Hour and minute shown (PST/PDT) correspond to the time these observations were taken by the weather station. Generally between minutes 9 and 10 of each, even 10-minute interval. Normals and records shown are for Del Mar, CA. Total rainfall is for the season beginning last July 1st. The barometer is corrected to sea level pressure.
As an interim measure, the display of recent observations in tabular and graphical form will also be taken from the reports sent to CWOP. Subtract seven hours from UTC for PDT, eight hours for PST.
This station observes the following weather parameters:
Additional parameters are computed and also recorded and reported:
Wind chill, Temperature-humidity-wind index, Daily high and low values.
We are part of the National Weather Service's San Diego Forecasters' Mesonet--a group of about 100, non-NOAA stations, providing high-quality, real-time data directly to the regional forecasters in a format specified by them. Our participation is subject to meeting their standards in all respects.
Our observations are also reported every 10 minutes to NOAA through CWOP (Cooperative Weather Observers Program) to MADIS (Meteorolgical Assimilation Data Ingest System) in a format known as APRS. MADIS performs quality control analyses on our data, and issues a score. Our data is OK and gets "thumbs up", as can be seen by the green icons and statistics here.
In the following paragraphs the instumental specifications for our sensors are shown as provided by Davis Instruments, the manufacturer. However whether or not the observations are representative of the "weather" at the Visitor's Center depends on the placement of the sensors, the sampling interval, and any filtering or averaging applied to the raw observation.
The temperature sensor is a precision platinum wire thermistor which produces a resistance change proportional to temperature. The sensor is housed in a radiation shield in an exposed location.
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -50° to 140° F
Accuracy. . . . .. . . . . . . . . . . . . . . . . . . . . . . . ±1°F
Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1°
The humidity sensor is a thin film capacitor element. A dielectric polymer layer absorbs water molecules from the air through a thin metal electrode, which causes a change in capacitance proportional to relative humidity. The system also reports dew point as a measure of moisture in the air from the combination temperature-humidity sensor. The sensor is housed, together with the temperature sensor, in a radiation shield in an exposed location.
Range
Relative Humidity . . . . . . . . . . . . . . . . . . . . . 0-100%
Dew Point. . . . . . . . . . . . . . . . . . . . . . . . . . . . -99° to 140° F
Accuracy
Relative Humidity . . . . . . . . . . . . . . . . . . . . . ±3%, from 0 to 90% RH, ±4% from 90% to 100% RH
Dew Point. . . . . . . . . . . . . . . . . . . . . . . . . . . . ±4°F
Resolution
Relative Humidity . . . . . . . . . . . . . . . . . . . . . 1%
Dew Point. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1°F
Resolution and Units .................................. 0.01" of Hg
Range ........................................................... 26.00" to 32.00"
Accuracy ...................................................... ±0.05"
Trend (change in 1 hour) .......................... ±0.2"
The Anemometer includes both wind speed and wind direction sensors. Three cups and a magnetic switch sense wind speed. A wind vane and potentiometer sense wind direction. Digital filtering, is applied to wind direction measurements. Additional digital filtering separates average wind speed from maximum gust.
Range
Wind Speed (small wind cups) ................. 3 to175mph
WindDirection............................................... 0° to 360°
Accuracy
Wind Speed (small wind cups)................. ±3mph or ±5%, whichever is greater
Wind Direction............................................. ±7°
Resolution
Wind Speed................................................. 1mph
Wind Direction............................................. 1°(0°to355°)
The Rain Collector is designed to meet the guidelines of the World Meteorological Organization. Rain enters the collector cone, passes through a debris-filtering screen, and collects in one chamber of the tipping bucket. The bucket tips when it has collected an amount of water equal to the increment in which the collector measures (0.01"). As the bucket tips, it causes a switch closure and brings the second tipping bucket chamber into position. The rain water drains out through the screened drains in the base of the collector. In this area annual rainfall is usually stated for the period July1 through June 30.
DailyRainfall.................................. 0.00” to 99.99”
TotalRainfall.................................. 0.00” to 99.99”
Accuracy ....................................... ±4%, ±1rainfall count between0.01" and 2.00"per hour;
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5%, ±1 rainfall count between 2.00" and 4.00" per hour
Resolution...................................... 0.01”