Marina Peña-Gallardo

Recent changes of relative humidity: regional connections with land and ocean processes

We analyzed changes in surface relative humidity (RH) at the global scale from 1979 to 2014 using both observations and the ERA-Interim dataset. We compared the variability and trends in RH with those of land evapotranspiration and ocean evaporation in moisture source areas across a range of selected regions worldwide. The sources of moisture for each particular region were identified by integrating different observational data and model outputs into a Lagrangian approach. The aim was to account for the possible role of changes in air temperature over land, in comparison to sea surface temperature (SST), but also the role of land evapotranspiration and the ocean evaporation on RH variability. The results demonstrate that the patterns of the observed trends in RH at the global scale cannot be linked to a particular individual physical mechanism. Our results also stress that the different hypotheses that may explain the decrease in RH under a global warming scenario could act together to explain recent RH trends. Albeit with uncertainty in establishing a direct causality between RH trends and the different empirical moisture sources, we found that the observed decrease in RH in some regions can be linked to lower water supply from land evapotranspiration. In contrast, the empirical relationships also suggest that RH trends in other target regions are mainly explained by the dynamic and thermodynamic mechanisms related to the moisture supply from the oceanic source regions. Overall, while this work gives insights into the connections between RH trends and oceanic and continental processes at the global scale, further investigation is still desired to assess the contribution of both dynamic and thermodynamic factors to the evolution of RH over continental regions.

Average annual and seasonal Land Surface Temperature, Spanish Peninsular

ABSTRACT The first long-term Land Surface Temperature (LST) maps for the Peninsular Spain at annual and seasonal time scales for 1981–2015 is presented in this work. A robust protocol for correcting and calibrating NOAA-AVHRR images and computing LST datasets at the spatial resolution of 1.1 km has been used. Simultaneously, maximum air temperature (Tmax) maps at the same spatial resolution have been produced using data from meteorological stations. The comparison between the two datasets resulted in statistically significant spatial correlations at annual and seasonal scales. Finally, the Normalized Difference Vegetation Index (NDVI) data were also compared with the obtained LST datasets and the results showed significant negative correlations between the two variables, especially in summer.

Global Assessment of the Standardized Evapotranspiration Deficit Index (SEDI) for Drought Analysis and Monitoring

The dataset contains one zip file corresponding to the SEDI. The format of the file is netCDF3. The file contains 1440 longitudes, 720 latitudes and 444 times (from January 1980 to December 2016). Projection is Geographic (WGS84). The SEDI is in standardized units. The dataset is made available under the Open Database License. Any rights in individual contents of the database are licensed under the Database Contents License. Please, read the full ODbL 1.0 license text for the exact terms that apply. Users of the dataset are free to: Share: copy, distribute and use the database, either commercially or non-commercially. Create: produce derivative works from the database. Adapt: modify, transform and build upon the database. Under the following conditions: Attribution: You must attribute any public use of the database, or works produced from the database. For any use or redistribution of the database, or works produced from it, you must make clear to others the license of the original database. Share-Alike: If you publicly use any adapted version of this database, or works produced from an adapted database, you must also offer that adapted database under the ODbL.

Seasonal and annual daily precipitation risk maps for the Andean region of Peru

We develop for the first time maps of annual and seasonal extreme precipitation risk in the Andean region of Peru. For this purpose, we used the complete daily precipitation records existing in Peru. In each meteorological station, we obtained series of events of de-clustered daily intensity, total precipitation duration, total magnitude and dry-spell length. Using a peak-overthreshold approach we fitted the annual and seasonal series of these variables to a GeneralizedPareto distribution, obtained the distribution parameters and validated the performance of different thresholds to obtain reliable estimations of the precipitation probability. The parameters obtained in the different meteorological stations were mapped using a universal krigging approach using the elevation and the distance to the ocean as co-variables. Maps of parameters were validated using a jack-knife approach and maximum expected precipitation intensity, magnitude, duration and dryspell length estimated for a period of 25 and 50 years. The reliability of the spatial methodology was validated comparing observed precipitation and estimated by the spatial modelling in the different stations.