Response to Dr Herbert Dardik

Farrando Sicilia, Jordi; Lecea, Ignasi de; Fuente Fuente, Carlos; Ribas Seix, Anna; Masana Padrós, Judit; Delgado, José L

Climatology, variability, and trends in near-surface wind speeds over the North Atlantic and Europe during 1979-2018 based on ERA5

This study presents the monthly 10‐m wind speed climatology, decadal variability and possible trends in the North Atlantic and Europe from ERA5 reanalysis from 1979 to 2018 and investigates the physical reasons for the decadal variability. Additionally, temporal time series are examined in three locations: the central North Atlantic, Finland and Iberian Peninsula. The 40‐year mean and the 98th percentile wind speeds emphasize a distinct land‐sea contrast and a seasonal variation with the strongest winds over the ocean and during winter. The strongest winds and the highest variability are associated with the storm tracks and local wind phenomena such as the mistral. The extremeness of the winds is examined with an extreme wind factor (the 98th percentile divided by mean wind speeds) which in all months is higher in southern Europe than in northern Europe. Mostly no linear trends in 10‐m wind speeds are identified in the three locations but large annual and decadal variability is evident. The decadal 10‐m wind speeds were stronger than average in the 1990s in northern Europe and in the 1980s and 2010s in southern Europe. These decadal changes were largely explained by the positioning of the jet stream and storm tracks and the strength of the north–south pressure gradient in the North Atlantic. The 10‐m winds have a positive correlation with the North Atlantic Oscillation in the central North Atlantic and Finland on annual scales and during cold season months and a negative correlation in Iberian Peninsula mostly from July to March. The Atlantic Multi‐decadal Oscillation has a moderate negative correlation with the winds in the central North Atlantic but no correlation in Finland and Iberian Peninsula. Overall, our results emphasize that while linear trends in wind speeds may show a general long‐term trend, more information on the changes is obtained by analysing long‐term variability.This study presents the monthly 10-m wind speed climatology, decadal variability and possible trends in the North Atlantic and Europe from ERA5 reanalysis from 1979 to 2018 and investigates the physical reasons for the decadal variability. Additionally, temporal time series are examined in three locations: the central North Atlantic, Finland and Iberian Peninsula. The 40-year mean and the 98th percentile wind speeds emphasize a distinct land-sea contrast and a seasonal variation with the strongest winds over the ocean and during winter. The strongest winds and the highest variability are associated with the storm tracks and local wind phenomena such as the mistral. The extremeness of the winds is examined with an extreme wind factor (the 98th percentile divided by mean wind speeds) which in all months is higher in southern Europe than in northern Europe. Mostly no linear trends in 10-m wind speeds are identified in the three locations but large annual and decadal variability is evident. The decadal 10-m wind speeds were stronger than average in the 1990s in northern Europe and in the 1980s and 2010s in southern Europe. These decadal changes were largely explained by the positioning of the jet stream and storm tracks and the strength of the north-south pressure gradient in the North Atlantic. The 10-m winds have a positive correlation with the North Atlantic Oscillation in the central North Atlantic and Finland on annual scales and during cold season months and a negative correlation in Iberian Peninsula mostly from July to March. The Atlantic Multi-decadal Oscillation has a moderate negative correlation with the winds in the central North Atlantic but no correlation in Finland and Iberian Peninsula. Overall, our results emphasize that while linear trends in wind speeds may show a general long-term trend, more information on the changes is obtained by analysing long-term variability.Peer reviewe

