XX:30:00, or XX:45:00. Select “am” or “pm”.

8. Select “Enable/Disable Channels”.
9. For Channels 1-4, you should see of select the following:

i.                     -40 oF to +212 oF  [TMC6-HA].  (checked)

ii.                   Select “Apply”

10. Select “Start”.

Data Logger Installation

Field Guide

Task

To install the launched logger in the instrument shelter.

What You Need

- Launched data logger - Desiccant - Data logger data sheet

In the Field

1. Open the door of the instrument shelter and uncap the empty data logger box.
2. Make sure that the logger and cable plugs are dry. Replace the desiccant as is necessary.
3. Carefully plug each sensor cable into the appropriate data logger channel. Make sure that each plug is fully inserted and seated in its jack.

i.                     Plug cable #1 into jack #1 (air temperature sensor)

ii.                   Plug cable #2 into jack #2 (5 cm sensor)

iii.                  Plug cable #3 into jack #3 (10 cm sensor)

iv.                 Plug cable #4 into jack #4 (50 cm sensor)

4. Carefully seal the water-tight data logger box and place out of the way in the instrument shelter.
5. The data logger is now collecting data. We recommend you download the data weekly when school is in session or monthly during longer vacations.

Data Collection

Lab Guide

Task

To download the data stored in your data logger to your computer.

What You Need

- Data logger disconnected from the four sensor cables - Computer: 386 or better, 4 Mb RAM, Windows 3.1 or later, 1 available COM (serial) port - Data logger data sheet

In the Lab

1. Make sure that your computer's clock is reading the correct local time.
2. Run BoxCar® software.
3. Connect the HOBO® 4-Channel External logger to the serial cable using the bottom and largest plug.
4. Select “Readout” (or Ctrl R) under the “Logger” button on the main menu bar.
5. You should see:

i.                     A pop-up box will indicate that the software is searching for the HOBO® data logger.

ii.                   A pop-up box will indicate that the data are being downloaded.

iii.                  A warning will be given if the data-logger and shuttle clocks are unsynchronized.

iv.                 Battery Level: replace the battery after saving the data if the battery level falls below 30%.

v.                   A “Save As” box.

6. Rename the data file (.dtf file) and save it. It is recommended to use a file name like "SSYYMMDD" where,

i.                     “SS” is a two character school  or site code and "YYMMDD" are the two digit values for year, month and day (i.e., 010315) for the date that you downloaded (READOUT) these data from your logger. Note: this BoxCar® software is limited to 8 character filenames.

ii.                   Make sure to select or take note of the output data directory.

7. Take time to preview the data using BoxCar's graphing capabilities.

Data Manipulation and Submission to GLOBE

Lab Guide

Task

To convert the data in the appropriate format for reporting to GLOBE.

What You Need

- Computer: 386 or better, 4 Mb RAM, Windows 3.1 or later, 1 available COM (serial) port
- BoxCar® software
- Excel or other spreadsheet software
- Data logger data sheet

In the Lab

You should send in your data to GLOBE as often as you download your logger, which should be approximately weekly to monthly.

1.      Double click on the BoxCar®  icon to run this software.

2.      Under “File” select “Open” and open the BoxCar® file (.dtf) that contains the data you are preparing to submit to GLOBE

3.      Under “File” select “Export” and then “Excel” or the appropriate spreadsheet choice (or just select the “Excel” icon on the shortcut toolbar).

4.      The “Export Set-Up” box will appear

5.      Select all four channels that contain Celsius measurements by selecting each channel marked “Temperature [*C]” in the “Units” box (be sure to deselect the first default value which is marked “Temperature [*F]”).

6.      Select “Export”.

7.      Maintain the name as “SSYYMMDD.txt”

8.      Select “OK”.

9.      Launch Excel or other spreadsheet software.

10.  Under “File” select “Open” and choose the file that contains your data (SSYYMMDD.txt).

11.  Make sure to select “All Files (*.*)” under “Files of Type”.

12.  Select “Open”.

13.  The “Text Import Wizard” should be set to “Delimited”, “Start Import at Row 1”, “File origin Windows (ANSI).

14.  Select “Finish” directly without passing through the intermediate steps. You should see one column of time data and four columns of temperature data with units of [*C].

15.  Graph your data following the steps under “Looking at the Data”.

16.  If you have any data that are unquestionably bad or suspect, replace those values with a “M”. Bad data will often occur at the beginning or end of your data record due to sampling while the sensors were disconnected.

17.  If one of your sensors was missing or not working, replace the appropriate columns or rows of data with an “X”, which is the null or missing data flag or symbol.

18.  Select the whole first row that contains the titles (by clicking on “1”) and remove it, by selecting “Delete” under the “Edit” menu.

19.  Format the whole first column that contains the time and date (by clicking on “A”) and choose “Cells” under the “Format” menu.

20.  In the pop-up box that appears select “Custom” under “Category” and under “Type” enter yyyymmddhhmm. Hit “OK”. The date and time entries are now in the format required by GLOBE.

