Adjusting temperature parameters to reflect well-watered conditions

Adjustment coefficients for air temperature and dew point temperature measu rements at dry weather sites are determined for predicting reference evapot ranspirations (ET0) for irrigated conditions. Seasonal and regional variati on in changes in temperature parameters versus the ratio of effective preci pitation to ET0 are analyzed. The determined adjustment coefficients are te sted for validity using weather data from reference weather stations, and p aired reference and dry stations. The effects of adjusting air temperature and dew point temperature for site aridity are analyzed using the FAO Penna n-Monteith and the Hargreaves equations. Maximum reductions in ET0 caused b y adjustments of temperature data for aridity effects was as high as 25%.