Winds and windstorms in northern Europe and Finland

Strong winds can cause large impacts and damage to society. Many sectors, such as wind energy, forestry and insurance, are highly affected by winds. Thus, preparedness and adaptation to winds and windstorms is essential in both weather (days) and climate (decades) time scales. The aim of this thesis is to better understand the near surface mean and extreme wind climate in northern Europe and Finland and the role of extratropical cyclones in contributing to the extreme winds. This thesis investigated the main characteristics of wind and windstorm climate in northern Europe and Finland over a 40-year period. The wind and windstorm climate was found to have large inter-annual and decadal variability and no significant linear trends. The well-known seasonal cycle was detected: winds in northern Europe are up to 30 % stronger in winter than in summer and while there are on average 5–6 windstorms per month in winter in northern Europe there are none in summer months. A more surprising result was that the number of all extratropical cyclones does not vary between seasons. Windstorms were found to be the most frequent over the Barents Sea whereas weaker extratropical cyclones occur over the land areas in northern Europe. The development and structure of strong winds in windstorms in northern Europe and Finland were examined. The results show that the strongest wind gusts associated with windstorms shift and extend from the warm sector to behind the cold front during the evolution. The cold-season (Oct–Mar) windstorms are overall stronger and spatially larger than warm-season (Apr–Sep) windstorms. For example, the central pressure is on average 9 hPa deeper and the maximum wind gust 2 ms-1 stronger in cold-season windstorms than in warm-season windstorms. Analysing a case study of storm Mauri, a damaging windstorm in Finland in September 1982, shows that an individual windstorm development can vary largely from the climate’s general concept. The case study also found that during storm Mauri the wind speeds over land areas in Finland are underestimated in the weather model by 2–13 ms-1 compared to observations, but the location of strong winds is correctly predicted. Lastly, this thesis investigated what meteorological factors affect the intensity of windstorms in northern Europe. This was studied by using an ensemble sensitivity method. The sensitivities of windstorm intensity to all studied meteorological factors were 20–75 % higher in the cold season than in the warm season. This implies that cold season windstorms are potentially better predictable than warm-season windstorms. The strongest impact to the intensity of northern Europe windstorms is from the low-level temperature gradient which is therefore an important variable to follow when forecasting windstorms. The results from this thesis highlight the importance of examining long-term inter-annual variations, instead of just linear trends, to get a broader understanding of the climate. Moreover, the results emphasize the need of both general conceptual models and individual case studies to better understand the large variety of windstorm development paths.Voimakkaat tuulet voivat aiheuttaa vaikutuksia ja tuhoja yhteiskunnalle. Tuulisuus vaikuttaa moniin aloihin, kuten tuulienergia-, metsä- ja vakuutussektoreihin. Varautuminen ja sopeutuminen tuuliin ja myrskyihin ovat näin ollen tärkeitä sekä sään (päiviä) että ilmaston (vuosikymmeniä) aikaskaaloissa. Tämän väitöskirjan tavoitteena on ymmärtää paremmin maanpinnan läheisten keski- ja äärituulten ilmastoa Pohjois-Euroopassa ja Suomessa sekä keskileveysasteiden matalapaineiden roolia äärituulten aiheuttajana. Tässä väitöskirjassa tutkittiin Pohjois-Euroopan ja Suomen tuuli- ja myrskyilmaston tyypillisiä piirteitä 40 vuoden jaksolta. Tuuli- ja myrskyilmastolle havaittiin tyypilliseksi suuri vuosien ja vuosikymmenien välinen vaihtelu ilman merkitseviä pitkänajan trendejä. Tutkimuksessa osoitettiin tiedetty kausivaihtelu: tuulet ovat Pohjois Euroopassa jopa 30 % voimakkaampia talvella kuin kesällä, ja talvikuukausina Pohjois-Euroopassa esiintyy keskimäärin 5–6 myrskyä kuukaudessa kun taas kesäkuukausina ei yhtään. Yllättävämpi tulos oli, että kaikkien matalapaineiden määrässä ei löydetty kausittaista vaihtelua. Myrskyjä havaittiin esiintyvän eniten Barentsin meren yllä kun taas heikommat matalapaineet esiintyvät Pohjois-Euroopan maa-alueilla. Työssä tutkittiin Pohjois-Euroopan myrskyihin liittyvien voimakkaiden tuulten kehittymistä ja rakennetta. Tulokset osoittavat, että voimakkaimmat myrskyihin liittyvät puuskat siirtyvät ja leviävät lämpimästä sektorista kylmän rintaman taakse myrskyn kehittymisen aikana. Kylmän vuodenajan (loka–maaliskuu) myrskyt ovat yleisesti voimakkaampia ja alueellisesti laajempia kuin lämpimän vuodenajan (huhti–syyskuu) myrskyt. Esimerkiksi myrskyn minimipaine on keskimäärin 9 hPa matalampi ja maksimipuuska 2 ms-1 voimakkaampi kylmänä kuin lämpimänä vuodenaikana. Tapaustutkimus Mauri-myrskystä, tuhoisasta myrskystä Suomessa 22.9.1982, osoittaa, että yksittäisen myrskyn kehitys voi poiketa suuresti ilmaston yleisestä kehitysmallista. Tapaustutkimuksessa selvisi myös, että säämalli aliarvioi Suomen maa-alueilla Mauri-myrskyn tuulennopeuksia 2–13 ms-1 havaintoihin verrattuna, mutta voimakkaiden tuulten sijainnit on ennustettu oikein. Viimeisimpänä väitöskirjassa tutkittiin mitkä meteorologiset tekijät vaikuttavat myrskyn voimakkuuteen Pohjois Euroopassa. Tätä tutkittiin käyttämällä nk. parviherkkyysmenetelmää. Myrskyn voimakkuuden herkkyydet kaikkiin tutkittuihin meteorologisiin tekijöihin olivat 20–75 % korkeampia kylmänä kuin lämpimänä vuodenaikana. Tämä viittaa siihen, että kylmän vuodenajan myrskyt ovat potentiaalisesti paremmin ennustettavissa kuin lämpimän vuodenajan myrskyt. Pohjois-Euroopan myrskyjen voimakkuuteen vaikuttaa eniten alailmakehän vaakasuuntainen lämpötilaero, joka täten on tärkeä seurattava muuttuja myrskyjä ennustettaessa. Tämän väitöskirjan tulokset korostavat tärkeyttä tarkastella pitkänajan vuosien välistä vaihtelua pelkkien lineaaristen trendien sijaan, jotta ilmastoa ymmärrettäisiin laajemmin. Lisäksi tulokset korostavat tarvetta sekä yleisille käsitemalleille että yksitäisille tapaustutkimuksille, jotta myrskyjen moninaisia kehityspolkuja ymmärrettäisiin paremmin

