Forecast indices from a ground-based microwave radiometer for operational meteorology

摘要

Today, commercial microwave radiometer profilers (MWRPs) are robust andunattended instruments providing real-time, accurate atmospheric observationsat ~ 1 min temporal resolution under nearly all weatherconditions. Common commercial units operate in the 20–60 GHz frequency rangeand are able to retrieve profiles of temperature, vapour density, andrelative humidity. Temperature and humidity profiles retrieved from MWRPdata are used here to feed tools developed for processing radiosondeobservations to obtain values of forecast indices (FIs) commonly used inoperational meteorology. The FIs considered here include K index, totaltotals, KO index, Showalter index, T1 gust, fog threat, lifted index, S index (STT), Jefferson index, microburst day potential index (MDPI), Thompson index, TQ index, and CAPE (convective available potential energy).Values of FIs computed from radiosonde and MWRP-retrieved temperature andhumidity profiles are compared in order to quantitatively demonstrate thelevel of agreement and the value of continuous FI updates. This analysis isrepeated for two sites at midlatitude, the first one located at low altitudein central Europe (Lindenberg, Germany) and the second one located athigh altitude in North America (Whistler, Canada). It is demonstrated thatFIs computed from MWRPs well correlate with those computed from radiosondes,with the additional advantage of nearly continuous updates. The accuracy ofMWRP-derived FIs is tested against radiosondes, taken as a reference, showingdifferent performances depending upon index and environmental situation.Overall, FIs computed from MWRP retrievals agree well with radiosonde values,with correlation coefficients usually above 0.8 (with few exceptions). Weconclude that MWRP retrievals can be used to produce meaningful FIs, with theadvantage (with respect to radiosondes) of nearly continuous updates.