Multi-year Scales Research Articles

Intercomparison of reanalysis and satellite precipitation products in endorheic and exorheic basins on the Tibetan Plateau

Study Region: Endorheic and exorheic basins of the Tibetan Plateau (TP). Study Focus: Reanalysis and satellite precipitation products provide alternatives for regions of sparse ground precipitation observation, but pose a tough task to select a suitable one for the TP. This study conducts a multi-scale evaluation of six reanalysis and satellite precipitation products in endorheic and exorheic basins using water balance and extended triple collocation (ETC) methods. The reanalysis precipitation products include ECMWF Re-Analysis version 5 (ERA5-Land), China Meteorological Forcing Dataset (CMFD), Global Land Data Assimilation Systems (GLDAS), and High-resolution Precipitation dataset for the Third Pole region (TPHiPr). The satellite precipitation data include Global Precipitation Measurements (GPM) and Tropical Rainfall Measuring Mission (TRMM) products. New Hydrological Insights for the Region: The precipitation products vary in accuracy from basin to basin, with better performance in exorheic than endorheic basins. Reanalysis-based ERA5-land, TPHiPr, and CMFD perform well in most basins at annual scale, among which TPHiPr performs best at daily scale. At regional scale, GPM performs well in endorheic region, and ERA5-land in exorheic region. While all the products increase significantly in accuracy from basin to regional scale in endorheic region, ERA5-land shows best performance at annual and multi-year scales in the entire region. Our findings provide valuable supports for precipitation product selection in the Tibetan endorheic and exorheic basins.

A global streamflow indices time series dataset for large-sample hydrological analyses on streamflow regime (until 2022)

Abstract. With the booming big data techniques, large-sample hydrological analysis on streamflow regime is becoming feasible, which could derive robust conclusions on hydrological processes from a big-picture perspective. However, there is a lack of a comprehensive global large-sample dataset for components of the streamflow regime yet. This paper presents a new time series dataset on global streamflow indices calculated from daily streamflow records after data quality control. The dataset contains 79 indices over seven major components of streamflow regime (i.e., magnitude, frequency, duration, changing rate, timing, variability, and recession) of 41 263 river reaches globally on yearly and multiyear scales. Streamflow indices values until 2022 are covered in the dataset. Time span of the time series dataset is from 1806 to 2022 with an average length of 36 years. Compared to existing global datasets, this global dataset covers more stations and more indices, especially those characterizing the frequency, duration, changing rate, and recession of streamflow regime. With the dataset, research on streamflow regime will become easier without spending time handling raw streamflow records. This comprehensive dataset will be a valuable resource to the hydrology community to facilitate a wide range of studies, such as studies of hydrological behaviour of a catchment, streamflow regime prediction in data-scarce regions, as well as variations in streamflow regime from a global perspective. The dataset can be accessed at https://doi.org/10.57760/sciencedb.07227 (Chen et al., 2023a).

Agonism does not covary with territoriality in a gregarious reptile

Natural selection for territoriality is theorised to occur under conditions favouring intra-sexual phenotypic variation in physiology, morphology, and behaviour. In this context, certain suites of behavioural traits associated with territoriality are expected to consistently covary among individuals (sometimes referred to as ‘behavioural syndromes’) within sexes. Agonism (conflict-associated behaviours that may or may not be associated with physical aggression) and movement—for example, ranging, or relocation within or across seasons—are two behavioural components that are associated with territoriality and may be expected to covary in this context. Territorial males are expected to employ agonistic behaviours to actively establish and defend areas and resources and show more stability in their location across the landscape. However, the interaction between agonism and movement especially for wild reptiles has rarely been tested. We investigated whether agonistic and movement behaviours correlate at the individual level both within one year and across multiple years, in a wild population of Australian eastern water dragons, Intellagama lesueurii. Although both types of behaviours exhibited among-individual repeatability over year and multi-year scales, we found no evidence of an agonistic-movement behavioural syndrome. These findings indicate that agonistic and movement behaviours are likely independent traits, and thus, territoriality may not drive shared selective pressures for both. It is possible that other social behaviours and strategies are in place to maintain social structure in this wild population.Significance statementMales of many animals establish and maintain or defend territories. Territory defence is expected to be associated with behaviours associated with conflict or expressions of dominance, to signal territory boundaries to encroaching individuals, or more aggressive approaches for active defence. We investigated whether such agonistic behaviours correlated with the distances individuals ranged or dispersed within and between years, as an indicator of territoriality. Through thousands of observations of a wild population of Australian eastern water dragons, Intellagama lesueurii, we found that although individuals showed repeatable patterns of both agonistic and movement behaviours, we found no evidence that these were correlated. It appears that territory establishment and defence may therefore not rely on agonistic signals in this species in direct contrast to other taxa, indicating that other systems are in place to maintain social structures.