Characteristics of extratropical cyclones and precursors to windstorms in northern Europe

Peer reviewe

Winds and windstorms in northern Europe and Finland

Strong winds can cause large impacts and damage to society. Many sectors, such as wind energy, forestry and insurance, are highly affected by winds. Thus, preparedness and adaptation to winds and windstorms is essential in both weather (days) and climate (decades) time scales. The aim of this thesis is to better understand the near surface mean and extreme wind climate in northern Europe and Finland and the role of extratropical cyclones in contributing to the extreme winds. This thesis investigated the main characteristics of wind and windstorm climate in northern Europe and Finland over a 40-year period. The wind and windstorm climate was found to have large inter-annual and decadal variability and no significant linear trends. The well-known seasonal cycle was detected: winds in northern Europe are up to 30 % stronger in winter than in summer and while there are on average 5–6 windstorms per month in winter in northern Europe there are none in summer months. A more surprising result was that the number of all extratropical cyclones does not vary between seasons. Windstorms were found to be the most frequent over the Barents Sea whereas weaker extratropical cyclones occur over the land areas in northern Europe. The development and structure of strong winds in windstorms in northern Europe and Finland were examined. The results show that the strongest wind gusts associated with windstorms shift and extend from the warm sector to behind the cold front during the evolution. The cold-season (Oct–Mar) windstorms are overall stronger and spatially larger than warm-season (Apr–Sep) windstorms. For example, the central pressure is on average 9 hPa deeper and the maximum wind gust 2 ms-1 stronger in cold-season windstorms than in warm-season windstorms. Analysing a case study of storm Mauri, a damaging windstorm in Finland in September 1982, shows that an individual windstorm development can vary largely from the climate’s general concept. The case study also found that during storm Mauri the wind speeds over land areas in Finland are underestimated in the weather model by 2–13 ms-1 compared to observations, but the location of strong winds is correctly predicted. Lastly, this thesis investigated what meteorological factors affect the intensity of windstorms in northern Europe. This was studied by using an ensemble sensitivity method. The sensitivities of windstorm intensity to all studied meteorological factors were 20–75 % higher in the cold season than in the warm season. This implies that cold season windstorms are potentially better predictable than warm-season windstorms. The strongest impact to the intensity of northern Europe windstorms is from the low-level temperature gradient which is therefore an important variable to follow when forecasting windstorms. The results from this thesis highlight the importance of examining long-term inter-annual variations, instead of just linear trends, to get a broader understanding of the climate. Moreover, the results emphasize the need of both general conceptual models and individual case studies to better understand the large variety of windstorm development