scholarly journals From Validation Statistics to Uncertainty Estimates: Application to VIIRS Ocean Color Radiometric Products at European Coastal Locations

2021 ◽  
Vol 8 ◽  
Author(s):  
Frédéric Mélin
Keyword(s):  
Satellite Data ◽  
Field Data ◽  
Spectral Characteristics ◽  
Ocean Color ◽  
Field Measurements ◽  
Uncertainty Budget ◽  
Field Observations ◽  
Validation Process ◽  
Uncertainty Estimates ◽  
European Seas

Uncertainty estimates are needed to assess ocean color products and qualify the agreement between missions. Comparison between field observations and satellite data, a process defined as validation, has been the traditional way to assess satellite products. However validation statistics can provide only an approximation for satellite data uncertainties as field measurements have their own uncertainties and as the validation process is imperfect, comparing data potentially differing in temporal, spatial or spectral characteristics. This study describes a method to interpret in terms of uncertainties the validation statistics obtained for ocean color remote sensing reflectance RRS knowing the uncertainties associated with field data. This approach is applied to observations collected at sites part of the Ocean Color component of the Aerosol Robotic Network (AERONET-OC) located in coastal regions of the European seas, and to RRS data from the VIIRS sensors on-board the SNPP and JPSS1 platforms. Similar estimates of uncertainties σVRS (term accounting for non-systematic contributions to the uncertainty budget) are obtained for both missions, decreasing with wavelength from the interval 0.8–1.4 10−3 sr−1 in the blue to a maximum of 0.24 10−3 sr−1 in the red, values that are at least twice (but up to 8 times) the uncertainties reported for the field data. These uncertainty estimates are then used to qualify the agreement between the VIIRS products, defining the extent to which they agree within their stated uncertainty. Despite significant biases between the two missions, their RRS products appear fairly compatible.

ASSESSMENT OF HYDROPHYSICAL CONDITIONS FOR VISTULA LAGOON BY FIELD DATA AND REMOTE SENSING DATA

2018 ◽  
Author(s):  
Д. Домнин ◽  
D. Domnin ◽  
В. Пилипчук ◽  
V. Pilipchuk
Keyword(s):  
Remote Sensing ◽  
Satellite Data ◽  
Field Data ◽  
Remote Sensing Data ◽  
Field Measurements ◽  
Measured Data ◽  
Vistula Lagoon ◽  
Large Array ◽  
Data Files ◽  
Time Description

In the study, a large array of data (more than 15 thousand records and 180 full-scale measurements with satellite data files) for the period 1994–2012 (by ABIORAS) was systematized. Comparative analysis of the literary and fullscale satellite data has been executed. Based mainly on the stock of field measurements were made modern space-time description of the water masses in the lagoon (temperature, salinity). The discrepancy between the intra-variation in temperature between the periods 1966–1976 and 1994–2004 were identified. The paper contains a comparison and the subsequent correlation of field and satellite data, defined regularity of temperature exceeding of satellite data over the measured data. Lagoon area is divided into districts.

Saturated Hydraulic Conductivity of Clayey Tills and the Role of Fractures

1990 ◽  
Vol 21 (2) ◽  
pp. 119-132 ◽  
Author(s):  
Johnny Fredericia
Keyword(s):  
Hydraulic Conductivity ◽  
American Studies ◽  
Field Measurements ◽  
Present Knowledge ◽  
Saturated Hydraulic Conductivity ◽  
Field Observations ◽  
Laboratory Measurements ◽  
Vertical Hydraulic Conductivity ◽  
Data Field

The background for the present knowledge about hydraulic conductivity of clayey till in Denmark is summarized. The data show a difference of 1-2 orders of magnitude in the vertical hydraulic conductivity between values from laboratory measurements and field measurements. This difference is discussed and based on new data, field observations and comparison with North American studies, it is concluded to be primarily due to fractures in the till.

Sediment transport under dry weather conditions in a small sewer system

1998 ◽  
Vol 37 (1) ◽  
pp. 155-162
Author(s):  
Flemming Schlütter ◽  
Kjeld Schaarup-Jensen
Keyword(s):  
Sediment Transport ◽  
Field Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sewer System ◽  
Transport Models ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Initial Results

Increased knowledge of the processes which govern the transport of solids in sewers is necessary in order to develop more reliable and applicable sediment transport models for sewer systems. Proper validation of these are essential. For that purpose thorough field measurements are imperative. This paper renders initial results obtained in an ongoing case study of a Danish combined sewer system in Frejlev, a small town southwest of Aalborg, Denmark. Field data are presented concerning estimation of the sediment transport during dry weather. Finally, considerations on how to approach numerical modelling is made based on numerical simulations using MOUSE TRAP (DHI 1993).

