Improved data gap-filling schemes for estimation of net ecosystem exchange in typical East-Asian croplands

The estimation of carbon exchange between ecosystems and the atmosphere suffers unavoidable data gaps in eddy-covariance technique, especially for short-living and fast-growing croplands. In this study we developed a modified gap-filling scheme introducing a leaf area index factor as the vegetation status information based on the conventional light response function for two East-Asian cropland sites (rice and potatoes). This scheme’s performance is comparable to the conventional time window scheme, but has the advantage when the gaps are large compared to the total length of the time series. To investigate how the time binning approach performs for fast-growing croplands, we tested different widths of the time window, showing that a four-day window for the potato field and an eight-day time window for the rice field perform the best. The insufficiency of the conventional temperature binning approach was explained as well as the influence of vapor pressure deficit. We found that vapor pressure deficit plays a minor role in both the potato and the rice fields under Asian monsoon weather conditions with the exception of the early pre-monsoon growing stage of the potatoes. Consequently, we recommend using the conventional time-window scheme together with our new leaf-light response function to fill data gaps of net ecosystem exchange in fast-growing croplands.

Characteristics of land-atmosphere energy and turbulentfluxes over the plateau steppe in central Tibetan Plateau

The land-atmosphere energy and turbulence exchange is key to understanding land surface processes on the Tibetan Plateau(TP). Using observed data for Aug. 4 to Dec. 3, 2012 from the Bujiao observation point(BJ) of the Nagqu Plateau Climate and Environment Station(NPCE-BJ), different characteristics of the energy flux during the Asian summer monsoon(ASM) season and post-monsoon period were analyzed. This study outlines the impact of the ASM on energy fluxes in the central TP. It also demonstrates that the surface energy closure rate during the ASM season is higher than that of the post-monsoon period. Footprint modeling shows the distribution of data quality assessments(QA) and quality controls(QC) surrounding the observation point. The measured turbulent flux data at the NPCE-BJ site were highly representative of the target land-use type. The target surface contributed more to the fluxes under unstable conditions than under stable conditions. The main wind directions(180° and 210°) with the highest data density showed flux contributions reaching 100%, even under stable conditions. The lowest flux contributions were found in sectors with low data density, e.g., 90.4% in the 360° sector under stable conditions during the ASM season. Lastly, a surface energy water balance(SEWAB) model was used to gap-fill any absent or corrected turbulence data. The potential simulation error was also explored in this study. The Nash-Sutcliffe model efficiency coefficients(NSEs) of the observed fluxes with the SEWAB model runs were 0.78 for sensible heat flux and 0.63 for latent heat flux during the ASM season, but unrealistic values of-0.9 for latent heat flux during the post-monsoon period.

A scalable software package for time series reconstruction of remote sensing datasets on the Google Earth Engine platform

Spatiotemporal residual noise in terrestrial earth observation products,often caused by unfavorable atmospheric conditions,impedes their broad applications.Most users prefer to use gap-filled remote sensing products with time series reconstruction(TSR)algorithms.Applying currently available implementations of TSR to large-volume datasets is time-consuming and challenging for non-professional users with limited computation or storage resources.This study introduces a new open-source software package entitled‘HANTS-GEE’that implements a well-known and robust TSR algorithm,i.e.Harmonic ANalysis of Time Series(HANTS),on the Google Earth Engine(GEE)platform for scalable reconstruction of terrestrial earth observation data.Reconstruction tasks can be conducted on user-defined spatiotemporal extents when raw datasets are available on GEE.According to site-based and regional-based case evaluation,the new tool can effectively eliminate cloud contamination in the time series of earth observation data.Compared with traditional PC-based HANTS implementation,the HANTS-GEE provides quite consistent reconstruction results for most terrestrial vegetated sites.The HANTS-GEE can provide scalable reconstruction services with accelerated processing speed and reduced internet data transmission volume,promoting algorithm usage by much broader user communities.To our knowledge,the software package is thefirst tool to support full-stack TSR processing for popular open-access satellite sensors on cloud platforms.

Chinese legislative reform for wet multimodal transportation of goods:What shall we learn from the Rotterdam Rules and what hold us back in the way of joining the Rules as a contracting state?

This article purports to shed light on some thoughts on China’s legislative reform in respect of rules pertaining to regulate the multimodal transportation involving a sea leg. While the section of multimodal transportation in the Chinese Maritime Code has not been much challenged in the legal practice, the recent Rotterdam Rules that deals with contracts of carriage of goods wholly or partly by sea certainly probes the area with new solutions. These new solutions have enlightened the debates among the scholars and practitioners over the routes for the reform of the wet multimodal transport provisions in the Code. In this article, the author attempts to assess the Rotterdam Rules solutions in connection with the characteristics of Chinese import and export trades that involve multimodal transportation as well as the relevant domestic legislation and international treaties to which China has entered into as member state that regulate transport of goods by modes other than sea. Based on the analysis, it finds out that some of the former solutions may give rise to unexpected results that hinder their adoption in the future Code : it could narrow the existing scope of application of the Chinese Maritime Code and would let the multimodal transport operators escape the mandatory regime of the Code.And if provision like the Art.26 of the Rotterdam Rules is adopted in the Code, a great market difference might be created as between the fragmented transportation under various contracts and the multimodal transportation under a single contract. However,certain rules are positive so that can be adopted in the future Code: the hypothetical contract approach adopted in the Art. 26 of the Rotterdam, Rules and the gap-filling approach adopted in the Arts. 26 and 82 of the Rules may provide better certainties in respect of issues such as time for suit, liability for delay, transport documents.Moreover, Chinese legislators may consider to extend the multimodal liability regime to the independent contractors or subcontractors of the MTOs that are involved in maritime carriage and related operations.