Recent Changes in Frost Days in Central Southern South America

FERNANDEZ LONG, MARIA ELENA; MÜLLER GABRIELA V

Beijing, China.

Conferencia; Earth System Science Partnership (ESSP) Global Environmental Change Open Science Conference; 2006

One of the changes expected with an increase in surface temperature is a change in what are currently considered extreme temperatures, in particular cold extremes reflected in the number of day with frost. Therefore, the aim of this paper is to evaluate the annual and monthly trends (March-October) of frost days and minimum temperature for the period 1064-2003. The frost day is defined as days when the minimum temperature is below 0ºC at the meteorological stations of the central-eastern region of Argentina, known as the Wet Pampa. Annual frost frequency in the region decreased, though not significantly, in the 40 years studied. This result are consistent with the analyses of mean annual temperature trends. Far from being uniform; annual trends at the different stations can be grouped latitudinally and longitudinally. To the south of 34ºS, there is a well defined dipole with decreased frequency of frost days in the west and increased frequency in the east in a smaller area in the south of Buenos Aires. To the north of this parallel, the inverse situation takes place, i.e., positive trends in the west and negative in the east, but with values lower than the south. The annual minimum temperature displays a positive (negative) trend in those places where the frost frequency shows a negative (positive) trend.