Interannual Variation of Landfast Ice Using Ascending and Descending Sentinel-1 Images from 2019 to 2021: A Case Study of Cambridge Bay

Landfast ice has undergone a dramatic decline in recent decades, imposing potential effects on ice travel for coastal populations, habitats for marine biota, and ice use for industries. The mapping of landfast ice deformation and the investigation of corresponding causes of changes are urgent tasks that can provide substantial data to support the maintenance of the stability of the Arctic ecosystem and the development of human activities on ice. This work aims to investigate the time-series deformation characteristics of landfast ice at multi-year scales and the corresponding influence factors. For the landfast ice deformation monitoring technique, we first combined the small baseline subset approach with ascending and descending Sentinel-1 images to obtain the line-of-sight deformations for two flight directions, and then we derived the 2D deformation fields comprising the vertical and horizontal directions for the corresponding periods by introducing a transform model. The vertical deformation results were mostly within the interval [−65, 23] cm, while the horizontal displacement was largely within the range of [−26, 78] cm. Moreover, the magnitude of deformation observed in 2019 was evidently greater than those in 2020 and 2021. In accordance with the available data, we speculate that the westerly wind and eastward-flowing ocean currents are the dominant reasons for the variation in the horizontal direction in Cambridge Bay, while the factors causing spatial differences in the vertical direction are the sea-level tilt and ice growth. For the interannual variation, the leading cause is the difference in sea-level tilt. These results can assist in predicting the future deformation of landfast ice and provide a reference for on-ice activities.

Annual 30-m big Lake Maps of the Tibetan Plateau in 1991\u20132018

Lake systems on the Tibetan Plateau (TP) are important for the supply and storage of fresh water to billions of people. However, previous studies on the dynamics of these lakes focused on monitoring on multi-year scales and therefore lack sufficient temporal information. Here we present a new dataset comprising annual maps of big lakes (>10 km2) on the TP for 1991–2018, generated by utilizing all available Landsat images in conjunction with Google Earth Engine. The annual lake maps with high overall accuracy (~96%) highlight distinctive lake distribution and lake changes: (1) about 70% number and area of lakes concentrated in the Inner basin; (2) generally increasing trends in both the area (by 33%) and number (by 30%) of lakes from 1991 to 2018; (3) the total area changes were dominated by larger lakes (>50 km2) while more fluctuations in the lake number changes were found in medium lakes (10−50 km2). Our dataset infills temporal gaps in long-term inter-annual variations of big lakes, contributing towards enhanced knowledge of TP lake systems.

Assessing Changes in 21st Century Mean and Extreme Climate of the Sacramento–San Joaquin Delta in California

This work aims to assess potential changes in the mean and extreme precipitation and temperature across the Sacramento–San Joaquin Delta (Delta) in California in the 21st century. The study employs operative climate model projections from the Coupled Model Inter-comparison Project Phase 5 (CMIP5). Specifically, 64 individual downscaled daily projections (1/16 degree, approximately 6 by 6 km) on precipitation and temperature from 32 Global Circulation Models (GCMs) under two emission scenarios (RCP 4.5 and RCP 8.5) from 2020–2099 are utilized for the analysis. The results indicate increasing warming (in mean, minimum, and maximum temperature) further into the future under both emission scenarios. Warming also exhibits a strong seasonality, with winters expecting lower and summers expecting higher increases in temperature. In contrast, for mean annual total precipitation, there is no consistent wetter or drier signal. On average, the changes in annual total precipitation are minimal. However, dry season precipitation is projected to decline. The study also shows that the number of wet days is projected to decrease while the number of very wet (daily precipitation over 10 mm) and extremely wet (daily precipitation over 20 mm) days is projected to increase. Moreover, the study illustrates that only about half of the changes in total annual precipitation are projected to come from changes in the wettest 10% of wet days. In contrast, a majority of changes in variance of the annual precipitation comes from changes in variance of the wettest 10% of the wet days. This suggests that fluctuations in large storms are projected to dictate the variability of precipitation in the Delta. Additionally, a general upward trend in dry conditions measured by the Standardized Precipitation-Evapotranspiration Index is expected during the projection period. The trending signal is stronger at multi-year temporal scales (one to four years) and under the higher emission scenario. These change patterns are generally similar across three sub-regions of the Delta (i.e., North, South, and West), even though some changes in the South Delta are the most pronounced. This study further discusses challenges posed by these changes to the Delta’s water supply and ecosystems, along with the Delta’s resiliency and potential ways to address these challenges.

