Sentinel-3 Microwave Radiometers: Instrument Description, Calibration and Geophysical Products Performances

Copernicus Sentinel-3 Surface Topography Mission embarks a two-channel microwave radiometer combined with the altimeter in order to correct the altimeter range for the excess path delay resulting from the presence of water vapour in the troposphere. The in-flight calibration of a single instrument is the critical point to achieve the expected performances. In the context of a constellation, the inter-calibration is even more important. After a presentation of the instrument design, we present the diagnoses used for the calibration of Sentinel-3A, using vicarious calibration over specific areas and double difference methods. The inter-calibration of Sentinel-3B with Sentinel-3A is performed during the tandem phase, using the residual differences of co-located measurements. Finally performances are assessed at crossover points with two parameters, first the wet troposphere correction by comparison with Jason-3; secondly on the Sea Surface Height by difference of variance. Analysis results have shown that Sentinel-3A is well calibrated, consistent with other instruments, and that Sentinel-3B is calibrated within 0.4 K with Sentinel-3A as a reference. Performances and stability fulfill the requirements for both missions.

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Assessing the accuracy of microwave radiometers and radio acoustic sounding systems for wind energy applications

10.5194/amt-2016-321 ◽

2016 ◽

Cited By ~ 2

Author(s):

Laura Bianco ◽

Katja Friedrich ◽

James Wilczak ◽

Duane Hazen ◽

Daniel Wolfe ◽

...

Keyword(s):

Remote Sensing ◽

Boundary Layer ◽

Relative Humidity ◽

Mean Absolute Error ◽

Microwave Radiometer ◽

Absolute Error ◽

Acoustic Sounding ◽

Energy Applications ◽

Virtual Temperature ◽

Microwave Radiometers

Abstract. To assess current remote-sensing capabilities for wind energy applications, a remote-sensing system evaluation study, called XPIA (eXperimental Planetary boundary layer Instrument Assessment), was held in the spring of 2015 at NOAA’s Boulder Atmospheric Observatory (BAO) facility. Several remote-sensing platforms were evaluated to determine their suitability for the verification and validation processes used to test the accuracy of numerical weather prediction models. The evaluation of these platforms was performed with respect to well-defined reference systems: the BAO’s 300-m tower equipped at 6 levels (50, 100, 150, 200, 250, and 300 m) with 12 sonic anemometers and 6 temperature and relative humidity sensors; and approximately 60 radiosonde launches. In this study we first employ these reference measurements to validate temperature profiles retrieved by two co-located microwave radiometers, as well as virtual temperature measured by co-located wind profiling radars equipped with radio acoustic sounding systems. Results indicate a mean absolute error in the temperature retrieved by the microwave radiometers below 1.5 °C in the lowest 5 km of the atmosphere, and a mean absolute error in the virtual temperature measured by the radio acoustic sounding systems below 0.8 °C in the layer of the atmosphere covered by these measurements (up to approximately 1.6–2 km). We also investigated the benefit of the vertical velocity applied to the speed of sound before computing the virtual temperature by the radio acoustic sounding systems. We find that using this correction frequently increases the RASS error, and that it should not be routinely applied to all data. Water vapor density profiles measured by the MWRs were also compared with similar measurements from the soundings, showing the capability of MWRs to follow the vertical profile measured by the sounding, and finding a mean absolute error below 0.5 g m−3 in the lowest 5 km of the atmosphere. However, the relative humidity profiles measured by the microwave radiometer lack the high-resolution details available from radiosonde profiles. An encouraging and significant finding of this study was that the coefficient of determination between the lapse rate measured by the microwave radiometer and the tower measurements over the tower levels between 50 and 300 m ranged from 0.76 to 0.91, proving that these remote-sensing instruments can provide accurate information on atmospheric stability conditions in the lower boundary layer.

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Combined Microwave Radiometer and Altimeter Retrieval of Wet Path Delay for the GEOSAT Follow-On

IEEE Transactions on Geoscience and Remote Sensing ◽

10.1109/tgrs.1996.508416 ◽

1996 ◽

Vol 34 (4) ◽

pp. 991 ◽

Cited By ~ 5

Author(s):

C.S. Ruf ◽

R.P. Dewan ◽

B. Subramanya

Keyword(s):

Microwave Radiometer ◽

Path Delay ◽

Wet Path Delay

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PAU in SeoSAT: A Proposed Hybrid L-band Microwave Radiometer/GPS Reflectometer to Improve Sea Surface Salinity Estimates from Space

2008 Microwave Radiometry and Remote Sensing of the Environment ◽

10.1109/micrad.2008.4579467 ◽

2008 ◽

Cited By ~ 7

Author(s):

A. Camps ◽

N. Rodriguez-Alvarez ◽

X. Bosch-Lluis ◽

J.F. Marchan ◽

I. Ramos-Perez ◽

...

