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The coloured dissolved organic matter (CDOM) concentration is the standard measure of humic substance in natural waters. CDOM measurements by remote sensing is calculated using the absorption coefficient (a) at a certain wavelength (e.g. 440nm). This paper presents a comparison of four machine learning methods for the retrieval of CDOM from remote sensing signals: regularized linear regression (RLR), random forest (RF), kernel ridge regression (KRR) and Gaussian process regression (GPR). Results are compared with the established polynomial regression algorithms. RLR is revealed as the simplest and most efficient method, followed closely by its nonlinear counterpart KRR., Comment: 7 pages, 4 figures

Heat fluxes at the lake surface play an integral part in determining the energy budget and thermal structure in lakes, including regulating how lakes respond to climate change. We explore patterns in turbulent heat fluxes, which vary across temporal and spatial scales, using in situ high-frequency monitoring data from 45 globally distributed lakes. Our analysis demonstrates that some of the lakes studied follow a marked seasonal cycle in their turbulent surface fluxes and that turbulent heat loss is highest in larger lakes and those situated at low latitude. The Bowen ratio, which is the ratio of mean sensible to mean latent heat fluxes, is smaller at low latitudes and, in turn, the relative contribution of evaporative to total turbulent heat loss increases toward the tropics. Latent heat transfer ranged from similar to 60% to > 90% of total turbulent heat loss in the examined lakes. The Bowen ratio ranged from 0.04 to 0.69 and correlated significantly with latitude. The relative contributions to total turbulent heat loss therefore differ among lakes, and these contributions are influenced greatly by lake location. Our findings have implications for understanding the role of lakes in the climate system, effects on the lake water balance, and temperature-dependent processes in lakes.

Heat fluxes at the lake surface play an integral part in determining the energy budget and thermal structure in lakes, including regulating how lakes respond to climate change. We explore patterns in turbulent heat fluxes, which vary across temporal and spatial scales, using in situ high‐frequency monitoring data from 45 globally distributed lakes. Our analysis demonstrates that some of the lakes studied follow a marked seasonal cycle in their turbulent surface fluxes and that turbulent heat loss is highest in larger lakes and those situated at low latitude. The Bowen ratio, which is the ratio of mean sensible to mean latent heat fluxes, is smaller at low latitudes and, in turn, the relative contribution of evaporative to total turbulent heat loss increases toward the tropics. Latent heat transfer ranged from ~ 60% to > 90% of total turbulent heat loss in the examined lakes. The Bowen ratio ranged from 0.04 to 0.69 and correlated significantly with latitude. The relative contributions to total turbulent heat loss therefore differ among lakes, and these contributions are influenced greatly by lake location. Our findings have implications for understanding the role of lakes in the climate system, effects on the lake water balance, and temperature‐dependent processes in lakes.

Heat fluxes at the lake surface play an integral part in determining the energy budget and thermal structure in lakes, including regulating how lakes respond to climate change. We explore patterns in turbulent heat fluxes, which vary across temporal and spatial scales, using in situ high‐frequency monitoring data from 45 globally distributed lakes. Our analysis demonstrates that some of the lakes studied follow a marked seasonal cycle in their turbulent surface fluxes and that turbulent heat loss is highest in larger lakes and those situated at low latitude. The Bowen ratio, which is the ratio of mean sensible to mean latent heat fluxes, is smaller at low latitudes and, in turn, the relative contribution of evaporative to total turbulent heat loss increases toward the tropics. Latent heat transfer ranged from ~ 60% to > 90% of total turbulent heat loss in the examined lakes. The Bowen ratio ranged from 0.04 to 0.69 and correlated significantly with latitude. The relative contributions to total turbulent heat loss therefore differ among lakes, and these contributions are influenced greatly by lake location. Our findings have implications for understanding the role of lakes in the climate system, effects on the lake water balance, and temperature‐dependent processes in lakes.

