This thesis is focused on the aerosols and clouds optical properties and the effects that these parameters have on the solar radiation transfer in the atmosphere. The first chapter provides a brief description of the basic concepts of radiative transfer. The radiative transfer theory is described, along with various approximations, used to address specific atmospheric transfer problems. The atmospheric constituents, which are of interest of this thesis, aerosols and clouds, are described, in terms of their types and radiative properties and the main aspects of the scattering and absorption that they induce on the solar radiation, are provided. The second chapter provides a description of the networks, models and satellite instruments, whose data were used in this thesis, along with a description of the radiative transfer model, used for the simulations. Chapter three focuses on the aerosol optical properties in the ultraviolet and visible wavelength ranges, in the Mediterranean. Three datasets, from ground-based stations, global aerosol models and satellite instruments, are used to simulate the corresponding irradiances in the UV and VIS, in eight stations in the Mediterranean basin. Data from AERONET, AeroCom and MODIS are used and the differences on the modeled irradiances, which arise from the different aerosol optical properties provided by each dataset, are examined. The irradiance simulations are performed with the libRadtran radiative transfer model. The MODIS aerosol optical depth climatology shows better agreement with AERONET data. The highest difference in the monthly average values is equal to 0.09 at 550nm, while the differences between the AERONET and the AeroCom climatologies reach 0.25 and 0.15 in the UV and VIS wavelengths respectively. As a result, the AERONET modeled VIS and UV irradiances are closer to MODIS, with the absolute differences in average values reaching 6%, while absolute differences with AeroCom irradiances can reach up to 12%. The differences are higher in areas affected by desert dust aerosols. In chapter four, the aerosol direct effect on the UV solar irradiance, is examined, at a typical West European site. Measurements from a Brewer instrument, operating at the site, are used, along with model simulations, provided from libRadtran, to estimate the aerosol forcing efficiency in the 300-360 nm spectral region and in the UV-B region of 300-315nm. Instrument measurements and model calculations are subsequently used to derive the aerosol single scattering albedo at low UV-A and at UV-B wavelengths. In the 300-360 nm spectral region, the highest values were revealed at 30o (-6.9 ± 0.9 W/m2), while at 60o the RFE was almost 2.5 times lower (-2.7 ±0.1 W/m2). In the UV-B region (300-315nm), the RFE value at 60o and 30o was estimated to be equal to -0.069 ±0.005 W/m2 and -0.35 ±0.04 W/m2, respectively. The estimated monthly averages of the Brewer single scattering albedo