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  • 1
    Publication Date: 2022-03-29
    Description: A reanalysis is a physically consistent set of optimally merged simulated model states and historical observational data, using data assimilation. High computational costs for modeled processes and assimilation algorithms has led to Earth system specific reanalysis products for the atmosphere, the ocean and the land separately. Recent developments include the advanced uncertainty quantification and the generation of biogeochemical reanalysis for land and ocean. Here, we review atmospheric and oceanic reanalyzes, and more in detail biogeochemical ocean and terrestrial reanalyzes. In particular, we identify land surface, hydrologic and carbon cycle reanalyzes which are nowadays produced in targeted projects for very specific purposes. Although a future joint reanalysis of land surface, hydrologic, and carbon processes represents an analysis of important ecosystem variables, biotic ecosystem variables are assimilated only to a very limited extent. Continuous data sets of ecosystem variables are needed to explore biotic‐abiotic interactions and the response of ecosystems to global change. Based on the review of existing achievements, we identify five major steps required to develop terrestrial ecosystem reanalysis to deliver continuous data streams on ecosystem dynamics.
    Description: Plain Language Summary: A reanalysis is a unique set of continuous variables produced by optimally merging a numerical model and observed data. The data are merged with the model using available uncertainty estimates to generate the best possible estimate of the target variables. The framework for generating a reanalysis consists of the model, the data, and the model‐data‐fusion algorithm. The very specific requirements of reanalysis frameworks have led to the development of Earth‐compartment specific reanalysis for the atmosphere, the ocean and land. Here, we review atmospheric and oceanic reanalyzes, and in more detail biogeochemical ocean and terrestrial reanalyzes. In particular, we identify land surface, hydrologic, and carbon cycle reanalyzes which are nowadays produced in targeted projects for very specific purposes. Based on a review of existing achievements, we identify five major steps required to develop reanalysis for terrestrial ecosystem to shed more light on biotic and abiotic interactions. In the future, terrestrial ecosystem reanalysis will deliver continuous data streams on the state and the development of terrestrial ecosystems.
    Description: Key Points: Reanalyzes provide decades‐long model‐data‐driven harmonized and continuous data sets for new scientific discoveries. Novel global scale reanalyzes quantify the biogeochemical ocean cycle, terrestrial carbon cycle, land surface, and hydrologic processes. New observation technology and modeling capabilities allow in the near future production of advanced terrestrial ecosystem reanalysis.
    Description: European Union's Horizon 2020 research and innovation programme
    Description: Deutsche Forschungsgemeinschaft
    Description: U.S. Department of Energy
    Description: Emory University's Halle Institute for Global Research and the Halle Foundation Collaborative Research
    Description: NSF
    Description: NASA
    Description: Natural Environment Research Council
    Description: European Union'’s Horizon 2020 research and innovation programme
    Description: NSERC Discovery program, the Ocean Frontier Institute, and MEOPAR
    Description: Research Foundation Flanders (FWO)
    Description: Helmholtz Association
    Description: NASA Terrestrial Ecosystems
    Keywords: ddc:550
    Language: English
    Type: doc-type:article
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  • 2
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    In:  IAG 150 Years : Proceedings of the IAG Scientific Assembly in Postdam, Germany, 2013 | International Association of Geodesy Symposia
    Publication Date: 2020-02-12
    Type: info:eu-repo/semantics/bookPart
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5310-5312 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ν1 (H–O) stretches of HOSi+ and DOSi+ have been observed with the difference frequency laser system in the hollow cathode discharge. The ions were observed either by discharge of (CH3)3SiOH or (CH3)3SiOD in a buffer containing H2 (or D2) and He, or by discharging SiH4 and N2O in a buffer of H2 or H2 and He. Discharging SiH4 and H2O in buffers of H2 and H2 and He was not successful in producing HOSi+. The constants obtained were: ν0=3662.364 67(15) cm−1, B000=18 260.75(22) MHz, D000=20.44(31) kHz, B100=18 195.05(23) MHz, and D100=19.91(34) kHz for HOSi+. For DOSi+ we obtained: ν0=2716.558 13 (12) cm−1, B000=16 231.05(24) MHz, D000=15.69(38) kHz, B100=16 154.41(22) MHz, and D100=15.60(33) kHz. These values agree well with the theory. The combination of the two B0 values results in r0(H–O)=0.940 A(ring) and r0(O–Si) =1.537 A(ring). The differences between these values and the calculated equilibrium values are similar to the corresponding results for HOC+.