OceanRAIN, a new in-situ shipboard global ocean surface-reference dataset of all water cycle components

Abstract

OceanRAIN—the Ocean Rainfall And Ice-phase precipitation measurement Network—provides in-situ along-track shipboard data of precipitation, evaporation and the resulting freshwater flux at 1-min resolution over the global oceans from June 2010 to April 2017. More than 6.83 million minutes with 75 parameters from 8 ships cover all routinely measured atmospheric and oceanographic state variables along with those required to derive the turbulent heat fluxes. The precipitation parameter is based on measurements of the optical disdrometer ODM470 specifically designed for all-weather shipboard operations. The rain, snow and mixed-phase precipitation occurrence, intensity and accumulation are derived from particle size distributions. Additionally, microphysical parameters and radar-related parameters are provided. Addressing the need for high-quality in-situ precipitation data over the global oceans, OceanRAIN-1.0 is the first comprehensive along-track in-situ water cycle surface reference dataset for satellite product validation and retrieval calibration of the GPM (Global Precipitation Measurement) era, to improve the representation of precipitation and air-sea interactions in re-analyses and models, and to improve understanding of water cycle processes over the global oceans.

The Latitudinal Variability of Oceanic Rainfall Properties and Its Implication for Satellite Retrievals: 1. Drop Size Distribution Properties

“…The OceanRAIN database has been described extensively in Klepp et al (). Here we only briefly provide information relevant to this study.…”

“…These data sets were (and are still being) collected during the long-term installations and special campaigns onboard eight research vessels from June 2010 covering all latitudes (see Figure 1), oceanic basins and seasons and comprise 696,740 precipitation minutes. The high quality of the ODM470 observations in harsh marine environments has been demonstrated in Klepp et al (2018) using quantitative comparisons between T-matrix calculations of 24 GHz radar reflectivity using the ODM470 DSDs and direct measurements of 24 GHz reflectivity from a micro rain radar (MRR-2, Klugmann et al, 1996) during the CAPRICORN (Clouds, Aerosols, Precipitation, Radiation, and atmospherIc Composition Over the southeRN ocean) experiment; Mace & Protat, 2018). Correlation between the two estimates was 0.75, with no detectable instrumental artifact at low or high reflectivities.…”

Assessment of Level-3 Gridded Global Precipitation Mission (GPM) Products Over Oceans

“…The ODM470 instrument used in OceanRAIN can measure very light precipitation (from 0.01 mm·h −1 to 0.09 mm·h −1 ) unlike common gauges. As highlighted in Klepp et al [29], when an insignificant number of particles is recorded, the measurement is flagged and assigned a value of 0.00 mm·h −1 . Moreover, to avoid unrealistic spikes, quality control is maintained through routine visual inspections.…”

Effect of disdrometer type on rain drop size distribution characterisation: a new dataset for south-eastern Australia

“…Relations between quantitative precipitation estimates (QPEs) and microwave signal (back)scattering, e.g. reflectivity and attenuation, highly depend on the rain microstructure, and an accurate QPE therefore requires detailed knowledge of the rain microstructure (Uijlenhoet, 2001;Krajewski and Smith, 2002;Uijlenhoet et al, 2003a, b;Adirosi et al, 2018).…”