21.  Select columns A,B,C and insert three new columns by selecting “Columns” under the “Insert” menu.

22.  Scroll down to the last row of data.

23.  Type “DLOG” in column A.

24.  Enter your GLOBE School ID in column B.

25.  Enter the GLOBE site type and number where the data logger is installed (atmosphere site = ATM-dd or soil moisture site = SMS-dd; e.g., ATM-01 or SMS-01) in column C.

26.  Highlight the three cells containing “DLOG”, your GLOBE school ID , and the site type and number and select “Copy” under the “Edit” menu.

27.  Highlight the first three columns in the second to last row of data and then use the following two keystrokes to highlight all the cells in columns A-C that contain data: “End”, “Shift Up Arrow”.

28.  Select “Paste” under the “Edit” menu so that these three values are copied to the selected area of columns A-C.

29.  Select column E and insert one new column by selecting “Columns” under the “Insert” menu.

30.  Format the whole fifth column (by clicking on “E”) and choose “Cells” under the “Format” menu.

31.  In the format cells “Number” pop-up box that appears, select “Text”. Move to the format cells “Alignment” tab and select “Right” within the “Horizontal” selection box. Hit “OK”

32.  Scroll down to the last roll of data, if necessary.

33.  In column E,  enter the UT offset between your site and the prime meridian (UT_offset = UT_time – Local_time). This will be a constant unless there has been a local time shift (ie. day light savings) during the period of observation. Enter this value using a ±hhmm scheme (example: +0400 for a 4 hour offset for the East coast of the U.S. or –1030 for a –10 hour 30 minute offset for central Australia). Note, the sign of these offsets are opposite the standard value. Unfortunately, the coming and going of daylight savings varies by country. Please consult local authorities as to what local time you need to make this adjustment (or visit www.worldtimezone.com/daylight.htm).

34.  Highlight the cell containing your offset and select “Copy” under the “Edit” menu.

35.  Highlight the empty cell in column E in the second to last row and then use the following two keystrokes to highlight all the cells in column E that contain data: “End”, “Shift Up Arrow”.

36.  Select “Paste” under the “Edit” menu so that this value is copied to the selected area of column E.

37.  Save this document by selecting “Save As”  under the “File” menu.

38.  Change the name of this GLOBE formatted file to “DLYYMMDD.txt” (ignore the warning about file format generated by “Excel” ) and save as a tab-delimited text file.

39.  You are now ready to send your data to GLOBE by email.

40.  Launch your email program without quitting Excel.

41.  In the “To:” field of your message enter “GLOBE@FSL.NOAA.GOV”.

42.  In the “Subject:” field enter “DATA”.

43.  The first line of the text of your message must be “//AA”. This tells the GLOBE server that the lines that follow will contain data.

44.  Copy and paste the nine columns of  the spreadsheet file that contains your logger data:

                                                               i.      Switch back to Excel or other spreadsheet and highlight the portion of the nine columns that contain information.

                                                             ii.      Select “Copy” under the “Edit” menu.

                                                            iii.      Switch back to your email program, put the cursor on the line below the “//AA” entry in the text portion of the message, and select “Paste” under the “Edit” menu. The whole table should now appear in the body of the email message.

45.  After you insert the table with your data, type on the last line of your message “//ZZ”. This tells the computer that there are no more data in your message. See an example of what your email should look like below.

46.  Send the email to GLOBE.

Example of an email containing air and soil temperature data collected with a data logger .

//AA
DLOG  ZZUSTEST      ATM-01           200105141600   +0400   M         M         M         M
DLOG  ZZUSTEST      ATM-01           200105141615   +0400   24.79    24.79    24.79    24.79
DLOG  ZZUSTEST      ATM-01           200105141630   +0400   24.79    24.79    24.79    24.79
DLOG  ZZUSTEST      ATM-01           200105141645   +0400   24.79    24.79    24.79    24.79
DLOG  ZZUSTEST      ATM-01           200105141700   +0400   24.79    24.79    24.79    24.79
DLOG  ZZUSTEST      ATM-01           200105141715   +0400   24.79    24.4      24.79    24.79
DLOG  ZZUSTEST      ATM-01           200105141730   +0400   24.79    24.4      24.79    24.79
DLOG  ZZUSTEST      ATM-01           200105141745   +0400   24.79    24.4      24.79    24.79
DLOG  ZZUSTEST      ATM-01           200105141800   +0400   24.79    24.4      24.4      24.79
DLOG  ZZUSTEST      ATM-01           200105141815   +0400   24.79    24.4      X          24.79
DLOG  ZZUSTEST      ATM-01           200105141830   +0400   24.79    24.79    X          24.79
DLOG  ZZUSTEST      ATM-01           200105141845   +0400   24.79    24.79    X          24.79
DLOG  ZZUSTEST      ATM-01           200105141900   +0400   24.79    25.17    X          24.79
DLOG  ZZUSTEST      ATM-01           200105141915   +0400   24.79    25.17    X          24.79
//ZZ

Looking at the Data

Data Logger Graphing and Analysis

Task

Graphing and analyzing your data logger data

What You Need

• Classroom computer: 386 or better, 4 Mb RAM, Windows 3.1 or later, 1 available COM (serial) port.
  
