Time–space continuity of daily maps of fractional snow cover and albedo from MODIS

Using reflectance values from the seven MODIS “land” bands with 250 or 500 m resolution, along with a corresponding cloud product, we estimate the fraction of each 500 m pixel that snow covers, along with the albedo of that snow. The daily products have data gaps and errors because of cloud cover and sensor viewing geometry. Rather than make users interpolate and filter these patchy daily maps without completely understanding the retrieval algorithm and instrument properties, we use the daily time series to improve the estimate of the measured snow properties for a particular day. We use a combination of noise filtering, snow/cloud discrimination, and interpolation and smoothing to produce our best estimate of the daily snow cover and albedo. We consider two modes: one is the “predictive” mode, whereby we estimate the snow-covered area and albedo on that day using only the data up to that day; the other is the “retrospective” mode, whereby we reconstruct the history of the snow properties for a previous period.     

First comprehensive fine-resolution global land cover map in the world from China—Comments on global land cover map at 30-m resolution

<正>Land cover maps are of fundamental importance in studies of the complex interactions between human activities and global change.Mapping land cover using remote sensing is a traditional but still very active field.In the past 45 years,nearly 30000 papers about land cover mapping were published worldwide,including approximately 10000 papers     

Do model parameters change under changing climate and land use in the upstream of the Lancang River Basin,China?

ABSTRACT

Hydrological model parameters may vary under the impacts of climate and land-use change. This study proposes a hydrological modelling framework based on the Soil and Water Assessment Tool (SWAT) to investigate the variability of model parameters in three different experiments and to assess the impacts of climate and/or land-use change on these parameters in the upstream of the Lancang River Basin, China. In Experiment 1 (E1), most parameters show clear temporal trends under changing climate and land use, implying that model parameters are strongly influenced by their combined effects. Experiments 2 (E2) and 3 (E3) investigate the separate impacts of land-use change and climate change, respectively. Due to the almost invisible changes in land use in E2, there is no change detected in the model parameters. Temporal trends are found in most parameters in E3 and over half of them show consistent trends with E1, which indicates that climate change has greater impacts on model parameter variability. The simulated extreme streamflow and sediment fluxes vary substantially with time-variant parameters, implying that the variations in model parameters do matter for hydrological prediction.     

Complexity analysis of precipitation using the Lempel–Ziv algorithm and a multi-scaling approach: a case study in Jilin province,China

Precipitation is an important part of the hydrologic cycle, and its complexity is closely related to surface runoff and changing groundwater dynamics, which in turn influences the accuracy of precipitation forecasts. In this study, we used the Lempel–Ziv algorithm (LZA) and a multi-scaling approach to assess precipitation complexity for 1958–2011 by analyzing time series data from 28 gauging stations located throughout Jilin province, China. The spatial distribution of normalized precipitation complexity was measured by LZA, a symbolic dynamics algorithm, and by a multi-scaling approach, which is described by fractals. In addition, the advantages and limitations of these two methods were investigated. The results indicate that both methods are applicable and consistent for calculating precipitation complexity, and that the degree of relief is a primary factor controlling precipitation complexity in the mountainous area; in the plain terrain, however, the prominent influencing factor is climate.     

An examination of the presence and topography of the D＇＇ discontinuity under the Russia–Kazakhstan border region using seismic waveform data from a deep earthquake in Spain

The D＇＇ layer,which is located atop the core–mantle boundary,has long been an area of focus for global seismology studies. A widely used approach to study the discontinuities in the D＇＇ layer involves the use of the SdS phases between the S and ScS phases,which requires that certain stringent conditions be satisfied with respect to an epicentral distance and earthquake depth. Therefore,this approach is only practical for investigating the presence and topography of velocity interfaces in certain local regions around the world. The Russia–Kazakhstan border region has been a ‘‘blind spot＇＇ with respect to this detection method. The seismic network deployed in the northeastern margin of the Tibetan Plateau has recorded relatively clear SdS phases for the MS6.3 earthquake that occurred in Spain on April 11,2010,allowing this blind spot to be studied. This paper compares the observed waveforms and synthetics and uses the travel times of the relevant phases to obtain a D＇＇ discontinuity depth between2,610 and 2,740 km in the examined area. This study provides the first results regarding the depth of the D＇＇ layer discontinuity for this region and represents an important addition to the global studies of the D＇＇ layer.     

