scholarly journals Temporal disaggregation of satellite-derived monthly precipitation estimates and the resulting propagation of error in partitioning of water at the land surface

2001 ◽  
Vol 5 (1) ◽  
pp. 27-38 ◽  
Author(s):  
S.A. Margulis ◽  
D. Entekhabi
Keyword(s):  
Land Surface ◽  
Error Propagation ◽  
Temporal Structure ◽  
Low Earth Orbit ◽  
Monthly Precipitation ◽  
Monthly Scale ◽  
Precipitation Estimates ◽  
Temporal Disaggregation ◽  
Using Data ◽  
Hydrological Applications

Abstract. Global estimates of precipitation can now be made using data from a combination of geosynchronous and low earth-orbit satellites. However, revisit patterns of polar-orbiting satellites and the need to sample mixed-clouds scenes from geosynchronous satellites leads to the coarsening of the temporal resolution to the monthly scale. There are prohibitive limitations to the applicability of monthly-scale aggregated precipitation estimates in many hydrological applications. The nonlinear and threshold dependencies of surface hydrological processes on precipitation may cause the hydrological response of the surface to vary considerably based on the intermittent temporal structure of the forcing. Therefore, to make the monthly satellite data useful for hydrological applications (i.e. water balance studies, rainfall-runoff modelling, etc.), it is necessary to disaggregate the monthly precipitation estimates into shorter time intervals so that they may be used in surface hydrology models. In this study, two simple statistical disaggregation schemes are developed for use with monthly precipitation estimates provided by satellites. The two techniques are shown to perform relatively well in introducing a reasonable temporal structure into the disaggregated time series. An ensemble of disaggregated realisations was routed through two land surface models of varying complexity so that the error propagation that takes place over the course of the month could be characterised. Results suggest that one of the proposed disaggregation schemes can be used in hydrological applications without introducing significant error. Keywords: precipitation, temporal disaggregation, hydrological modelling, error propagation

scholarly journals Evaluating the Evolution of ECMWF Precipitation Products Using Observational Data for Iran: From ERA40 to ERA5

2021 ◽  
Author(s):  
Navid Ghajarnia ◽  
Mahdi Akbari ◽  
Peyman Saemian ◽  
Mohammad Reza Ehsani ◽  
Seyed-Mohammad Hosseini-Moghari ◽  
...  
Keyword(s):  
Observational Data ◽  
Model Development ◽  
Decomposition Methods ◽  
Global Scale ◽  
Skill Scores ◽  
Precipitation Estimates ◽  
Using Data ◽  
Annual Scale ◽  
Error Decomposition ◽  
Hydrological Applications

ECMWF Reanalysis (ERA), one of the most widely used precipitation products, has evolved over time from ERA-40 to ERA-20CM, ERA-20C, ERA-Interim, and ERA5. Studies evaluating the performance of individual ERA precipitation products cannot adequately assess the evolution in the products. Therefore, we compared the performance of five successive ERA precipitation products using data at daily, monthly, and annual scale (1980-2018) from more than 2100 precipitation gauges in Iran, and applied various statistical and categorical metrics and error decomposition methods. The results indicated that ERA-40 performed worst, followed by ERA-20CM, which showed only minor improvements over ERA-40. ERA-20C considerably outperformed its predecessors, benefiting from assimilation of observational data. Although several previous studies have reported full superiority of ERA5 over ERA-Interim, our results revealed several shortcomings compared with ERA-Interim, in ERA5 precipitation estimates for Iran. Both ERA-Interim and ERA5 performed best overall, with ERA-Interim showing better statistical and categorical skill scores, and ERA5 performing better in estimating extreme precipitations. These results suggest that the accuracy of ERA precipitation products improved from ERA-40 to ERA-Interim, but not consistently from ERA-Interim to ERA5. These findings are useful for model development at global scale and for hydrological applications in Iran.

scholarly journals The Sentinel-3 SLSTR Atmospheric Motion Vectors Product at EUMETSAT

