Improvement of Microphysical Parameterization through Observational Verification Experiment

Abstract

Despite continual increases in numerical model resolution and significant improvements in the forecasting of many meteorological parameters, progress in quantitative precipitation forecasting (QPF) has been slow. This is attributable in part to deficiencies in the bulk microphysical parameterization (BMP) schemes used in mesoscale models to simulate cloud and precipitation processes. These deficiencies have become more apparent as model resolution has increased. To address these problems requires comprehensive data that can be used to isolate errors in QPF due to BMP schemes from those due to other sources. These same data can then be used to evaluate and improve the microphysical processes and hydrometeor fields simulated by BMP schemes. In response to the need for such data, a group of researchers is collaborating on a study titled the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE). IMPROVE has included two field campaigns carried out in the Pacific Northwest: an offshore frontal precipitation study off the Washington coast in January–February 2001, and an orographic precipitation study in the Oregon Cascade Mountains in November–December 2001. Twenty-eight intensive observation periods yielded a uniquely comprehensive dataset that includes in situ airborne observations of cloud and precipitation microphysical parameters; remotely sensed reflectivity, dual-Doppler, and polarimetric quantities; upper-air wind, temperature, and humidity data; and a wide variety of surface-based meteorological, precipitation, and microphysical data. These data are being used to test mesoscale model simulations of the observed storm systems and, in particular, to evaluate and improve the BMP schemes used in such models. These studies should lead to improved QPF in operational forecast models.

Influence of the wind profile on the initiation of convection in mountainous terrain

“…The Mesoscale Alpine Programme (MAP, Bougeault et al, 2001; Copyright c 2011 Royal Meteorological Society Volkert et al, 2007) in autumn 1999 had the aim of a better understanding of the precipitation enhancement over high-mountain regions. Similar questions were addressed by the IMPROVE campaign in the northwestern USA (Stoelinga et al, 2003), which considered wintertime stratiform precipitation. CuPIDO (Damiani et al, 2008) was an example of a smaller field campaign dedicated to the specific issue of convection over an isolated mountain.…”

NORA–Nowcasting of Orographic Rainfall by means of Analogues

“…Many field experiments conducted over the last twenty years have been devoted to precipitation over complex terrain: the Taiwan Area Mesoscale Experiment (TAMEX; Kuo and Chen, 1990), the California Landfalling Jets Experiment (CALJET; Ralph et al, 1999), the Improvement of Microphysical Parametrization through Observational Verification Experiment (IMPROVE; Stoelinga et al, 2003), and MAP (Rotunno and Houze, 2007). The main objective of these projects was a better understanding of orographic precipitation mechanisms, without giving a special emphasis to nowcasting issues.…”

Quantitative precipitation forecasting in the Alps: The advances achieved by the Mesoscale Alpine Programme

“…High-resolution (4 km) real-time forecasts using MM5 were initiated in 1998 (Mass and Kuo, 1998) and the results were reported in Colle et al (2001) and Mass et al (2002). Meanwhile, a number of field projects were designed and conducted, either immediately before or after MAP, to better understand precipitation over complex terrain, such as CALJET (California Land-falling Jets experiment, Ralph et al, 1999), PACJET (Pacific Land-falling Jets experiment, Neiman et al, 2002), IPEX (Intermountain Precipitation Experiment, Schultz et al, 2002) and IMPROVE (Improvement of Microphysical Parameterization through Observational Verification Experiment, Stoelinga et al, 2003). In CAL-JET, orographically modified precipitation was studied in connection with the 'landfall' of oceanic cyclones and associated fronts (Kingsmill et al, 2006).…”