The plumbing of land surface models: is poor performance a result of methodology or data quality?

The PALS Land sUrface Model Benchmarking Evaluation pRoject (PLUMBER) illustrated the value of prescribing a priori performance targets in model intercomparisons. It showed that the performance of turbulent energy flux predictions from different land surface models, at a broad range of flux tower sites using common evaluation metrics, was on average worse than relatively simple empirical models. For sensible heat fluxes, all land surface models were outperformed by a linear regression against downward shortwave radiation. For latent heat flux, all land surface models were outperformed by a regression against downward shortwave, surface air temperature and relative humidity. These results are explored here in greater detail and possible causes are investigated. We examine whether particular metrics or sites unduly influence the collated results, whether results change according to time-scale aggregation and whether a lack of energy conservation in flux tower data gives the empirical models an unfair advantage in the intercomparison. We demonstrate that energy conservation in the observational data is not responsible for these results. We also show that the partitioning between sensible and latent heat fluxes in LSMs, rather than the calculation of available energy, is the cause of the original findings. Finally, we present evidence suggesting that the nature of this partitioning problem is likely shared among all contributing LSMs. While we do not find a single candidate explanation for why land surface models perform poorly relative to empirical benchmarks in PLUMBER, we do exclude multiple possible explanations and provide guidance on where future research should focus.

Acute adrenal failure following anticoagulation with dabigatran after hip replacement and thrombolysis for massive pulmonary embolism.

A 75-year-old woman presented 9 days post-total hip replacement with sudden onset of shortness of breath and fever. She had been discharged taking dabigatran. The patient was treated for sepsis with antibiotics and fluids. However, she deteriorated and was transferred to the intensive care unit. Following a 10 s asystolic episode the patient was thrombolysed with alteplase for presumed massive pulmonary embolism. Initially, her blood pressure and oxygen saturation improved. However, over the next few days, she remained persistently hypotensive. A CT scan of her chest, abdomen and pelvis demonstrated bilateral adrenal haemorrhages. A short synacthen test confirmed acute adrenal failure.