### Abstract

P-band radar remote sensing applied during the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) mission has shown great potential for estimation of root zone soil moisture. When retrieving the soil moisture profile (SMP) from P-band radar observations, a mathematical function describing the vertical moisture distribution is required. Because only a limited number of observations are available, the number of free parameters of the mathematical model must not exceed the number of observed data. For this reason, an empirical quadratic function (second order polynomial) is currently applied in the AirMOSS inversion algorithm to retrieve the SMP. The three free parameters of the polynomial are retrieved for each AirMOSS pixel using three backscatter observations (i.e., one frequency at three polarizations of Horizontal-Horizontal, Vertical-Vertical and Horizontal-Vertical). In this paper, a more realistic, physically-based SMP model containing three free parameters is derived, based on a solution to Richards' equation for unsaturated flow in soils. Evaluation of the new SMP model based on both numerical simulations and measured data revealed that it exhibits greater flexibility for fitting measured and simulated SMPs than the currently applied polynomial. It is also demonstrated that the new SMP model can be reduced to a second order polynomial at the expense of fitting accuracy.

Language | English (US) |
---|---|

Article number | 17 |

Journal | Remote Sensing |

Volume | 9 |

Issue number | 1 |

DOIs | |

State | Published - 2017 |

### Fingerprint

### Keywords

- Airborne microwave observatory of subcanopy and subsurface (AirMOSS)
- P-band remote sensing
- Radar backscatter
- Richards' equation
- Root zone
- Soil moisture profile

### ASJC Scopus subject areas

- Earth and Planetary Sciences(all)

### Cite this

*Remote Sensing*,

*9*(1), [17]. DOI: 10.3390/rs9010017

**Advancing NASA's AirMOSS p-band radar root zone soil moisture retrieval algorithm via incorporation of richards' equation.** / Sadeghi, Morteza; Tabatabaeenejad, Alireza; Tuller, Markus; Moghaddam, Mahta; Jones, Scott B.

Research output: Research - peer-review › Article

*Remote Sensing*, vol 9, no. 1, 17. DOI: 10.3390/rs9010017

}

TY - JOUR

T1 - Advancing NASA's AirMOSS p-band radar root zone soil moisture retrieval algorithm via incorporation of richards' equation

AU - Sadeghi,Morteza

AU - Tabatabaeenejad,Alireza

AU - Tuller,Markus

AU - Moghaddam,Mahta

AU - Jones,Scott B.

PY - 2017

Y1 - 2017

N2 - P-band radar remote sensing applied during the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) mission has shown great potential for estimation of root zone soil moisture. When retrieving the soil moisture profile (SMP) from P-band radar observations, a mathematical function describing the vertical moisture distribution is required. Because only a limited number of observations are available, the number of free parameters of the mathematical model must not exceed the number of observed data. For this reason, an empirical quadratic function (second order polynomial) is currently applied in the AirMOSS inversion algorithm to retrieve the SMP. The three free parameters of the polynomial are retrieved for each AirMOSS pixel using three backscatter observations (i.e., one frequency at three polarizations of Horizontal-Horizontal, Vertical-Vertical and Horizontal-Vertical). In this paper, a more realistic, physically-based SMP model containing three free parameters is derived, based on a solution to Richards' equation for unsaturated flow in soils. Evaluation of the new SMP model based on both numerical simulations and measured data revealed that it exhibits greater flexibility for fitting measured and simulated SMPs than the currently applied polynomial. It is also demonstrated that the new SMP model can be reduced to a second order polynomial at the expense of fitting accuracy.

AB - P-band radar remote sensing applied during the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) mission has shown great potential for estimation of root zone soil moisture. When retrieving the soil moisture profile (SMP) from P-band radar observations, a mathematical function describing the vertical moisture distribution is required. Because only a limited number of observations are available, the number of free parameters of the mathematical model must not exceed the number of observed data. For this reason, an empirical quadratic function (second order polynomial) is currently applied in the AirMOSS inversion algorithm to retrieve the SMP. The three free parameters of the polynomial are retrieved for each AirMOSS pixel using three backscatter observations (i.e., one frequency at three polarizations of Horizontal-Horizontal, Vertical-Vertical and Horizontal-Vertical). In this paper, a more realistic, physically-based SMP model containing three free parameters is derived, based on a solution to Richards' equation for unsaturated flow in soils. Evaluation of the new SMP model based on both numerical simulations and measured data revealed that it exhibits greater flexibility for fitting measured and simulated SMPs than the currently applied polynomial. It is also demonstrated that the new SMP model can be reduced to a second order polynomial at the expense of fitting accuracy.

KW - Airborne microwave observatory of subcanopy and subsurface (AirMOSS)

KW - P-band remote sensing

KW - Radar backscatter

KW - Richards' equation

KW - Root zone

KW - Soil moisture profile

UR - http://www.scopus.com/inward/record.url?scp=85010664514&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85010664514&partnerID=8YFLogxK

U2 - 10.3390/rs9010017

DO - 10.3390/rs9010017

M3 - Article

VL - 9

JO - Remote Sensing

T2 - Remote Sensing

JF - Remote Sensing

SN - 2072-4292

IS - 1

M1 - 17

ER -