Observer's Duties
This page describes what to do and when to do it.
See the instrument procedures for details on how to use and maintain the
various instruments.
Also, see the list of the various computer files that must be kept up to date as part of the regular duties.
Daily duties
Weekly duties
Monthly duties
Yearly duties
NOTE:
ALL TIMES ARE IN EASTERN STANDARD TIME (EST) UNLESS
OTHERWISE NOTED.
Daily Observer's Duties:
There are three primary manual observations at 7 AM, 10 AM, and 1 PM EST with secondary observations
at the intervening hours. The observer is expected to be present at BHO for the three primary
daily observations and to follow the specific observational procedures detailed below and summarized
in the daily observation checklist. In addition, the observer
will determine the hourly and daily weather for the previous calendar day as collected digitally or by
chart recording. Note that all Observatory operations are performed in EST to prevent the
interruptions in data that would be caused by the biannual shifts between EST and Daylight Saving Time.
Finally, the observer is responsible for properly archiving and disseminating this information as
described elsewhere in this document.
Specific Observation Procedures
0630-0645 EST: Arrive at Observatory and prepare for primary manual observation at
0700 EST (1200 UTC)
1) Check that the indoor recorders (wind charts and barographs) are operating properly, and restore operation,
if necessary.
2) Verify the time on the electric wall clock with the time standard at the
Naval Observatory or
NIST. The wall clock should be within 5-10 seconds of these time
standards. If it is not, reset the clock to be as close as possible to the reference time.
3) Cut off 420C wind gust, wind speed, and Aerovane wind charts at the end of the prior calendar day
(midnight EST) and place on workbench for later preparation of hourly data. Stamp BHO address and
date (previous day) at noon on the chart. All charts are midnight to midnight.
4) Record maximum and minimum temperatures from Nimbus and MCTA sensors.
0645-0655 EST: Perform preliminary outdoor readings
1) In enclosure temperature shelter, read and record maximum and minimum temperatures and note current
temperature.
2) Saturate wet-bulb wick with clean water and turn on fan to ventilate. Minimum thermometer must
be read before turning on the fan to avoid being affected by fan vibration. Close enclosure door to
allow psychrometer to reach equilibrium, which can take several minutes or longer if freezing occurs.
3) If temperature is at or below freezing saturate wick on hand-held psychrometer and place on fence to
north of tower (not in direct sunlight if sunrise has occurred) to obtain backup dry and wet bulb readings.
4) Make preliminary visual observation from office, tower roof, or outside, of visibility, total sky cover,
present weather, obstructions to vision, and mountains visible.
0655-0703 EST: Primary 0700E indoor observation
1) Read mercury barometer and its thermometer.
2) Change daily microbarograph chart. Make sure chart is seated on the drum properly and held in
place with rubber bands. Wind clock and add ink to pen if necessary.
3) Record current temperature on Nimbus and MCTA (recheck for any new maximum or minimum) and reset both.
4) Read 24-hour precipitation total, if any, from Nimbus digital recorder, which is connected to the
Rainwise rain gage in the enclosure.
5) Read Maximum (#1) peak wind gust and reset. Read Merlin peak wind gust and direction and the average
wind speed and direction and reset both. Each of these measurements are for the 24 hours endingn at 0700
EST.
6) Observe 420C wind direction to get 1-minute average and note variation in direction of 60 degrees
or more.
0703-0707 EST: Primary 0700E outdoor observation
1) In enclosure shelter, record dry and wet bulb temperatures and turn off fan. Note whether wet bulb is
liquid or ice-covered if below freezing.
2) If precipitation has occurred in the past 24 hours, replace rain gage with dry tube and bring tube with
rainfall into office for measurement.
3) Record 24-hour precipitation in plastic 4-inch gage, empty gage, and replace. (not currently in use)
4) If snow has occurred in the past 24-hours take several measurements on snowboard with precipitation stick
and record average to the nearest 0.1 inch.. Clear all snow from snowboard. Measure depth of snow
cover on ground at several places in enclosure or in clearing to northeast of the Observatory and record average
to the nearest inch.