Keyword(s):

Microwave Radiometer ◽

Sea Surface ◽

Sea Surface Salinity ◽

Surface Salinity ◽

L Band

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The CIMR mission and its unique capabilities for soil moisture sensing

10.5194/egusphere-egu21-9484 ◽

2021 ◽

Author(s):

Maria Piles ◽

Roberto Fernandez-Moran ◽

Luis Gómez-Chova ◽

Gustau Camps-Valls ◽

Dara Entekhabi ◽

...

Keyword(s):

Soil Moisture ◽

Land Surface ◽

Spatial Scales ◽

Microwave Radiometer ◽

Critical Time ◽

Global Scale ◽

The Arctic ◽

Temporal Perspective ◽

Microwave Radiometers ◽

Moisture Sensing

<p>The Copernicus Imaging Microwave Radiometer (CIMR) mission is currently being developed as a High Priority Copernicus Mission to support the Integrated European Policy for the Arctic. Due to its measurement characteristics, CIMR has exciting capabilities to enable a unique set of land surface products and science applications at a global scale. These characteristics go beyond what previous microwave radiometers (e.g. AMSR series, SMAP and SMOS) provide, and therefore allow for entirely new approaches to the estimation of bio-geophysical products from brightness temperature observations. Most notably, CIMR channels (L-,C-,X-,Ka-,Ku-bands) are very well fit for the simultaneous retrieval of soil moisture and vegetation properties, like biomass and moisture of different plant components such as leaves, stems or trunks. Also, the distinct spatial resolution of each frequency band allows for the development of approaches to cascade information and obtain these properties at multiple spatial scales. From a temporal perspective, CIMR has a higher revisit time than previous L-band missions dedicated to soil moisture monitoring (about 1 day global, sub-daily at the poles). This improved temporal resolution could allow resolving critical time scales of water processes, which is relevant to better model and understand land-atmosphere exchanges and feedbacks. In this presentation, new opportunities for soil moisture remote sensing made possible by the CIMR mission, as well as synergies and cross-sensor opportunities will be discussed.&#160;&#160;</p>

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Copernicus Imaging Microwave Radiometer (CIMR) Benefits for the Copernicus Level 4 Sea-Surface Salinity Processing Chain

Remote Sensing ◽

10.3390/rs11151818 ◽

2019 ◽

Vol 11 (15) ◽

pp. 1818 ◽

Cited By ~ 2

Author(s):

Daniele Ciani ◽

Rosalia Santoleri ◽

Gian Luigi Liberti ◽

Catherine Prigent ◽

Craig Donlon ◽

...

Keyword(s):

Soil Moisture ◽

High Resolution ◽

Microwave Radiometer ◽

Ocean Surface ◽

Sea Surface ◽

Sea Surface Salinity ◽

Optimal Interpolation ◽

Surface Salinity ◽

Processing Chain

We present a study on the potential of the Copernicus Imaging Microwave Radiometer (CIMR) mission for the global monitoring of Sea-Surface Salinity (SSS) using Level-4 (gap-free) analysis processing. Space-based SSS are currently provided by the Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) satellites. However, there are no planned missions to guarantee continuity in the remote SSS measurements for the near future. The CIMR mission is in a preparatory phase with an expected launch in 2026. CIMR is focused on the provision of global coverage, high resolution sea-surface temperature (SST), SSS and sea-ice concentration observations. In this paper, we evaluate the mission impact within the Copernicus Marine Environment Monitoring Service (CMEMS) SSS processing chain. The CMEMS SSS operational products are based on a combination of in situ and satellite (SMOS) SSS and high-resolution SST information through a multivariate optimal interpolation. We demonstrate the potential of CIMR within the CMEMS SSS operational production after the SMOS era. For this purpose, we implemented an Observing System Simulation Experiment (OSSE) based on the CMEMS MERCATOR global operational model. The MERCATOR SSSs were used to generate synthetic in situ and CIMR SSS and, at the same time, they provided a reference gap-free SSS field. Using the optimal interpolation algorithm, we demonstrated that the combined use of in situ and CIMR observations improves the global SSS retrieval compared to a processing where only in situ observations are ingested. The improvements are observed in the 60% and 70% of the global ocean surface for the reconstruction of the SSS and of the SSS spatial gradients, respectively. Moreover, the study highlights the CIMR-based salinity patterns are more accurate both in the open ocean and in coastal areas. We conclude that CIMR can guarantee continuity for accurate monitoring of the ocean surface salinity from space.

