In: Wagner W., Szekely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
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The difference of the results derived from active and passive 
microwave remote sensing time series is essential for 
understanding the near-surface earth system changes. The 
SSM/I’s result could indicate the soil temperature switch from 
negative to positive values, while the QuikSCAT’s result could 
deduce the soil water states change from ice to liquid water. 
Such kind of phenomenon would be related to the climate 
change and extreme environment (e.g. springtime dust emission) 
in this area for better understanding the Earth surface 
interactions. 
-10 
-15 
-20 
-25 
■ Frozen samples 
■ Non-frozen samples 
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Modeled soil moisture (mm) 
2) The passive microwave remote sensing (SSM/I) based result 
had a good relationship with the near-surface soil temperature, 
while the active microwave remote sensing (QuikSCAT) based 
result had both relationships with temperature and soil moisture 
conditions, especially soil moisture conditions. And also, 
QuikSCAT result identifies the geographical boundary 
conditions of the thaw event in springtime of 2004, which is 
crucial for understanding the different types of springtime near 
surface soil thaw at middle latitudes. 
Since both SSM/I brightness temperature and QuikSCAT 
backscatter are available from 1999 to 2009, further analysis is 
undergoing for understanding the interaction of springtime soil 
thaw event with other near-surface events. 
REFERENCES 
Han, L., Tsunekawa, A., Tsubo, M., 2010a. Monitoring near 
surface soil freeze-thaw cycles in northern China and Mongolia 
from 1998 to 2007. International Journal of Earth Observation 
and Geoinformation, doi: 10.1016/j.jag.2010.04.009.(in press) 
Han, L., Tsunekawa, A., Tsubo, M., 2010b. Radar remote 
sensing of springtime near-surface soil thaw events at mid 
latitudes. Submitted to International Journal of Remote Sensing. 
Figure 4. Near-surface air temperature and soil moisture 
conditions’ difference between samples with/without soil thaw 
events detected by QuikSCAT backscatter. 
6. CONCLUSION 
Tsunekawa, A., Ito, T. Y., Shinoda, M., Nemoto, M., Suhama, 
T., Ju, H., Shimizu, H. 2005. Methodology for assessment of 
desertification based on vegetation degradation using net 
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192. 
SSM/I brightness temperature and QuikSCAT Ku-band 
backscatter were applied in this study at a case study area of 
northern China and Mongolia in springtime of 2004. 
Conclusions could be approached as follows: 
1) Both soil freeze-thaw algorithm for SSM/I brightness 
temperature and multi-step method for QuikSCAT backscatter 
were effective for springtime near-surface soil thaw events 
detection. A reliability of R = 0.8, P < 0.05 was obtained 
between estimated primary thaw date and the date when 
consecutive days’ average air temperature keeping positive 
values; and R = 0.85, P < 0.05 was obtained in result from 
passive microwave remote sensing with comparison between 
estimated onset/offset of the thaw and field measured soil thaw 
event. 
Yamaguchi, Y. and Shinoda, M. (2002). Soil moisture modeling 
based on multiyear observations in the Sahel. Journal of 
Applied Meteorology, 41,1140-1146. 
Zhang, B., Tsunekawa, A., Tsubo, M. 2008. Contributions of 
sandy lands and stony deserts to long-distance dust emission in 
China and Mongolia during 2000-2006. Global and Planetary 
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Zhang, T., Barry, R. G., Armstrong, R. L., 2004. Application of 
satellite remote sensing techniques to frozen ground studies. 
Polar Geography, 28, 163-196. 
Zwally, H. J., and Gloersen, P., 1977. Passive microwave 
images of the Polar Regions and research applications. Polar 
Record, 18,431-450.