An examination of the presence and topography of the D″ discontinuity under the Russia–Kazakhstan border region using seismic waveform data from a deep earthquake in Spain

The D″ layer, which is located atop the core–mantle boundary, has long been an area of focus for global seismology studies. A widely used approach to study the discontinuities in the D″ layer involves the use of the SdS phases between the S and ScS phases, which requires that certain stringent conditions be satisfied with respect to an epicentral distance and earthquake depth. Therefore, this approach is only practical for investigating the presence and topography of velocity interfaces in certain local regions around the world. The Russia–Kazakhstan border region has been a “blind spot” with respect to this detection method. The seismic network deployed in the northeastern margin of the Tibetan Plateau has recorded relatively clear SdS phases for the M _S 6.3 earthquake that occurred in Spain on April 11, 2010, allowing this blind spot to be studied. This paper compares the observed waveforms and synthetics and uses the travel times of the relevant phases to obtain a D″ discontinuity depth between 2,610 and 2,740 km in the examined area. This study provides the first results regarding the depth of the D″ layer discontinuity for this region and represents an important addition to the global studies of the D″ layer.     

Reply to “Comments on the paper “A crustal-upper mantle model for southeastern Sicily (Italy) from the integration of petrologic and geophysical data” by ”

We reply to the comments of Beccaluva et al. (2013) on the paper “A crustal-upper mantle model for southeastern Sicily (Italy) from the integration of petrologic and geophysical data” by Manuella et al. (2013). We entirely reject their speculative comments and strongly confirm our viewpoint on the aged oceanic nature of the lithospheric basement of southeastern Sicily and its offshore area.     

Hydrological appraisal of rainfall estimates from radar,satellite, raingauge and satellite–gauge combination on the Qinhuai River Basin,China

ABSTRACT

Multisource rainfall products can be used to overcome the absence of gauged precipitation data for hydrological applications. This study aims to evaluate rainfall estimates from the Chinese S-band weather radar (CINRAD-SA), operational raingauges, multiple satellites (CMORPH, ERA-Interim, GPM, TRMM-3B42RT) and the merged satellite–gauge rainfall products, CMORPH-GC, as inputs to a calibrated probability distribution model (PDM) on the Qinhuai River Basin in Nanjing, China. The Qinhuai is a middle-sized catchment with an area of 799 km². All sources used in this study are capable of recording rainfall at high spatial and temporal resolution (3 h). The discrepancies between satellite and radar data are analysed by statistical comparison with raingauge data. The streamflow simulation results from three flood events suggest that rainfall estimates using CMORPH-GC, TRMM-3B42RT and S-band radar are more accurate than those using the other rainfall sources. These findings indicate the potential to use satellite and radar data as alternatives to raingauge data in hydrological applications for ungauged or poorly gauged basins.     

Origin of Late Permian Emeishan basaltic rocks from the Panxi region (SW China): Implications for the Ti-classification and spatial–compositional distribution of the Emeishan flood basalts

Basalts and a mafic dyke collected from the city of Panzhihua show characteristics of high-Ti and low-Ti Emeishan basalts respectively. The dyke yielded a SHRIMP zircon U–Pb mean age of 261 ± 5 Ma making it contemporaneous with the eruption of Emeishan basalts. The basalts have I_Sr ranging from 0.7059 to 0.7062 with εNd_(T) ranging from ?1.1 to + 0.7 whereas the dyke has I_Sr ranging from 0.7056 to 0.7064 with εNd_(T) ranging from + 0.3 to + 0.5. Trace element modeling shows that the two rock types can be generated by different degrees of partial melting from the same garnet-bearing source. Assimilation of crustal material is required in order to produce the depletion of some trace elements (e.g. Nb and Ta) of the dyke however crustal assimilation is not required to produce the basalts. Trace element modeling and isotopic data of the Emeishan basalts suggest that, in general, the high- and low-Ti basaltic rocks are likely derived from the same source and represent different degrees of partial melting with or without crustal assimilation. The location and geological relationships of the ‘high-Ti’ basalts indicate they erupted relatively early and within the central part of the ELIP, casting doubt on the previous spatial–compositional distribution of the Emeishan basalts.     

