Modelling windfarm wakes in operational forecasting model HARMONIE-AROME

<p>Wind power production in the European Union (EU) is steadily increasing, specifically on the North-Sea. Wind farms are growing both in number and size, while weather models evolve to higher resolutions. This means that the effect of wind farms can no longer be ignored by weather prediction models. Wind farms essentially decelerate the wind (blockage and wake effects) and increase turbulence, indirectly influencing temperature and humidity. In this study, we have included the widely used Fitch et al. (2012) windfarm parameterisation in the operational mesoscale model HARMONIE-AROME. Using our method, we are able to include individual turbines both on- and offshore. The model is evaluated using various datasets, e.g. production data from Elia (Belgium), floating lidar measurements at Borssele Wind Farm, and anemometer measurements from the FINO-towers. The inclusion of the windfarm parameterisation improves the wind forecast near wind farms, also improving the estimate in power production. In addition, we are able to model the effects of wind farms on the boundary-layer temperature and humidity.</p><p>Fitch, A. C., Olson, J. B., Lundquist, J. K., Dudhia, J., Gupta, A. K., Michalakes, J., & Barstad, I. (2012). Local and mesoscale impacts of wind farms as parameterized in a mesoscale NWP model. Monthly Weather Review, 140(9), 3017–3038.</p>

MPDATA method for non–uniform mesh

<p> </p><p><strong>MPDATA method for non–uniform mesh</strong></p><p> </p><p>Xinpeng Yuan</p><p>State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences,China </p><p>Meteorological Administration, Beijing 100081, China </p><p> </p><p><strong>Keyword:</strong> Atmospheric dynamics, MPDATA, non–uniform mesh, precision</p><p><strong>Abstract: </strong>MPDATA[1,2]（multidimensional positive definite advection transport algorithm） is proposed by Piotr K. Smolarkiewicz in 1983. This method is used to efficiently solve the advection transport problem of non-negative thermodynamic variables (such as liquid water or water vapor) in the atmospheric dynamics model. This method has been proved to be an effective numerical solution to the advection transport problem for uniform meshes. However, since there is no uniform mesh division on the sphere, the traditional MPDATA method is faced with the incompatibility problem for the non-uniform and quasi-uniform meshing of the sphere, resulting in the numerical algorithm failing to reach the designed second-order accuracy. Firstly, this paper analyzes the insufficiency of traditional MPDATA methods for non-uniform grids. That is, the incompatibility of the first-order numerical scheme and the approximation of boundary derivative.Then the MPDATA method suitable for non-uniform grid is proposed. According to the characteristics of non-uniform grid and the characteristics of well-balance[3] central grid point algorithm, the MPDATA method suitable for 1-d and 2-d complex grid structure is designed. The consistency and positivity of the algorithm are proved by mathematical analysis. Finally, the theoretical proof is verified by numerical simulation.</p><p><strong> </strong></p><p><strong>Reference</strong></p><p>[1] Smolarkiewicz P. A Simple Positive Definite Advection Scheme with Small Implicit Diffusion[J]. Monthly Weather Review. 1983.</p><p>[2] Smolarkiewicz P K, Szmelter J. MPDATA: An edge-based unstructured-grid formulation[J]. Journal of Computational Physics. 2005, 206(2): 624-649.</p><p>[3] Kurganov A, Levy D. Central-Upwind Schemes for the Saint-Venant System[J]. ESAIM: Mathematical Modelling and Numerical Analysis. 2002, 36(3): 397-425.</p><p> </p>

Quantifying the Volunteer Effort of Scientific Peer Reviewing

A survey of 310 reviewers for Monthly Weather Review addresses how much time and effort goes into the peer-review process and provides insight into how reviewers function. Using these data, the individual and collective contributions of volunteer peer reviewers to the peer-review process can be determined. Individually, respondents to the survey review an average of 2 manuscripts a year for Monthly Weather Review, 4 manuscripts a year for AMS journals, and 8 manuscripts a year in total, although some review more than 20 manuscripts a year. Each review takes an average of 9.6 h. Summing the individual contributions of the reviewers, respondents averaged 18 h yr−1 performing reviews for Monthly Weather Review, 36 h yr−1 for AMS journals, and 63 h yr−1 for all journals. The collective time that all of the reviewers put into the peer-review process for all manuscripts submitted to Monthly Weather Review for each year amounts to 362,179 h, or more than 4 years of voluntary labor valued at over $2.34 million. Nearly all respondents (95%) are comfortable with their current load, but only 30% said that they would be willing to perform more reviews. Because the number of submissions to journals has been increasing over time and is unlikely to decrease in the near future, this burden is anticipated to grow. Options for reducing the burden include using fewer reviewers per manuscript, increasing the number of unilateral decisions made by editors, and increasing the size of the reviewer pool (particularly from active retired and early-career scientists).

A Monthly Upper-Air Dataset for North America Back to 1922 from the Monthly Weather Review

Upper-air observations with kites, aircraft, and radiosondes were performed in the United States operationally since the 1890s. In this paper, the authors present a reevaluation of newly digitized monthly mean values from the Monthly Weather Review back to 1922. Data from 46 U.S. weather stations are presented with a focus on early kite and aircraft observations during the 1922–38 period. A quality assessment of the data, based on reconstructed reference series, is carried out and the quality of the monthly mean data is found to be sufficient for analysis of variability in upper-level circulation. Anomalies of upper-level temperatures from the reevaluated station data, together with surface fields, are shown for selected periods.

The Time between a Field Experiment and its Published Results

A survey of the Journal of the Atmospheric Sciences, the Journal of Applied Meteorology, and the Monthly Weather Review shows that the number of publications per year resulting from GATE (GARP Atlantic Tropical Experiment) peaked in 1980, six years after the experiment's field phase.