paths.Voimakkaat tuulet voivat aiheuttaa vaikutuksia ja tuhoja yhteiskunnalle. Tuulisuus vaikuttaa moniin aloihin, kuten tuulienergia-, metsä- ja vakuutussektoreihin. Varautuminen ja sopeutuminen tuuliin ja myrskyihin ovat näin ollen tärkeitä sekä sään (päiviä) että ilmaston (vuosikymmeniä) aikaskaaloissa. Tämän väitöskirjan tavoitteena on ymmärtää paremmin maanpinnan läheisten keski- ja äärituulten ilmastoa Pohjois-Euroopassa ja Suomessa sekä keskileveysasteiden matalapaineiden roolia äärituulten aiheuttajana. Tässä väitöskirjassa tutkittiin Pohjois-Euroopan ja Suomen tuuli- ja myrskyilmaston tyypillisiä piirteitä 40 vuoden jaksolta. Tuuli- ja myrskyilmastolle havaittiin tyypilliseksi suuri vuosien ja vuosikymmenien välinen vaihtelu ilman merkitseviä pitkänajan trendejä. Tutkimuksessa osoitettiin tiedetty kausivaihtelu: tuulet ovat Pohjois Euroopassa jopa 30 % voimakkaampia talvella kuin kesällä, ja talvikuukausina Pohjois-Euroopassa esiintyy keskimäärin 5–6 myrskyä kuukaudessa kun taas kesäkuukausina ei yhtään. Yllättävämpi tulos oli, että kaikkien matalapaineiden määrässä ei löydetty kausittaista vaihtelua. Myrskyjä havaittiin esiintyvän eniten Barentsin meren yllä kun taas heikommat matalapaineet esiintyvät Pohjois-Euroopan maa-alueilla. Työssä tutkittiin Pohjois-Euroopan myrskyihin liittyvien voimakkaiden tuulten kehittymistä ja rakennetta. Tulokset osoittavat, että voimakkaimmat myrskyihin liittyvät puuskat siirtyvät ja leviävät lämpimästä sektorista kylmän rintaman taakse myrskyn kehittymisen aikana. Kylmän vuodenajan (loka–maaliskuu) myrskyt ovat yleisesti voimakkaampia ja alueellisesti laajempia kuin lämpimän vuodenajan (huhti–syyskuu) myrskyt. Esimerkiksi myrskyn minimipaine on keskimäärin 9 hPa matalampi ja maksimipuuska 2 ms-1 voimakkaampi kylmänä kuin lämpimänä vuodenaikana. Tapaustutkimus Mauri-myrskystä, tuhoisasta myrskystä Suomessa 22.9.1982, osoittaa, että yksittäisen myrskyn kehitys voi poiketa suuresti ilmaston yleisestä kehitysmallista. Tapaustutkimuksessa selvisi myös, että säämalli aliarvioi Suomen maa-alueilla Mauri-myrskyn tuulennopeuksia 2–13 ms-1 havaintoihin verrattuna, mutta voimakkaiden tuulten sijainnit on ennustettu oikein. Viimeisimpänä väitöskirjassa tutkittiin mitkä meteorologiset tekijät vaikuttavat myrskyn voimakkuuteen Pohjois Euroopassa. Tätä tutkittiin käyttämällä nk. parviherkkyysmenetelmää. Myrskyn voimakkuuden herkkyydet kaikkiin tutkittuihin meteorologisiin tekijöihin olivat 20–75 % korkeampia kylmänä kuin lämpimänä vuodenaikana. Tämä viittaa siihen, että kylmän vuodenajan myrskyt ovat potentiaalisesti paremmin ennustettavissa kuin lämpimän vuodenajan myrskyt. Pohjois-Euroopan myrskyjen voimakkuuteen vaikuttaa eniten alailmakehän vaakasuuntainen lämpötilaero, joka täten on tärkeä seurattava muuttuja myrskyjä ennustettaessa. Tämän väitöskirjan tulokset korostavat tärkeyttä tarkastella pitkänajan vuosien välistä vaihtelua pelkkien lineaaristen trendien sijaan, jotta ilmastoa ymmärrettäisiin laajemmin. Lisäksi tulokset korostavat tarvetta sekä yleisille käsitemalleille että yksitäisille tapaustutkimuksille, jotta myrskyjen moninaisia kehityspolkuja ymmärrettäisiin paremmin

Increasing melanism along a latitudinal gradient in a widespread amphibian: local adaptation, ontogenic or environmental plasticity?

