The first Forecasters Handbook for West Africa

Bridging the gap between rapidly moving scientific research and specific forecasting tools, Meteorology of Tropical West Africa: The Forecasters' Handbook’, gives unprecedented access to the latest science and combines this with pragmatic approaches to forecasting. It is set to change the way forecasters, researchers and students learn about tropical meteorology and will serve to drive demand for new forecasting tools. The Handbook builds upon the legacy of the AMMA project, making the latest science applicable to forecasting in the region. By bringing together, at the outset, researchers and forecasters from across the region, and linking to applications, user communities and decision-makers, the Forecasters’ Handbook provides a template for finding much needed solutions to critical issues such as building resilience to climate change in West Africa

Rainfall interception by two deciduous Mediterranean forests of contrasting stature in Slovenia

Measurements of precipitation above the canopy, throughfall and stemflow were\ud made on the south and north-facing slopes of a deciduous forest on the experimental\ud watershed of the Dragonja river in SW Slovenia. The Dragonja watershed was\ud chosen for the experimental watershed, being of interest because of intensive natural\ud reforestation in the last decades that caused a decrease in minimum and maximum\ud flows. At the same time no noticeable precipitation and temperature changes were\ud observed. Two forest plots were selected. One is located on the north-facing slope\ud (1419 m2) and the other on the south-facing slope (615 m2). Analyses and modelling\ud were made for a one-year period from October 2000 to September 2001. The leaf\ud area index (LAI) was estimated by three methods, one direct and two indirect ones.\ud The obtained values of LAI with the direct method were 6.6 and 6.9 for the south and\ud north slopes, respectively. Measurements and regression analyses gave the mean\ud annual throughfall value (± standard error) on the south plot 67.1 (± 9.6) % of gross\ud precipitation, and 71.5 (± 11.6) % on the north plot. The average stemflow values\ud were 4.5 (± 0.8) % of gross precipitation in the south plot and 2.9 (± 0.6) % in the\ud north plot. The average annual interception losses amount to 28.4 (± 4.1) and 25.4 (±\ud 4.0) % for the south and north slopes, respectively. In the study a significant influence\ud of the south-east wind was proven. With regression analyses and the classification\ud decision tree model it was established that at the events with more than 7 mm of\ud precipitation and south-east wind with a speed higher than 4 m/s an unusually low\ud amount of throughfall occurred and thus high interception losses. The analytical\ud Gash model of rainfall interception (Gash, 1979; Gash et al., 1995) was successfully\ud applied. The results of the modelling corresponded well to the observed values and\ud were within the limits of the standard error of the observed values

Interannual variability of tropospheric composition:the influence of changes in emissions, meteorology and clouds

We have run a chemistry transport model (CTM) to systematically examine the drivers of interannual variability of tropospheric composition during 1996-2000. This period was characterised by anomalous meteorological conditions associated with the strong El Nino of 1997-1998 and intense wildfires, which produced a large amount of pollution. On a global scale, changing meteorology (winds, temperatures, humidity and clouds) is found to be the most important factor driving interannual variability of NO2 and ozone on the timescales considered. Changes in stratosphere-troposphere exchange, which are largely driven by meteorological variability, are found to play a particularly important role in driving ozone changes. The strong influence of emissions on NO2 and ozone interannual variability is largely confined to areas where intense biomass burning events occur. For CO, interannual variability is almost solely driven by emission changes, while for OH meteorology dominates, with the radiative influence of clouds being a very strong contributor. Through a simple attribution analysis for 1996-2000 we conclude that changing cloudiness drives 25% of the interannual variability of OH over Europe by affecting shortwave radiation. Over Indonesia this figure is as high as 71%. Changes in cloudiness contribute a small but non-negligible amount (up to 6%) to the interannual variability of ozone over Europe and Indonesia. This suggests that future assessments of trends in tropospheric oxidizing capacity should account for interannual variability in cloudiness, a factor neglected in many previous studies

Predictability associated with extratropical transition of tropical cyclones as defined by operational ensemble prediction systems

The poleward movement of a decaying tropical cyclone often results in a rapidly-moving, explosively-deepening midlatitude cyclone. The re-intensification of the remnant tropical cyclone as an extratropical cyclone depends on the phasing between the decaying tropical cyclone and a midlatitude environment that is favorable for midlatitude cyclogenesis (Klein et al. 2001). Because of the typical rapid translation speed (Jones et al. 2003) of the decaying tropical cyclone, accurate extended-range prediction of the phasing between the remnant tropical circulation and the midlatitude environment into which it is moving is critical.This research has been supported by the Office of Naval Research, Marine Meteorology