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Whitecap Observations by Microwave Radiometers: With Discussion on Surface Roughness and Foam Contributions

Remote Sensing ◽

10.3390/rs12142277 ◽

2020 ◽

Vol 12 (14) ◽

pp. 2277

Author(s):

Paul A. Hwang

Keyword(s):

Surface Roughness ◽

Dielectric Properties ◽

Surface Wave ◽

Wave Breaking ◽

Microwave Radiometer ◽

Video Recording ◽

Ocean Surface ◽

Optical Observations ◽

Microwave Signals ◽

Microwave Radiometers

Ocean surface whitecaps manifest surface wave breaking. Most of the whitecap data reported in the literature are based on optical observations through photographic or video recording. The air in whitecaps modifies the dielectric properties of microwave emissions and scattering. Therefore, whitecap information is intrinsic to microwave signals. This paper discusses a method to retrieve the ocean surface whitecap coverage from microwave radiometer signals.

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Numerical Simulation of the Fractal-Fractional Ebola Virus

Fractal and Fractional ◽

10.3390/fractalfract4040049 ◽

2020 ◽

Vol 4 (4) ◽

pp. 49 ◽

Cited By ~ 1

Author(s):

H. M. Srivastava ◽

Khaled M. Saad

Keyword(s):

Numerical Simulation ◽

Ebola Virus ◽

Numerical Solutions ◽

Finite Difference Methods ◽

Polynomial Functions ◽

Fractional Differentiation ◽

Lagrange Polynomial ◽

New Models ◽

Difference Methods ◽

Two Parameters

In this work we present three new models of the fractal-fractional Ebola virus. We investigate the numerical solutions of the fractal-fractional Ebola virus in the sense of three different kernels based on the power law, the exponential decay and the generalized Mittag-Leffler function by using the concepts of the fractal differentiation and fractional differentiation. These operators have two parameters: The first parameter ρ is considered as the fractal dimension and the second parameter k is the fractional order. We evaluate the numerical solutions of the fractal-fractional Ebola virus for these operators with the theory of fractional calculus and the help of the Lagrange polynomial functions. In the case of ρ=k=1, all of the numerical solutions based on the power kernel, the exponential kernel and the generalized Mittag-Leffler kernel are found to be close to each other and, therefore, one of the kernels is compared with such numerical methods as the finite difference methods. This has led to an excellent agreement. For the effect of fractal-fractional on the behavior, we study the numerical solutions for different values of ρ and k. All calculations in this work are accomplished by using the Mathematica package.

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End-to-End Simulation of WCOM IMI Sea Surface Salinity Retrieval

Remote Sensing ◽

10.3390/rs11030217 ◽

2019 ◽

Vol 11 (3) ◽

pp. 217 ◽

Cited By ~ 2

Author(s):

Yan Li ◽

Hao Liu ◽

Aili Zhang

Keyword(s):

Water Cycle ◽

Earth Science ◽

Global Climate ◽

Microwave Radiometer ◽

Sea Surface ◽

Sea Surface Salinity ◽

Surface Salinity ◽

Open Sea ◽

End To End ◽

Change Intensity

The Water Cycle Observation Mission (WCOM) is an Earth science mission focused on the observation of the water cycle global climate change intensity through three different payloads. WCOM’s main payload is an interferometric microwave imager (IMI). IMI is a tri-frequency, one-dimensional aperture synthesis microwave radiometer operating at the L-, S-, and C-bands to perform measurements of soil moisture and ocean salinity. Focusing on sea surface salinity (SSS), an end-to-end simulator of WCOM/IMI has been realized and tested on climatological data. Results indicate a general agreement between original and retrieved SSS, with a single measurement root mean square error of 0.26 psu and with an orbital measurement of 0.17 psu in open sea. In accordance with previous studies, good results are obtained in open sea, while strong contamination is observed in coastal areas.

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