High-Resolution Reanalysis of the Mediterranean Sea Biogeochemistry (1999–2019)

Ocean reanalyses integrate models and observations to provide a continuous and consistent reconstruction of the past physical and biogeochemical ocean states and variability. We present a reanalysis of the Mediterranean Sea biogeochemistry at a 1/24° resolution developed within the Copernicus Marine Environment Monitoring Service (CMEMS) framework. The reanalysis is based on the Biogeochemical Flux Model (BFM) coupled with a variational data assimilation scheme (3DVarBio) and forced by the Nucleus for European Modeling of the Ocean (NEMO)–OceanVar physical reanalysis and European Centre for medium-range weather forecasts (ECMWF) reanalysis ERA5 atmospheric fields. Covering the 1999–2019 period with daily means of 12 published and validated biogeochemical state variables, the reanalysis assimilates surface chlorophyll data and integrates EMODnet data as initial conditions, in addition to considering World Ocean Atlas data at the Atlantic boundary, CO2 atmospheric observations, and yearly estimates of riverine nutrient inputs. With the use of multiple observation sources (remote, in situ, and BGC-Argo), the quality of the biogeochemical reanalysis is qualitatively and quantitatively assessed at three validation levels including the evaluation of 12 state variables and fluxes and several process-oriented metrics. The results indicate an overall good reanalysis skill in simulating basin-wide values and variability in the biogeochemical variables. The uncertainty in reproducing observations at the mesoscale and weekly temporal scale is satisfactory for chlorophyll, nutrient, oxygen, and carbonate system variables in the epipelagic layers, whereas the uncertainty increases for a few variables (i.e., oxygen and ammonium) in the mesopelagic layers. The vertical dynamics of phytoplankton and nitrate are positively evaluated with specific metrics using BGC-Argo data. As a consequence of the continuous increases in temperature and salinity documented in the Mediterranean Sea over the last 20 years and atmospheric CO2 invasion, we observe basin-wide biogeochemical signals indicating surface deoxygenation, increases in alkalinity, and dissolved inorganic carbon concentrations, and decreases in pH at the surface. The new, high-resolution reanalysis, open and freely available from the Copernicus Marine Service, allows users from different communities to investigate the spatial and temporal variability in 12 biogeochemical variables and fluxes at different scales (from the mesoscale to the basin-wide scale and from daily to multiyear scales) and the interaction between physical and biogeochemical processes shaping Mediterranean marine ecosystem functioning.

Projected Changes in Water Year Types and Hydrological Drought in California’s Central Valley in the 21st Century

The study explores the potential changes in water year types and hydrological droughts as well as runoff, based on which the former two metrics are calculated in the Central Valley of California, United States, in the 21st century. The latest operative projections from four representative climate models under two greenhouse-gas emission scenarios are employed for this purpose. The study shows that the temporal distribution of annual runoff is expected to change in terms of shifting more volume to the wet season (October–March) from the snowmelt season (April–July). Increases in wet season runoff volume are more noticeable under the higher (versus lower) emission scenario, while decreases in snowmelt season runoff are generally more significant under the lower (versus higher) emission scenario. In comparison, changes in the water year types are more influenced by climate models rather than emission scenarios. When comparing two regions in the Central Valley, the rain-dominated Sacramento River region is projected to experience more wet years and less critical years than the snow-dominated San Joaquin River region due to their hydroclimatic and geographic differences. Hydrological droughts in the snowmelt season and wet season mostly exhibit upward and downward trends, respectively. However, the uncertainty in the direction of the trend on annual and multi-year scales tends to be climate-model dependent. Overall, this study highlights non-stationarity and long-term uncertainty in these study metrics. They need to be considered when developing adaptive water resources management strategies, some of which are discussed in the study.

