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Precipitation forecasts made by Numerical Weather Prediction (NWP) models are typically verified using precipitation gauge observations that are often prone to the wind‐induced undercatch of solid precipitation. Therefore, apparent model biases in solid precipitation forecasts may be due in part to the measurements and not the model. To reduce solid precipitation measurement biases, adjustments in the form of transfer functions were derived within the framework of the World Meteorological Organization Solid Precipitation Inter‐Comparison Experiment (WMO‐SPICE). These transfer functions were applied to single‐Alter shielded gauge measurements at selected SPICE sites during two winter seasons (2015–2016 and 2016–2017). Along with measurements from the WMO automated field reference configuration at each of these SPICE sites, the adjusted and unadjusted gauge observations were used to analyze the bias in a Global NWP model precipitation forecast. The verification of NWP winter precipitation using operational gauges may be subject to verification uncertainty, the magnitude and sign of which varies with the gauge‐shield configuration and the relation between model and site‐specific local climatologies. The application of a transfer function to alter‐shielded gauge measurements increases the amount of solid precipitation reported by the gauge and therefore reduces the NWP precipitation bias at sites where the model tends to overestimate precipitation, and increases the bias at sites where the model underestimates the precipitation. This complicates model verification when only operational (non‐reference) gauge observations are available. Modelers, forecasters, and climatologists must consider this when comparing modeled and observed precipitation.

Presentación realizada en la 3rd European Nowcasting Conference, celebrada en la sede central de AEMET en Madrid del 24 al 26 de abril de 2019.

The Solid Precipitation Intercomparison Experiment (SPICE) was conducted as an internationally coordinated project, initiated and guided by the Commission for Instruments and Methods of Observation (CIMO) of the World Meteorological Organization (WMO). The SPICE field experiments took place between 2013 and 2015, with a preparatory stage during the winter of 2012/13. SPICE was carried out as a major international effort, and has been remarkable for the diversity of organizations which hosted SPICE tests, contributed with instruments, and were engaged in the data analysis and the derivation of results. In addition to National Meteorological and Hydrological Services, research organizations, academia, and the private sector played active roles and made unique contributions. Field experiments were conducted at twenty sites located in fifteen countries, on all continents except Africa and Antarctica, as outlined in Section 2 of this report. The instrument manufacturing community made a significant contribution to SPICE, as more than twenty instrument manufacturers provided instruments measuring precipitation amount, snow depth, and snow water equivalent. Each instrument model was tested on one or more sites in different climate regimes and over a large range of environmental conditions, providing a solid foundation for the results presented in this report.

Comunicación presentada en: TECO-2018 (Technical Conference on Meteorological and Environmental Instruments and Methods of Observation) celebrada en Amsterdam, del 8 al 11 de octubre de 2018. The Global Cryosphere Watch (GCW) is being developed by the WMO as a mechanism for providing dependable data, information, and analysis on the past, current, and future state of the cryosphere. To achieve its goals, GCW promotes consistent and sustainable measurements, of demonstrated quality, of all cryospheric components such as solid precipitation, snow, glaciers and ice caps, ice sheets, ice shelves, icebergs, sea ice, lake and river ice, and permafrost and seasonally frozen ground. As part of the GCW Observations Working Group, a Best Practices team was tasked with compiling an authoritative guide on measurement best practices for cryospheric variables for use at the GCW CryoNet stations as well as broader applications involving cryospheric observations. Recognizing the complexity and diversity of this task, the first priority has been given to the development of best practices for snow, sea ice, and glaciers. The intent of the guide proposed by GCW is to fill a void where current measurement guidelines are incomplete or fragmented and to compile and update existing measurement procedures to reflect current technologies and associated recommendations. For example, results from the recently completed WMO Solid Precipitation Inter-Comparison Experiment (SPICE) are incorporated to add recommendations on the automated measurement of snow on the ground. The Guide for the Measurement of Cryospheric Variables will include specific chapters for each component of the cryosphere and a general chapter reflecting broader aspects of cryosphere observations. These will be published in conjunction with the Guide to Meteorological Instruments and Methods of Observation, WMO-No. 8, as it evolves to broaden its scope to include the full spectrum of observations within the context of the Integrated Global Observing System. This will ensure that the information will be widely accessible and used by the community. This presentation will provide an introduction to the new Guide for the Measurement of Cryospheric Variables and most recent developments.

Comunicación presentada en: TECO-2018 (Technical Conference on Meteorological and Environmental Instruments and Methods of Observation) celebrada en Amsterdam, del 8 al 11 de octubre de 2018.

Presentación realizada en: American Meteorological Society Annual Meeting (2017) celebrado en Seattle (Washington) del 22 al 26 de enero de 2017.