In lake-rich regions, the gathering of information about water quality is challenging because only a small proportion of the lakes can be assessed each year by conventional methods. One of the techniques for improving the spatial and temporal representativeness of lake monitoring is remote sensing from satellites and aircrafts. The experimental material included detailed optical measurements in 11 lakes, air- and spaceborne remote sensing measurements with concurrent field sampling, automatic raft measurements and a national dataset of routine water quality measurements from over 1100 lakes. The analyses of the spatially high-resolution airborne remote sensing data from eutrophic and mesotrophic lakes showed that one or a few discrete water quality observations using conventional monitoring can yield a clear over- or underestimation of the overall water quality in a lake. The use of TM-type satellite instruments in addition to routine monitoring results substantially increases the number of lakes for which water quality information can be obtained. The preliminary results indicated that coloured dissolved organic matter (CDOM) can be estimated with TM-type satellite instruments, which could possibly be utilised as an aid in estimating the role of lakes in global carbon budgets. Based on the results of reflectance modelling and experimental data, MERIS satellite instrument has optimal or near-optimal channels for the estimation of turbidity, chlorophyll a and CDOM in Finnish lakes. MERIS images with a 300 m spatial resolution can provide water quality information in different parts of large and medium-sized lakes, and in filling in the gaps resulting from conventional monitoring. Algorithms that would not require simultaneous field data for algorithm training would increase the amount of remote sensing-based information available for lake monitoring. The MERIS Boreal Lakes processor, trained with the optical data and concentration ranges provided by this study, enabl, Kaukokartoituksella saadaan alueellisesti ja ajallisesti kattavaa tietoa järvistä ja niiden vedenlaadusta. Tämän kaltaiselle tiedolle on erityistä tarvetta runsasjärvisillä alueilla, joilla vain pientä osaa järvistä pystytään vuosittain seuraamaan perinteisin menetelmin. Tässä väitöskirjatyössä selvitettiin eri tulkintamenetelmien ja kaukokartoitusinstrumenttien soveltuvuutta Suomen järvien vedenlaadun arvioimiseksi sekä menetelmiä valon tunkeutumissyvyyden määrittämiseksi. Kaukokartoitus soveltuu instrumentin ominaisuuksista riippuen sameuden, rehevyystason, humuksen ja näkösyvyyden arviointiin. Väitöskirjassa osoitettiin, että boreaalisille järville kehitetyn prosessorin avulla tulkitut MERIS satelliittikuvat arvioivat sameutta hyvällä tarkkuudella ilman kuvakohtaista kalibrointia. Prosessorin opettamiseen käytettiin Suomen järvien optisia ominaisuuksia ja vedenlaadun vaihtelua. Menetelmät, jotka eivät vaadi kenttähavaintoja algoritmien kalibrointiin, lisäävät huomattavasti käyttökelpoisten kaukokartoitusarvioiden määrää. Alueellisesti tarkkojen TM-tyyppisten satelliittikuvien ilmakehäkorjaus ei riittävästi korjannut kuvien välistä vaihtelua. Näin ollen näiden kuvien käyttö järvien seurantaan edellyttää ylilennon kanssa samanaikaisia kenttämittauksia tulkinnan avuksi. Suomessa yleiset humusjärvet ovat kaukokartoituksen kannalta haasteellisia, koska niistä heijastuvan valon määrä on alhainen. Kenttämittaukset ja mallinnustulokset osoittivat, että humuspitoisuuden arviointi onnistuu näissäkin järvissä, mutta satelliittikuvista korkeiden humuspitoisuuksien tulkinta riippuu pitkälti ilmakehäkorjauksen onnistumisesta ja instrumentin ominaisuuksista. Korkea humuspitoisuus voi häiritä a-klorofyllin arviointia, mutta tulkintaa voidaan parantaa luokittelemalla järvet humuspitoisuuden perusteella. Tarkan alueellisen resoluution lentokonekuvat osoittivat, että rehevissä järvissä a-klorofylli vaihtelee huomattavasti alueellisesti. Perinteisillä menetelmillä saatava arvio voi

