The Soil Moisture Active Passive (SMAP) radar: Measurements at high latitudes and of surface freeze/thaw state

Abstract. The Mediterranean environment is characterized by strong temporal variations in rainfall volume and intensity, soil moisture and vegetation cover along the year. These factors play a key role on soil erosion. The aim of this work is to identify different erosive periods in function of the temporal changes in rainfall and runoff characteristics (erosivity, maximum intensity and number of erosive events), soil properties (soil erodibility in relation to freeze-thaw processes and soil moisture content) and current tillage practices in a set of agricultural fields in a mountainous area of the Central Pyrenees in NE Spain. To this purpose the rainfall and runoff erosivity (R), the soil erodibility (K) and the cover-management (C) factors of the empirical RUSLE soil loss model were used. The R, K and C factors were calculated at monthly scale. The first erosive period extends from July to October and presents the highest values of erosivity (87.8 MJ mm ha−1 h−1), maximum rainfall intensity (22.3 mm h−1) and monthly soil erosion (0.25 Mg ha−1 month−1) with the minimum values of duration of erosive storms, freeze-thaw cycles, soil moisture content and soil erodibility (0.007 Mg h MJ−1 mm−1). This period includes the harvesting and the plowing tillage practices. The second erosive period has a duration of two months, from May to June, and presents the lowest total and monthly soil losses (0.10 Mg ha−1 month−1) that correspond to the maximum protection of the soil by the crop-cover ($C$ factor = 0.05) due to the maximum stage of the growing season and intermediate values of rainfall and runoff erosivity, maximum rainfall intensity and soil erodibility. The third erosive period extends from November to April and has the minimum values of rainfall erosivity (17.5 MJ mm ha−1 h−1) and maximum rainfall intensity (6.0 mm h−1) with the highest number of freeze-thaw cycles, soil moisture content and soil erodibility (0.021 Mg h MJ−1 mm−1) that explain the high value of monthly soil loss (0.24 Mg ha−1 month−1). The interactions between the rainfall erosivity, soil erodibility, and cover-management factors explain the similar predicted soil losses for the first and the third erosive periods in spite of the strong temporal differences in the values of the three RUSLE factors. The estimated value of annual soil loss with the RUSLE model (3.34 Mg ha−1 yr−1) was lower than the measured value with 137Cs (5.38 Mg ha−1 yr−1) due to the low values of precipitation recorded during the studied period. To optimize agricultural practices and to promote sustainable strategies for the preservation of fragile Mediterranean agrosystems it is necessary to delay plowing till October, especially in dryland agriculture regions. Thus, the protective role of the crop residues will extend until September when the greatest rainfall occurs together with the highest runoff erosivity and soil losses.

Download Full-text

Sampling depth of L-band radiometer measurements of soil moisture and freeze-thaw dynamics on the Tibetan Plateau

Remote Sensing of Environment ◽

10.1016/j.rse.2019.03.029 ◽

2019 ◽

Vol 226 ◽

pp. 16-25 ◽

Cited By ~ 7

Author(s):

Donghai Zheng ◽

Xin Li ◽

Xin Wang ◽

Zuoliang Wang ◽

Jun Wen ◽

...

Keyword(s):

Soil Moisture ◽

Tibetan Plateau ◽

The Tibetan Plateau ◽

Sampling Depth ◽

Freeze Thaw ◽

L Band ◽

Band Radiometer

Download Full-text

Simulating high-latitude permafrost regions by the JSBACH terrestrial ecosystem model

Geoscientific Model Development ◽

10.5194/gmd-7-631-2014 ◽

2014 ◽

Vol 7 (2) ◽

pp. 631-647 ◽

Cited By ~ 67

Author(s):

A. Ekici ◽

C. Beer ◽

S. Hagemann ◽

J. Boike ◽

M. Langer ◽

...