2021 ◽  
Vol 13 (9) ◽  
pp. 1702
Author(s):  
Kévin Barbieux ◽  
Olivier Hautecoeur ◽  
Maurizio De Bartolomei ◽  
Manuel Carranza ◽  
Régis Borde
Keyword(s):  
Land Surface ◽  
Weather Prediction ◽  
Forecast Model ◽  
Low Earth Orbit ◽  
Reference Image ◽  
Motion Vectors ◽  
Infrared Imager ◽  
Atmospheric Motion ◽  
Atmospheric Motion Vectors ◽  
Leo Satellite

Atmospheric Motion Vectors (AMVs) are an important input to many Numerical Weather Prediction (NWP) models. EUMETSAT derives AMVs from several of its orbiting satellites, including the geostationary satellites (Meteosat), and its Low-Earth Orbit (LEO) satellites. The algorithm extracting the AMVs uses pairs or triplets of images, and tracks the motion of clouds or water vapour features from one image to another. Currently, EUMETSAT LEO satellite AMVs are retrieved from georeferenced images from the Advanced Very-High-Resolution Radiometer (AVHRR) on board the Metop satellites. EUMETSAT is currently preparing the operational release of an AMV product from the Sea and Land Surface Temperature Radiometer (SLSTR) on board the Sentinel-3 satellites. The main innovation in the processing, compared with AVHRR AMVs, lies in the co-registration of pairs of images: the images are first projected on an equal-area grid, before applying the AMV extraction algorithm. This approach has multiple advantages. First, individual pixels represent areas of equal sizes, which is crucial to ensure that the tracking is consistent throughout the processed image, and from one image to another. Second, this allows features that would otherwise leave the frame of the reference image to be tracked, thereby allowing more AMVs to be derived. Third, the same framework could be used for every LEO satellite, allowing an overall consistency of EUMETSAT AMV products. In this work, we present the results of this method for SLSTR by comparing the AMVs to the forecast model. We validate our results against AMVs currently derived from AVHRR and the Spinning Enhanced Visible and InfraRed Imager (SEVIRI). The release of the operational SLSTR AMV product is expected in 2022.

scholarly journals Validation of CHIRPS Precipitation Estimates over Taiwan at Multiple Timescales

2021 ◽  
Vol 13 (2) ◽  
pp. 254 ◽  
Author(s):  
Jie Hsu ◽  
Wan-Ru Huang ◽  
Pin-Yi Liu ◽  
Xiuzhen Li
Keyword(s):  
Annual Cycle ◽  
Interannual Variation ◽  
Winter Precipitation ◽  
Monthly Precipitation ◽  
Precipitation Estimation ◽  
Precipitation Estimates ◽  
Precipitation Variation ◽  
Global Precipitation ◽  
Multiple Timescale ◽  
Better Than

The Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), which incorporates satellite imagery and in situ station information, is a new high-resolution long-term precipitation dataset available since 1981. This study aims to understand the performance of the latest version of CHIRPS in depicting the multiple timescale precipitation variation over Taiwan. The analysis is focused on examining whether CHIRPS is better than another satellite precipitation product—the Integrated Multi-satellitE Retrievals for Global Precipitation Mission (GPM) final run (hereafter IMERG)—which is known to effectively capture the precipitation variation over Taiwan. We carried out the evaluations made for annual cycle, seasonal cycle, interannual variation, and daily variation during 2001–2019. Our results show that IMERG is slightly better than CHIRPS considering most of the features examined; however, CHIRPS performs better than that of IMERG in representing the (1) magnitude of the annual cycle of monthly precipitation climatology, (2) spatial distribution of the seasonal mean precipitation for all four seasons, (3) quantitative precipitation estimation of the interannual variation of area-averaged winter precipitation in Taiwan, and (4) occurrence frequency of the non-rainy grids in winter. Notably, despite the fact that CHIRPS is not better than IMERG for many examined features, CHIRPS can depict the temporal variation in precipitation over Taiwan on annual, seasonal, and interannual timescales with 95% significance. This highlights the potential use of CHIRPS in studying the multiple timescale variation in precipitation over Taiwan during the years 1981–2000, for which there are no data available in the IMERG database.