Lung and bronchial diseases, especially asthma and allergies, have been increasing in frequency for a long time because of environmental factors and the changed living circumstances. Returning to nature is not possible and smoking has not decreased remarkably therefore lung problems have come to stay. Lung sound research has rapidly become intensified with the possibilities granted by new technology. Traditionally respiratory sound analysis is based on the auscultation made by the doctor with the stethoscope and the sounds heard and empirically recognized. Signal processing and pattern recognition offer new tools for the separation of breath sounds. Self-organizing feature map (SOM) is a neural network that imitates the biological neural system. It has successfully been utilized in speech recognition already during three decades. In this thesis, we have for the first time in the world applied the method of self-organizing feature map created by academician Teuvo Kohonen for the classification of lung sounds. The feature vector is assembled according to the model used in speech recognition with signal rms-value and FFT frequency components. The program composed according to Kohonen's theory comprises pattern computation, teaching of the self-organizing map, recognition of lung sounds and visualization of classification results. The method organizes the teaching sound patterns on the map forming clusters of the lung sound groups according to their features. The organized map can be used for the recognition of normal and adventitious breath sounds and for the separation of diseases. The results of the experiments indicate that the method is suit-able for classification of lung sounds. However, the findings of this study suggest that the feature vector modified from speech recognition is not the best possible. A fairly extensive literature review has been done in this study. Tentatively, some alternative feature vectors have been evaluated referring to publications conc, Hengityselinsairaudet, erityisesti astma ja allergia, ovat ympäristötekijöiden ja muuttuneiden elinolojen vuoksi jo pitkään lisääntyneet. Paluuta luontoon ei ole näköpiirissä eikä tupakointikaan ole ratkaisevasti vähentynyt, joten keuhkojen ongelmat ovat tulleet jäädäkseen. Hengitysäänitutkimus on voimistunut nopeasti uuden tekniikan suomien mahdollisuuksien ansiosta. Hengitysäänien analyysi perustuu perinteisesti lääkärin stetoskoopilla tekemään auskultointiin ja kuultujen äänien kokemusperäiseen tunnistamiseen. Signaalinkäsittely ja hahmontunnistus tarjoavat uusia välineitä hengitysäänien erotteluun. Itseorganisoituva piirrekartta (IOK, SOM) on biologisen hermojärjestelmän tapaan toimiva neuroverkko, jota on menestyksellisesti hyödynnetty puheentunnistuksessa jo kolmen vuosikymmenen ajan. Tässä diplomityössä on ensimmäisenä maailmassa sovellettu akateemikko Teuvo Kohosen luomaa itseorganisoituvaa piirre-karttamenetelmää hengitysäänien luokitteluun. Piirrevektori koostetaan puheentunnistuksesta saadun mallin mukaan signaalin tehollisarvosta ja FFT-spektristä poimituista taajuuskomponenteista. Työssä on laadittu Kohosen teorian pohjalle ohjelmisto, joka sisältää hahmolaskennan, itseorganisoituvan kartan opetuksen, hengitysäänien tunnistuksen sekä luokitustulosten havainnollistamisen. Menetelmä järjestää opetusääniryhmien hahmot kartalle muodostaen niistä klustereita äänien piirteiden perusteella. Organisoitunutta karttaa voidaan käyttää erilaisten normaalien ja poikkeavien hengitysäänien tunnistamiseen ja sairauksien erotteluun. Työssä tehtyjen useiden luokittelututkimusten tulokset osoittavat, että menetelmä sopii hengitysäänien luokitteluun. Työssä kuitenkin havaittiin, että puheentunnistuksessa käytetty piirrevektori ei hieman muokattunakaan ole paras mahdollinen. Työssä on tehty melko laaja kirjallisuuskatsaus. Julkaisuihin ja oman tutkimusryhmän saavutuksiin viitaten työssä arvioidaan alustavasti joitakin vaihtoehtoisia piirrevektoreita. Pohdinnoissa tehdään se

Reduced tillage was compared with traditional ploughing in terms of erosion and phosphorus (P) and nitrogen (N) losses in an experimental field in southern Finland. One part of the field has been ploughed (treatment PF) and the other part harrowed (treatment NPF) every autumn since 1986. Flow volume and water quality data was collected separately from surface runoff and subsurface drainage waters during 1991-1995 (surface runoff volume since 1993). Erosion was higher in PF (on average 234 kg ha-1yr-1 in drainage flow and 479 kg ha-1 yr-1 in surface runoff) than in NPF (158 kg ha-1yr-1 in drainage flow and 160 kg ha-1yr-1 in surface runoff). Total N loss in drainage flow was also higher in PF (7.2 kg ha-1yr-1) than in NPF (4.6 kg ha-1yr-1). Total P losses did not differ much; approximately 0.7 kg ha-1yr-1 was transported from both fields. Dissolved reactive P loss in surface runoff was higher in NPF (0.21 kg ha-1yr-1) than in PF (0.05 kg ha-1yr-1). This was probably attributable to the higher accumulation of P in the surface soil in NPF. The differences between the treatments were largely similar to those found in previous studies.

