PRACTICAL CONSIDERATIONS FOR THE COMPUTATIONS OF RADAR ALTIMETER PATH DELAY

摘要

Estimation of the path delay of the altimeter radar signalrndue to the existence of dry and wet (due to waterrnvapour) air is very important to compensate for it in thernsea surface height measurements. Atmospheric fieldsrnproduced from numerical weather prediction models arernusually used to perform this. The difference betweenrnusing the model fields at native model levels versus thernuse of the vertically interpolated fields at ～25 constantpressurernlevels is examined. For the dry component ofrnthe path delay, the difference is negligible. In the case ofrnthe wet component, the differences cannot be ignored.rnTherefore, the use of pressure level fields for wet pathrndelay cannot be recommended. For the reduction of datarnvolume and computational costs, the fields at the lowestrn～60% of model levels are sufficient for the wet delayrncomputations with negligible differences compared tornthe use of all levels.