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| ALMA-J Site Testing |
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| ＞ALMA-J Site Testing Archive |
Last update
2005-01-24
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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.
Specifications
| Anemometer | Type | WS-942 (Ogasawara Keiki Inc.) |
| Response | ?? m (distance constant) | |
| Wind velocity range | 2 - 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 | |
| Weight | 4 kg | |
| Thermometer Hygrometer | Type | P-HMP35A (Ogasawara Keiki Inc.) |
| Sensor (thermometer) | Pt 100 ohm | |
| Sensor (hygrometer) | thin film capacitor | |
| Temperature range | -40 - +40 deg | |
| Humidity range | 0 - 100% | |
| Accuracy (thermometer) | (+/-)5% | |
| Accuracy (hygrometer) | (+/-)5% | |
| Weight | 180 g | |
| Actinometer | Type | P-PCM-01 (Ogasawara Keiki Inc.) |
| Sensor | thermocouple | |
| Range | 0 - 1.5 kW m-2 | |
| Wavelength range | 305 - 2800 nm | |
| Sensitivity | 7 mV (kW m-2)-1 | |
| Time response | 1 s | |
| Accuracy | (+/-)3% | |
| Weight | 2.5 kg | |
| System | Total weight | ?? kg |
| Sampling interval | 1 - 20 min | |
| Power supply | DC 12V; 100 A h |
Technical Description
References
- Sakamoto, S., Handa, K., Kohno, K., Nakai, N., Otarola, A., Radford, S. J. E., Butler, B., & Bronfman, L. 2000, "Comparison of meteorological data at the Pampa La Bola and Llano de Chajnantor sites," LMSA Memo 2000-008 (also ALMA Memo 322)
- Nakai, N., Handa, K., Kato, T., Otarola, A., Bronfman, L., & Vallada, G. 1996, "Measurement of meteorological data in northern Chile (August - October 1994)," LMSA Memo 1996-002