Reduced tillage was compared with traditional ploughing in terms of erosion and phosphorus (P) and nitrogen (N) losses in an experimental field in southern Finland. One part of the field has been ploughed (treatment PF) and the other part harrowed (treatment NPF) every autumn since 1986. Flow volume and water quality data was collected separately from surface runoff and subsurface drainage waters during 1991-1995 (surface runoff volume since 1993). Erosion was higher in PF (on average 234 kg ha-1yr-1 in drainage flow and 479 kg ha-1 yr-1 in surface runoff) than in NPF (158 kg ha-1yr-1 in drainage flow and 160 kg ha-1yr-1 in surface runoff). Total N loss in drainage flow was also higher in PF (7.2 kg ha-1yr-1) than in NPF (4.6 kg ha-1yr-1). Total P losses did not differ much; approximately 0.7 kg ha-1yr-1 was transported from both fields. Dissolved reactive P loss in surface runoff was higher in NPF (0.21 kg ha-1yr-1) than in PF (0.05 kg ha-1yr-1). This was probably attributable to the higher accumulation of P in the surface soil in NPF. The differences between the treatments were largely similar to those found in previous studies.

Reduced tillage was compared with traditional ploughing in terms of erosion and phosphorus (P) and nitrogen (N) losses in an experimental field in southern Finland. One part of the field has been ploughed (treatment PF) and the other part harrowed (treatment NPF) every autumn since 1986. Flow volume and water quality data was collected separately from surface runoff and subsurface drainage waters during 1991-1995 (surface runoff volume since 1993). Erosion was higher in PF (on average 234 kg ha-1yr-1 in drainage flow and 479 kg ha-1 yr-1 in surface runoff) than in NPF (158 kg ha-1yr-1 in drainage flow and 160 kg ha-1yr-1 in surface runoff). Total N loss in drainage flow was also higher in PF (7.2 kg ha-1yr-1) than in NPF (4.6 kg ha-1yr-1). Total P losses did not differ much; approximately 0.7 kg ha-1yr-1 was transported from both fields. Dissolved reactive P loss in surface runoff was higher in NPF (0.21 kg ha-1yr-1) than in PF (0.05 kg ha-1yr-1). This was probably attributable to the higher accumulation of P in the surface soil in NPF. The differences between the treatments were largely similar to those found in previous studies.

Reduced tillage was compared with traditional ploughing in terms of erosion and phosphorus (P) and nitrogen (N) losses in an experimental field in southern Finland. One part of the field has been ploughed (treatment PF) and the other part harrowed (treatment NPF) every autumn since 1986. Flow volume and water quality data was collected separately from surface runoff and subsurface drainage waters during 1991-1995 (surface runoff volume since 1993). Erosion was higher in PF (on average 234 kg ha-1yr-1 in drainage flow and 479 kg ha-1 yr-1 in surface runoff) than in NPF (158 kg ha-1yr-1 in drainage flow and 160 kg ha-1yr-1 in surface runoff). Total N loss in drainage flow was also higher in PF (7.2 kg ha-1yr-1) than in NPF (4.6 kg ha-1yr-1). Total P losses did not differ much; approximately 0.7 kg ha-1yr-1 was transported from both fields. Dissolved reactive P loss in surface runoff was higher in NPF (0.21 kg ha-1yr-1) than in PF (0.05 kg ha-1yr-1). This was probably attributable to the higher accumulation of P in the surface soil in NPF. The differences between the treatments were largely similar to those found in previous studies.

Reduced tillage was compared with traditional ploughing in terms of erosion and phosphorus (P) and nitrogen (N) losses in an experimental field in southern Finland. One part of the field has been ploughed (treatment PF) and the other part harrowed (treatment NPF) every autumn since 1986. Flow volume and water quality data was collected separately from surface runoff and subsurface drainage waters during 1991-1995 (surface runoff volume since 1993). Erosion was higher in PF (on average 234 kg ha-1yr-1 in drainage flow and 479 kg ha-1 yr-1 in surface runoff) than in NPF (158 kg ha-1yr-1 in drainage flow and 160 kg ha-1yr-1 in surface runoff). Total N loss in drainage flow was also higher in PF (7.2 kg ha-1yr-1) than in NPF (4.6 kg ha-1yr-1). Total P losses did not differ much; approximately 0.7 kg ha-1yr-1 was transported from both fields. Dissolved reactive P loss in surface runoff was higher in NPF (0.21 kg ha-1yr-1) than in PF (0.05 kg ha-1yr-1). This was probably attributable to the higher accumulation of P in the surface soil in NPF. The differences between the treatments were largely similar to those found in previous studies.