scholarly journals Applying the concept of uncertainty to the sFlt-1/PlGF cut-offs for diagnosis and prognosis of preeclampsia

2021 ◽  
Vol 59 (4) ◽  
pp. 681-686
Author(s):  
Pacifique Lévy ◽  
Safouane Hamdi ◽  
Jean Guiboudenche ◽  
Marie Clothilde Haguet ◽  
Sophie Bailleul ◽  
...  
Keyword(s):  
Quality Control ◽  
Growth Factor ◽  
Tyrosine Kinase ◽  
Error Propagation ◽  
Placental Growth Factor ◽  
Internal Quality ◽  
Diagnosis And Prognosis ◽  
Diagnosis By Exclusion ◽  
Using Data ◽  
Plgf Ratio

Abstract Objectives Placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) assays and the corresponding ratios (sFlt-1/PlGF) have been proposed to aid in the diagnosis by exclusion and/or prognosis of preeclampsia (PE). A method for evaluating ratio uncertainties (RUs), based on the theory of error propagation, was applied to the sFlt-1/PlGF ratio. Methods RUs were calculated using data derived from sFlt-1 and PlGF Internal Quality Control (IQC) results collected from four centers using Elecsys (Roche) or Kryptor (Thermo Fisher) sFlt-1 and PlGF assays. The corresponding ratio uncertainties were defined for each ratio value. Results The RUs increased linearly with the sFlt-1/PlGF ratio values. The Elecsys RUs were lower than the Kryptor RUs. Although RUs cannot eliminate differences in ratio values observed among various immunoassays, it can affect interpretation of the sFlt-1/PlGF ratio, especially when results are within the range of predefined PE diagnosis or prognosis cut-offs. Conclusions Since RUs are only a function of PlGF and sFlt-1 precision, they can be calculated for each assay from each laboratory to adjust the interpretation of sFlt-1/PlGF ratio results in the context of PE.

Hydrological evaluation of high-resolution precipitation estimates from the WRF model in the Third Pole river basins

2021 ◽  
Author(s):  
He Sun ◽  
Fengge Su ◽  
Zhihua He ◽  
Tinghai Ou ◽  
Deliang Chen ◽  
...  
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Hydrological Modeling ◽  
Climate Model ◽  
Regional Climate ◽  
Wrf Model ◽  
Infiltration Capacity ◽  
Flood Prediction ◽  
Daily Streamflow ◽  
Precipitation Estimates

AbstractIn this study, two sets of precipitation estimates based on the regional Weather Research and Forecasting model (WRF) –the high Asia refined analysis (HAR) and outputs with a 9 km resolution from WRF (WRF-9km) are evaluated at both basin and point scales, and their potential hydrological utilities are investigated by driving the Variable Infiltration Capacity (VIC) large-scale land surface hydrological model in seven Third Pole (TP) basins. The regional climate model (RCM) tends to overestimate the gauge-based estimates by 20–95% in annual means among the selected basins. Relative to the gauge observations, the RCM precipitation estimates can accurately detect daily precipitation events of varying intensities (with absolute bias < 3 mm). The WRF-9km exhibits a high potential for hydrological application in the monsoon-dominated basins in the southeastern TP (with NSE of 0.7–0.9 and bias of -11% to 3%), while the HAR performs well in the upper Indus (UI) and upper Brahmaputra (UB) basins (with NSE of 0.6 and bias of -15% to -9%). Both the RCM precipitation estimates can accurately capture the magnitudes of low and moderate daily streamflow, but show limited capabilities in flood prediction in most of the TP basins. This study provides a comprehensive evaluation of the strength and limitation of RCMs precipitation in hydrological modeling in the TP with complex terrains and sparse gauge observations.

