Aspectes bioclimàtics del carst de Mallorca

[cat] El clima de Mallorca, mediterrani, amb temperatures entre suaus i càlides durant tot l’any (mitjana anual de 16,6ºC), permet una notable activitat dels processos càrstics; no tan intensa com a les zones tropicals, però superior a la de zones mes fredes. Damunt aquest nivell general d'activitat es superposen pautes de variació espacials i temporals, degudes a la gran variabilitat dels elements climàtics, principalment de la precipitació. Aquesta presenta valors que oscil·len entre els 1.400 mm, a la Serra de Tramuntana, i quantitats al voltant dels 300 mm a I'extrem meridional de l’illa.[eng] The climate in Mallorca, typically Mediterranean, with temperatures between mild and bot throughout the year (annual average of 16.6 OC), allows a remarkable activity of karstic processes; not so intense as in the tropical areas, but superior to colder areas. Above this general level of activity spatial and temporary variation patterns are superposed, due to the great variability of climatic elements, mainly from precipitation. This shows values that range from 1,400 mm, in Serra de Tramuntana mountain range, to around 300 mm in the southern end of the island

Cálculo de evapotranspiraciones potenciales mensuales en Baleares por el método de Linacre

Abstract not availabl

Croatian high‑resolution monthly gridded dataset of homogenised surface air temperature

Homogenised climatological series and gridded data are the basis for climate monitoring and climate change detection. Considering this, monthly mean temperatures from 122 Croatian stations were homogenised, and high-resolution monthly gridded data were developed for the 1981–2018 period. Homogenisation needs to be performed on stations from the same climate region; therefore, hierarchical clustering is introduced to defne those climate regions in Croatia. The breaks of homogeneity were detected by the standard normal homogeneity test on 54 stations. Regression kriging was applied to produce monthly grids for each month in the analysed period. The quality of the interpolation assessed by leave-one-out cross-validation resulted in a root mean square error of 0.7 °C. The quality of spatial interpolation is supplemented with normalised error maps. The derived homogenised station data and monthly grids are necessary for national climate monitoring, the production of climate normals and the estimation of trends. After 1999, average annual anomalies from the 30-year climate standard normal 1981–2010 were positive and up to 1.4 °C warmer than the average and only occasionally negative. The measured amount, sign and signifcance of the trend were accurately captured on the trend maps calculated from the monthly maps. Signifcant strong warming was observed and mapped over the entire Croatian territory in April, June, July, August and November. It was stronger inland than on the coast. Annual trends were signifcant and ranged from 0.3 °C/decade to 0.7 °C/ decade. There was no observational evidence of enhanced elevation-dependent warming over elevations from 750 to 1594 m.Research of MPT was supported by employer, Croatian Meteorological and Hydrological Service, and by the project UKV − Carstic Coastal Water Management Endangered by Climate Changes (KK.05.1.1.02.0022). Open access funding is provided by Croatian Meteorological and Hydrological Service

Variabilidad de las tendencias de las temperaturas e impacto en su comunicación al público: ejemplo en las Islas Baleares

Ponencia presentada en: XII Congreso de la Asociación Española de Climatología celebrado en Santiago de Compostela entre el 19 y el 21 de octubre de 2022.[ES]Hacia comienzos de 2021 aparecieron dos mensajes contradictorios en sendos medios de Baleares, afirmando uno de ellos que el archipiélago lideraba el calentamiento climático en España mientras que el otro anunciaba que Baleares era una de las regiones donde menos había subido la temperatura desde 1961. Como ambos medios decían basarse en trabajos publicados por instituciones científicas, esta contradicción no podía sino generar desconfianza en el público receptor de estos mensajes. El problema parece residir en que el cálculo de las tendencias en las series climáticas (temperaturas en este caso) puede arrojar resultados muy diferentes según el periodo utilizado, el número de series y si éstas se han sometido previamente a un proceso de homogeneización o no. En este trabajo revisamos los distintos valores de las tendencias de la temperatura en Baleares publicadas en el pasado y las comparamos con nuevos cálculos actualizados hasta 2020, tanto de series observadas y promedios de retícula como de reanálisis. Los diferentes resultados obtenidos suscitan la cuestión de cómo comunicar estas tendencias y sus incertidumbres al público sin menoscabar su credibilidad en el actual contexto de preocupación por el cambio climático.[EN]Two contradictory messages appeared around the beginning of 2021 in two Balearic media. One of them claimed this archipelago was leading the climate warming in Spain, while the other advertised that the Balearic Islands were one of the regions where the temperature had risen the least since 1961. As both media claimed to be based on works published by scientific institutions, this contradiction can only generate distrust in the public receiving these messages. The problem seems to be that the calculation of the trends of climatic series (temperatures in this case) can yield very different results depending on the period used, the number of series and whether or not they have previously undergone a homogenization process. In this work we review the different values of the temperature trends in the Balearic Islands published in the past and compare them with new calculations updated until 2020, both from observed series and grid averages and from reanalysis. The different results obtained raise the question of how to communicate these trends and their uncertainties to the public without undermining their credibility in the current context of concern about climate change

