From late August to early November, fruit farmers would struggle against frost damages in apple, pears and apricot trees along Limay, Neuquén and Negro rivers valleys.
In 1992 our group began to obtain data in several points of the region, to study the characteristics of nocturnal inversion layer across each valley, during frost occurrence nights. The project was continued up to 1996-frost season.
Temperature and wind profiles were obtained using radiosondes with captive globes, and surface records by means of automatic meteorological stations.
The stations were located in Cinco Saltos, Colonia Valentina, Allen and Centenario towns in the argentine Comahue region.
Topographical effects are shown when analyzing relationships among the three valleys characteristics. These effects are mainly observed in wind speed profile. The position of wind speed maximum with height fluctuates following topography pattern and the direction following the synoptic scale flow direction.
The variation of temperature with height changes according to the horizontal distance of the registers points up to the plain.
In Cinco Saltos and San Patricio del Chañar (Neuquén river valley) the rate of variation of temperature with height is 0.33 °C/m, in Colonia Valentina (Limay river valley) 0.16°C/m, and in Allen (Negro river valley) the rate is 0.26 °C/m.
Temperature decrease is partly moderated in zones near rivers. Over the plain, wind speed present high gust frequency, meanwhile, in the valley, the situations present calm periods with some wind irruption's during night, varying from one place to another.
The knowledge of temperature and wind characteristics along the different valleys is very useful to design frost protection strategies and to optimize farmers' resources.