A method is described for incorporating surface-emitted surface-reflected (SESR) radiation into the infrared emissivity calculation for an anisotropic wind-roughened sea surface slope distribution model that depends on both wind speed and direction. First, the direct emissivity is obtained by ignoring the SESR radiation. Then, the first order SESR emissivity is obtained by using the direct emission as a radiation source. Finally, the ith order SESR emissivity (i ≥ 2) is recursively obtained by using the i-1st SESR emission. Sea surface emissivity up to the second order is calculated for wavelengths of 3.7, 11, and 12 μm at wind speeds of 3, 5, 10, and 15 m/s.
   Sea surface emissivity derived from the isotropic slope distribution model, which depends only on wind speed, is widely used in radiative transfer models, and validations have been performed through comparisons with measurements. This study examines the applicability of sea surface emissivity calculations to remote sensing measurements with respect to wind speed, emission angle, and the required accuracy of sea surface temperature, by use of sea surface emissivity derived from the anisotropic slope distribution model as a reference. For example, the sea surface temperature accuracy was better than 0.3 K for emission angles below 68° and 56° for isotropic slope distribution models with and without SESR radiation, respectively, for a wavelength of 11 μm, wind speed of 10 m/s, and sea surface temperature of 288 K.
   The isotropic model without SESR radiation performs well for satellite remote sensing data up to an emission angle of at least ∼50° provided the wind speed is less than ∼10 m/s. Ground based measurements with emission angles larger than 70° could be improved using the anisotropic model with SESR radiation.

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[in Japanese]

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   We documented precipitation changes in Japan from 1901 to 2009 using five climatological indices and daily data at 51 stations. Annual precipitation amount (PRCPTOT) decreased over the 109 years, and the number of days with precipitation (R1mm) decreased even more, causing their ratio (SDII), an indicator of precipitation intensity, to increase. The consecutive dry days index (CDD) increased, and the consecutive wet days index (CWD) decreased, as a result of fewer days of precipitation. Linear trends of the indices during each season show complicated regional features that are highly incoherent among the seasons, whereas trends of monthly and six-pentad (thirty-day) mean values show sub-seasonal variations, which implies heterogeneous climate changes on the sub-seasonal scale. Some of these results, such as the tendency for the Baiu period to shift to later in the summer over eastern and western Japan, agree with climate change projections, although more robust information on the regionality and seasonality of long-term precipitation trends will require further study on underlying changes in atmospheric circulation systems.

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   We investigated the vertical distribution and chemical nature of strong ligands for copper(II) in the western North Pacific based on measurements of organically complexed copper(II) with two experimental procedures having different properties. The first involved fractionation of copper(II) complexes on the basis of their stability: exclusion of copper(II) complexed with weak ligands and, consequently, extraction of only highly stable copper(II) complexed with strong ligands (conditional stability constant of log K′_CuL > 14) by use of a ligand-exchange reaction with ethylenediaminetetraacetic acid. We also detected two weaker ligand classes having log K′_CuL = 9-10 (L₁) and log K′_CuL ∼ 7 (L₂) with the copper(II) titration of an aliquot of the concentrated and desalted seawater. The second procedure involved the separation of hydrophobic copper(II) complexes from the original seawater by adsorption onto a resin. We determined the conditional stability constant of the hydrophobic copper(II) complex to be log K′_CuL ≤ 10.26 based on measurements of copper(II) complexes collected after copper(II) titration.
   We detected strong ligands (log K′_CuL > 14) at all depths from the surface to 1000 m, and we determined their concentrations to be 0.02-0.19 nM. The concentrations of hydrophobic ligands were lower than those of strong ligands at most depths, especially in surface waters. The vertical profile of strong ligands showed small maxima in the euphotic zone that did not coincide with chlorophyll a maxima. We estimated strong ligands to be present quantitatively (> 99.9%) in the form of copper(II) complexes throughout the entire 1000-m water column based on the concentrations of inorganic copper(II) measured by means of hydrophobic chromatography. In contrast, the copper(II)-complexed fraction of the hydrophobic ligands (log K′_CuL = 10.26) varied from 15% at 120 m to 78% at 1000 m and was positively correlated with the concentration of inorganic copper(II). Strong ligands appeared to have different ligand sites and different structural units in their environments compared to the hydrophobic ligands. The strong ligands appeared to be relatively hydrophilic because their ligand sites were multidentate and were composed of several polar functional groups.
   We characterized at least three types of organic ligands with different affinities for copper(II) and different hydrophobic properties. Each ligand was associated with copper(II) with a different efficiency that varied with depth in the oceanic water column. In surface layers it appeared that strong ligands played an important role that enabled copper(II) to be present stably in seawater as a soluble form, whereas at depth, hydrophobic ligands also contributed to the copper(II) speciation. Knowledge of ligand speciation is of noteworthy importance to the investigation of the abundance, distribution, and dynamics of copper(II) and organic ligands in the ocean.

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   Monthly temperature data for the period 1916-2010 in Japan were analyzed to quantitatively evaluate background (non-urban) and urban warming trends. In addition to data available from electronic devices, published data books were digitized in order to acquire adequate data at non-urban sites from the early to middle 20th century. To homogenize the temperature time series at each station, adjustments were made to eliminate bias arising from changes in observation times and schedules, and data at non-urban stations recorded with different observation systems were combined using principal component analysis and spatial interpolation. The results indicate that the warming trend of background (non-urban) daily mean temperature was 0.88°C/century averaged over the country, with a larger trend for minimum temperature (1.21°C/century) than maximum temperature (0.67°C/century). Trends were found to be higher at stations with higher population densities in the surrounding area. The anomaly relative to the non-urban trend was found to exceed 1°C/century at highly urbanized stations with population densities of 3000 km^-2 or more, but statistically significant albeit small anomalous warming was also detected at stations in sparsely urbanized areas with population densities of 300 to 1000 km^-2.

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   We investigated processes generating convection cells in tropical regions using a high-resolution, 3-dimensional, non-hydrostatic model. Convection cells near Sumatra Island were reproduced by using reanalysis data of the Japan Meteorological Agency Climate Data Assimilation System. Downscaled experiments with a horizontal grid interval of 1 km showed that convection cells were generated by the passage of updrafts of low-level waves over an area of large-scale convergence or over the leading edge of a weak cold pool. The large-scale convergence gradually decreased the temperature and increased the relative humidity of the atmosphere below a height of 2 km. The atmosphere above the leading edge of the weak cold pool was almost saturated. These atmospheric conditions were favorable for the generation of convection. The updrafts of low-level waves also decreased the temperature and increased the relative humidity in the updraft regions. These changes caused by the low-level waves triggered new convection cells. The low-level waves had the structure of gravity waves, as shown by the temporal lag of about 90°, of temperature minimums behind the updraft maximums. The changes in the lower atmosphere caused by the large-scale convergence created conditions that allowed convection cells to be generated easily, but the intensity of the low-level waves determined the timing of the generation.

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