| Autor: |
Harrison RG; Department of Meteorology, University of Reading, Earley Gate, Reading RG6 6BB, United Kingdom., Marlton GJ; Department of Meteorology, University of Reading, Earley Gate, Reading RG6 6BB, United Kingdom., Nicoll KA; Department of Meteorology, University of Reading, Earley Gate, Reading RG6 6BB, United Kingdom., Airey MW; Department of Meteorology, University of Reading, Earley Gate, Reading RG6 6BB, United Kingdom., Williams PD; Department of Meteorology, University of Reading, Earley Gate, Reading RG6 6BB, United Kingdom. |
| Abstrakt: |
Charge is observed in clouds of all forms, which may influence their development and properties. In-cloud charge measurements require a wide dynamic range, extending from charge in aerosols and dusts to that present in thunderstorms. Unexpectedly large charge densities (>200 pC m -3 ) have recently been detected in layer clouds using balloon-carried linear electrometers. These, however, lead to instrument saturation if sufficient sensitivity for aerosol and droplet charge is maintained. Logarithmic electrometers provide an alternative but suffer strong non-linear thermal effects. This is a limitation for balloon-carried instruments that encounter temperature changes up to ∼100 °C, as full thermal compensation requires complexity inappropriate for disposable devices. Here, a novel hybrid system is described, combining linear and logarithmic electrometers to provide extended dynamic range (±50 pA), employing the negligible (±4%) total temperature drift of the linear device to provide in situ calibration of the logarithmic device. This combination opens up new measurement opportunities for charge in clouds, dusts, and aerosols. |
