Shipboard Radar Rainfall Patterns within the TOGA COARE IFA

Abstract

Radar rainfall measurements over the equatorial western Pacific warm pool were collected by two shipboard Doppler radars as part of the Tropical Oceans Global Atmosphere Coupled Ocean-Atmosphere Response Experiment during the intensive observing period (November 1992-February 1993). A comprehensive dataset of gridded rainfall fields, convective/stratiform identification maps, and vertical structure products has been produced, covering an area approximately 400 km (E-W) by 300 km (N-S) within the Intensive Flux Array (IFA), centered near 2°S, 156°E. The radar rainfall product, which was used as validation for the Third Algorithm Intercomparison Project of the Global Precipitation Climatology Project, indicates an overall average of 4.8 mm day-1 ; however, correction for range dependence increases the total to 5.4 mm day-1. Rainfall patterns varied considerably during the experiment with isolated convection dominating periods of light winds, while squall lines and organized mesoscale systems were abundant during two westerly wind bursts. An area-average rainfall of 9.9 mm day-1 was observed during the active 2-week period at the end of December, while 0.4 mm day-1 was observed during the quiescent week of 2-8 February. The eastern portion of the IFA received the most rainfall with localized maxima exceeding 16 mm day-1 for the most active 3-week period. Comparison of daily radar rainfall totals with those observed by an optical rain gauge (ORG) on the 2°S, 156°E buoy shows ORG totals to be systematically higher, by a factor of 2.5. The discrepancy results from a higher average rainfall rate, when raining, as reported by the buoy ORG. However, rainfall rate statistics from the ORGs on the research vessel Xiang Yang Hong #5 and from its radar are in excellent agreement under the following conditions: 1) the ship is drifting, and 2) the radar data are in the near vicinity of the ship (3-7 km).

Direct Assimilation of Multichannel Microwave Brightness Temperatures and Impact on Mesoscale Numerical Weather Prediction over the TOGA COARE Domain

“…The quasiequilibrium assumptions on humidity and convective instability in model precipitation areas are used to assimilate TB's in rainy areas and rain flag data that are functions of precipitation. This assimilation was successful in producing model precipitation areas agreeing with the TOGA radar data given by Short et al (1997).…”

“…3) Assimilation of rain flag and TB's in rainy areas successfully produced model precipitation areas agreeing with radar observation data by Short et al (1997).…”

Rain Microphysical Budget in the Tropical Deep Convective Regime: A 2-D Cloud-Resolving Modeling Study

“…Li and Gao (2011) calculated the linear correlation coefficient between simulated and observed rain rates, which is 0.45. The observational rain rates are derived by taking an average over a 150 × 150 km 2 area, which is based on radar reflectivity data taken from the Massachusetts Institute of Technology Doppler radar and the TOGA radar located within the IFA region (Short et al 1997). A Studentʼs t-test on the significance of the correlation coefficients shows that the critical correlation coefficient at the 1% significant level is 0.128.…”

Heavy tailed durations of regional rainfall

“…The entire series corresponds to the full period of Cruise 1 (November 10, 1992 through December 9, 1992), consisting of 1992 scans, and to the early part of Cruise 2 (December 21, 1992 through December 29, 1992), consisting of 617 scans. A good source of detailed information about TOGA-COARE and its objectives is Short et al [38]. The experience showed that the multiscaling analysis of wet and dry durations can be restricted to spatial scales ranging from 120 km down to 2 km, following the rule of half (approximately).…”