• Any spreadsheet/graphing software (such as MS EXCEL)
  

In the Lab/Classroom

Visualizing your data is the first and best way to start analyzing your data logger output - trends, correlations, extreme values and unexpected variability should be readily apparent. The following suggestions are based on MS Excel on Windows. There are many different ways to accomplish the same thing so this is intended to be a simple example to get you started. In what follows, a series of “Excel” spreadsheet operations or options are given in a condensed format, simply separated by commas.

Step I: Import the data into your spreadsheet

• Select: File, Open, Change to data directory, File Type:Text, T1YYMMDD.txt
• In the Text Import Wizard (tab delimited mode), select Finish to accept defaults.

In order to graph other data files with this one, repeat this process with a new file:

• Select: File, Open, File Type:Text, T2YYMMDD.txt.
• In the Text Import Wizard (tab delimited mode), select Finish to accept defaults.
• Edit, Move or Copy Sheet, To Book: T1YYMMDD.txt, Move to End.

Step II: Graphing your data

• Highlight column A, Format, Cells, Custom, yyyymmddhhmm
• Insert, Chart (gets you to the Chart Wizard).
• Select: XY(scatter), Points(default), Source(default) , Options(many), Location (as new sheet)
• You can change any objects’ properties by selecting (highlighting) it and then right click to bring up a pop-up format box.

Step II: Analyzing your data

• Can you explain all the relationships and trends displayed in your chart?
• Is there any data that does not fit in?
• The plot below might look like your data after 10 days:
• Why do all four sensors start off together?
• Why is there a break in the data?
• Why is the daily mean of the 30 cm (C4) sensor above the 10 cm (C3) sensor?
• What happens on the last day when the pattern changes?

Frequently Asked Questions

Q. When I try to download the logger, there is no data. What happened?
A. This could happen if you did not complete a proper launch sequence prior to setting your logger in the field. Make sure you do not try to launch a data logger that has not been downloaded as all the data will be lost.

Q. How do you tell if one of your sensors is not working?
A. The two most common problems are a broken wire or an open circuit, usually due to an animal bite or because the connection between plug and socket is not good. An open circuit will produce a very unrealistic value, which might vary slightly. Another warning sign is a reading that does not change. Contact Onset or the GLOBE help desk if you need help.

Q. We did not get our logger to the field site for two days after it was launched, should we delete the data during this time period when we know the logger was not plugged in to our sensors?
A. Never delete rows of data - we want to know when you were attempting to collect data. However, if you have any data that are unquestionably bad or suspect, replace those values with a “M”. If one of your sensors was missing or not working, replace those data columns or rows with an “X”. Be sure to record and send in a metadata description of the problem you experienced.

Q. We managed to plug our sensors into the wrong channels. What should we do?
A. If you are comfortable transposing the columns of data, you can do this in a spreadsheet program. Otherwise, send the .dtf and .txt files to jwash@hwr.arizona.edu with a description of the problem and I will correct it. In general, the daily range of the data should decrease from the air temperature to the 50 cm soil temperature.

Key Definitions

• Attenuation: to reduce in magnitude, to lessen
• Conduction: transmission of heat (or electricity) through a substance.
• Data Logger: a microcomputer capable of recording and storing both time and measurement data in the field. The only system maintenance required is to periodically download the stored data.
• Desiccant: a substance such as calcium sulfide which will repeatedly absorb excess humidity after it is oven dried.
• Diurnal: varying regularly throughout the day.
• Energy balance: a conservative balance between incoming and outgoing energy components (solar, sensible heat, latent heat, soil heat) at a point, such as the Earth's surface.
• Phase-shift: the period of a wave-like phenomena (ocean waves, sound waves) determines how far it is between adjacent peaks (maxima). A phase shift occurs when two waves have the same period but the maxima occur at different times.
• Sinusoidal: like a sine wave; many radiation phenomena are greatest midday and least at night.

Activity – Exploring Thermal Properties

Soil is a great insulator. Animals in especially hot and cold climates take advantage of these soil properties to survive. Here is a test you can run in your classroom "lab" to investigate the relative importance of various factors such as volume, soil moisture, and soil texture. Use the short sensor to monitor air temperature while you place the other sensors in 250 mL, 1 L and 5 L of various materials. Run the tests for 24 hours. You might even want to go outside to see how active solar heating (or freezing) affects your results. It's also interesting to try other materials: air, cotton, foam, water.

Lab Guide

·        Connect the logger to the serial cable

·        Confirm that your computer's clock is showing the current local time.

·        Set "Interval" to "30 min" and "Description" to "LTyymmdd", where yymmdd is today’s year, month and day.

·        Use three sensors to monitor 3 different samples and one sensor to monitor air temperature.

·        After 24 or 48 hours, readout your data.

·        Try to import your data into a computer spreadsheet and graph it.

·        What do you see? Why? Does it make sense?

·        Try the same experiment outside. Remember to rename the data file.

Data Logger Work Sheet