Meteorological studies conducted by contract NONR 4071 (00) : final report

During April and August 1963 the Barbados Weather Modification Project made extensive use of whole-sky, time-lapse and conventional photography to investigate cloud and rain formation over tropical heat sources. These observations were made from land-based, ship-borne and aircraft stations. In July 1965 further photographic studies were carried out over the eastern Caribbean Sea to evaluate the effect of seeding cumulus clouds with silver iodide bombs.The Office of Naval Research under Contract Nonr-4071 (00

Survey of El Nino 1957-58 in its relation to tropical pacific meteorology

ENGLISH: The survey aims at demonstrating the close relationship between anomalies of sea temperature observed along the tropical Pacific coast of the Americas and those observed in the oceanwide tropical belt. The survey also covers the variations, from 1952 to the present, of the trade-wind circulations which prove to be responsible for the major part of the anomalies in sea surface temperature. Finally, the thermal feedback effects of the oceanic anomalies upon the large-scale circulation of the atmosphere are treated in a preliminary fashion. SPANISH: El estudio trata de demostrar la estrecha relación que existe entre las anomalías observadas de la temperatura del mar a lo largo de la costa tropical de las Américas y las observadas en la faja tropical de todo el océano. El estudio incluye también las variaciones, desde 1952 hasta el presente, de la circulación de los vientos alisios que demuestra ser responsable por la mayor parte de las anomalías de temperatura de la superficie del mar. Finalmente los efectos termales de las anomalías oceánicas sobre la circulación en gran escala de la atmósfera son tratados en forma preliminar. (PDF contains 62 pages.

Statistical Deterministic and Ensemble Seasonal Prediction of Tropical Cyclones in the Northwest Australian Region

Statistical seasonal prediction of tropical cyclones (TCs) has been ongoing for quite some time in many different ocean basins across the world. While a few basins (e.g., North Atlantic and western North Pacific) have been extensively studied and forecasted for many years, Southern Hemispheric TCs have been less frequently studied and generally grouped as a whole or into two primary basins: southern Indian Ocean and Australian. This paper investigates the predictability of TCs in the northwest Australian (NWAUS) basin of the southeast Indian Ocean (105°–135°E) and describes two statistical approaches to the seasonal prediction of TC frequency, TC days, and accumulated cyclone energy (ACE). The first approach is a traditional deterministic seasonal prediction using predictors identified from NCEP–NCAR reanalysis fields using multiple linear regression. The second is a 100-member statistical ensemble approach with the same predictors as the deterministic model but with a resampling of the dataset with replacement and smearing input values to generate slightly different coefficients in the multiple linear regression prediction equations. Both the deterministic and ensemble schemes provide valuable forecasts that are better than climatological forecasts. The ensemble approach outperforms the deterministic model as well as adding quantitative uncertainty that reflects the predictability of a given TC season

Meteorology and Cimatology: On-Line Weather Studies

Through the Virginia Earth Science Collaborative (VESC), a partnership of nine institutes of higher education, non-profit organizations, and eighty-three school divisions, a 3-credit, graduate-level meteorology course was offered six times between Spring 2006 and Fall 2007. The course, entitled Meteorology, was offered at three locations (Richmond, Abingdon, and Harrisonburg), and a local instructor facilitated each section. Funding for the course development, instructor stipends, and participant expenses (including travel, meals, and tuition) was provided through a competitive Mathematics and Science Partnership (MSP) grant funded through the federal No Child Left Behind legislation of 2001. The framework of the course was the American Meteorological Society\u27s Online Weather Studies program, which provides meteorological content and laboratory investigations, and relies heavily on the use of Internet-accessed, real-time weather data to teach meteorological topics in a distance learning format. The 115 teacher participants were required to complete text readings and written assignments, conduct laboratory investigations, design projects using real—time meteorological data, complete exams, and attend three face-to-face meetings. For the purpose of the VESC grant evaluation, pre-test and post-test data were collected on 110 of the participants which indicated an average 14.7% increase in participants‘ content knowledge and use of real-time meteorological products (weather maps, satellite images, station models, etc.) in their instructional delivery