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1843-1845 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report significant improvement in the optical switching times of symmetric self-electro-optic effect devices due to enhanced tunneling by using a 35 A(ring) barrier versus the previous 60 A(ring) barrier thick multiple quantum well GaAs/AlxGa(1−x)As devices. Also, the voltage required for bistability was reduced from 10 V in the thick barrier devices to 3 V in the thin barrier devices with no apparent degradation in the contrast ratio.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 66-68 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report that at room temperature the field-induced escape of photogenerated carriers out of shallow GaAs/AlxGa1−xAs multiple quantum wells is as fast as for pure GaAs of the same thickness, if the value of x does not exceed 0.04. Our experimental findings can be explained by assuming that carriers are efficiently scattered into the unconfined barrier states by absorption of a LO phonon, as long as the effective barrier height is less than the LO-phonon energy. The application of shallow quantum wells with x≤0.04 in self-electro-optic effect devices, providing not only strong excitonic electroabsorption but also fast sweep-out times at small biases, should lead to shorter switching times.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 430-432 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the saturation of optical absorption in GaSb at wavelengths close to the band gap, and have determined the nonlinear absorption (α2) and refraction (n2) coefficients. At liquid-helium temperature a sharp free-exciton absorption line is observed which saturates with increasing incident laser intensity; we obtain values ||α2||=70 cm W−1 and ||n2||≈0.2 cm2 kW−1. At room temperature we do not observe a well-defined exciton; saturation of the residual interband absorption occurs at much higher intensity, and it is found to be obscured by strong thermal effects.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2315-2317 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the heavy hole excitation saturation intensity in GaAs/AlGaAs quantum wells as a function of applied electric field and AlGaAs barrier design. We find that the saturation intensity increased with increasing applied field, and decreasing barrier thickness or height, because of increased carrier sweep-out rates. Time-resolved sweep-out time and temperature-dependent saturation intensity measurement point out the roles of both thermionic emission and tunneling in the field and barrier-dependent carrier escape time. By reducing the barrier Al composition from 30 to 20%, we achieved an increase in the saturation intensity by a factor of ∼6.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 4287-4298 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the relaxation dynamics of highly excited GaxIn1−xAsyP1−y/InP with 5-ps resolution using a mode-locked 1.054-μm Nd:glass laser. Two samples with band gaps of 1.49 and 1.24 μm were studied at room temperature by the time-resolved nonlinear transmission and transient grating techniques. At excited carrier densities (approximately-greater-than)5×1018 cm−3 carrier relaxation times as short as 6 ps have been measured. The results are consistent with ultrafast decay by stimulated radiative recombination, and time-integrated luminescence measurements support this interpretation. We find no evidence for plasma expansion. At lower densities the carrier relaxation is determined by Auger and bimolecular recombination, and longer decay constants in the range 100–500 ps are measured.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the investigation of the room-temperature optoelectronic behavior of a metal–semiconductor–metal two-dimensional electron gas photodiode based on the two-dimensional electron gas of a high electron mobility transistor structure. The photodetector is fabricated in the InP/InGaAs material system, without use of Al-containing layers. Optoelectronic measurements on a device with a finger spacing of 3 μm show a full width at half-maximum (FWHM) of the pulse response of ≤60 ps, which is the resolution limit of our measurement equipment. Low-temperature measurements at 40 K with electro-optical sampling at a wavelength of 890 nm show a FWHM of 1 ps. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 2917-2919 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the vertical transport mechanisms in GaAs/AlxGa1−xAs multiple quantum wells in electric fields from the temperature dependence of the photocurrent. On heating from 10 K, we observed a decrease in the photocurrent up to ∼100 K, followed by a steady increase up to room temperature. The decrease is shown to be consistent with charged-impurity-assisted nonresonant tunneling which varies as T−1/2 in two dimensions, while the increase is consistent with thermal emission. The low field activation energy measured in a sample with x=0.33 is consistent with the thermal emission of heavy holes.
    Type of Medium: Electronic Resource
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