0707-0710 EST: Primary 0700E tower roof observation
1) Confirm earlier estimates of total cloud cover (to the nearest eighth), height of cloud layers, and
cloud types.
2) Note average horizontal visibility, mountains visible, and condition of mountains.
3) Record present weather and obstructions to vision (prevailing visibility must be six miles or less to
report fog (F), haze (H), blowing snow (BS), or smoke (K).
0710-0755 EST: Office duties
1) Determine station pressure and sea-level pressure from mercury barometer reading.
2) Calculate dew point and relative humidity from observed dry and wet bulb temperatures.
3) Record 0700E hourly observation (in SA format) in daily observation computer file (e.g. bhobs06.xls) and
in electronic B-16 form (e.g. January2006.xls).
4) Prepare corrections for microbarograph chart to obtain 1900E station pressure for previous day.
5) Record digital barometer 0700E reading and three hour tendency.
6) Begin preparing previous day's peak wind gust, hourly wind speeds, and hourly mean wind direction from
wind charts. Wind directions are obtained from Aerovane chart recording.
7) Record ASOS data for previous day on white index card including maximum and minimum temperatures and times
of occurance, peak gust and peak 2-minute wind (with directions and times), daily average wind speed, and
daily precipitation from ASOS display computer.
8) Write the 0700E maximum and minimum temperatures from the Enclosure (Hazen and Cotton-Region shelters)
Nimbus and MCTA on index card. Also record 24-hour precipitation for all gages and wind information
from Maximum #1 and Merlin, which were read at 0700E.
9) Note time at which sun card was last changed. Replace sun card as late as possible during the shift
while preventing over burn from previous day.
10) If precipitation has occurred, note time at which ombroscope chart was last changed. Replace ombroscope
chart (even if it is precipitating) before rainfall or snowfall marks from previous day are obscured.
11) In enclosure shelter, saturate wet bulb wick and turn on fan 5-10 minutes prior to reading at 0800E.
0755-0805 EST: Hygrothermograph chart change
1) In enclosure shelter, read and record dry and wet bulb temperatures,then turn off fan.
2) Replace hygrothermograph chart making sure that the chart is positioned properly on the cylinder, that rubber
bands will not obstruct the pens, and that pens have enough ink and are writing on the chart.
3) Reset maximum and minimum thermometers and close shelter door.
4) If rainfall has occurred in the past 24 hours and is not presently occurring, place a small stone in weighing
precipitation gage to raise pen above previous traces.
0805-0855 EST: Office duties
1) Continue preparing previous day’s hourly wind data if not completed earlier.
2) Prepare corrections for hygrothermograph chart to obtain hourly temperatures and 6-hourly (1AM, 7AM, 1PM, 7PM)
relative humidities for previous 24 hours.
3) Check timing on all wind charts and note whether sufficient paper remains in 420C gust recorder, wind speed
recorder, and Aerovane for operation until the next day.
0900 EST: Hourly temperature
1) Record current temperature from the Hazen shelter dry bulb thermometer in enclosure.
0905-0955 EST: Office duties
1) Update Word and Excel computer files with data from the current day and the
previous day.
0950-0955 EST: Observation duties
1) Saturate wet bulb wick and turn on fan in shelter 5-10 minutes before 1000E observation, and saturate wet bulb
wick on hand-held psychrometer and place on fence in below freezing conditions. Be sure wicks are fully wet
and any ice is melted.
0955-1000 EST: Backup barograph change (every fourth day as necessary)
1) Read mercury barometer and its thermometer.
2) Change four-day barograph chart. Make sure chart is seated on the drum properly and held in place with
rubber bands. Wind clock and add ink to pen.
0955-1005 EST: 1000E standard observation
1) In office, note 2-minute average wind direction and variation.
2) In Hazen shelter, record dry and wet bulb temperatures. Record dry and wet bulb from hand-held psychrometer
if needed.
3) Measure any new rainfall (since 0700E) or snowfall on snow board with precipitation stick.
4) From tower roof, record visual observation of sky cover, cloud types and heights, visibility and mountains
visible.
1100, 1200 EST: Hourly temperatures
1) Record current temperature from the Hazen shelter dry bulb thermometer in enclosure.
