Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

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Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: 2 Microwave data. Chairman: N. Lannelongue, Liaison: L. Krul

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Relating L-band scatterometer data with soil moisture content and roughness. P. J. F. Swart

Document type:: Multivolume work

Structure type:: Chapter

186 In a first order approximation (9) can be written as: 2 2 Y = F.(4ak cos 0) for a « X/4ttcos0 We see that for low frequencies and large incidence angles only the product of moisture content and rough ness, contained in F.a can be determined. We selected three bare or barely vegetated fields and will compare the gamma versus incidence plots with equality (9). The first results of the applica tion of the described model are presented in fig. 8. Corresponding field parameters of interest are given in table 1. FIELD: 1 Incidence angle <cteg. > —> field: 6 Incidence ANGLE <degr. > > FIELD: 15 Incidence angle <d=g- > —> Figure 8. Comparison between the calculated backscat- tering coefficient for field 1, 6 and 15 and relation (9) for large incidence angles. Table 1. Characteristic field parameters. Field a F (dB) Mg(g/g) 1 40 -10 0.34 6 11 - 5 0.36 15 11 - 3 0.42 In this table we see the rms roughness parameter a as measured during the ground data collection and the model parameter F found for field 1, 6 and 15 along with the measured gravimetric water content, M , in terms of gram water per gram dry soil. As expected, F and M do exhibit a similar behavior. It must be stated though that the relationship between the intensity factor and the gravimetric water content needs more investigation. Comparison of the results for the same fields on two succeeding days might shed some more light on this relationship. In this however we are restricted by fact that only large moisture contents were present during the SIR-B experiment. The large values of gamma observed in fig. 8 for small incidence angles are caused by a coherent con tribution which has to be added with the right side of equation (9). This coherent term is best under stood if we consider a perfectly conducting flat surface that appears to the radar as a mirror from which the main contribution to the received power comes from nadir. At the intersection angle of the incoherent term of eq. (9) and the coherent term the backscattering coefficient exhibits the least depen dence on roughness (Ulaby 1979) . Because of this fact and eq. (10) also the behavior of y for small incidence angles will have to be taken into consider ation in future investigations in spite of the bad resolution here. 6 CONCLUSIONS It is possible to use the data gathered in the SIR-B project with DUTSCAT working at 1.2 GHz as an extra source in the semi-empirical solution of the inter action problem of microwaves with various types of agricultural fields and the question how to extract information from this interaction. We must note however that the data set is rather limited in soil moisture variation and inherent to the airborne si tuation not very accurate for small incidence angles At this moment a variety of aspects is studied more closely. REFERENCES Attema, E.P.W. 1979. Radar backscattering from bare soil, model prediction and observed responses. Proc. Earsel-workshop: Microwave Remote Sensing on Bare Soil, p.96-105. Attema, E.P.W. & P.J. van Kats & L. Krul 1982. A radar signature model for partially coherent scat tering from irregular surfaces. IEEE Trans. Geosc. Rem. Sens. Vol GE-20, no.l, p.76-84. Attema, E.P.W. & P. Snoeij 1984. Dutscat, a 6-fre quency airborne scatterometer. Proc. Earsel-work shop. ESA.sp 227, p.127-129, Amsterdam. Krul, L. 1979. The modelling problem, an introduc tion. Proc. Earsel-workshop: Microwave Remote Sensing on Bare Soil, p.85-95. Krul, L. 1986. The microwave remote sensing program for agriculture and forestry in the Netherlands. This issue. Loor, G.P. de e.a. 1982. The Dutch ROVE program. IEEE Trans. Geosc. Rem. Sens., Vol GE-20, no.l, p.3-11. Smit, M.K. 1978. Radar reflectrometry in the Nether lands: measurement system, data handling and some results. Proc. Int. Conf. on Earth Observation. ESA-sp-134, p.377-387, Toulouse. Stroosnijder, L. & J. Stolp & G.G. Lemoine 1984. L-band radar experiment groundtruth Flevo '84. Technical report of the ROVE radar working group soils. Ulaby, F.T. 1979. Active microwave sensing of soil moisture, synopsis and prognosis. Proc. Earsel-workshop: Microwave Remote Sensing on Bare Soil, p.2-22. Ulaby, F.T. & R.K. Moore & A.K. Fung 1982. Micro- wave remote sensing, active and passive. Vol II., p.583-590, Addison-Wesley Inc., London

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