Seasonal–latitudinal variations of PMC particle size from SME measurements for the northern 1983 season and SNOE measurements for the northern 2000 and southern 2000/2001 seasons

The ultraviolet spectrometers (UVS) on the solar mesosphere explorer (SME) and student nitric oxide explorer (SNOE) measured scattered limb radiance at small and large scattering angles from polar mesospheric clouds (PMCs). The SME data are for the northern summer hemisphere (NH) in 1983 and 1984. The SNOE measurements are for the NH in 2000 and for the southern hemisphere (SH) in the 2000/2001 season. From this database, we deduce the modal particle size from the measured scattering angle asymmetry in radiance. This quantity is determined as a function of time within the PMC season, and latitude, assuming several scattering models depending on the adopted size distribution and particle shape. For assumed spherical particles with a Gaussian distribution of width of 14 nm, the results for SME show mode particle sizes that vary from about 35 to 60 nm throughout the season. The results for SNOE under the same assumption show that for high latitudes in the NH the particle size grows systematically from the seasonal onset, from about 25 nm to a maximum of about 45 nm at 30 days after solstice. Lower latitudes show a similar time dependence, but with smaller particle sizes. SH PMC particle sizes display a more complicated seasonal variability. Generally, variability in measured cloud height is anti-correlated with particle size for the seasons analyzed here. Particle sizes in the SH are generally smaller than those in the NH, consistent with the northern bias in PMC brightness, and with previous satellite studies. These results are interpreted in terms of our understanding of PMC microphysics and inter-hemispheric differences in temperature and dynamics. Our quantitative results for mode radius depend on the assumption of a constant distribution width. If the width varies with latitude or time, our calculated gradients of mode radius would be different.     

40Ar–39Ar dating of volcanogenic products from the AND-2A core (ANDRILL Southern McMurdo Sound Project, Antarctica): correlations with the Erebus Volcanic Province and implications for the age model of the core

The AND-2A drillcore (Antarctic Drilling Program—ANDRILL) was successfully completed in late 2007 on the Antarctic continental margin (Southern McMurdo Sound, Ross Sea) with the aim of tracking ice proximal to shallow marine environmental fluctuations and to document the 20-Ma evolution of the Erebus Volcanic Province. Lava clasts and tephra layers from the AND-2A drillcore were investigated from a petrographic and stratigraphic point of view and analyzed by the ⁴⁰Ar–³⁹Ar laser technique in order to constrain the age model of the core and to gain information on the style and nature of sediment deposition in the Victoria Land Basin since Early Miocene. Ten out of 17 samples yielded statistically robust ⁴⁰Ar–³⁹Ar ages, indicating that the AND-2A drillcore recovered ≤230 m of Middle Miocene (∼128–358 m below sea floor, ∼11.5–16.0 Ma) and >780 m of Early Miocene (∼358–1093 m below sea floor, ∼16.0–20.1 Ma). Results also highlight a nearly continuous stratigraphic record from at least 358 m below sea floor down hole, characterized by a mean sedimentation rate of ∼19 cm/ka, possible oscillations of no more than a few hundreds of ka and a break within ∼17.5–18.1 Ma. Comparison with available data from volcanic deposits on land, suggests that volcanic rocks within the AND-2A core were supplied from the south, possibly with source areas closer to the drill site for the upper core levels, and from 358 m below sea floor down hole, with the “proto-Mount Morning” as the main source.