Geography 455 Lecture 2 Climate Data: types and sources

Needs: a few example instrument, paper charts, Internet access

A. Introduction 1. Need to know how data is collected in order to appreciate its limitations 2. data available and readily accessible as never before on CD-ROM and the Internet

B. Site issues 1. changes in exposure (building and vegetation changes) 2. urban-induced changes 3. changes in locations over time (relative and absolute relief), site histories 4. changes in instruments over time

C. Data Accumulation issues 1. average annual temperature from once-daily measurements versus “continuous” measurements

D. Conventional (Old-style) instruments (manual, daily or hourly) and non-digital automation (paper chart analog with wind-up clocks) 1. —“standard gauge”, tipping bucket and weighing gauges a. snow fall and snow-on-the-ground measurement problems b. sources of error c. Deer Sloan (near East Lansing, MI) network example 2. Temperature and Humidity a. mercury (max.) or alcohol (min.-obs.) in glass b. bi-metallic strip for thermographs c. wet bulb for humidity (sling psychrometer) d. “hair” e. shelter considerations—“cotton region”, Stevenson screen, maintenance f. sources of error (separations, etc.) 3. Wind Speed and Direction--cup and vane 4. Sunshine hours a. a number of early devices (one involved burning a trace on paper) b. bimetallic black-white strips cause differential heating 5. Evaporation-large containers filled with water or smaller devices a. difficult to compare 6. (mercury or most common aneroid) 7. River Flow a. speed of flow and depth recorded on a chart b. Deer-Sloan (near East Lansing, MI) network example Geography 455 Applied Climatology Lecture 2 Climate Data page 2

E. Modern (new generation) instruments (digital, electronic, “continuous”) 1. Precipitation--tipping bucket or weighing gauge connected to electronic recorder/counter a. same problems as before, no cheap and effective way to monitor snow 2. Temperature and Humidity a. resistance , where resistance of a metal varies with temperature b. capacitor hygrometer, where capacitance varies relative to humidity c. problems of comparability with conventional data, implications for trend analyses 3. Wind Speed and Direction, Barometric pressure, and River flow--similar to developments for precipitation 4. Solar and Net Radiation a. actual amounts of energy received can be recorded b. net energy (using one plate to monitor incoming and another for outgoing radiation are most meaningful) 5. Evaporation can be estimated from temperature, humidity, wind speed, and net radiation data

F. Data loggers and Telemetry 1. cheap “PC” technology--data monitoring of a large number of parameters in a near- continuous stream 2. Telemetry--ability to record data in remote sites with minimal power 3. Internet--expanded access to remote data through the “Web” 4. Example--Oklahoma (see link under my home page)

G. National Weather Data Policies 1. U.S. versus other nations--have different views of data collection and provision a. U.S.--no cost for data, cost is only to provide it, data “free” on the web b. “minimal cost” countries (, Germany)– some data free on the web, but more detailed requests (multiple years/multiple stations) require a fee (usually a few hundred $US) c. “full cost” countries (New Zealand)--cost of collecting data is factored in, as well as a “profit” (period-of-record daily maximum-minimum data from 12 stations would cost about US$500) c. these policies threaten the International data sharing established by the WMO that have resulted in the great progress in atmospheric sciences over the last 50 years--because countries may resent giving “free” data to the U.S. and then have people in their own country get it from the NCDC at less cost than they want to sell it for (NCDC does freely redistribute some data). d. such restrictions/fees slow access to data Geography 455 Applied Climatology Lecture 2 Climate Data page 3

H. Sources of Weather Data and “Visualization” 1. CD-ROMs replace magnetic tapes--huge cost reduction and easier accessibility on PCs a. U.S. Coop. Network data on CD ($225, period of record, all stations to 2004) 2. Internet (raw data, but more importantly processed data for classroom and research visualizations a. Weather links on my home page b. Remote Sensing links on my home page c. NCDC home page: http://www.ncdc.noaa.gov/oa/ncdc.html--Visualizations, Satellite Gallery, other great stuff d. NCDC climate data online: http://cdo.ncdc.noaa.gov/pls/plclimprod/poemain.accessrouter?datasetabbv=SOD&countryabbv=US&georegionabbv=&forceoutside= e. SSEC data page: http://www.ssec.wisc.edu/data/