Climatological diurnal variability in sea surface temperature characterized from drifting buoy data

Drifting buoy sea-surface temperature (SST) records have been used to characterize the diurnal variability of ocean tem- perature at a depth of order 20 cm. We use measurements covering the period 1986–2012 from the International Com- prehensive Ocean-Atmosphere Data Set (ICOADS) version 2.5, which is a collection of marine surface observations that includes individual SST records from drifting buoys. Appropriately transformed, this dataset is well suited for estimation of the diurnal cycle, since many drifting buoys have high temporal coverage (many reports per day), and are globally distributed. For each drifter for each day, we compute the local-time daily SST variation relative to the local-time daily mean SST. Climatological estimates of subdaily SST variability are found by averaging across various strata of the data: in 10° latitudinal bands as well as globally; and stratified with respect to season, wind speed and cloud cover. A parame- terization of the diurnal variability is fitted as a function of the variables used to stratify the data, and the coefficients for this fit are also provided with the data. Results are consistent with expectations based on the previous work: the diurnal temperature cycle peaks in early afternoon (circa 2 pm local time); there is an increase in amplitude and a decrease in seasonality towards the equator. Generally, the ocean at this depth cools on windy days and warms on calm days, so that a component of subdaily variability is the SST tendency on slower timescales. By not ‘closing’ the diurnal cycle when stratified by environmental conditions, this dataset differs from previously published diurnal-cycle parameter- izations. This thorough characterization of the SST diurnal cycle will assist in interpreting SST observations made at different local times of day for climatological purposes, and in testing and constraining models of the diurnal-cycle and air-sea interaction at high temporal resolution

Near-surface ocean temperature

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): C02004, doi:10.1029/2004JC002689.The first open ocean deployment of the Skin Depth Experimental Profiler (SkinDeEP) was from the R/V Melville in the Gulf of California during the Marine Optical Characterization Experiment (MOCE–5). SkinDeEP is an autonomous, vertical profiler for the upper few meters of the ocean. During MOCE–5, SkinDeEP was deployed on 10 separate occasions, and profiles were made at intervals of approximately one minute each. A total of 976 profiles were acquired during the cruise. The ocean skin temperatures were measured by the Marine Atmosphere Emitted Radiance Interferometer (M–AERI), an infrared spectroradiometer. Typical meteorological conditions were of low winds and high insolation. The dataset provided captures the near-surface temperature structure that decouples the skin layer from the conventional in–situ bulk sea surface temperature measurements made at a depth of a few meters. Data from SkinDeEP showed strong diurnal warming within the upper few meters, with one extreme case of 4.6 K. There were large discrepancies when computing the skin–bulk temperature difference with bulk temperatures at different depths. Results also show the strong dependency of estimating air–sea heat flux based on SST, with warm–layer errors of almost 60 Wm-2 associated with intense stratification. This indicates the importance of the inclusion of the skin temperature for accurate calculation of latent, sensible, and net longwave heat fluxes.The development of SkinDeEP was funded through the Research Council of Norway (Prosjektnr. 127872/720). Support was provided by the European Commission under the Marie Curie Fellowship contract ERBFMBICT983162. Further supportwas provided by NSF grant OCE–0241834 and National Oceanographic Partnership Program Award No. NNG04GM56G

Assessing the value of intangible benefits of property level flood risk adaptation (PLFRA) measures

© 2015, Springer Science+Business Media Dordrecht. Studies in the UK and elsewhere have identified that flooding can result in diverse impacts, ranging from significant financial costs (tangible) to social (intangible) impacts on households. At the same time, it is now clear that large-scale flood defence schemes are not the panacea to flood risk, and there is an increasing responsibility on property owners to protect their own properties. Hence, there is an emerging expectation for homeowners to take action in the form of investing in property level flood risk adaptation (PLFRA) measures to protect their properties. However, hitherto the level of uptake of such measures remains very low. The tangible financial benefits of investing in PLFRA measures are generally well understood and have been demonstrated to be cost beneficial for many properties at risk from frequent flooding. Importantly, these estimates tend to take little account of the value of the intangible benefits of PLFRA measures and therefore may be under estimating their full benefits. There remains a need to develop an improved understanding of these intangible benefits, and this research sets out to bridge this knowledge gap. Based on a synthesis of the literature, the contingent valuation method was selected as a means to value intangible impacts of flooding on households. A questionnaire survey of homeowners affected in the 2007 flooding was employed to elicit willingness to pay (WTP) values to avoid the intangible impacts of flooding on their households. The analysis of the questionnaire survey data revealed that the average WTP per household per year to avoid intangible flood impacts was £653. This therefore represents the value of the intangible benefits of investing in PLFRA measures and is significantly higher than previously estimated. This research builds on previous research in suggesting a higher value to the intangible impacts of flooding on households by assessing wider range of intangible impacts and focussing on more experienced individuals. Furthermore, the research indicates that factors which influence the WTP values were principally stress of flood, worrying about loss of house values, worrying about future flooding and age of respondents, with income showing a weak correlation. The establishment of a new value for the intangible impacts of flooding on households in the UK is helpful in the domain of flood risk management when evaluating the total benefits (tangible and intangible) of investing in flood protection measures, thus providing a robust assessment for decision-making on flood adaptation measures at an individual property level

A global study of diurnal warming

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A global study of diurnal warming

The diurnal cycle is a fundamental mode of the climate system associated with solar forcing.  Sea surface temperature (SST) is directly affected by the diurnal cycle of the sun’s radiation. This thesis presents a detailed study of the diurnal variability of SST using a variety of data sources from satellites, moored buoys and a 1-D mixed layer model.  10 years of daily day- and night time satellite data are analysed to provide the first global long-term assessment of diurnal warming patterns.  In situ buoy and model data are used to investigate the variability of diurnal warming.  A 1-D mixed layer numerical model is used to investigate the sensitivity of the evolution of the diurnal warm layer to the presence of chlorophyll.  Under low wind conditions, the distribution of solar energy is largely determined by the optical properties of the water column.  Chlorophyll has little impact on the heating within the top few centimetres of the ocean, but below 0.7m, the presence of chlorophyll increases the diurnal heating rate and consequently temperature. High resolution buoy data are analysed to investigate the sensitivity of the evolution of the diurnal warm layer to fluctuations in the meteorological conditions.  Over three hundred individual diurnal cycles of SST, insolution and wind speed are analysed.  the results reveal that the evolution of the warm layer is strongly dependent on the time variability of the forcing fields.  The shallower the warm layer, the greater its sensitivity to meteorological fluctuations.  Under low winds, large differences in SST can occur between the surface and 1m.  Based on these results, a new parameterisation is developed to estimate to diurnal variation of SST at the surface and at 1m, taking into consideration the time variability of the forcing fields.</p

Diurnal variations of surface ocean pCO(2) and sea-air CO2 flux evaluated using remotely sensed data

This paper evaluates the effect of diurnal variations of sea surface temperature (SST) and wind speed on the surface ocean CO2 partial pressure (pCO2sw) and sea-air CO2 flux. This is carried out using a combination of climatological and remote sensing data. The calculations show that the diurnal heating cycle can drive a diurnal pCO2sw variability which may cause the global ocean uptake of CO2 to be more than twice as large during night than during day. The effect of diurnal wind speed variations on the sea-air CO2 flux is restricted to the tropics. The concurrent variations of SST and wind speed on diurnal time scales bring around covariance terms that may contribute to the monthly mean flux. These were estimated and found to be negligible. Thus, this study validates the use of diurnally averaged fields for computation of sea-air CO2 fluxes