at 320 nm are in very close agreement (within ±0.01) with measurements at 440nm from a collocated CIMEL sunphotometer. Chapter five focuses on the aerosol effect on the Direct Normal Irradiance, in the area of Europe. Data from the MODIS satellite instrument, AERONET network and model simulations with SBDART, are used to calculate the daily amount of Direct Normal Irradiance received in the European continent, with a spatial resolution of 1°x1°, for a 13-year period. The clear-sky aerosol radiative forcing is calculated and possible variations in the received Direct Normal Irradiance, during the 13-year studied period, are examined. The clear-sky aerosol radiative forcing on Direct Normal Irradiance is high in areas influenced by desert dust and intense anthropogenic activities, such as the Mediterranean basin and the Po Valley in Italy. In May, the attenuation from aerosols, over these areas, can reach values up to 35% and 35-45%, which corresponds to 4 and 4.5-6 kWh/m2 per day, respectively. The Direct Normal Irradiance received, seems to have increased during the recent period, due to the decreasing trend of aerosol load, over many parts of Europe. The largest increases are around 6 to 12%, which correspond to an amount of 0.5 to 1.25 more kWh/m2 received per day. Finally, chapter six focuses on the retrieval of solar irradiance on the ground, based on satellite-derived cloud data. The SEVIRI instrument, onboard the MSG satellites, is used to provide data regarding the cloud modification factor. These data are used, along with model simulations, performed with libRadtran, to derive the global solar irradiance incident on a horizontal surface, a surface with a tilted orientation and the direct normal irradiance. The study focuses on the area of Greece and the work is part of the Hellenic Network for Solar Energy, developed to support solar energy applications. The daily amount of solar energy, as well as the monthly and annual sums, are estimated, during an 11-year period and a monthly climatology is derived. Results are compared with measurements from various ground stations in Greece. Comparison shows a general good agreement between satellite and stations data, with the highest differences occurring in cases of broken cloud conditions or very thick clouds. Solar energy collected from surfaces under tilted orientations can provide 15-25 % higher amounts than horizontal surfaces. In Greece, the highest collected monthly solar energy values are found during summer months, in Southern Peloponnese, Crete and the Cyclades islands, and exceed 250 kWh/m2. / Η παρούσα διατριβή ασχολείται με τις οπτικές ιδιότητες των αιωρούμενων σωματιδίων και των νεφών και τις επιδράσεις που αυτές έχουν στη διάδοση της ηλιακής ακτινοβολίας στην ατμόσφαιρα. Το πρώτο κεφάλαιο παρέχει μια σύντομη περιγραφή των βασικών αρχών που διέπουν τη διάδοση της ηλιακής ακτινοβολίας. Η θεωρία της διάδοσης της ακτινοβολίας