Abstract
Offshore of many coastal regions, the ocean surface wind varies in speed and direction throughout the day, owing to forcing from land/sea temperature differences and orographic effects. Far offshore, both diurnal and semidiurnal wind vector variability has been noted in the Tropical Atmosphere Ocean-TRIangle Trans-Ocean buoy Network (TAO-TRITON) mooring data in the tropical Pacific Ocean. In this manuscript, the tropical diurnal wind variability is examined with microwave radiometer-derived winds from the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM), merged with RapidScat and other scatterometer data. Since the relationship between wind speed and its zonal and meridional components is nonlinear, this manuscript describes an observationally based methodology to merge the radiometer and scatterometer-based wind estimates as a function of observation time, to generate a multi-year dataset of diurnal wind variability. Compared to TAO-TRITON mooring array data, the merged satellite-derived wind components fairly well replicate the semidiurnal zonal wind variability over the tropical Pacific but generally show more variability in the meridional wind components. The meridional component agrees with the associated mooring location data in some locations better than others, or it shows no clear dominant diurnal or semidiurnal mode. Similar discrepancies are noted between two forecast model reanalysis products. It is hypothesized that the discrepancies amongst the meridional winds are due to interactions between surface convergence and convective precipitation over tropical ocean basins.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Relatively few observational investigations have been undertaken that attempt to estimate these daily modes of ocean surface wind variability
These are the ERA-Interim (ERA-I) global atmospheric reanalysis produced by the European Centre for MediumRange Weather Forecasts (ECMWF) [28] and the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA2) reanalysis produced by the NASA Global
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Relatively few observational (satellite-based) investigations have been undertaken that attempt to estimate these daily modes of ocean surface wind variability (hereafter, the term daily refers to all variations within a 24-h period, and diurnal and semidiurnal will refer to the first and second harmonics of the daily cycle, respectively) Such an observational capability would be useful to understand the mechanisms linking convective precipitation to the diurnal. The best known of these is the brief seven-month “tandem period” in 2003, overlapping the Seawinds scatterometer onboard the Advanced Earth Observation Satellite (ADEOS-2) and the QuikSCAT satellite, which provided four (u, v) observations per day, nearly spaced in time, enabling estimation of the diurnal mode These data triggered several studies of the diurnal ocean surface wind vector variability [11,20,21] and timing of oceanic convergence [22].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