The opening chapter of this thesis is split in two with part one providing a summary of the existing methods for palladium-catalysed oxypalladation reactions resulting in the synthesis of oxygen containing heterocycles. Part two focuses on a niche area of palladium catalysis. Here, palladium-catalysed isohypsic reactions, in which the oxidation state of the palladium does not change throughout the entire catalytic cycle, are described and summarised. Chapter 2 describes the extension of the heteroallylation reaction to incorporate the synthesis of lactones and the pursuit of an enantioselective oxyallylation reaction. The oxyallylation reaction in the synthesis of lactones was successfully applied to include five- and six- membered lactone rings in good yields, with the first enantioselective oxyallylation reaction being developed. Building upon this work, a copper-mediated oxyallylation reaction was developed. Additionally, a palladium-catalysed arylallylation reaction and C-H−cyclisation reaction were pursued. Ensuing work, detailed in chapter 3, focused on the development of a novel isohypsic−redox sequence, combining both the palladium-catalysed isohypsic heteroallylation reaction with more traditional redox chemistry. The transformations developed give rise to the synthesis of heterocycles with complex functionality both quickly and efficiently using the one palladium source. Experimental procedures and data are summarised in Chapter 4.

Within the framework of the WMO-SPICE (Solid Precipitation Intercomparison Experiment) at the Formigal-Sarrios test site located in the Pyrenees mountain range of Spain, the Thies tipping bucket precipitation gauge was assessed against the SPICE reference. The Thies gauge is the most widely-used precipitation gauge by the Spanish Meteorological State Agency (AEMET) for the measurement of all precipitation types, including snow. It is therefore critical that its performance be characterized. The first objective of this study is to derive transfer functions based on the relationships between catch ratio and wind speed and temperature. Multiple linear regression was applied to 1 h and 3 h accumulation periods, confirming that wind is the most dominant environmental variable affecting the gauge catch efficiency, especially during snowfall events. At wind speeds of 1.5 m s-1 the average catch ratio was 0.7. At 3 m s-1 , the average catch ratio was 0.5, and was even lower for temperatures below -2ºC and decreased to 0.2 or less for higher wind speeds. Following this, this study outlines two areas in Northern Spain that exhibit different catch ratios under weather conditions leading to snowfall events, highlighting the importance of how the precipitation gauge behaves in various conditions.

Comunicación presentada en: TECO-2016 (Technical Conference on Meteorological and Environmental Instruments and Methods of Observation) celebrada en Madrid, del 27 al 30 de septiembre de 2016. One of the objectives of the WMO Solid Precipitation Intercomparison Experiment (SPICE) was to assess the performance and capabilities of automated sensors for measuring snow on the ground (SoG), including sensors that measure snow depth and snow water equivalent (SWE). The intercomparison focused on five snow depth sensors (models SHM30, SL300, SR50A, FLS-CH 10 and USH-8) and two SWE sensors (models CS725 and SSG1000) over two winter seasons (2013/2014 and 2014/2015). A brief discussion of the measurement reference(s) and an example of the intercomparisons are included. Generally, each of the sensors under test operated according to the manufacturer’s specifications and compared well with the site references, exhibiting high correlations with both the manual and automated reference measurements. The use of natural and artificial surface targets under snow depth sensors were examined in the context of providing a stable and representative surface for snow depth measurements. An assessment of sensor derived measurement quality and sensor return signal strength, where available as an output option, were analysed to help explain measurement outliers and sources of uncertainty with the goal of improving data quality and maximizing the sensor capabilities. Finally, where possible, relationships are established between the gauge measurement of solid precipitation and the measurement of snow on the ground. This paper will provide a brief summary of these results with more detail included in the WMO SPICE Final Report.

Comunicación presentada en: TECO-2016 (Technical Conference on Meteorological and Environmental Instruments and Methods of Observation) celebrada en Madrid, del 27 al 30 de septiembre de 2016. Although precipitation has been measured for many centuries, precipitation measurements are still beset with significant biases and errors. Solid precipitation is particularly difficult to measure accurately, and biases between winter-time precipitation measurements from different measurement networks or different regions can exceed 100%. Using precipitation gauge results from the WMO Solid Precipitation Intercomparison Experiment (WMO-SPICE), errors in precipitation measurement caused by gauge uncertainty, spatial variability in precipitation, hydrometeor type, and wind are quantified. The methods used to calculate gauge catch efficiency and correct known biases are described briefly. Transfer functions describing catch efficiency as a function of air temperature and wind speed are also presented. In addition, the biases and errors associated with the use of a single transfer function to correct gauge undercatch at multiple sites are discussed.