περιγράφεται, μαζί με διάφορες προσεγγίσεις, που χρησιμοποιούνται για τη λύση συγκεκριμένων προβλημάτων στις ατμοσφαιρικές επιστήμες. Τα συστατικά της ατμόσφαιρας, που είναι άμεσου ενδιαφέροντος σε αυτήν τη διατριβή, τα αιωρούμενα σωματίδια και τα νέφη, περιγράφονται, με βάση τους τύπους τους και τις οπτικές τους ιδιότητες, ενώ περιγράφονται ακόμα οι βασικές αρχές της σκέδασης και της απορρόφησης, μέσω των οποίων επηρρεάζουν τη διάδοση της ηλιακής ακτινοβολίας. Το δεύτερο κεφάλαιο παρέχει μια περιγραφή των επίγειων δικτύων, μοντέλων και δορυφορικών οργάνων, των οποίων τα δεδομένα χρησιμοποιήθηκαν, για τη διεκπαιρέωση αυτής της διατριβής, μαζί με την περιγραφή του μοντέλου διάδοσης της ακτινοβολίας, που χρησιμοποιήθηκε για τους θεωρητικούς υπολογισμούς. Το τρίτο κεφάλαιο επικεντρώνεται στις οπτικές ιδιότητες των αιωρούμενων σωματιδίων, στο υπεριώδες και ορατό κομμάτι του ηλεκτρομαγνητικού φάσματος, στην Μεσόγειο. Τρεις ξεχωριστές βάσεις δεδομένων, από επίγειους σταθμούς, μοντέλα και δορυφορικά όργανα, χρησιμοποιούνται για τον υπολογισμό της ακτινοβολίας στο υπεριώδες και ορατό, σε οχτώ σταθμούς στην περιοχή της Μεσογείου. Χρησιμοποιούνται δεδομένα από το AERONET, το AeroCom και το MODIS και μελετούνται οι διαφορές στις υπολογιζόμενες, από το μοντέλο, ακτινοβολίες, οι οποίες προκύπτουν από τις διαφορές στις οπτικές ιδιότητες των αιωρούμενων σωματιδίων, που παρέχονται από κάθε βάση δεδομένων. Οι ακτινοβολίες υπολογίζονται με το μοντέλο διάδοσης ακτινοβολίας libRadtran. Τα δεδομένα του MODIS βρίσκονται σε καλύτερη συμφωνία με αυτά του AERONET, με τη μέγιστη διαφορά στο οπτικό βάθος, στα 550 nm, να είναι ίση με 0.09, ενώ οι αντίστοιχες διαφορές με το AeroCom υπολογίζονται στα 0.25 και 0.15, για το υπεριώδες και ορατό αντίστοιχα. Ως αποτέλεσμα, οι απόλυτες διαφορές στις υπολογιζόμενες ακτινοβολίες, μεταξύ AERONET και MODIS υπολογίζονται γύρω στο 6%, ενώ αυτές που αφορούν την κλιματολογία AeroCom φτάνουν το 12%. Οι μεγαλύτερες διαφορές αφορούν περιοχές που επηρεάζονται από σωματίδια ερημικής σκόνης. Στο τέταρτο κεφάλαιο, η άμεση επίδραση των αιωρούμενων σωματιδίων, στην υπεριώδη ακτινοβολία, μελετάται, για μια τυπική περιοχή της Δυτικής Ευρώπης. Μετρήσεις από ένα όργανο Brewer, που λειτουργεί στην περιοχή και θεωρητικοί υπολογισμοί με το μοντέλο libRadtran, χρησιμοποιούνται για τον υπολογισμό της ικανότητας κλιματικού εξαναγκασμού των αιωρούμενων σωματιδίων, στο φάσμα 300-360 nm και στο UV-B φάσμα των 300-315nm. Μετρήσεις από το όργανο και θεωρητικοί υπολογισμοί, χρησιμοποιούνται στη συνέχεια για τον υπολογισμό της ανακλαστικότητας μεμονωμένης σκέδασης των αιωρούμενων σωματιδίων, σε χαμηλά UV-A και σε UV-B μήκη κύματος. Στο φάσμα 300-360 nm, οι μεγαλύτερες τιμές της ικανότητας κλιματικού εξαναγκασμού, παρατηρούνται στις 30o (-6.9 ± 0.9 W/m2), ενώ στις 60o οι τιμές είναι σχεδόν 2.5 φορές χαμηλότερες (-2.7 ±0.1 W/m2). Στο UV-B κομμάτι του φάσματος (300-315nm), οι αντίστοιχες τιμές στις 60o και 30o υπολογίζονται