On the Variability of Charleston South Carolina Winds, Atmospheric Temperatures, Water Levels, Waves and Precipitation

Atmospheric winds, air temperatures, water levels, precipitation and oceanic waves in the Charleston South Carolina (SC) coastal zone are evaluated for their intrinsic, internal variability over temporal scales ranging from hours to multi-decades. The purpose of this study was to bring together a plethora of atmospheric and coastal ocean state variable data in a specific locale, to assess temporal variabilities and possible relationships between variables. The questions addressed relate to the concepts of weather and climate. Data comprise the basis of this study. The overall distributions of atmospheric and coastal oceanic state variable variability, including wind speed, direction and kinematic distributions and state variable amplitudes over a variety of time scales are assessed. Annual variability is shown to be highly variable from year to year, making arithmetic means mathematically tractable but physically meaningless. Employing empirical and statistical methodologies, data analyses indicate the same number of intrinsic, internal modes of temporal variability in atmospheric temperatures, coastal wind and coastal water level time series, ranging from hours to days to weeks to seasons, sub-seasons, annual, multi-year, decades, and centennial time scales. This finding demonstrates that the atmosphere and coastal ocean in a southeastern U.S. coastal city are characterized by a set of similar frequency and amplitude modulated phenomena. Kinematic hodograph descriptors of atmospheric winds reveal coherent rotating and rectilinear particle motions. A mathematical statistics-based wind to wave-to-wave algorithm is developed and applied to offshore marine buoy data to create an hour-by-hour forecast capability from 1 to 24 hours; with confidence levels put forward. This affects a different approach to the conventional deterministic model forecasting of waves.

Long-term temporal structure of catchment sediment response to precipitation in a humid mountain badland area

A long-term database with information on precipitation, discharge and sediment yield dynamics was analyzed to characterize the temporal structure response of a catchment in a humid mountain badland area. Due to the non-linearity and non-stationary nature of the data, a combination of frequency analysis and wavelet reconstruction techniques were initially used to determine the dominant time scales of the precipitation, discharge and sediment yield. Within the full spectrum of time scales, the spectral frequency analysis could distinguish the dominant ones governing the overall trend of the time-series. Furthermore, the temporal multiresolution wavelet technique enabled accurate de-noising of the hydrometric and sediment time-series, by filtering out the high frequency intermittent processes superimposed on the main signal. Geomorphological metrics were subsequently applied to the filtered data and link to the temporal structure of the catchment response. The combined frequency-geomorphological analysis provides a physical explanation of the complete temporal structure of the catchment response to precipitation. This analysis features components from intra-annual, annual and multi-year scales. Intra-annual and annual time scales are led by climatological characteristics of the catchment site (seasonal rainfall patterns of a mountain Pyrenean catchment). The multi-year response related to the sediment yield reveals the importance of the sediment storage/depletion cycle in the catchment: although the main driver of the sediment yield is the discharge, weathering processes and sediment storage are also major control factors. Therefore, correct management of the catchment requires the combined multi-temporal response of water and sediment fluxes to be controlled. The temporal spectral analysis herein outlined provides a detailed analysis of the long-term temporal structure of databases and can be accepted as an adequate tool for catchment management in terms of flood forecasting or reservoir operation.

The green and blue crop water requirement WATNEEDS model and its global gridded outputs

Accurately assessing green and blue water requirements from croplands is fundamental to promote sustainable water management. In the last decade, global hydrological models have provided important insights into global patterns of water requirements for crop production. As important as these models are, they do not provide monthly crop-specific and year-specific data of green and blue water requirements. Gridded crop-specific products are therefore needed to better understand the spatial and temporal evolution of water demand. Here, we present a global gridded database of monthly crop-specific green (rain-fed) and blue (irrigated) water requirements for 23 main crops and 3 crop groups obtained using our WATNEEDS model. For the time periods in which our dataset matched, these estimates are validated against existing global products and satellite based datasets of evapotranspiration. The data are publicly available and can be used by practitioners in the water-energy-food nexus to assess the water sustainability of our food and energy systems at multiple spatial (local to global) and temporal (seasonal to multi-year) scales.

