Estimating surface soil moisture from SMAP observations using a Neural Network technique.

A Neural Network (NN) algorithm was developed to estimate global surface soil moisture for April 2015 to March 2017 with a 2-3 day repeat frequency using passive microwave observations from the Soil Moisture Active Passive (SMAP) satellite, surface soil temperatures from the NASA Goddard Earth Observing System Model version 5 (GEOS-5) land modeling system, and Moderate Resolution Imaging Spectroradiometer-based vegetation water content. The NN was trained on GEOS-5 soil moisture target data, making the NN estimates consistent with the GEOS-5 climatology, such that they may ultimately be assimilated into this model without further bias correction. Evaluated against in situ soil moisture measurements, the average unbiased root mean square error (ubRMSE), correlation and anomaly correlation of the NN retrievals were 0.037 m3m-3, 0.70 and 0.66, respectively, against SMAP core validation site measurements and 0.026 m3m-3, 0.58 and 0.48, respectively, against International Soil Moisture Network (ISMN) measurements. At the core validation sites, the NN retrievals have a significantly higher skill than the GEOS-5 model estimates and a slightly lower correlation skill than the SMAP Level-2 Passive (L2P) product. The feasibility of the NN method was reflected by a lower ubRMSE compared to the L2P retrievals as well as a higher skill when ancillary parameters in physically-based retrievals were uncertain. Against ISMN measurements, the skill of the two retrieval products was more comparable. A triple collocation analysis against Advanced Microwave Scanning Radiometer 2 (AMSR2) and Advanced Scatterometer (ASCAT) soil moisture retrievals showed that the NN and L2P retrieval errors have a similar spatial distribution, but the NN retrieval errors are generally lower in densely vegetated regions and transition zones.

Is the intensity of the highest fat oxidation at the lactate concentration of 2 mmol L(-1)? A comparison of two different exercise protocols.

BACKGROUND: The exercise intensity eliciting highest fat oxidation is important for a variety of populations and its precise determination requires an adequate exercise protocol. The aim of this study was to compare fat oxidation, concentration of lactate and lactate threshold during an established exercise protocol using fixed workloads with a protocol based upon the subject's individual heart rate response to exercise. MATERIALS AND METHODS: Highest fat oxidation, concentration of lactate and lactate threshold were compared between two different exercise protocols in moderately trained men (n = 48) and women (n = 30). In randomized order subjects completed a standardized (STAND) and an individual (IND) submaximal exercise test. The increments during IND were adapted by the subjects' individual heart rate response to exercise compared to STAND with defined steps. RESULTS: In men, fat oxidation was significantly higher at the intensity eliciting highest fat oxidation in STAND than in IND (P = 0.019), but not in women. In both genders lactate concentration (P < 0.001) and heart rate (HR) (P < 0.001) were significantly higher in IND compared to STAND at this intensity. A significant correlation between O2 at lactate threshold and the intensity eliciting the highest fat oxidation was found in both genders in IND (women r = 0.73; men r = 0.43) and in STAND (women r = 0.57; men r = 0.56). CONCLUSION: Different exercise increments and stage durations have an influence on lactate concentration and HR at the intensity eliciting the highest fat oxidation. The shorter test duration of STAND favours this protocol to determine maximal fat oxidation. For the untrained, start of exercise should be at very low intensity.

[Changes in body composition during an extreme endurance run]. / Veränderung der Körperzusammensetzung bei einem Ultralauf.

We measured before, during and after a six-day-run in one athlete body weight, skinfold thickness, circumference of extremities, energy expenditure and nutritional intake. Despite an increased fat and protein intake during the race we found a significantly decrease in adipose subcutaneous tissue of the whole body and muscle mass in the active limbs whereas body weight remained stable. We presume that during running as eccentric exercise subcutaneous adipose tissue and muscle mass will be oxidised.