ίσες με -0.069 ±0.005 W/m2 και -0.35 ±0.04 W/m2. Συγκρίνοντας τις τιμές που προκύπτουν για την ανακλαστικότητα μεμονωμένης σκέδασης στα 320 nm, με αυτές από το γειτονικό CIMEL στα 440 nm, προκύπτει πολύ καλή συμφωνία (±0.01). Το πέμπτο κεφάλαιο, επικεντρώνεται στην επίδραση των αιωρούμενων σωματιδίων στην άμεση ηλιακή ακτινοβολία, σε επίπεδο κάθετο στην κατεύθυνση της ακτινοβολίας, στην περιοχή της Ευρώπης. Δεδομένα από το MODIS, το AERONET και θεωρητικοί υπολογισμοί με το μοντέλο SBDART, χρησιμοποιούνται για τον υπολογισμό της ημερήσιας ποσότητας άμεσης ηλιακής ακτινοβολίας, στην Ευρώπη, με χωρική ανάλυση 1°x1° για μια χρονική περίοδο 13 ετών. Ο κλιματικός εξαναγκασμός, υπό ανέφελο ουρανό, των αιωρούμενων σωματιδίων και πιθανές μεταβολές στην ληφθείσα άμεση ακτινοβολία κατά τη διάρκεια αυτής της περιόδου, μελετούνται. Οι επιδράσεις των αιωρούμενων σωματιδίων είναι σημαντικές σε περιοχές που επηρεάζονται από σωματίδια ερημικής σκόνης και περιοχές με έντονη ανθρωπογενή δραστηριότητα, όπως η Μεσόγειος και η κοιλάδα του Πάδου στην Ιταλία. Σε αυτές τις περιοχές η μείωση της ακτινοβολίας, λόγω αιωρούμενων σωματιδίων, φτάνει, το Μάιο, το 35% και 35-45%, που αντιστοιχεί σε 4 και 4.5-6 kWh/m2 την ημέρα. Η ληφθείσα άμεση ακτινοβολία έχει αυξηθεί κατά τα τελευταία χρόνια, λόγω ελάττωσης της συγκέντρωσης των αιωρούμενων σωματιδίων σε πολλά μέρη της Ευρώπης. Οι μεγαλύτερες αυξήσεις κυμαίνονται μεταξύ 6 και 12%, ποσοστό που αντιστοιχεί σε 0.5 με 1.25 kWh/m2 την ημέρα. Στο έκτο κεφάλαιο, αυτής της διατριβής, μελετάται ο υπολογισμός της ηλιακής ακτινοβολίας στο έδαφος, χρησιμοποιώντας δορυφορικά δεδομένα για την επίδραση των νεφών. Το όργανο SEVIRI, στους δορυφόρους MSG, χρησιμοποιείται για την παροχή δεδομένων σχετικά με το συντελεστή επίδρασης των νεφών. Τα δεδομένα αυτά, μαζί με θεωρητικούς υπολογισμούς με το μοντέλο libRadtran, χρησιμοποιούνται για τον υπολογισμό της ολικής ηλιακής ακτινοβολίας, σε οριζόντια επιφάνεια και σε επιφάνεια υπό κλίση, καθώς και τον υπολογισμό της άμεσης συνιστώσας σε επιφάνεια κάθετη στη διεύθυνση της ακτινοβολίας. Η μελέτη πραγματοποιείται για της περιοχή της Ελλάδας και αποτελεί κομμάτι του Ελληνικού Δικτύου Ηλιακής Ενέργειας, που έχει αναπτυχθεί για την υποστήριξη εφαρμογών και συστημάτων ηλιακής ενέργειας. Υπολογίζονται οι ημερήσιες ποσότητες ακτινοβολίας, οι μηνιαίες και οι ετήσιες τιμές, για μια περίοδο 11 ετών, καθώς και η μηνιαία κλιματολογία που προκύπτει για αυτήν την περίοδο. Η σύγκριση των αποτελεσμάτων με μετρήσεις από επίγειους σταθμούς, δίνει πολύ καλή συμφωνία, ενώ οι μεγαλύτερες διαφορές παρατηρούνται σε περιπτώσεις πολύ πυκνών νεφών. Η ηλιακή ακτινοβολία που συλλέγεται σε κεκλιμένη επιφάνεια, παρέχει 15-25 % μεγαλύτερα ποσά, σε σχέση με αυτήν που παρέχουν οριζόντιες επιφάνειες συλλογής. Στην Ελλάδα, τα μεγαλύτερα μηνιαία ποσά ηλιακής ενέργειας, παρατηρούνται κατά τους θερινούς μήνες, στη Νότια Πελοπόννησο, την Κρήτη και τις Κυκλάδες και ξεπερνούν τις 250 kWh/m2.