Variations in contributions of dead copepods to vertical fluxes of particulate organic carbon in the Beaufort Sea

Dead zooplankton, including crustaceans, are increasingly recognized as important agents of vertical carbon export from surface waters and in marine food webs. Quantifying the contribution of passively sinking copepods (PSCs) to vertical fluxes of total particulate organic carbon (POC) is important for understanding marine ecosystem carbon budgets. Information on this is limited because identifying PSCs in sediment trap samples is difficult. Generally, swimmers (undecomposed metazoans, including PSCs, caught in sediment traps) are removed from a trap sample before the POC content is measured, although ignoring PSCs causes the total POC flux to be significantly underestimated. We quantified temporal and regional variability in PSC flux and contribution of PSCs to total POC flux (PSCs + detrital sinking particles, generally analyzed to estimate detrital POC flux) at the Mackenzie Shelf margins in the Beaufort Sea. Six datasets were used to examine PSC flux variability at ~100 m depth, which is deeper than the winter pycnocline depth (30-50 m), at the continental margin. The average (±SD) annual PSC flux (1378 ± 662 mg C m-2 yr-1, n = 6 [datasets]) and PSC contribution to the total POC flux (21 ± 10%, n = 6) suggested that PSCs, especially Pareuchaeta glacialis, were important agents of POC export from the surface layer (~100 m) to deeper water at the inter-regional and multiyear scales. We propose a hypothesis that processes controlling PSC flux variability may vary seasonally, perhaps relating to life cycle (reproduction) in winter (February) and osmotic stress in July-October when the PSC flux is relatively high.

Hydrologically Induced Deformation in Long Valley Caldera and Adjacent Sierra Nevada

AbstractVertical and horizontal components of GNSS displacements in the Long Valley Caldera and adjacent Sierra Nevada range show a clear correlation with hydrological trends at both multiyear and seasonal time scales. We observe a clear vertical and horizontal seasonal deformation pattern primarily attributable to the solid earth response to hydrological surface loading at large‐to‐regional (Sierra Nevada range) scales. Several GNSS sites, located at the eastern edge of the Sierra Nevada along the southwestern rim of Long Valley Caldera, also show significant horizontal deformation that cannot be explained by elastic deformation from surface loading. Due to the location of these sites and the strong correlation between their horizontal displacements and spring discharge, we hypothesize that this deformation reflects poroelastic processes related to snowmelt runoff water infiltrating into the Sierra Nevada slopes around Long Valley Caldera. Interestingly, this is also an area where water infiltrates to feed the local hydrothermal system, and where snowmelt‐induced earthquake swarms have been recently detected.

Multi-scale structure of tropical rainfall response to SST fluctuations

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 78:165-178 (2019) - DOI: https://doi.org/10.3354/cr01566 Multi-scale structure of tropical rainfall response to SST fluctuations Miguel Nogueira* Instituto Dom Luiz, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal *Corresponding author: mdnogueira@fc.ul.pt ABSTRACT: The sensitivity of tropical rainfall to sea surface temperature (SST) fluctuations was investigated using a multi-scale analysis framework, covering time scales between a few days and 1 decade. The analysis includes an intercomparison between a satellite-based observational dataset and two twentieth century general circulation model (GCM)-based products: the ERA-20CM ensemble of atmospheric simulations and the ERA-20C reanalysis. The results provide robust evidence for the physical linear response of regional rainfall to SST fluctuations at multi-year time scales. All datasets showed tight correlations between rainfall and local SST, the Niño 3.4 index and local surface downwelling longwave radiation (DLR) over wide tropical regions. Additionally, the rainfall-DLR correlation held under a clear sky approximation. These 3 correlations are tightly related since the Niño 3.4 index and clear sky DLR can be computed from SST alone. The latter requires a robust correlation between local precipitable water vapor (W) and SST (i.e. Clausius-Clapeyron relationship), which was confirmed at multi-year scales over large portions of the tropics. All datasets also showed a robust transition in all these correlations at faster time scales (below ~1 yr), suggesting a change in the physical mechanisms controlling rainfall (and W) variability. Based on the linear sensitivities, 3 simplified models were proposed to reconstruct 3-yearly tropical rainfall time series at 5° resolution, forced only by ERA-20CM’s prescribed SST fields. The simplified linear response models were shown to reproduce observations with similar accuracy to GCM-based products, despite having a (easily correctable) systematic bias. The good agreement between all datasets, including the simplified model, provides confidence to the representation of the tropical rainfall response to SST fluctuations in GCM-based and satellite-based products, at least at multi-year time scales. KEY WORDS: Tropical Rainfall · Multiscale Analysis · Rainfall sensitivity · Statistical modelling Full text in pdf format PreviousNextCite this article as: Nogueira M (2019) Multi-scale structure of tropical rainfall response to SST fluctuations. Clim Res 78:165-178. https://doi.org/10.3354/cr01566 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 78, No. 2. Online publication date: August 08, 2019 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2019 Inter-Research.

