Estimativa de rugosidade de solo em regiões semi-áridas por meio dos dados de radar de abertura sintética (banda C, satélite ERS-1)

rbcs Revista Brasileira de Ciência do Solo Rev. Bras. Ciênc. Solo 1806-9657 Sociedade Brasileira de Ciência do Solo Viçosa, MG, Brazil Neste estudo, analisou-se a relação entre dados de radar de abertura sintética (banda C, satélite ERS-1 - European Remote Sensing Satellite) e medidas de rugosidade do terreno numa região semi-árida do Arizona, EUA. Os coeficientes de retroespalhamento obtidos de imagens das épocas seca e chuvosa foram comparados com 47 medidas de rugosidade do terreno obtidas da Microbacia do Walnut Gulch, localizado no sudeste do estado do Arizona, EUA. Foi observada correlação exponencial entre dados de radar da época seca e medidas de rugosidade (R² = 0,80). Com relação aos dados de radar da época chuvosa, também foi observada correlação exponencial, porém com dispersão maior de pontos (R² = 0,59). Esta correlação mais baixa deveu-se, provavelmente, à maior influência da umidade de solo nos processos de retroespalhamento na banda C, na época chuvosa. Os resultados deste experimento indicaram que dados de radar na banda C são promissores quanto à estimativa de rugosidade de terreno em regiões semi-áridas. SEÇÃO V - GÊNESE, MORFOLOGIA E CLASSIFICAÇÃO DO SOLO Estimation of surface roughness in a semiarid region from C-band ERS-1 synthetic aperture radar data(1) Estimativa de rugosidade de solo em regiões semi-áridas por meio dos dados de radar de abertura sintética (banda C, satélite ERS-1) E. E. SanoI; A. R. HueteII; M. S. MoranIII IPesquisador da Embrapa, Caixa Postal 515, CEP 73301-970 Planaltina (DF) Brazil. E-mail: [e-mail] IIProfessor da Universidade do Arizona, 429 Shantz Bldg no 38, Tucson, AZ, 85721, USA IIIPesquisadora da USDA-SWRC, 2000 E. Rodovia Allen, Tucson, AZ, 85719, USA ABSTRACT In this study, we investigated the feasibility of using the C-band European Remote Sensing Satellite (ERS-1) synthetic aperture radar (SAR) data to estimate surface soil roughness in a semiarid rangeland. Radar backscattering coefficients were extracted from a dry and a wet season SAR image and were compared with 47 in situ soil roughness measurements obtained in the rocky soils of the Walnut Gulch Experimental Watershed, southeastern Arizona, USA. Both the dry and the wet season SAR data showed exponential relationships with root mean square (RMS) height measurements. The dry C-band ERS-1 SAR data were strongly correlated (R2 = 0.80), while the wet season SAR data have somewhat higher secondary variation (R2 = 0.59). This lower correlation was probably provoked by the stronger influence of soil moisture, which may not be negligible in the wet season SAR data. We concluded that the single configuration C-band SAR data is useful to estimate surface roughness of rocky soils in a semiarid rangeland. Index terms: surface roughness, radar remote sensing, microwave. RESUMO Neste estudo, analisou-se a relação entre dados de radar de abertura sintética (banda C, satélite ERS-1 - European Remote Sensing Satellite) e medidas de rugosidade do terreno numa região semi-árida do Arizona, EUA. Os coeficientes de retroespalhamento obtidos de imagens das épocas seca e chuvosa foram comparados com 47 medidas de rugosidade do terreno obtidas da Microbacia do Walnut Gulch, localizado no sudeste do estado do Arizona, EUA. Foi observada correlação exponencial entre dados de radar da época seca e medidas de rugosidade (R2 = 0,80). Com relação aos dados de radar da época chuvosa, também foi observada correlação exponencial, porém com dispersão maior de pontos (R2 = 0,59). Esta correlação mais baixa deveu-se, provavelmente, à maior influência da umidade de solo nos processos de retroespalhamento na banda C, na época chuvosa. Os resultados deste experimento indicaram que dados de radar na banda C são promissores quanto à estimativa de rugosidade de terreno em regiões semi-áridas. Termos de indexação: rugosidade do terreno, sensoriamento remoto por radar, microondas. Texto completo disponível apenas em PDF. Full text available only in PDF format. ACKNOWLEDGMENTS Special thanks are due to Dr. D. Goodrich for providing the orthophotos of the watershed, and R. Simanton for allowing the use of the roughness meter. The assistance of personnel at the ARS Walnut Gulch Experimental Watershed facility in Tombstone, AZ, was also very important. This work was partially supported by the NASA-EOS Interdisciplinary Research Program in Earth Sciences (NASA IDP-88-086), National Science Foundation grant (INT-9314872), and NASA Landsat Team grant (# -41396-F). LITERATURE CITED (1 ) Parte da Tese de PhD do primeiro autor, Universidade do Arizona, Tucson, AZ, USA. ALTESE, E.; BOLOGNANI, O.; MANCINI, M. & TROCH, P.A. 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