Darbo tikslas - nustatyti ir įvertinti asmens svaikatos priežiūros įstaigų medicinos personalo (gydytojų radiologų ir radiologijos laborantų) informuotumą apie pacientų gaunamą apšvitą ir radiacinę saugą Vilniaus mieste. Tyrimo objektas – gydytojai radiologai ir radiologijos laborantai. Tyrimo metu buvo apklausti 140 respondentų iš 15 asmens sveikatos priežiūros įstaigų. Viso buvo apklausta 35 gydytojai radiologai (iš jų 15 vyrų ir 20 moterų) ir 105 radiologijos laborantai (iš jų 4 vyrai ir 101 moteris), o tai atitinkamai sudarė 25,0% ir 75,0%. Apklaustųjų amžius svyruoja nuo 23 iki 71 metų (vidurkis 47,43). Tyrimo tikslui ir uždaviniams pasiekti panaudotas aprašomasis tyrimo tipas bei anketinės apklausos metodas. Statistinė duomenų analizė atlikta naudojant SPSS 13 programos versiją. Pateikiamas rodiklių pasiskirstymas absoliučiais skaičiais ir procentais, apskaičiuotas chi kvadratas (Chi-kv.). Sirtumas statistiškai reikšmingas kai pasikliovimo lygmuo p<0,05. Atlikta mokslinių straipsnių, sveikatos sistemos teisinės ir normatyvinės medžiagos ir t.t., analizė. Gautos šios išvados: įvertinus bendrą žinių lygį tarp apklaustų respondentų, galima teigti, kad gydytojai radiologai ir radiologijos laborantai pakankamai gerai žino radiacinės saugos principus bei apšvitos keliamą pavojų. Tačiau atliktas tyrimas taip pat parodė, kad jiems vis dar trūksta žinių kai kuriais specifiniais klausimais, pavyzdžiui tokiais kaip tipinės efektinės dozės gaunamos atliekant įvairias procedūras... [toliau žr. visą tekstą] / Main task – to estimate and evaluate medical personnel’s of health care (doctors of radiology and radiology assistants) informativeness about receivable irradiance towards patients and radiational safety in city of Vilnius. Object of research - doctors of radiology and radiology assistants. During this research 140 respondents were questioned from 15 health care institutions. Overall 35 radiologists were questioned (15 men and 20 women), 105 radiology assistants (4 men and 101 women) and that’s accordingly 20, 0% and 75, 0%. Age variance of the respondents is from 23 up to 71 years old (average of 47.43 years old). Descriptive research type and survey was used in order to achieve the goals of this research. Statistical data analysis was performed by using SPSS program, version 13. The given distribution of index is in natural numbers and in percentage, Chi-square is counted (Chi-sq). Statistically the difference is meaningful when the level of probability is p<0,05. The analysis of science articles, law normative materials, health care systems, etc. was accomplished. The conclusion: after the evaluation of knowledge of the respondents it is clear that, doctors of radiology and radiology assistants have enough knowledge about radiational safety and dangers of irradiance. The research also revealed that they do not have enough knowledge concerning the specific topics, for example the doses that are received during variable procedures, the dependence of the dose, the observation... [to full text]

The spring bloom of microalgae within the bottom of sea ice provides a significant contribution to primary production in the Arctic Ocean. The aim of this research was to improve observations of the ice algae bloom using a transmitted irradiance technique to remotely estimate biomass, and to examine the influence of physical processes on biomass throughout the sea ice melt season. Results indicate that bottom ice temperature is highly influential in controlling biomass variability and bloom termination. Snow depth is also significant as it buffers ice temperature from the atmosphere and largely controls transmission of photosynthetically active radiation (PAR). The relationship between snow depth and biomass can change over the spring however, limiting biomass accumulation early on while promoting it later. Brine drainage, under-ice current velocity, and surface PAR in the absence of snow cover are also important factors. Overall this research helps to characterize the spring ice algae bloom in the Arctic by improving in situ biomass estimates and identifying primary factors controlling it.

The spring bloom of microalgae within the bottom of sea ice provides a significant contribution to primary production in the Arctic Ocean. The aim of this research was to improve observations of the ice algae bloom using a transmitted irradiance technique to remotely estimate biomass, and to examine the influence of physical processes on biomass throughout the sea ice melt season. Results indicate that bottom ice temperature is highly influential in controlling biomass variability and bloom termination. Snow depth is also significant as it buffers ice temperature from the atmosphere and largely controls transmission of photosynthetically active radiation (PAR). The relationship between snow depth and biomass can change over the spring however, limiting biomass accumulation early on while promoting it later. Brine drainage, under-ice current velocity, and surface PAR in the absence of snow cover are also important factors. Overall this research helps to characterize the spring ice algae bloom in the Arctic by improving in situ biomass estimates and identifying primary factors controlling it.