Field observations on growth and development of Morchella rotunda and Mitrophora semilibera in relation to forest soil temperature

1989 ◽  
Vol 67 (2) ◽  
pp. 589-593 ◽  
Author(s):  
F. Buscot
Keyword(s):  
Soil Temperature ◽  
Forest Soil ◽  
Growth And Development ◽  
Field Data ◽  
Higher Plants ◽  
Field Observations ◽  
Upper Rhine

In the upper Rhine forests, ascocarps of Morchella rotunda (Pers.) Boudier and Mitrophora semilibera (DC.) Lév. develop at the expense of preexisting subterranean mycelial structures (connective mycelium and mycelial muffs) associated with higher plants. Field data correlate the initial extent of springtime reheating of soil with ascocarp maturation and suggest that mycelial muffs may be storage and resistance structures formed as early as the summer preceding the spring fruiting. This suggests morels are biennial.

scholarly journals Geostatistical integration to improve representativeness of satellite precipitation estimates and field measurements

10.29007/glj1 ◽  
2019 ◽  
Author(s):  
Felipe-Omar Tapia-Silva
Keyword(s):  
Spatial Variability ◽  
Satellite Data ◽  
Field Measurements ◽  
Auxiliary Variable ◽  
Measured Parameter ◽  
Geostatistical Methods ◽  
Variability Pattern ◽  
Distance Weighted ◽  
Precipitation Estimates ◽  
Leave One Out

Since the network of rainfall gauges and ground radars is generally not dense enough, satellite data have been used to estimate Precipitation (P). These data have the ability to capture the spatial variability pattern of the parameter, but are often inaccurate in relation to the value of the field measured parameter. Therefore, geostatistical methods were evaluated to improve the spatial representativeness of field measurements (FM) and satellite estimates. The work has been made for a hydrological sub region in the Mexican tropic. The geostatistical methods used to interpolate P-FM were ordinary kriging (KO), universal kriging (KU) and regression kriging (RK) as well as the Inverse Distance Weighted (IDW) mechanical interpolator for comparison purposes. Furthermore, the values at the pixel centers of the Tropical Rainfall Monitoring Mission (TRMM) images were interpolated using OK and evaluated using leave-one-out cross validation (LOO-CV). The best LOO-CV evaluated method consisted of the RK interpolation of the point FM taking as auxiliary variable the OK interpolation of the TRMM cell centers. It is concluded that the geostatistical integration between rainfall estimates from satellite data and FM data is promising because satellite information has the ability to capture spatial variability and the point FM add accuracy to the results. These characteristics combined can produce a P product useful for modeling activities and environmental management.

Use of Laboratory and Field Data to Evaluate the Pier Scour Equation from Hydraulic Engineering Circular 18

2017 ◽  
Vol 2638 (1) ◽  
pp. 113-121
Author(s):  
Stephen T. Benedict ◽  
Thomas P. Knight
Keyword(s):  
South Carolina ◽  
Field Data ◽  
Field Measurements ◽  
The United States ◽  
Prediction Equation ◽  
Hydraulic Engineering ◽  
Bridge Engineering ◽  
Geological Survey ◽  
Pier Scour ◽  
Primary Focus

The Hydraulic Engineering Circular 18 (HEC-18) pier scour prediction equation is the most widely used pier scour prediction equation in the United States, if not the world, and understanding the equation’s performance is of interest to the bridge engineering community. Previous evaluations of the equation’s performance were limited to smaller sets of laboratory and field data. In 2014, the U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, published a U.S. Geological Survey pier scour database, consisting of 569 laboratory and 1,858 field measurements of pier scour. This extensive database is a valuable resource for evaluating the HEC-18 pier scour equation, which is the primary focus of the investigation presented in this paper. Although comparing predicted and measured values is a common method for evaluating the performance of a prediction equation, the present investigation used a different approach and evaluated the HEC-18 equation by comparing selected data from the USGS database with the dimensionless relationship used to develop the original equation. This alternative approach highlighted some of the strengths and weaknesses of the equation, which are not as evident in the more common approach of comparing predicted and measured values. The findings of the investigation are presented in this paper.

In situ creep of frozen soil, Fenghuo Shan, Tibet Plateau, China

1995 ◽  
Vol 32 (3) ◽  
pp. 545-552 ◽  
Author(s):  
B. Wang ◽  
Hugh M. French
Keyword(s):  
Key Words ◽  
Power Flow ◽  
Field Data ◽  
Field Measurements ◽  
Frozen Soil ◽  
Tibet Plateau ◽  
Soil Creep ◽  
Extreme Variability ◽  
The Mean

Field measurements of frozen soil creep in the upper 3.0 m of permafrost indicate that creep occurs in both winter and summer. Between 1992 and 1993, the mean rate of creep ranged from 0.44 cm at 1.6 m depth to 0.16 cm at 2.8 m depth but there was extreme variability. Creep parameters n and A, as defined by the power flow law, were calculated from field data. Parameter n ranged between 1.96 and 2.29 and increased with depth, while A decreased with depth. Comparisons of creep rates for different permafrost environments suggest that ground temperature largely controls the magnitude of permafrost creep. Key words : permafrost, creep parameters, Tibet Plateau.

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