Large-scale diurnal variability in the oceans: observation, modelling, assimilation and effects
Lead Research Organisation:
University of Edinburgh
Department Name: Sch of Geosciences
Abstract
More than two-thirds of the Earth's surface is covered by ocean. The current state of the ocean and how it will evolve is of practical importance to weather forecasting and maritime activities. 'Analysis' of the ocean state is the process of using available observations of the ocean to create the best possible picture of the ocean at a given time. The temperature of the surface of the ocean (referred to as SST) is one of the important parameters describing the ocean, and is observed by a limited number of ships and buoys and globally by satellites. One complication is that there is a daily signal in the SST as the near-surface warms in response to heating by sunlight and then cools again as the sun goes down. At present in ocean and weather simulations, this effect is largely ignored, partly because adequate observations of the phenomenon occuring from hour to hour through the day over large areas of ocean have not been available. In this project, we will use new hourly satellite observations of the daily warming and cooling of the ocean surface and of the amount of heating by sunlight to do several things. The first thing is to describe the size and frequency of significant daily warming events in different areas of oceans in different months. Second, we will explore how to correct satellite SSTs for daily warming events when doing SST analysis (using a new analysis system at the UK Met Office). Third, we will verify that we are able to run computer simulations based on the physics of daily heating events that give good estimates of their size. Fourth, we will calculate the importance of the daily variability to the exchange of carbon dioxide between the air and sea (which is sensitive to SST amongst other things). Lastly, we will conduct a case study of how to use the new satellite observations to improve SST analyses such that they capture daily warming for the first time.
People |
ORCID iD |
Christopher Merchant (Principal Investigator) |
Publications
Carella G
(2018)
Estimating Sea Surface Temperature Measurement Methods Using Characteristic Differences in the Diurnal Cycle
in Geophysical Research Letters
Fiedler E
(2019)
Intercomparison of long-term sea surface temperature analyses using the GHRSST Multi-Product Ensemble (GMPE) system
in Remote Sensing of Environment
Filipiak M
(2012)
An empirical model for the statistics of sea surface diurnal warming
in Ocean Science
Gentemann C
(2008)
Multi-satellite measurements of large diurnal warming events
in Geophysical Research Letters
Kettle H
(2009)
The impact of diurnal variability in sea surface temperature on the central Atlantic air-sea CO<sub>2</sub> flux
in Atmospheric Chemistry and Physics
Merchant C
(2008)
Diurnal warm-layer events in the western Mediterranean and European shelf seas
in Geophysical Research Letters
Merchant CJ
(2019)
Satellite-based time-series of sea-surface temperature since 1981 for climate applications.
in Scientific data
Rayner N
(2007)
The Global Ocean Data Assimilation Experiment High-resolution Sea Surface Temperature Pilot Project
in Bulletin of the American Meteorological Society
Zhang H
(2018)
Comparison of SST Diurnal Variation Models Over the Tropical Warm Pool Region
in Journal of Geophysical Research: Oceans
Description | The diurnal temperature range in sea surface temperature can be larger than previously thought, under persistent low wind conditions. This affects air-sea interactions. |
Exploitation Route | Within coupled data assimilation of sea surface temperature. |
Sectors | Environment |
Description | They have helped improve physical models of sea surface temperature diurnal temperature range, which feeds into numerical weather prediction. |
Sector | Environment |
Description | Copernicus Climate Change Service |
Amount | € 440,000 (EUR) |
Organisation | European Centre for Medium Range Weather Forecasting ECMWF |
Sector | Public |
Country | United Kingdom |
Start | 10/2016 |
End | 09/2018 |
Description | European Space Agency Climate Change Iniative |
Amount | € 4,400,000 (EUR) |
Organisation | European Space Agency |
Sector | Public |
Country | France |
Start | 07/2010 |
End | 03/2017 |
Title | Along Track Scanning Radiometer Sea Surface Temperature |
Description | A twenty-year independent record of sea surface temperature for climate from Along-track Scanning Radiometers. |
Type Of Material | Database/Collection of data |
Year Produced | 2012 |
Provided To Others? | Yes |
Impact | Figure in 5th assessment report of IPCC, showing global ocean temperature changes over recent decades. |
URL | http://catalogue.ceda.ac.uk/uuid/e6497acddf9cd8345ffbd0643c0d9729 |