Η εργασία αυτή ασχολείται κατά πρώτον με την στατιστική επεξεργασία πεντάλεπτων μετρήσεων φυσικού φωτισμού κατά τη διάρκεια ενός έτους και την παραγωγή διαγραμμάτων μέσων ωριαίων μηνιαίων τιμών για κάθε τύπο καιρού και για κάθε μέγεθος (ολικός φωτισμός, διάχυτος φωτισμός, ολική ηλιακή ακτινοβολία, διάχυτη ηλιακή ακτινοβολία) και κατά δεύτερον με τη δικτύωση μελλοντικών σταθμών στην Αττική (με ενσύρματο ή ασύρματο τρόπο) που μετρούν το φυσικό φωτισμό. / --

With the ever-growing energy demand that world is currently going through and the danger of climate change around the corner, wagering in renewable energy seems to be the right path to create a more smart and green future. Sweden has put great effort on decreasing its dependency on oil, in fact in 2012 more than 50 % of its electricity came from the renewable source and has a plan in making it 100 % in 2040. However, when it comes to heating systems Sweden depends greatly on district heating, and situations which buildings are located outside the district heating system’s reach is not uncommon, hence for those buildings, other options such as solar power or heat pumps are considered. Many buildings located in Skutskär suffer from the problem stated above. The particular building analyzed in this thesis uses electrical radiator and furnace as sources of heat, which implies high energy uses and financial expenses. For this reason technical and financial analysis of using each alternative system for a single family house located in Skutskär had been done. Using solar powered system is deemed to be quite ineffective, as Sweden has poor solar radiation. In order to compensate the poor sun hours during the winter, 51 photovoltaic (PV) panels or 19 solar thermal panels would be required. This high initial investment needs long period of time in order to be profitable, 15 years for solar thermal system and 21 years for solar PV system. On the other hand, the results from the heat pumps are quite satisfactory, the fastest payback period is around 4 years. This is achieved by using air source heat pump (ASHP), the annual saving in this case is three times higher than using solar photovoltaic panels, making the usage of ASHP more attractive than any solar energy system. However, when annual saving is concerned, the ground source heat pump (GSHP) system is capable of generating even higher saving, but the initial investment is significantly higher, extending the payback period to 6 years.

Measurement uncertainty is an indication of the quality of a given measurement and ultimately translates into the confidence with which a decision can be made. In the context of PV, measurement uncertainties propagate into energy yield uncertainty, which in turn culminates into financial risk associated with an investment. This risk increases the cost of a PV installation. The aim of this thesis is to contribute towards the reduction of PV related measurement uncertainties. This is done in two ways. One is via developing and utilising more comprehensive methodologies for uncertainty propagation of complex measurands. The other is via more detailed estimates of the uncertainty contributors. In particular, the areas addressed in this thesis are the uncertainty estimation of the temperature coefficient measurements of modules; the uncertainty estimation of energy rating and module performance ratio measurements; and the uncertainties due to spectral effects on measurements performed with a flash solar simulator. The reported deviation in measurements of the temperature coefficients of P_MAX of modules is in the order of ±10% to ±15%. This is larger than the difference in the temperature coefficients of modules of the same type. The first step to improving the deviation between measurements is to estimate the uncertainty in a robust way. It was identified that there was no accepted approach of doing this. These measurements are strongly correlated, which complicates the uncertainty estimates. For the sake of simplicity, previously correlations have been avoided and conservative estimates used instead. In this work, uncertainties in both temperature and power and their correlations are estimated and propagated into the overall temperature coefficient uncertainty. Furthermore, temperature coefficients were calculated via weighing the measurements with their associated uncertainties. This was done for five different measurement setups that represent the majority of setups used worldwide. The approach was validated with measurement intercomparison of two modules measured on all systems. The approach reduced the overall uncertainty by half compared to the previous conservative estimates. It was demonstrated that uncertainties as low as 3% are achievable. The improved uncertainty estimates enabled the identification of a systematic