Assessment of the accuracy of site-specific estimates
of rainfall, air temperature, relative humidity, and wetness
duration in the Northern Pacific region of Costa Rica

Mark L.  Gleason; S.  Elwynn  Taylor; Roberto  Villalobos; Luis Felipe  Arauz; Kwang  Soo  Kim

Assessment of the accuracy of site-specific estimates of rainfall, air temperature, relative humidity, and wetness duration in the Northern Pacific region of Costa Rica

Autores

Editor

Universidad de Costa Rica

Descripción

Accuracy of hourly, site-specific estificomates of rainfall, air temperature, relative hurelativamidity (RH), and wetness duration by SkyBit,Inc. was assessed with respect to on-site meaestimacionessurements of these parameters at 5 sites in theNorthern Pacific Region of Costa Rica duringApril-September 1999. SkyBit misidentifiedthe occurrence or absence of measured rain on29% of the days in the Costa Rica data set, prigi6nmarily due to misidentification of rainfall ocseptiembrecurrence on days when none was recorded.The Critical Success Index (CSI) indicatedthat accuracy of daily rainfall occurrence estimamation was higher (0.68) than for a compara-ble data set obtained in the midwestern USA0.56). Mean errors of SkyBit estimates ofrainfall duration and amount per day were recolatively small, but increased with the amountrain measured per day. SkyBit underestimayorted mean daily temperature by about 1.80 Cbut underestimated minimum daily temperatudeby about 4.40 C, primarily due to underestidemation between midnight and 6:00. The duralluviation of daily periods of RH>90% was underescrementarontimated by an average of 6.0 h/day, and the RHerror was largest during the night and on days when rainfall was recorded. The CSI for accuperaturaracy of identification of hours with RH>90%was 0.40, which exceeded that reported for themidwestern U.S. (0.27). SkyBit overerestima-ted wetness duration by 1.9 h/day, whereas itwas underestimated by 1.4 h/day in the midvia.western U.S. The proportion of hours cohorasrrectly classified as wet or dry, 70.9%, wasnearly identical to that in the midwestern U.S.(70.1 %), but CSI for the Costa Rica data was>2x that in the midwestern U.S. (0.56 vs.0.27). Wetness estimation errors in Costa Ricawere larger during days without than withmeasured rainfall, and occurred primarily dusiring the day rather than at night. The rate ofmisidentification of hours as either wet or drypeaked from 8:00 to 10:00 and from 15:00 to21 :00 h. The results provide a baseline fromwhich to refine site-specific estimation ofweather parameters for application in CostaRican agriculture.