The National Aeronautics and Space Administration (NASA) Soil Moisture Active Passive (SMAP) satellite was launched in January 2015. In order to validate the soil moisture retrieval algorithms that fully exploit the unique capabilities of SMAP, the algorithms need to be tested over different conditions worldwide. In response to this need, the Terrestrial Hydrology Experiment 2018 in Mexico (THEx-MEX 18) was conducted in Huamantla, Tlaxcala, Mexico over a six-month period. Ground crews collected soil moisture data, crop measurements, and biomass samples in support of this campaign. The objective of THEx-MEX was to create a soil moisture network over an agricultural area in Mexico, understand the spatial distribution of soil moisture, and compare the SMAP soil moisture retrievals with in-situ measurements. This work details the field data collection as well as data calibration and analysis. A first comparison between in-situ data and SMAP retrievals of soil moisture is presented. It is demonstrated that absolute soil moisture values can be delivered by satellite observations. SMAP soil moisture estimates closely follow dry down and wetting events observed during the field experiment.
Estimation of Biophysical Variables
Operational Implementation Plan
This file describes the protocols implemented to characterize the soil and vegetation conditions.
- fAPAR (Fraction of Absorbed Photosynthetically Active Radiation)
- LAI (Leaf Area Index)
- Plant height
|Typical Field Size||5 fields of about 6300 m^2|
|Climatic Zone||Tropics, warm|
|Major Crops and Calendars|
|Soil Type & Texture|
|Soil Drainage Class|
|Other Site Details|
The agricultural fields are located in Huamantla, Central Mexico (19º 18’ 51.09’’ N; 97º 51’ 27.91’’W). Huamantla is a small city in Huamantla Municipality located in the eastern half of the Mexican state of Tlaxcala. The municipality’s economy is still heavily agricultural, with almost a third of its workforce dedicated to crops and livestock. Over half of the municipality’s territory is used for farming and grazing but agriculture’s role has been diminishing. In 2009, the municipality had 24,424 hectares under cultivation with crops such as corn, beans, wheat, animal feed, peaches and rye. Livestock includes cattle (mostly dairy), pigs, sheep, goats and domestic fowl. The climate of Huamantla is characteristically temperate (subhumid). Rainfall occurs from May to October, ranging from 500 mm per year East to 800-1000 mm in the Southwest. Rainfall variations in the mid-summer months can lead to extended droughts. Average monthly temperatures fluctuate within a narrow range, with January being the coldest month (0-9 ºC) and April or May generally the warmest (19-27 ºC). Huamantla soils are generally sandy and highly drained, though some soils are gravelly or rocky. Depth varies from 10 cm in the Lithosols of the west and north central regions to deep Fluviols on the plains of Huamantla.
In Situ Observations
Biomass, geometric description, soil moisture, soil texture, surface roughness
- Crop Type(s): Maize
- Collection Protocol:
The protocols implemented are described in the following file:
- Frequency: Every three weeks over six months
Optical Data Requirements
SAR Data Requirements
Passive Microwave Data Requirements
Thermal Data Requirements
Documents and FilesMonsivaisAGUHuamantla.png Reporte-final-Huamantla-2018.pdf HuamantlaFieldWorkJul2019.pdf
Links to paper
Calzada Ticomán 600, Colonia San José Ticoman, Delegación Gustavo A. Madero.
Mexico City. Z.P. 07340.
Other Team Members