Intra- and inter-annual variability in metabolism in an oligotrophic lake

Lakes are sentinels of change in the landscapes in which they are located. Changes in lake function are reflected in whole-system metabolism, which integrates ecosystem processes across spatial and temporal scales. Recent improvements in high-frequency open-water metabolism modeling techniques have enabled estimation of rates of gross primary production (GPP), respiration (R), and net ecosystem production (NEP) at high temporal resolution. However, few studies have examined metabolic rates over daily to multi-year temporal scales, especially in oligotrophic ecosystems. Here, we modified a metabolism modeling technique to reveal substantial intra- and inter-annual variability in metabolic rates in Lake Sunapee, a temperate, oligotrophic lake in New Hampshire, USA. Annual GPP and R increased each summer, paralleling increases in littoral, but not pelagic, total phosphorus concentrations. Storms temporarily decoupled GPP and R, resulting in greater decreases in GPP than R. Daily rates of GPP and R were positively correlated on warm days that had stable water columns, and metabolism model fits were best on warm, sunny days, indicating the importance of lake physics when evaluating metabolic rates. These metabolism data span a range of temporal scales and together suggest that Lake Sunapee may be moving toward mesotrophy. We suggest that functional, integrative metrics, such as metabolic rates, are useful indicators and sentinels of ecosystem change. We also highlight the challenges and opportunities of using high-frequency measurements to elucidate the drivers and consequences of intra- and inter-annual variability in metabolic rates, especially in oligotrophic lakes.

Spatial ecology and conservation of Manta birostris in the Indo-Pacific

Information on the movements and population connectivity of the oceanic manta ray (Manta birostris) is scarce. The species has been anecdotally classified as a highly migratory species based on the pelagic habitats it often occupies, and migratory behavior exhibited by similar species. As a result, in the absence of ecological data, population declines in oceanic manta have been addressed primarily with international-scale management and conservation efforts. Using a combination of satellite telemetry, stable isotope and genetic analyses we demonstrate that, contrary to previous assumptions, the species appears to exhibit restricted movements and fine-scale population structure. M. birostris tagged at four sites in the Indo-Pacific exhibited no long-range migratory movements and had non-overlapping geographic ranges. Using genetic and isotopic analysis, we demonstrate that the observed movements and population structure persist on multi-year and generational time scales. These data provide the first insights into the long-term movements and population structure of oceanic manta rays, and suggest that bottom-up, local or regional approaches to managing oceanic mantas could prove more effective than existing, international-scale management strategies. This case study highlights the importance of matching the scales at which management and relevant ecological processes occur to facilitate the effective conservation of threatened species.

Long-term GNSS measurements from the northern Adria microplate reveal fault-induced fluid mobilization

Due to the development of denser permanent Global Navigation Satellite System (GNSS) networks over the last decade, the observation of transient deformations has significantly increased, mainly in high strain-rate zones. We analyzed the data from a group of permanent GNSS sites on the N-Adria microplate, where anomalous southward tilting and low-frequency tremors preceded the 1976 Mw=6.4 earthquake. We present records from different stations of a transient signal with an approximately 2-year period that propagated through the northern edge of Adria, in a region 150km wide. This represents the first time a transient deformation event has been observed in a continental collision area. We exclude surface and groundwater hydrological load effects because we corrected the data for such effects at seasonal, annual, and multiyear scales. The movement is initially upward, except in one location, with slight tilting parallel to the direction of the main tectonic structures. Later, the opposite behavior is observed.The novel methods used include earthquake location techniques and tomographic inversion of the arrival times. These methods demonstrated that the transient source was located spatially and temporally close to the 2004 Mw=5.2 event in Bovec (Slovenia), attributed to the activity of the Ravne fault. We interpret the transient rises as the expression of a porosity wave, possibly produced by fault valve behavior of the NW tip of the Ravne fault. The propagation velocity is consistent with this hypothesis. As a further test, we invert the arrival times of the transient through hydraulic tomography to obtain hydraulic diffusivity: the values are compatible with the lithotypes present in the region and the literature. By substituting the tomographic velocity and diffusivity in the solitary/porosity wave equation, we infer an initial effective stress of approximately 0.23bar, sufficient to alter the equilibrium of some fault segments and influence the subsequent seismicity.