effect due to a class B spectrum. This work culminated in the lowest reported measurement deviation of ±3.2% for module P_MAXtemperature coefficient measurements that was within the stated measurement uncertainties. The clear benefit of accounting for correlations was extended to measurements at different irradiance conditions and into the calculation of module performance ratio and energy rating. This was done via defining all the correlations between measurements and then propagating them with Monte Carlo simulations. The simulations are done with samples of a multivariate normal distribution with a variance-covariance matrix that corresponds to the estimated measurement correlations. It is demonstrated that both the energy rating and module performance ratio uncertainties strongly depend on the correlation estimates and that they cannot be conservatively overestimated. The module performance ratio uncertainty can be significantly lower than the measurement uncertainty at STC. This is because of the additional knowledge encoded into the selection of the underlying model used for calculating the energy rating. Therefore, the significance of the choice of model in the upcoming standard has been highlighted. It was confirmed that both bilinear interpolation and the proposed climatic datasets could be used for energy rating, but there are some areas that may need further investigation. An alternative way of improving uncertainty estimates and in turn reducing the associated uncertainty is via a more detailed characterisation of the uncertainty sources. A key uncertainty source is due to spectral effects in flash solar simulators. To better quantify this source, a complementary device was built to monitor the spectrum. The device is based on a matrix of photodiodes with commercially available interference filters situated on top and custom designed data acquisition electronics. This device is used in conjunction with the spectroradiometer to estimate the effects of flash-variation on the spectrum, the spectral temporal stability of the flash and spectral uniformity of the simulator and the attenuation masks used for altering the irradiance levels. It was demonstrated that the spectrum changes significantly during the flash and between flashes. While this effect is partially corrected for via the monitoring cell, it introduces additional uncertainty for non c-Si modules. This uncertainty is minimised by changes in the operational procedures. The spectral non-uniformity of the attenuation masks was shown to be significant, i.e. as large as 4%, in the NIR, prompting further investigation of the additional uncertainty for non c-Si modules. In this work, the methodology of estimating and propagating correlations in PV related measurements and the benefits of doing so are demonstrated. It is also highlighted that the uncertainty due to spectral effects goes beyond the uncertainty of spectroradiometer measurements. Finally, it is shown how they can be estimated with a complementary spectral monitor.

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abstract: Although mimetic animal coloration has been studied since Darwin's time, many questions on the efficacy, evolution, and function of mimicry remain unanswered. Müller (1879) hypothesized that unpalatable individuals converge on the same conspicuous coloration to reduce predation. However, there are many cases where closely related, unpalatable species have diverged from a shared conspicuous pattern. What selection pressures have led to divergence in warning colors? Environmental factors such as ambient light have been hypothesized to affect signal transmission and efficacy in animals. Using two mimetic pairs of Heliconius butterflies, Postman and Blue-white, I tested the hypothesis that animals with divergent mimetic colors segregate by light environment to maximize conspicuousness of the aposematic warning signal under their particular environmental conditions. Each mimetic pair was found in a light environment that differed in brightness and spectral composition, which affected visual conspicuousness differently depending on mimetic color patch. I then used plasticine models in the field to test the hypothesis that mimics had higher survival in the habitat where they occurred. Although predation rates differed between the two habitats, there was no interactive effect of species by habitat type. Through choice experiments, I demonstrated that mimetic individuals preferred to spend time in the light environment where they were most often found and that their absolute visual sensitivity corresponds to the ambient lighting of their respective environment. Eye morphology was then studied to determine if differences in total corneal surface area and/or facet diameters explained the differences in visual