Laserfiche WebLink
<br />\ <br /> <br />'" "~,~ <br />\ <br /> <br />ABSTRACT <br /> <br />\ <br />\ <br />\ <br /> <br />Research studies were conduc:ted to identify upper air data requirements <br /> <br />and their role in experimental designs for future weather modification <br /> <br />programs in the Upper Colorado B~iver Basin. These studies addressed specific <br /> <br />questions of rawinsonde network density and location requirements, frequency <br /> <br />of observations, and importance for forecasting development and covariate <br /> <br />investigations. <br /> <br />Special rawinsonde (R/S) sites were established at Craig and Durango, <br /> <br />Colorado, for the winter of 1977-78 to increase the density of the existing <br />------ <br />NWS R/S network. Interpolated values of temperature,relative humidity, <br /> <br />and wind direction obtained from the NWS network alone were compared with <br /> <br />observations taken from the denser network. To assess tpe utility of special <br /> <br />R/S for improving the predictability of quantitative precipitation computations, <br /> <br />the orographic precipitation model by Rhea (1978) was employed to obtain model <br /> <br />output data both with and without the special R/S observations as input. <br /> <br />Model calculated values of precipitation were then compared with observed <br /> <br />precipitation to assess changes in model accuracy. <br /> <br />Comparisons of interpolated vs. observed upper air data revealed several <br /> <br />systematic differences. (1) Observed temperatures were consistently colder <br /> <br />than interpolated values by 1 to 20C. Since elevations at Craig and Durango <br /> <br />are higher than all of the NWS R/S stations, this suggests air mass cooling by <br /> <br />terrain lifting. (2) For wind directions that give local upslope flow at the <br /> <br />special sites, the observed relative humidities were usually higher than inter- <br /> <br /> <br />polated values. (3) Relative \iI'arming and drying was evident for wind directions <br /> <br />giving localized downslope flow, especially at Durango. (4) Topographic- <br /> <br /> <br />induced deflections of the observed winds from the interpolated wind field <br /> <br />