利用探空资料计算水汽压

利用L波段探空资料的相对湿度值及温度值计算水汽压时,由于探空测量的是相对于水面的相对湿度,只能用相对于水面的饱和水汽压公式来计算,低温时用相对于冰面的饱和水汽压公式计算水汽压可能不正确.对水相和冰相的不同处理所带来的偏差进行了分析和讨论.以CIMO规定的温度-45℃和0℃为界,分别计算了用相对于冰面的饱和水汽压公式和相对于水面的饱和水汽压公式得到的水汽压值,并进行了比较.结果表明,在计算实际水汽压的过程中,用不同的饱和水汽压公式所产生的绝对偏差虽然不大,但相对偏差最大可能达到50％,不容忽视,对确定对流层上部的气候效应可能产生影响.

Calculation of Vapor Pressure Using Sounding Data

While calculating vapor pressure using relative humidity and temperature of L-band radar sounding, the water saturation vapor pressure formula must be used, since the relative humidity is based on water surface. There may be an error in using the ice saturation vapor pressure formula. The comparison of vapor pressure bias between water and ice saturation vapor pressure formulas is discussed. Taking -45℃ and 0℃ as a threshold, vapor pressure values are analyzed when using the ice and water saturation vapor pressure formulas, respectively. Results show that the absolute deviation produced by ice and water saturation vapor pressure formulas is not very great, but the relative deviation may be up to 50%, which has climatic effects on upper troposphere for actual water vapor pressure.