Assimilation of Ocean Colour Data Into a Biochemical Model of the North Atlantic Part 1. Data Assimilation Experiments

An advanced multivariate sequential data assimilation method, the ensemble Kalman filter (EnKF), has been investigated with a three-dimensional biochemical model of the North Atlantic, utilizing real chlorophyll data from the from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). The approach chosen here differs significantly from conventional parameter estimation techniques. We keep the parameters fixed, and instead update the actual model state, allowing for unknown errors in the dynamical formulation. In the ensemble Kalman filter, estimates of the true dynamical error covariances are provided from an ensemble of model states

Assimilation of Ocean Colour Data into a Biochemical Model of the North Atlantic - Part 2. Statistical Analysis

In a companion paper [J. Mar. Syst. 40/41 (2003)], hereafter referred to as Part 1, we investigated an advanced data assimilation technique, the ensemble Kalman filter, for sequentially updating the biochemical state of a three-dimensional coupled physical -- biochemical model of the North Atlantic. Within the methodology, an ensemble of model states is integrated forward to a measurement time, where an estimate based on information from both the model and the observations is calculated. The ensemble of states can provide estimates of any statistical moment, although moments of order three and higher are discarded in the analysis. In the Part 1 paper, we presented a simple demonstration experiment for the months April and May 1998, with some additional sensitivity tests at the first measurement time. The simulation included the early part of the spring bloom, which is characterized by strong nonlinear biochemical activity. It was concluded that the ensemble Kalman filter was able to provide an updated state consistent with the observations, and it was seen that the ensemble variance of the different biochemical components decreased during the analysis

Translating weight loss into agency: Men’s experiences 5 years after bariatric surgery

Fewer men than women with severe obesity undergo bariatric surgery for weight loss, and knowledge about men's situation after surgery, beyond medical status, is lacking. Our aim was to explore men's experiences with life after bariatric surgery from a long-term perspective. We conducted in-depth interviews with 13 men, aged 28–60 years, between 5 and 7 years after surgery. The analysis was inspired by Giorgi's phenomenological method. We found that agency was pivotal for how the men understood themselves and their lives after surgery. Weight loss meant regaining opportunities for living and acting in unrestricted and independent daily lives, yet surgery remained a radical treatment with complex consequences. Turning to surgery had involved conceptualizing their own body size as illness, which the men had resisted doing for years. After surgery, the rapid and major weight loss and the feelings of being exhausted, weak, and helpless were intertwined. The profound intensity of the weight loss process took the men by surprise. Embodying weight loss and change involved an inevitable renegotiating of experiences connected to the large body. Having bariatric surgery was a long-term process that seemed unfinished 5 years after surgery. Restrictions and insecurity connected to health and illness persist, despite successful weight loss and embodied change. Bariatric surgery initiated a complex and long-lasting life-changing process, involving both increased capacity for agency and illness-like experiences