GICS IN THE MAIN TRANSMISSION LINE “NORTHERN TRANSIT” IN RUSSIA AND IN THE MÄNTSÄLÄ FINLAND PIPELINE: A CASE STUDY

2021 ◽  
Vol 44 ◽  
pp. 20-23
Author(s):  
I.V. Despirak ◽  
◽  
P.V. Setsko ◽  
Ya.A. Sakharov ◽  
V.N. Selivanov ◽  
...  
Keyword(s):  
Negative Impact ◽  
Temporal Structure ◽  
Auroral Zone ◽  
Magnetic Data ◽  
Geomagnetically Induced Currents ◽  
Camera System ◽  
Natural Gas Pipeline ◽  
Spatio Temporal ◽  
Using Data

Geomagnetically induced currents (GICs), arising both on power lines and on pipelines, may have strong negative impact on the technological networks up to accidents ("blackouts"). Magnetospheric disturbances are one of the factors in the appearance of GICs, however there is no unambiguous relationship between substorm and presence of currents. In this paper, we consider two intense cases of GIC (15March 2012 and 17 March 2013), registered on two different technological networks: 1) on the "Nothern Transit" power line (Vykhodnoy, Revda and Kondopoga stations) located in the auroral zone, 2) on the Finnish natural gas pipeline near Mäntsälä located in the subauroral zone. Both GIC cases are compared with substorm development in the auroral zone, using data from IMAGE magnetometers network and MAIN camera system in Apatity. We found a good correlation between the GIC appearance and variations of geomagnetic indexes: IL – index, which characterized of westward electrojet intensity on the IMAGE meridian and Wp - index, which describes the wave activity of the substorm. Besides, it was shown also a good correlation between GICs and the thin spatio-temporal structure of the substorm development (the appearance and the propagation to the pole of substorm activations), which is appeared both in the magnetic data and in the all sky camera images.

scholarly journals Uncertainties in the Annual Cycle of Rainfall Characteristics over West Africa in CMIP5 Models

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 216
Author(s):  
Magatte Sow ◽  
Moussa Diakhaté ◽  
Ross D. Dixon ◽  
Françoise Guichard ◽  
Diarra Dieng ◽  
...  
Keyword(s):  
West Africa ◽  
Annual Cycle ◽  
Late Onset ◽  
Daily Rainfall ◽  
Cmip5 Models ◽  
Monthly Precipitation ◽  
Strongly Coupled ◽  
Precipitation Estimates ◽  
Latitudinal Position ◽  
Systematic Biases

We analyse uncertainties associated with the main features of the annual cycle of West African rainfall (amplitude, timing, duration) in 15 CMIP5 simulations over the Sahelian and Guinean regions with satellite daily precipitation estimates. The annual cycle of indices based on daily rainfall such as the frequency and the intensity of wet days, the consecutive dry (CDD) and wet (CWD) days, the 95th percentile of daily rainfall (R95), have been assessed. Over both regions, satellite datasets provide more consistent results on the annual cycle of monthly precipitation than on higher-frequency rainfall indices, especially over the Guinean region. By contrast, CMIP5 simulations display much higher uncertainties in both the mean precipitation climatology and higher-frequency indices. Over both regions, most of them overestimate the frequency of wet days. Over the Guinean region, the difficulty of models to represent the bimodality of the annual cycle of precipitation involves systematic biases in the frequency of wet days. Likewise, we found strong uncertainties in the simulation of the CWD and the CDD over both areas. Finally, models generally provide too early (late) onset dates over the Sahel (the Guinean region) and overestimate rainfall during the early and late monsoon phases. These errors are strongly coupled with errors in the latitudinal position of the ITCZ and do not compensate at the annual scale or when considering West Africa as a whole.

