Latent heat

About: Latent heat is a research topic. Over the lifetime, 13503 publications have been published within this topic receiving 302811 citations.

Evaluation of Mediterranean Sea water and heat budgets simulated by an ensemble of high resolution regional climate models

Abstract: Air-sea heat and freshwater water fluxes in the Mediterranean Sea play a crucial role in dense water formation. Here, we compare estimates of Mediterranean Sea heat and water budgets from a range of observational datasets and discuss the main differences between them. Taking into account the closure hypothesis at the Gibraltar Strait, we have built several observational estimates of water and heat budgets by combination of their different observational components. We provide then three estimates for water budget and one for heat budget that satisfy the closure hypothesis. We then use these observational estimates to assess the ability of an ensemble of ERA40-driven high resolution (25 km) Regional Climate Models (RCMs) from the FP6-EU ENSEMBLES database, to simulate the various components, and net values, of the water and heat budgets. Most of the RCM Mediterranean basin means are within the range spanned by the observational estimates of the different budget components, though in some cases the RCMs have a tendency to overestimate the latent heat flux (or evaporation) with respect to observations. The RCMs do not show significant improvements of the total water budget estimates comparing to ERA40. Moreover, given the large spread found in observational estimates of precipitation over the sea, it is difficult to draw conclusions on the performance of RCM for the freshwater budget and this underlines the need for better precipitation observations. The original ERA40 value for the basin mean net heat flux is −15 W/m2 which is 10 W/m2 less than the value of −5 W/m2 inferred from the transport measurements at Gibraltar Strait. The ensemble of heat budget values estimated from the models show that most of RCMs do not achieve heat budget closure. However, the ensemble mean value for the net heat flux is −7 ± 21 W/m2, which is close to the Gibraltar value, although the spread between the RCMs is large. Since the RCMs are forced by the same boundary conditions (ERA40 and sea surface temperatures) and have the same horizontal resolution and spatial domain, the reason for the large spread must reside in the physical parameterizations. To conclude, improvements are urgently required to physical parameterizations in state-of-the-art regional climate models, to reduce the large spread found in our analysis and to obtain better water and heat budget estimates over the Mediterranean Sea.

Convective Wakes in the Equatorial Western Pacific during TOGA

Abstract: The evolution of convective wakes was studied using composite time series calculated from data collected in the western Pacific warm pool during a pilot cruise and intensive observation period (IOP) of the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE). Hourly averaged observations from 42 convective wakes were used to compute wake-relative composite time series of the bulk meteorological variables, as well as sensible and latent heat fluxes. These analyses show great similarities between the convective wake characteristics of the pilot cruise and the IOP, despite differences in season and location. This result, combined with a strong correlation between individual wakes and the composite time series, demonstrates the representativeness of the composites. TOGA convective wakes were found to cause a significant decrease in air temperature, a significant increase in wind speed, and thus significant increases in sensible and latent heat fluxes, which is ...