“Trends” and variations of global oceanic evaporation data sets from remote sensing

The variability in global oceanic evaporation data sets was examined for the period 1988-2000. These data sets are satellite estimates based on bulk aerodynamic formulations and include the NASA/Goddard Space Flight Center Satellite-based Surface Turbulent Flux version 2 （ GSSTF2）, the Japanese-ocean flux using remote sensing observations （J-OFURO）, and the Hamburg Ocean-Atmosphere Parameters and Fluxes from Satellite version 2 （HOAPS2）. The National Center for Environmental Prediction （NCEP） reanalysis is also included for comparison. An increase in global average surface latent heat flux （SLHF） can be observed in all the data sets. Empirical mode decomposition （EMD） shows long-term increases that started around 1990 for all remote sensing data sets. The effect of Mt. Pinatubo eruption in 1991 is clearly evident in HOAPS2 but is independent of the longterm increase. Linear regression analyses show increases of 9.4%, 13.0%, 7. 3%, and 3.9% for GSSTF2, J-OFURO, HOAPS2 and NCEP, for the periods of the data sets. Empirical orthogonal function （EOF） analyses show that the pattern of the first EOF of all data sets is consistent with a decadal variation associated with the enhancement of the tropical Hadley circulation, which is supported by other satellite observations. The second EOF of all four data sets is an ENSO mode, and the correlations between their time series and an SO1 are 0.74, 0.71,0.59, and 0.61 for GSSTF2, J-OFURO, HOAPS2, and NCEP in that order. When the Hadley modes are removed from the remote sensing data, the residue global increases are reduced to 2.2% , 7. 3%, and 〈 1% for GSSTF2, J-OFURO and HOAPS, respectively. If the ENSO mode is used as a calibration standard for the data sets, the Hadley mode is at least comparable to, if not larger than, the ENSO mode during our study period.     

Study on fluctuations of plume front and turbidity maximum in the Hangzhou Bay by remote sensing data

On the basis of the time series of AVHRR data from NOAA satellites and the geographical information system PURSIS, fluctuations of the plume front and the turbidity maximum in the Hangzhou Bay, reflected by the distributions of temperature and suspended sediment concentration respectively, are studied in view of long-term behaviors or seasonal and tidal cycles. The data suggest that the effect of front plays an important role in the development of the turbidity maximum close to the Changjiang Estuary > while the effect of tide dominates over the development of another very turbid water situated in the shoal areas in the southern Hangzhou Bay.     

Declined trends of chlorophyll a in the South China Sea over 2005-2019 from remote sensing reconstruction

Chlorophyll a concentration(CHL) is an important proxy of the marine ecological environment and phytoplankton production.Long-term trends in CHL of the South China Sea(SCS) reflect the changes in the ecosystem’s productivity and functionality in the regional carbon cycle.In this study,we applied a previously reconstructed15-a(2005-2019) CHL product,which has a complete coverage at 4 km and daily resolutions,to analyze the longterm trends of CHL in the SCS.Quantile regression was used to elaborat...     

The remote sensing composite information of Nansha reef''s closed atoll and the model of its spatial structure evolution——Ⅰ

Based on the feature of the growth and the local limitation of the Nansha reef's closed atoll, also the relatedremote sensing information of it, the composite analysis is made. The closed atoll conception remote sensing system is constructed through the formation mechanism, development law and the space-time distribution of the closed atoll. Solution of the equation consisting of information function value and isostatic value of closed atoll and half-closed atoll using this system, and topologic analysis on the two kinds of atoll's morphologic growth are the basic foundation for the research of their evolutionary comparative model.     

