Accessing and Using National Long Term Ecological Research (LTER) Climate and Hydrology Data from ClimDB and HydroDB: A Tutorial Gordon M. Heisler USDA Forest Service, Syracuse, NY Gary Fisher U.S. Geological Survey, Baltimore, MD Jonathan Walsh Institute of Ecosystem Studies, Millbrook, NY An earlier version of this tutorial was presented on October 17, 2003 at the Baltimore Ecosystem Study annual meeting in Baltimore, MD. Please send corrections and suggestions for enhancements of this document to Gordon Heisler at gheisler@fs.fed.us. November 3, 2003 1
Weather and Climate and the Long Term Ecological Research (LTER) Program Weather Short term conditions of the atmosphere, usually reported at hourly intervals. A good time period for describing what is happening today, yesterday, or tomorrow. Climate The averages or extremes of weather over a long time period. Weather data are often summarized for studying the average conditions of an area or to compare different places on earth. Often the time period for summarization is one day or one month. The climate database described here uses 1-day time periods in a system called ClimDB. The LTER program is a National Science Foundation initiative that has cooperation from other government agencies such as the USDA Forest Service and U.S. Geological Survey; other research organizations, such as the Institute of Ecosystem Studies; and many universities. Research is carried out at 24 LTER sites in the United States and in Antarctica. The Baltimore Ecosystem Study (BES) is one of these LTER sites. 2
Daily meteorological and hydrological data from LTER sites are accessible by Internet in ClimDB and a companion system, HydroDB. 16 different variables are currently available (not all at all sites): Maximum, minimum, and mean air temperature Mean relative humidity Mean dew point Global radiation total Maximum, minimum, and mean water temperature Daily precipitation total Daily mean stream discharge Wind speed and direction measured two ways Mean atmospheric pressure Mean soil temperature 3
Climate data are available from all LTER sites 4
Clicking the URL for ClimDB, http://www.fsl.orst.edu/climhy/climdb/, will open a page that looks like this. 5
Climate and hydrology data are intermingled, and ClimDB and HydroDB have the same format. The HydroDB URL is http://www.fsl.orst.edu/climhy/hydrodb/. You can easily switch between ClimDB and HydroDB 6
Some U.S. Forest Service experimental forests that are not LTER sites are included in HydroDB. U.S. Forest Service experimental sites with hydrologic data Sites that currently have data in HydroDB LTER sites 7
A list of all ClimDB and HydroDB stations is available. 8
All LTER weather and stream gauging stations are listed with dates of the data and the last update. For example, site AND is the Andrews Experimental Forest in Oregon, and has data going back to 1952. The BES primary weather station was started in April 2000. 9
Forest Service sites with data in the HydroDB system 10
Check metadata (a description of data) to learn about the sites or variables that are measured. 11
Click down arrow to see the list of ClimDB metadata types, then select the one you want. 12
One kind of metadata describes the location of the meteorological station as below. ClimDB has no photos in the metadata, but more information may be available from URL s given in ClimDB. The BES McDonogh station and a visiting hydrology class. 13
HydroDB Metadata types 14
There is a separate page of metadata for each sensor. This is the start of metadata that describes BES air temperature measurements with two kinds of sensors. Gill shield with humidity and temperature sensor. Fan-aspirated shield 15 for temperature sensor.
There may be considerable detail in the metadata. This is some more about the BES air temperature measurements. 16
There is even more metadata for the temperature sensors. However, for some sites and sensors, metadata is not yet available. You might try to learn more or find contacts on the LTER site s home page, accessible on the National LTER home page. 17
Click Data, Plots, and Downloads to download data to a file or plot time series (graph of some variable vs. date) using ClimDB. 18
First select the site and let ClimDB know who you are. Note: While ClimDB data are freely available, the researchers and agencies who develop and support the stations and software systems that collect the data benefit by knowing of uses of the data. Providing information in this window is a way of reporting use. If you make extensive use of data for scientific publications, please see metadata for other means of acknowledging data providers. In some cases, coauthorship with data providers may be appropriate. 19
Select the variables you want to download or plot Even though there is only one station, you need to select it. 20
To compare two or more sites, select them holding down Ctrl, then click Submit. 21
As an example, we ll compare air temperatures at the BES site to a Phoenix site. 22
Choose a suitable period for your time series and them click submit. 23
The result is a graph of mean daily air temperatures at McDonogh1 (BES primary Station) in red and Phoenix- Encanto station (green), May 2000 thru Feb 2003. Which was the coolest Baltimore summer? 24
Another place to look for information (metadata) about the weather stations is with a search engine, such as Google. For the Phoenix-Encanto site, which does not yet have metadata in ClimDB, you can learn that the Encanto station is part of a weather station network called AZMET by searching Phoenix Arizona Encanto weather. The station is just southeast of the 14 th hole of the Encanto Golf Course, which is near the center of Phoenix. Irrigation probably produces relatively cool temperatures on the golf course. Many of the stations listed as CAP-LTER stations are part of AZMET, which began in the 1980 s, long before CAP-LTER. 25
Data can be downloaded as HTML, Tab delimited, or Comma delimited text files. Tab delimited makes easy-to-read columns. Site Station Date Winddir (mean deg) Flag BES MCDONOGH1 2002-03-01 263 G BES MCDONOGH1 2002-03-02 239 G BES MCDONOGH1 2002-03-03 266 G 26
To plot one variable versus another, download the data from ClimDB in tab or comma delimited format and use another kind of software to make graphs. Excel is used for these graphs that show that more moist air tends to come from the northeast in both Massachusetts (Harvard forest) and Baltimore (BES). Wind seldom comes between east through south at either location, but especially so in Baltimore. Harvard Forest LTER, Fisher Station Daily Mean RH vs Wind Direction, March 02 thru Feb 03 BES McDonogh Daily Mean RH vs. Wind Direction, March 02 thru Feb 03 Relative humidity, percent 100 90 80 70 60 50 40 30 20 10 0 0 45 90 135 180 225 270 315 360 Wind direction N NE E SE S SW W NW N Relative humidity, percent 100 90 80 70 60 50 40 30 20 10 0 0 45 90 135 180 225 270 315 360 Wind direction 27 N NE E SE S SW W NW N
The graph below shows average daily stream discharge in liters/sec (lps) from two small forested watersheds--pond Branch in Oregon Ridge County Park north of Baltimore and a control watershed on the Fernow Experimental Forest in West Virginia. Data for Pond Branch are from the US Geological Survey web site (http://md.water.usgs.gov/bes/01583570/index.html). The USGS uses units of cubic feet/sec (cfs), which must be converted to lps using 1 cfs =28.3 lps. Data from Fernow are from HydroDB. Why do similar-size watersheds at similar latitudes have rather different discharge patterns? Discharge from two forested watersheds, Fernow WS#4 vs. Pond Branch Stream discharge, mean daily lps 180 160 Pond Branch, 41 hectares 140 Fernow WS4, 39 hectares 120 100 80 60 40 20 0 10/1/99 10/31/99 11/30/99 12/30/99 1/29/00 2/28/00 3/29/00 4/28/00 5/28/00 6/27/00 7/27/00 8/26/00 9/25/00 Date 28
Conclusions ClimDB currently has readily available daily data for about 16 atmospheric, soil, or stream variables. At least some variables are available for all 24 LTER sites and another 9 USDA Forest Service Experimental Forests. All these locations report air temperature. Time series plots of one or more variables from one or more sites or stations can be easily created by ClimDB/HydroDB. ClimDB is a resource for both research and education 29