Keyword(s):

High Latitude ◽

Terrestrial Ecosystem ◽

Ecosystem Model ◽

Layered Soil ◽

Data Sets ◽

High Latitudes ◽

Current Version ◽

Freeze Thaw ◽

Terrestrial Ecosystem Model ◽

Permafrost Regions

Abstract. The current version of JSBACH incorporates phenomena specific to high latitudes: freeze/thaw processes, coupling thermal and hydrological processes in a layered soil scheme, defining a multilayer snow representation and an insulating moss cover. Evaluations using comprehensive Arctic data sets show comparable results at the site, basin, continental and circumarctic scales. Such comparisons highlight the need to include processes relevant to high-latitude systems in order to capture the dynamics, and therefore realistically predict the evolution of this climatically critical biome.

Download Full-text

Landscape freeze/thaw products from Soil Moisture Active/Passive (SMAP) radar and radiometer data

2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) ◽

10.1109/igarss.2016.7729025 ◽

2016 ◽

Author(s):

Xiaolan Xu ◽

R. Scott Dunbar ◽

Chris Derksen ◽

Andreas Colliander ◽

John Kimball ◽

...

Keyword(s):

Soil Moisture ◽

Freeze Thaw

Download Full-text

Winter Irrigation Effects on Soil Moisture, Temperature and Salinity, and on Cotton Growth in Salinized Fields in Northern Xinjiang, China

Sustainability ◽

10.3390/su12187573 ◽

2020 ◽

Vol 12 (18) ◽

pp. 7573

Author(s):

Ling Li ◽

Hongguang Liu ◽

Xinlin He ◽

En Lin ◽

Guang Yang

Keyword(s):

Soil Moisture ◽

Seedling Emergence ◽

Soil Layer ◽

Soil Salinization ◽

Control Treatment ◽

Freeze Thaw ◽

Irrigation Rate ◽

Significant Difference ◽

Emergence Rate ◽

Cotton Fields

Winter irrigation affected the movement of soil moisture, temperature, and salt, which was an effective improvement measure widely used in seasonal freeze–thaw areas. In this paper, we investigated the effects of different salinized cotton fields (mild salinization (S1), 5.15 g·kg−1; moderate salinization (S2), 8.17 g·kg−1; severe salinization (S3), 11.15 g·kg−1) and different winter irrigation rates (W0, 0 m3·hm-2; W1, 3000 m3·hm-2; W2, 3600 m3·hm-2; W3, 4200 m3·hm-2) on soil moisture, temperature, salinity, and cotton growth in seasonal freeze–thaw areas. The results showed that the winter irrigation affected the temporal and spatial dynamics of soil moisture, temperature, and salinity, and the winter irrigation rate and degree of soil salinization were significantly correlated with soil moisture, temperature, and salinity (p < 0.01). Winter irrigation stabilized the soil temperature and reduced the freeze–thaw index of the soil. The heat conservation effect of winter irrigation increased with increasing winter irrigation rate and salinization degree, with the greatest effect on the freezing index of S2 and on the thawing index of S3. The soil water content and total salt concentration before spring tillage were significantly correlated with winter irrigation rate and degree of soil salinization (p < 0.05), and when the winter irrigation quota of different salinized cotton fields was greater than 3600 m3·hm-2, the moisture content of soil layer 0–100cm increased by more than 20%, and the desalination reached over 40%, compared with the values before winter irrigation. Winter irrigation improved the emergence rate and yield of cotton, with the soil salinization degree being significantly negatively correlated and winter irrigation rate significantly positively correlated with the emergence rate and yield of cotton fields in the following year (p < 0.01). Compared with the control treatment without winter irrigation, the average increases in cotton yield were W3 (53.32%) > W2 (45.00%) > W1 (29.36%). There was no significant difference in seedling emergence rate or yield between slightly and moderately salinized cotton fields under high winter irrigation rates (W2 and W3) (p > 0.05), although the seedling emergence rate and yield of severely salinized cotton fields increased significantly with increasing winter irrigation rate. In conclusion, winter irrigation proved to be a valuable treatment for severely salinized cotton fields, and the results of this study allowed us to determine the optimal winter irrigation rate for saline alkali cotton fields.

Download Full-text