Climatologic comparison of HadISST1 and TMI sea surface temperature datasets

Two monthly datasets of sea surface temperature (SST), TMI SST retrieved from satellite observations by Remote Sensing System and HadISST1 (Hadley Centre Sea-ice and Sea-surface Temperature Data Set Version 1) derived from in situ measurements by Hadley Centre, were compared on climatologic multiple time scales over tropical and subtropical areas from 1998 to 2006. Results indicate that there is a good consistency in the horizontal global distribution, with 1.0° resolution on multi-year and multi-season mean scales between the two datasets, and also in the time series of global mean SST anomalies. However, there are still some significant differences between the datasets. Generally, TMI SST is relatively higher than Had-ISST1. In addition, the differences between the two datasets show not only remarkable regionality, but also distinct seasonal variations. Moreover, the maximum departure occurs in summer, while the minimum takes place in autumn. For all seasons, over 30% of the regions in the Tropical and Subtropical areas have a difference of more than 0.3°C. EOF analysis of the SST anomaly field also shows that there are differences between the two datasets, where HadISST1 has more significant statistical characteristics than TMI SST. On the other hand, results show that the difference between the two datasets is related to the vertical structure of ocean temperatures, as well as other simultaneously retrieved parameters in TMI products, such as wind speed, water vapor, liquid cloud water and rain rates. In addition, large biases between HadISST1 and TMI SST are found in coastal regions, where TMI SST cannot be accurately retrieved because of polluted microwave signals.

Multiyear Climate Variability and Dengue—El Niño Southern Oscillation, Weather, and Dengue Incidence in Puerto Rico, Mexico, and Thailand: A Longitudinal Data Analysis

The mosquito-borne dengue viruses are a major public health problem throughout the tropical and subtropical regions of the world. Changes in temperature and precipitation have well-defined roles in the transmission cycle and may thus play a role in changing incidence levels. The El Niño Southern Oscillation (ENSO) is a multiyear climate driver of local temperature and precipitation worldwide. Previous studies have reported varying degrees of association between ENSO and dengue incidence. We analyzed the relationship between ENSO, local weather, and dengue incidence in Puerto Rico, Mexico, and Thailand using wavelet analysis to identify time- and frequency-specific association. In Puerto Rico, ENSO was transiently associated with temperature and dengue incidence on multiyear scales. However, only local precipitation and not temperature was associated with dengue on multiyear scales. In Thailand, ENSO was associated with both temperature and precipitation. Although precipitation was associated with dengue incidence, the association was nonstationary and likely spurious. In Mexico, no association between any of the variables was observed on the multiyear scale. The evidence for a relationship between ENSO, climate, and dengue incidence presented here is weak. While multiyear climate variability may play a role in endemic interannual dengue dynamics, we did not find evidence of a strong, consistent relationship in any of the study areas. The role of ENSO may be obscured by local climate heterogeneity, insufficient data, randomly coincident outbreaks, and other, potentially stronger, intrinsic factors regulating transmission dynamics.

A method for retrieving high-resolution surface soil moisture from hydros L-band radiometer and Radar observations

NASA's Earth System Science Pathfinder Hydrospheric States (Hydros) mission will provide the first global scale space-borne observations of Earth's soil moisture using both L-band microwave radiometer and radar technologies. In preparation for the Hydros mission, an observation system simulation experiment (OSSE) has been conducted. As a part of this OSSE, the potential for retrieving useful surface soil moisture at spatial resolutions of 9 and 3 km was explored. The approach involved optimally merging relatively accurate 36-km radiometer brightness temperature and relatively noisy 3-km radar backscatter cross section observations using a Bayesian method. Based on the Hydros OSSE data sets with low and high noises added to the simulated observations or model parameters, the Bayesian method performed better than direct inversion of either the brightness temperature or radar backscatter observations alone. The root-mean-square errors of 9-km soil moisture retrievals from the Bayesian merging method were reduced by 0.5 %vol/vol and 1.4 %vol/vol from the errors of direct radar inversions for the entire OSSE domain of all 34 consecutive days for the low and high noise data sets, respectively. Improvement in soil moisture estimates using the Bayesian merging method over the direct inversions of radar or radiometer data were even more significant for soil moisture retrieval at 3-km resolution. However, to address the representativeness of these results at the global and multiyear scales, further performance comparison studies are needed, particularly with actual field data.