A marked interannual variability of haze linked to particulate sources and meteorological conditions in Tehran (Iran), 1990-2020

This research assessed for the first time the spatio-temporal changes of haze pollution (NHAZEs) and its relationship with levels of gaseous pollutants and meteorological conditions over Tehran metropolis (Iran) for 1990-2020. The results showed a significant decreasing trend of NHAZEs annually and in winter, along with a significant increasing trend in the horizontal visibility. However, a marked interannual variability linked to changes in PM2.5 concentrations and the influence of meteorological conditions was detected, which explained 65% and 30% of the NHAZEs variances, respectively. We found that the increasing trend of wind speed annually and in winter is the principal driver behind the decrease in NHAZEs and the increase in visibility; as winds control the movement and dispersion of air pollution. In relation to gaseous pollutants, a case study showed that the highest concentrations of PM2.5 and NHAZEs were recorded under high levels of SO2, CO, and NO2, and low levels of O3, which mainly occurred under stable anticyclonic circulations. Spatially, the NHAZEs mostly affected the western, southwestern, central, and some parts of the northern of Tehran metropolis, because of the location of industries, traffic, and lack of green areas

Opposite trends of sea‑breeze speeds and gusts in Eastern Spain, 1961–2019

Most studies on wind variability have deepened into the stilling vs. reversal phenomena at global to regional scales, while the long-term changes in local-scale winds such as sea-breezes (SB) represent a gap of knowledge in climate research. The state-of-the-art of the wind variability studies suggests a hypothetical reinforcement of SB at coastal stations. We first developed a robust automated method for the identification of SB days. Then, by using homogenized wind observations from 16 stations across Eastern Spain, we identified 9,349 episodes for analyzing the multidecadal variability and trends in SB speeds, gusts and occurrence for 1961–2019. The major finding is the opposite trends and decoupled variability of SB speeds and gusts: the SB speeds declined significantly in all seasons (except for winter), and the SB gusts strengthened at the annual scale and in autumn–winter, being most significant in autumn. Our results also show that the SB occurrence has increased across most of Eastern Spain, although presenting contrasting seasonal trends: positive in winter and negative in summer. We found that more frequent anticyclonic conditions, NAOI + and MOI + are positively linked to the increased winter occurrence; however, the causes behind the opposite trends in SB speeds and gusts remain unclear. The SB changes are complex to explain, involving both large-scale circulation and physical-local factors that challenge the understanding of the opposite trends. Further investigation is needed to assess whether these trends are a widespread phenomenon, while climate models could simulate the drivers behind these decoupled SB changes in a warmer climate.This research was funded by the following projects: IBER-STILLING (RTI2018-095749-A-I00, MCIU/AEI/FEDER,UE); and VENTS (GVA-AICO/2021/023). C.A.M was granted by Ramon y Cajal fellowship (RYC-2017–22830), and supported by a 2021 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation

Small-scale surface heterogeneity and potential inhomogeneities in temperature time series: a case study