1250-1310 EST: 1300E standard observation
1) Saturate wet bulb wick and turn on fan in shelter 5-10 minutes before 1300E observation, and saturate wet bulb
wick on hand-held psychrometer and place on fence in below freezing conditions. Be sure wicks are fully wet
and any ice is melted.
2) In office, note 2-minute average wind direction and variation.
3) In Hazen shelter, record dry and wet bulb temperatures. Record dry and wet bulb from hand-held psychrometer
if needed.
4) If precipitation has occurred in the past 6 hours and none is expected in the next 18 hours, replace standard
gage tube with dry tube. Measure and record precipitation.
5) Measure any new snowfall on snow board with precipitation stick.
6) From tower roof, record visual observation of sky cover, cloud types and heights, visibility and mountains
visible.
7) Update daily computer files with 1300E observation.
1310-1330 EST: Daily climate report
1) Prepare daily climate report summarizing previous day's weather by editing Notepad text file with recent
information. Copy text into an E-mail message and distribute to general E-mail list. A copy of the report will be
posted and archived on the Blue Hill Observatory web site.
Weekly Duties:
(Further details will be added in the future.)
1) Update monthly summary (form F-6) computer file with recent data.
2) Annotate backup 4-day barograph; determine corrections from observed 7 AM and 7 PM pressures.
3) Determine hourly precipitation values from the weighing rain gage chart. Also, determine greatest precipitation
amounts for various time intervals (5 min., 10 min, 30 min. etc.).
4) Find hourly minutes of bright sunshine (in EST, not solar time) from sun cards and enter uncorrected data in
daily B-16 computer file.
Monthly Duties:
(Further details will be added in the future.)
1) Complete monthly data in bhowxdYY.xls computer file.
Temperature: Calculate final average maximum and minimum temperatures, NWS mean temperature
[(max+min)/2], and corrected mean temperature (internal 2828 mean). Get departures from current (1971-2000) 30-year
normals.
Heating/Cooling Degree Days: Get final heating/cooling degree day total and departures from normal,
add heating/cooling degree days to seasonal total and find departure from normal.
Precipitation and Snowfall: Get final preciptation and snowfall amounts and departures from normal.
Wind:Get final peak gust, direction and date and get final fastest mile, direction and date
Pressure:
Transfer data to monthly summary F-6 computer file.
2) Complete monthly data in wind speed and wind direction spreadsheets.
Wind speed spreadsheet: wdcorYY.xls; Determine final corrected monthly mean wind speed
Wind direction spreadsheet: bhowndYY.xls; Determine prevailing wind direction for month (direction with
most hours)
Other wind data: Get final Aerovane peak gust, direction and date
Transfer data to monthly summary F-6 computer file. Also, write final corrected wind speed and prevailing
direction for month in right most column of the bhowndYY.xls spreadsheet.
3) Finalize uncorrected (sun card) and corrected (astronomical) sunshine totals (percent and hours of monthly possible
bright sunshine
Details of this procedure will be added in the future.
Transfer corrected sunshine data to monthly summary F-6 computer file.
4) Determine final mean station pressure for the month from average of 7 AM and 7 PM pressures. Determine maximum and
minimum station pressures for month from barograph charts.
Details of this procedure will be added in the future.
Transfer pressure data to monthly summary F-6 computer file.
5) Get average relative humidity for month from 1 AM, 7 AM, 1 PM and 7 PM readings
6) Finalize all monthly spreadsheets
7) Calculate maximum preciptation rates (for various time periods, e.g. 5 minutes, 10 minutes, etc.) from weighing
gage charts.
ASOS measurements are sometimes used for guidance, but should be used cautiously since ASOS precipitation times are delayed
by roughly six minutes due to the way the system operates.
8) Prepare coded CLIMAT report; Use file bhocli.doc to convert data into coded report
Transfer CLIMAT message to the bottom of the monthly summary F-6 computer file.
9) Prepare monthly notes (summary of unusual weather events and extremes).
Yearly Duties:
(Further details will be added in the future.)
1) Update annual spreadsheets
2) Update hand-written climate summary notebook (black cover)
3) Organize and prepare charts for storage at National Archives in Waltham (sent every five years)