sensitivities, but the differences found in Heliconius eye morphology did not match predictions based upon visual sensitivity. To further understand how eye morphology varies with light environments, I studied many tropical butterflies from open and closed habitats to reveal that forest understory butterflies have larger facets compared to butterflies occupying open habitats. Lastly, I tested avian perception of mimicry in a putative Heliconius mimetic assemblage and show that the perceived mimetic resemblance depends upon visual system. This dissertation reveals the importance of light environments on mimicry, coloration, behavior and visual systems of tropical butterflies. / Dissertation/Thesis / Doctoral Dissertation Biology 2016

Made available in DSpace on 2014-06-11T19:23:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-18Bitstream added on 2014-06-13T18:09:11Z : No. of bitstreams: 1 kusakariba_t_me_rcla.pdf: 605912 bytes, checksum: 3bb69f50b5447fd8858f1b6b6d084438 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Respostas de curto período das características fotossintéticas a temperatura e irradiância foram avaliadas na rodófita Batrachospermum delicatulum em condições naturais e em laboratório. A variação diária dos parâmetros fotossintéticos por fluorescência da clorofila foi amostrada em duas épocas (junho, período frio e seco; outubro, quente e chuvoso) em um riacho da região noroeste do Estado de São Paulo (20o43 24-S, 49o18 21-W). Os valores de RQE e RQP (rendimento quântico efetivo e potencial, respectivamente) apresentaram correlação negativa com a irradiância nas duas épocas e valores similares no início e final do dia, indicando respectivamente alta pressão de excitação sobre o fotossistema II (FSII) e boa capacidade de recuperação e ausência de fotodano ao aparato fotossintético. Os valores de NPQ (extinção não-fotoquímica) também apresentaram correlação negativa com irradiância (significativa apenas em junho), o que possivelmente indica baixa capacidade de dissipação da energia absorvida pelos centros de reação. Sob temperatura e irradiância fixas a variação diária para fotossíntese líquida foi caracterizada por dois picos: o primeiro (maior) durante a manhã e o segundo (menor) durante a tarde. Os valores de ETR (taxa de transporte de elétrons) também apresentaram padrão semelhante, o que demonstra a ocorrência de ritmos endógenos que controlam as taxas fotossintéticas. Curvas de fotossíntese-irradiância e de indução escuro/luz foram testadas em laboratório (sob condições de baixa e alta irradiância) e em campo sob luz natural (não-sombreada) e artificialmente sombreada em duas épocas (junho e novembro). O isolado em cultura e as plantas em condições naturais (novembro) tiveram maiores valores de fotossíntese máxima (Fmax), eficiência fotossintética ( ) e rendimento quântico em baixa irradiância... / Short-term responses of photosynthetic characteristics to temperature and irradiance were analyzed in the rhodophyte Batrachospermum delicatulum under natural and laboratory conditions. The diurnal variation of photosynthetic parameters by chlorophyll fluorescence was sampled in two seasons (June, cool and dry season; October, warm and rainy season) in a stream of northwest region of São Paulo state (20o43 24 S, 49o18 21 W). Values of EQY and PQY (effective and potential quantum yield, respectively) were negatively correlated with irradiance in both seasons and had similar values at the beginning and end of the day, indicating, respectively high excitation pressure on photosystem II (PSII) and good recovery capacity and lack of photodamage to the photosynthetic apparatus. Values of NPQ (non-photochemical quenching) were also negatively correlated with irradiance (significantly only in June) possibly indicating low dissipation capacity of absorbed energy by reaction centres. The diurnal variation of net photosynthesis under fixed conditions of temperature and irradiance was characterized by two peaks the first (higher) in the morning and the second (lower) in the afternoon. ETR (electron transport rate) values also presented a similar pattern, suggesting the occurrence of endogenous rhythm that controls photosynthetic rates. Photosynthesis-irradiance and dark/light (induction) curves were tested in laboratory (under low and high irradiance conditions) and in field under natural light (unshaded) and artificially shaded in two seasons (June and November). Specimens from culture isolate and in natural conditions (November) had higher values of maximum photosynthesis (Pmax) photosynthetic efficiency ( ) and EQY at low irradiance, whereas at high irradiance (laboratory and field), values of were significantly higher than at low irradiance. A positive correlation between of ETR with NPQ... (Complete abstract click electronic access below)