Measurements in seven sites in the Campus of the University of the Balearic Islands (UIB; Mallorca, Spain) during an experimental campaign to study the contribution of local surface heterogeneities on the surface energy budget at one point have been used to characterize the differences in extreme daily temperatures between the sites during a summer month. Absolute temperature differences in this month reached up to 1.92 (with a median of 0.73) and 2.02 (median of 1.21)°C for daily maximum and minimum, respectively. Higher differences in the minimum temperature can be attributed to the stably stratified and weak turbulent conditions at night that enhance local differences in the surface energy fluxes, especially in an area with strong variability of the surface characteristics like the UIB Campus. Instead, during daytime, maximum temperature differences are smoothed due to the convection and the horizontal advection due to the sea-breeze. Two sites with longer records allowed to study the seasonal variations of these differences, which were substantially lower in the colder months. These results suggest that relocation of observatories, even at distances as short as 200 m, may introduce important inhomogeneities in the temperature series. Therefore, raw values of series from nearby stations should not be used to infill missing data in other series without adequate statistical adjustments.This work was part of of the research project grants CGL2015-65627-C3-1-R and RTI2018- 098693-B-C31 funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe

Climatology of near-surface wind speed from observational, reanalysis and high-resolution regional climate model data over the Tibetan Plateau

As near-surface wind speed plays a role in regulating surface evaporation and thus the hydrological cycle, it is crucial to explore its spatio-temporal characteristics. However, in-situ measurements are scarce over the Tibetan Plateau, limiting the understanding of wind speed climate across this high-elevation region. This study explores the climatology of near-surface wind speed over the Tibetan Plateau by using for the frst time homogenized observations together with reanalysis products and regional climate model simulations. Measuring stations across the center and the west of the plateau are at higher elevations and display higher mean and standard deviation, confrming that wind speed increases with increasing altitude. By exploring wind characteristics with a focus on seasonal cycle through cluster analysis, three regions of distinct wind regimes can be identifed: (1) the central Tibetan Plateau, characterized by high elevation; (2) the eastern and the peripheral areas of the plateau; and (3) the Qaidam basin, a topographic depression strongly infuenced by the blocking efect of the surrounding mountainous terrain. Notably, the ERA5 reanalysis, with its improvements in horizontal, vertical, and temporal spacing, model physics and data assimilation, demonstrates closer agreement to the measured wind conditions than its predecessor ERA-Interim. It successfully reproduces the three identifed wind regimes. However, the newest ERA5-Land product does not show improvements compared to ERA5, most likely because they share most of the parametrizations. Furthermore, the two dynamical downscalings of ERA5 analyzed here fail to capture the observed wind statistics and exhibit notable biases and discrepancies also when investigating the diurnal variations. Consequently, these high-resolution downscaling products do not show add value in reproducing the observed climatology of wind speed compared to ERA5 over the Tibetan Plateau

Near-surface wind speed trends and variability over the Antarctic Peninsula, 1979–2022

Near-Surface Wind Speed (SWS) is a crucial but less studied climate variable in the northern Antarctic Peninsula (AP). This research evaluates, for the first time, 44 years (i.e., 1979–2022) of SWS trends and variability across the AP using two data sources: (i) observational data from quality-controlled and homogenized meteorological stations, and (ii) reanalysis data from ERA5; the accuracy of this product strongly depends on each station with an overall underestimation of observed SWS. Annual trends in observed SWS exhibit a positive trend, being statistically significant in autumn and spring, with a marked intraanual and spatial variability in the sign and magnitudes across the AP. In addition, the multidecadal variability of observed SWS showed a general positive trend until ∼2001 (varying between 1993 and 2007 depending on each season), followed by a period of slowdown in the last two decades. Over the AP, SWS changes are mainly driven by two principal modes of atmospheric variability: i.e., mainly the Southern Annular Mode (SAM) and, secondarily, by the El Niño-Southern Oscillation (ENSO). Overall, positive trends in SWS could be partly associated with the increase and poleward shift of the westerlies due to the positive trend of the SAM index. However, as previous studies pointed out for air temperature and precipitation, we found a non-stationary and complex relationship of these modes with SWS changes. This research addresses the gap in SWS changes and variability in the AP and surrounding Southern Ocean and the influence of the atmospheric circulation, a hotspot area in climate change research.This research was funded by the following projects: IBER-STILLING ( RTI2018-095749-A-I00, MCIU/AEI/FEDER,UE); VENTS (GVA-AICO/2021/023) and the CSIC Interdisciplinary Thematic Platform (PTI) Clima (PTI+ CLIMA). M. A-M was supported with a FPU grant ( FPU21/03748) from the “Ministerio de Universidades