Impact of an Exponential Profile of Saturated Hydraulic Conductivity within the ISBA LSM: Simulations over the Rhône Basin

2006 ◽  
Vol 7 (1) ◽  
pp. 61-80 ◽  
Author(s):  
B. Decharme ◽  
H. Douville ◽  
A. Boone ◽  
F. Habets ◽  
J. Noilhan
Keyword(s):  
High Resolution ◽  
Hydraulic Conductivity ◽  
Land Surface ◽  
Large Scale ◽  
Saturated Hydraulic Conductivity ◽  
Rooting Depth ◽  
Surface Model ◽  
Low Resolution ◽  
The Impact ◽  
Hydrological Applications

Abstract This study focuses on the influence of an exponential profile of saturated hydraulic conductivity, ksat, with soil depth on the water budget simulated by the Interaction Soil Biosphere Atmosphere (ISBA) land surface model over the French Rhône River basin. With this exponential profile, the saturated hydraulic conductivity at the surface increases by approximately a factor of 10, and its mean value increases in the root zone and decreases in the deeper region of the soil in comparison with the values given by Clapp and Hornberger. This new version of ISBA is compared to the original version in offline simulations using the Rhône-Aggregation high-resolution database. Low-resolution simulations, where all atmospheric data and surface parameters have been aggregated, are also performed to test the impact of the modified ksat profile at the typical scale of a climate model. The simulated discharges are compared to observations from a dense network consisting of 88 gauging stations. Results of the high-resolution experiments show that the exponential profile of ksat globally improves the simulated discharges and that the assumption of an increase in saturated hydraulic conductivity from the soil surface to a depth close to the rooting depth in comparison with values given by Clapp and Hornberger is reasonable. Results of the scaling experiments indicate that this parameterization is also suitable for large-scale hydrological applications. Nevertheless, low-resolution simulations with both model versions overestimate evapotranspiration (especially from the plant transpiration and the wet fraction of the canopy) to the detriment of total runoff, which emphasizes the need for implementing subgrid distribution of precipitation and land surface properties in large-scale hydrological applications.

scholarly journals Estimates of mean residence times of phosphorus in commonly considered inorganic soil phosphorus pools

2020 ◽  
Vol 17 (2) ◽  
pp. 441-454 ◽  
Author(s):  
Julian Helfenstein ◽  
Chiara Pistocchi ◽  
Astrid Oberson ◽  
Federica Tamburini ◽  
Daniel S. Goll ◽  
...  
Keyword(s):  
Land Surface ◽  
Soil Phosphorus ◽  
Land Surface Models ◽  
High Ph ◽  
Soil P ◽  
P Pools ◽  
Extractable P ◽  
Surface Models ◽  
Exchange Kinetic ◽  
Using Data

Abstract. Quantification of turnover of inorganic soil phosphorus (P) pools is essential to improve our understanding of P cycling in soil–plant systems and improve representations of the P cycle in land surface models. Turnover can be quantified using mean residence time (MRT); however, to date there is little information on MRT of P in soil P pools. We introduce an approach to quantify MRT of P in sequentially extracted inorganic soil P pools using data from isotope exchange kinetic experiments. Our analyses of 53 soil samples from the literature showed that MRT of labile P (resin- and bicarbonate-extractable P) was on the order of minutes to hours for most soils, MRT in NaOH-extractable P (NaOH-P) was in the range of days to months, and MRT in HCl-extractable P (HCl-P) was on the order of years to millennia. Multiple-regression models were able to capture 54 %–63 % of the variability in MRT among samples and showed that land use was the most important predictor of MRT of P in labile and NaOH pools. MRT of P in HCl-P was strongly dependent on pH, as high-pH soils tended to have longer MRTs. This was interpreted to be related to the composition of HCl-P. Under high pH, HCl-P contains mostly apatite, with a low solubility, whereas under low-pH conditions, HCl-P may contain more exchangeable P forms. These results suggest that current land surface models underestimate the dynamics of inorganic soil P pools and could be improved by reducing model MRTs of the labile and NaOH-P pools, considering soil-type-dependent MRTs rather than universal exchange rates and allowing for two-way exchange between HCl-P and the soil solution.

Sign in / Sign up

Export Citation Format

Share Document