Itsara Masiri

A Climatology of Ocean–Atmosphere Heat Flux Estimates over the Great Barrier Reef and Coral Sea: Implications for Recent Mass Coral Bleaching Events

Abstract A regional-scale estimate of the surface heat budget of the Great Barrier Reef and Coral Sea (10°–26°S, 142°–155°E) has been developed for the period 1995–2005 in the hope of understanding the trends of sea surface temperatures and the surface heat balance. This report describes the methodology to acquire input parameters from satellite observations, the resultant individual components of the surface heat budget, and their validation with existing datasets and surface measurements. The accuracy of individual flux components of the heat budget were analyzed with an array of surface measurements. Derived monthly averaged latent and sensible heat flux estimates show RMS errors of approximately 25.2 and 3.4 W m−2, respectively. Monthly averaged longwave and shortwave radiation flux estimates show RMS errors of approximately 6.7 and 13.3 W m−2, respectively. These improved estimates allow a higher confidence in studies that examine recent sea surface temperature (SST) trends and observed mass coral bl...

Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 2. A regional-scale predictive model for the Great Barrier Reef, Australia

A spatial risk assessment model is developed for the Great Barrier Reef (GBR, Australia) that helps identify reef locations at higher or lower risk of coral bleaching in summer heat-wave conditions. The model confirms the considerable benefit of discriminating nutrient-enriched areas that contain corals with enlarged (suboptimal) symbiont densities for the purpose of identifying bleaching-sensitive reef locations. The benefit of the new system-level understanding is showcased in terms of: (i) improving early-warning forecasts of summer bleaching risk, (ii) explaining historical bleaching patterns, (iii) testing the bleaching-resistant quality of the current marine protected area (MPA) network (iv) identifying routinely monitored coral health attributes, such as the tissue energy reserves and skeletal growth characteristics (viz. density and extension rates) that correlate with bleaching resistant reef locations, and (v) targeting region-specific water quality improvement strategies that may increase reef-scale coral health and bleaching resistance.

A semi-empirical model for estimating surface solar radiation from satellite data

This paper presents a semi-empirical model for estimating surface solar radiation from satellite data for a tropical environment. The model expresses solar irradiance as a semi-empirical function of cloud index, aerosol optical depth, precipitable water, total column ozone and air mass. The cloud index data were derived from MTSAT-1R satellite, whereas the aerosol optical depth data were obtained from MODIS/Terra satellite. The total column ozone data were derived from OMI/AURA satellite and the precipitable water data were obtained from NCEP/NCAR. A five year period (2006-2010) of these data and global solar irradiance measured at four sites in Thailand namely, Chiang Mai (18.78 °N, 98.98 °E), Nakhon Pathom (13.82 °N, 100.04 °E), Ubon Ratchathani (15.25 °N, 104.87 °E) and Songkhla (7.20 °N, 100.60 °E), were used to derive the coefficients of the model. To evaluate its performance, the model was used to calculate solar radiation at four sites in Thailand namely, Phisanulok (16.93 °N, 100.24 °E), Kanchanab...

An investigation of solar erythemal ultraviolet radiation at two sites in tourist attraction areas of Thailand

Islands on the southern coasts of Thailand are famous attractions for local and foreign tourists. Tourists usually expose their skins to solar radiation for tanning. Thus information on solar ultraviolet radiation (UV) is of importance for tourists to protect themselves from adverse effects of UV. In this work, solar erythemal ultraviolet radiation (EUV) at two touristic sites namely Samui island (9.451°N, 100.033°E) and Phuket island (8.104°N, 98.304°E) was investigated. In investigating EUV, broadband UV radiometers (Kipp & Zonen, model UVS-B-C) were installed at existing meteorological stations in Samui and Phuket islands. A one-year period of EUV data from these two sites was analyzed. The level of UV index at these sites was studied. The values of UV index higher than 12 at noon time of clear days are usually found in the summer at both sites. Seasonal variation of EUV at both sites was investigated. It was found that the tropical monsoons have strong influence on this variation. Finally, global broa...

Statistical models for estimating hourly diffuse solar radiation in different regions of Thailand

In this study, four statistical models for estimating diffuse solar radiation from global solar radiation in different regions of Thailand have been developed. In developing the models, a 12-year period of global and diffuse solar radiation measured at four of our solar radiation monitoring stations, situated in different regions of Thailand have been analyzed. The statistical models estimate diffuse fraction from clearness index at the hourly scale. The performance of these models have been compared with that of other models. The models developed in this study performed best for most cases.

An investigation of sky radiance from the measurement at a tropical site

The sky radiance was measured by using a sky scanner (EKO, model MS-321LR) at a tropical site in Nakhon Pathom (13.82° N, 100.04° E), Thailand. A three-year period of sky radiance data was analyzed. Sky radiance distribution for each season was investigated. The results showed that the monsoons had strong effect on the sky radiance distribution. The hourly clear sky radiance from the measurements was also compared with that obtained from the corresponding sky radiance calculated from the CIE model, which considers two different standard clear sky types. It was found that the measured and calculated sky radiances were in reasonable agreement, for both cases.