ALMA-J Site Testing
ALMA-J Site Testing Archive
Last update 2005-01-24

Weather Station

    Four identical weather stations have been operating to monitor the weather conditions such as temperature, water vapor pressure, wind speed, wind direction, and solar radiation flux. Two of them have been operating since 1994 November, when they were installed at Rio Frio (4100 m a.s.l.), Chile. One of them was also temporally installed at several other sites (4000 - 5000 m a.s.l.) in the Antofagasta Region. The second radiometer has been operating at Pampa la Bola (4800 m a.s.l.) since 1996 July. After side-by-side calibration of these weather stations and NRAO/ESO weather stations, one of them had been operating near the NRO containers at Pampa la Bola, two near the NRAO/ESO containers at Llano de Chajnantor, and the other at the saddle point between the Chascon and Chajnantor mountains. One of the two weather stations at Llano de Chajnantor was moved to the northeastern foot of Chascon in 2000 February. See this map for the present locations of these weather stations.


    AnemometerTypeWS-942 (Ogasawara Keiki Inc.)
    Response?? m (distance constant)
    Wind velocity range2 - 60 m s-1
    Survival conditions> 90 m s-1
    Accuracy (direction)(+/-)5 deg
    Accuracy (velocity)(+/-)0.5 m s-1; < 10 m s-1
    (+/-)5%; < 10 m s-1
    Weight4 kg
    TypeP-HMP35A (Ogasawara Keiki Inc.)
    Sensor (thermometer)Pt 100 ohm
    Sensor (hygrometer)thin film capacitor
    Temperature range-40 - +40 deg
    Humidity range0 - 100%
    Accuracy (thermometer)(+/-)5%
    Accuracy (hygrometer)(+/-)5%
    Weight180 g
    ActinometerTypeP-PCM-01 (Ogasawara Keiki Inc.)
    Range0 - 1.5 kW m-2
    Wavelength range305 - 2800 nm
    Sensitivity7 mV (kW m-2)-1
    Time response1 s
    Weight2.5 kg
    SystemTotal weight?? kg
    Sampling interval1 - 20 min
    Power supplyDC 12V; 100 A h

Technical Description