Comparison of Precipitation Derived from the ECMWF Operational Forecast Model and Satellite Precipitation Datasets

Abstract

Precipitation is an important component of the climate system, and the accurate representation of the diurnal rainfall cycle is a key test of model performance. Although the modeling of precipitation in the cooler midlatitudes has improved, in the tropics substantial errors still occur. Precipitation from the operational ECMWF forecast model is compared with satellite-derived products from the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) and TRMM Precipitation Radar (PR) to assess the mean annual and seasonal diurnal rainfall cycles. The analysis encompasses the global tropics and subtropics (40°N–40°S) over a 7-yr period from 2004 to 2011. The primary aim of the paper is to evaluate the ability of an operational numerical model and satellite products to retrieve subdaily rainfall. It was found that during the first half of the analysis period the ECMWF model overestimated precipitation by up to 15% in the tropics, although after the implementation of a new convective parameterization in November 2007 this bias fell to about 4%. The ECMWF model poorly represented the diurnal cycle, simulating rainfall too early compared to the TMPA and TRMM PR products; the model simulation of precipitation was particularly poor over Indonesia. In addition, the model did not appear to simulate mountain-slope breezes well or adequately capture many of the characteristics of mesoscale convective systems. The work highlights areas for further study to improve the representation of subgrid-scale processes in parameterization schemes and improvements in model resolution. In particular, the proper representation of subdaily precipitation in models is critical for hydrological modeling and flow forecasting.

Evaluation of an operational ocean model configuration at 1/12° spatial resolution for the Indonesian seas (NEMO2.3/INDO12) – Part 1: Ocean physics

“…It could be related to an E-P (evaporation-precipitation) bias in the ECMWF precipitation flux where the model simulation of precipitation is particularly poor over Indonesia (see Kidd et al, 2013;Dee et al, 2011). In a recent paper, Zeng et al (2014) argue that the smaller LST (Luzon Strait Transport) is a plausible cause of the freshening in 2012.…”

Sensitivities of Amazonian clouds to aerosols and updraft speed

“…Both processes are analyzed with a focus on cloud evolution. Our methodology should prove useful for better understanding aerosol-cloud interactions over the Amazon, which is a region, as are the tropics as a whole, with poor forecasting skill (Kidd et al, 2013). Section 2 describes the experiment, its data, and the methods used for the analysis.…”

HOAPS and ERA-Interim precipitation over the sea: validation against shipboard in situ measurements

“…North of 60 • N, Lindsay et al (2014) detected an overestimation in monthly precipitation in ERA-Interim, ranging from 10 to 25 %. Kidd et al (2013) found that precipitation in the tropical Atlantic is skewed to the east towards the African coast by ERA-Interim. On the other hand, several studies have shown that in the area of the Iberian Peninsula (Belo-Pereira et al, 2011) or in the area of four African river basins (Thiemig et al, 2012), ERA-Interim overestimates the frequency of rain events as well.…”