Identifying the importance of the “skipper effect” within sources of measured inefficiency in fisheries through data envelopment analysis (DEA)

Technical efficiency, uncertainties in data quality and natural fluctuations in fishing stocks constitute potential sources of fishing vessel inefficiency. Moreover, debate is on-going as to whether the skill of the fishermen (“skipper effect”) is an underlying actor in fishing efficiency. Therefore, this article monitors, calculates and quantifies the inefficiency caused by the “skipper effect”, if any, through the use of data envelopment analysis (DEA), with the aim of determining whether best practice target operational values in DEA, and their associated environmental impact reductions through LCA+DEA methodology, are achievable beyond the theoretical baseline they involve. A window analysis model is applied to the US menhaden fishery, a purse seining fleet with high homogeneity, since it is owned by the same company, with similar vessel and management characteristics. Results revealed relevant inefficiency levels in the four ports assessed, suggesting the existence of a “skipper effect” in all of them. Strong variances between vessels were identified, not only on an annual mean basis, but also per week of study. These variances could be attributed to random variation through time, if it were not for the fact that best performing vessels managed to repeatedly perform at high efficiency rates throughout the period. Moreover, standard deviations of low efficiency vessels were higher in all ports. Consequently, best performing targets calculated in LCA+DEA may be difficult to achieve in fleets where skipper skill strongly influences the sources of inefficiency. In these cases, the results suggest that resource minimization should be linked to specific measures to improve the individual skills of low performing vessels to attain best practice targets.     

“Living with our backs to the sea”: A critical analysis of marine and coastal governance in Guatemala

Guatemala's rich coastal and marine biodiversity provides essential ecosystem goods and services to local residents and the national economy through artisanal and commercial fisheries, aquaculture, port exports and, to a lesser extent, tourism. As in many other countries, national policies emphasise the significance of marine conservation and marine resources, primarily through implementing marine protected areas (MPAs). However, this assumes that governance, as reflected in legal, institutional and organizational frameworks, political capacity and human resources is sufficiently developed to ensure MPAs meet these goals. These issues are explored through presenting the first detailed analysis of coastal and marine governance in Guatemala. The research highlights a range of barriers to good governance which restrict the extent to which MPAs can function effectively. Recommendations are made which can capitalise upon the potential for locally managed marine areas as a means to facilitate the improved governance of coastal and marine resources in Guatemala.     

Influence analysis of gaseous absorption on “HY-1A” CZI data processing Simulation and correction for Rayleigh scattering

Besides ozone, oxygen and water vapour should be considered for their absorptive effects on ＂HY--1A＂ CZI data processing. First ,gaseous transmittances under various conditions are computed and analyzed for the band settings of this sensor. Second, transmittances under six standard atmospheres are approximated as functions of zenith angle, the water vapour transmittance is approximated as a function of water vapour content and zenith angle, and the ozone transmittance is approximated as a function of ozone content and zenith angle. Finally, taking Rayleigh scattering as an example, the influence of ignoring gaseous absorption when calculating TOA reflectance is analyzed, and the effect of applying the presented transmittance approximations to gaseous absorption correction for Rayleigh scattering in ＂HY--1A＂ CZI data processing is evaluated.     

Validation of the “HY-2” altimeter wet tropospheric path delay correction based on radiosonde data

Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- mate PD values, the ＂HY-2＂ system includes a calibration microwave radiometer （CMR） operating at 18.7, 23.8 and 37 GHz. The PD data of the CMR were compared and validated by coincident radiosonde profiles from ten globally distributed radiosonde stations during October 2011 to August 2012. The temporal interval was 1 h. In order to avoid land contamination, different spatial intervals between these two data sets were tested. The empirical fit function of PD uncertainty and spatial interval was found and extrapolated to the ideal situation that the data of CMR and radiosonde were totally coincident. The stability of the brightness temperature of the CMR and its impact on the PD correction was also studied. Consequently, the uncertainty of the PD algorithm of the CMR was estimated to be 2.1 cm.     

Some progress on ocean data assimilation in China: Introduction of the special section “Ocean Data Assimilation”

<正>This special section is the scientific legacy of the 13th National Ocean Data Assimilation and Numerical Simulation Conference of China, which was held in Changsha, China during December 3–4, 2020 with more than 160 participants from 35 units in China. It continued a series of National Ocean Data Assimilation conferences which began in 2003,