<p>Abstract</p> <p>Background</p> <p>The thermal benefits of melanism in ectothermic animals are widely recognized, but relatively little is known about population differentiation in the degree of melanism along thermal gradients, and the relative contributions of genetic <it>vs. </it>environmental components into the level of melanism expressed. We investigated variation in the degree of melanism in the common frog (<it>Rana temporaria</it>; an active heliotherm thermoregulator) by comparing the degree of melanism (i) among twelve populations spanning over 1500 km long latitudinal gradient across the Scandinavian Peninsula and (ii) between two populations from latitudinal extremes subjected to larval temperature treatments in a common garden experiment.</p> <p>Results</p> <p>We found that the degree of melanism increased steeply in the wild as a function of latitude. Comparison of the degree of population differentiation in melanism (<it>P_ST</it>) and neutral marker loci (<it>F_ST</it>) revealed that the <it>P_ST</it> ><it>F_ST</it>, indicating that the differences cannot be explained by random genetic drift alone. However, the latitudinal trend observed in the wild was not present in the common garden data, suggesting that the cline in nature is not attributable to direct genetic differences.</p> <p>Conclusions</p> <p>As straightforward local adaptation can be ruled out, the observed trend is likely to result from environment-driven phenotypic plasticity or ontogenetic plasticity coupled with population differences in age structure. In general, our results provide an example how phenotypic plasticity or even plain ontogeny can drive latitudinal clines and result in patterns perfectly matching the genetic differences expected under adaptive hypotheses.</p

Polycythemia is uncommon in dogs with chronic hypoxic pulmonary disease

Background Prolonged tissue hypoxia caused by chronic pulmonary disease is commonly regarded as an important mechanism in the development of secondary polycythemia, but little clinical data are available to support this hypothesis. Objective To study the prevalence and severity of erythrocytosis accompanying chronic hypoxic pulmonary disease in dogs. Animals Forty-seven dogs with hypoxic chronic pulmonary disease, 27 dogs with nonhypoxic chronic pulmonary disease, and 60 healthy controls. Methods Dogs with chronic pulmonary disease and chronic hypoxemia (partial pressure of arterial oxygen [PaO2] = 65%) was noted in any of the dogs. Red blood cell parameters were not associated with the severity of hypoxemia (correlation to PaO2: Erytr, r = -.14; Hb, r = -.21; Hct, r = -.14; P > .05 for all). Conclusions and Clinical Importance Polycythemia is uncommon, and usually mild if present, in dogs with chronic hypoxia caused by pulmonary disease.Peer reviewe

Turning Cones Off: the Role of the 9-Methyl Group of Retinal in Red Cones

Our ability to see in bright light depends critically on the rapid rate at which cone photoreceptors detect and adapt to changes in illumination. This is achieved, in part, by their rapid response termination. In this study, we investigate the hypothesis that this rapid termination of the response in red cones is dependent on interactions between the 9-methyl group of retinal and red cone opsin, which are required for timely metarhodopsin (Meta) II decay. We used single-cell electrical recordings of flash responses to assess the kinetics of response termination and to calculate guanylyl cyclase (GC) rates in salamander red cones containing native visual pigment as well as visual pigment regenerated with 11-cis 9-demethyl retinal, an analogue of retinal in which the 9-methyl group is missing. After exposure to bright light that photoactivated more than ∼0.2% of the pigment, red cones containing the analogue pigment had a slower recovery of both flash response amplitudes and GC rates (up to 10 times slower at high bleaches) than red cones containing 11-cis retinal. This finding is consistent with previously published biochemical data demonstrating that red cone opsin regenerated in vitro with 11-cis 9-demethyl retinal exhibited prolonged activation as a result of slowed Meta II decay. Our results suggest that two different mechanisms regulate the recovery of responsiveness in red cones after exposure to light. We propose a model in which the response recovery in red cones can be regulated (particularly at high light intensities) by the Meta II decay rate if that rate has been inhibited. In red cones, the interaction of the 9-methyl group of retinal with opsin promotes efficient Meta II decay and, thus, the rapid rate of recovery

A calibration method for broad-bandwidth cavity enhanced absorption spectroscopy performed with supercontinuum radiation

An efficient calibration method has been developed for broad-bandwidth cavity enhanced absorption spectroscopy. The calibration is performed using phase shift cavity ring-down spectroscopy, which is conveniently implemented through use of an acousto-optic tunable filter (AOTF). The AOTF permits a narrowband portion of the SC spectrum to be scanned over the full high-reflectivity bandwidth of the cavity mirrors. After calibration the AOTF is switched off and broad-bandwidth CEAS can be performed with the same light source without any loss of alignment to the set-up. We demonstrate the merits of the method by probing transitions of oxygen molecules O-2 and collisional pairs of oxygen molecules (O-2)(2) in the visible spectral range