Ground-based microwave radiometry and long-term observations of atmospheric water vapor

摘要: Microwave radiometer data and radiosonde from the time period 1981-1995 have been used to study long-term trends in integrated precipitable water vapor (IPWV). The two instruments operated 37 km apart on Swedish west coast. Model parameters are estimated for entire sets as well subsets of data. IPWV model a mean value, linear drift with time, amplitude phase an annual component. data, which uniformly sampled show increase 0.03 mm/yr statistical standard deviation 0.01 mm. microwave not at all -0.02+/-0.01 mm/yr. We that disagreement is caused by different sampling instruments. When reduced include only simultaneously, we find agreement between parameters, given their uncertainties. This suggests if had also operating continuously over 15-year period, its would implied trend similar result obtained general quality terms short scatter, has improved period. root square (RMS) difference measured radiosondes was 2.1 mm during first 5 years 1.6 last 4 years. These values real sites. bias, radiometer-radiosonde, 0.1 whole set varied -0.2 0.9 smaller few