Wet Extremes Research Articles

High- and low-latitude forcing of Plio-Pleistocene East African climate and human evolution

The late Cenozoic climate of East Africa is punctuated by episodes of short, alternating periods of extreme wetness and aridity, superimposed on a regime of subdued moisture availability exhibiting a long-term drying trend. These periods of extreme climate variability appear to correlate with maxima in the 400-thousand-year (kyr) component of the Earth's eccentricity cycle. Prior to 2.7 Ma the wet phases appear every 400 kyrs, whereas after 2.7 Ma, the wet phases appear every 800 kyrs, with periods of precessional-forced extreme climate variability at 2.7–2.5 Ma, 1.9–1.7 Ma, and 1.1–0.9 Ma before present. The last three major lake phases occur at the times of major global climatic transitions, such as the onset of Northern Hemisphere Glaciation (2.7–2.5 Ma), intensification of the Walker Circulation (1.9–1.7 Ma), and the Mid-Pleistocene Revolution (1.0–0.7 Ma). High-latitude forcing is required to compress the Intertropical Convergence Zone so that East Africa becomes locally sensitive to precessional forcing, resulting in rapid shifts from wet to dry conditions. These periods of extreme climate variability may have provided a catalyst for evolutionary change and driven key speciation and dispersal events amongst mammals and hominins in East Africa.

Tectonics, orbital forcing, global climate change, and human evolution in Africa: introduction to the African paleoclimate special volume

The late Cenozoic climate of Africa is a critical component for understanding human evolution. African climate is controlled by major tectonic changes, global climate transitions, and local variations in orbital forcing. We introduce the special African Paleoclimate Issue of the Journal of Human Evolution by providing a background for and synthesis of the latest work relating to the environmental context for human evolution. Records presented in this special issue suggest that the regional tectonics, appearance of C 4 plants in East Africa, and late Cenozoic global cooling combined to produce a long-term drying trend in East Africa. Of particular importance is the uplift associated with the East African Rift Valley formation, which altered wind flow patterns from a more zonal to more meridinal direction. Results in this volume suggest a marked difference in the climate history of southern and eastern Africa, though both are clearly influenced by the major global climate thresholds crossed in the last 3 million years. Papers in this volume present lake, speleothem, and marine paleoclimate records showing that the East African long-term drying trend is punctuated by episodes of short, alternating periods of extreme wetness and aridity. These periods of extreme climate variability are characterized by the precession-forced appearance and disappearance of large, deep lakes in the East African Rift Valley and paralleled by low and high wind-driven dust loads reaching the adjacent ocean basins. Dating of these records show that over the last 3 million years such periods only occur at the times of major global climatic transitions, such as the intensification of Northern Hemisphere Glaciation (2.7–2.5 Ma), intensification of the Walker Circulation (1.9–1.7 Ma), and the Mid-Pleistocene Revolution (1–0.7 Ma). Authors in this volume suggest this onset occurs as high latitude forcing in both Hemispheres compresses the Intertropical Convergence Zone so that East Africa becomes locally sensitive to precessional forcing, resulting in rapid shifts from wet to dry conditions. These periods of extreme climate variability may have provided a catalyst for evolutionary change and driven key speciation and dispersal events amongst mammals and hominins in Africa. In particular, hominin species seem to differentially originate and go extinct during periods of extreme climate variability. Results presented in this volume may represent the basis of a new theory of early human evolution in Africa.

Precipitation Extremes Estimated by GPCP and TRMM: ENSO Relationships

Abstract Global monthly and daily precipitation extremes are examined in relation to the El Niño–Southern Oscillation phenomenon. For each month around the annual cycle and in each 2.5° grid block, extremes in the Global Precipitation Climatology Project dataset are defined as the top five (wet) and bottom five (dry) mean rain rates from 1979 to 2004. Over the tropical oceans El Niño–Southern Oscillation events result in a spatial redistribution and overall increase in extremes. Restricting the analysis to land shows that El Niño is associated with an increase in frequency of dry extremes and a decrease in wet extremes resulting in no change in net extreme months. During La Niña an increase in frequency of dry extremes and no change in wet extremes are observed. Thus, because of the juxtaposition of tropical land areas with the ascending branches of the global Walker Circulation, El Niño (La Niña) contributes to generally dry (wet) conditions in these land areas. In addition, daily rain rates computed from the Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis are used to define extreme precipitation frequency locally as the number of days within a given season that exceeded the 95th percentile of daily rainfall for all seasons (1998–2005). During this period, the significant relationships between extreme daily precipitation frequency and Niño-3.4 in the Tropics are spatially similar to the significant relationships between seasonal mean rainfall and Niño-3.4. However, to address the shortness of the record extreme daily precipitation frequency is also related to seasonal rainfall for the purpose of identifying regions where positive seasonal rainfall anomalies can be used as proxies for extreme events. Finally, the longer (1979–2005) but coarser Global Precipitation Climatology Project analysis is reexamined to pinpoint regions likely to experience an increase in extreme precipitation during El Niño–Southern Oscillation events. Given the significance of El Niño–Southern Oscillation predictions, this information will enable the efficient use of resources in preparing for and mitigating the adverse effects of extreme precipitation.

The Prairie-Wetland Vegetation Continuum in the Chicago Region of Northeastern Illinois

We conducted a floristic ordination and gradient analysis of plant communities extending from prairie through graminoid-dominated wetlands in the Chicago region of northeastern Illinois. Data represented about 450 species from 103 stands sampled across a gradient of six soil moisture classes ranging from dry to hydric, and included sand, gravel, dolomite and loam prairies, as well as fen, sedge meadow, floating mat, marsh, and bog. As found in other midwestern grassland studies, vegetation aligned most strongly along a soil moisture gradient, with individualistic species distributions forming a hierarchical continuum, and lower species richness at the dry and wet extremes of the moisture gradient. Most species were infrequent, with about 70% occurring at less than 20% frequency and present in less than five communities. Species that were more frequent within communities were also more widespread among communities, fitting the niche-based model of species distribution. Moreover, less than 20% of all species sampled were significant indicators of soil moisture gradient classes, with most representing mesic and hydric habitats. Dominant prairie grasses extended from dry to wet habitats, merging with wetland species in graminoid fen, calcareous seep and sedge meadow habitats. Hydric habitat, represented by calcareous floating mat, marsh and bog, had fewer dominant prairie species and was dominated by a wetland flora. These results provide compositional and structural models for managing and restoring vegetation across the prairie-wetland vegetation gradient of the Chicago region.

Changes in daily temperature and precipitation extremes in central and south Asia

Changes in indices of climate extremes are studied on the basis of daily series of temperature and precipitation observations from 116 meteorological stations in central and south Asia. Averaged over all stations, the indices of temperature extremes indicate warming of both the cold tail and the warm tail of the distributions of daily minimum and maximum temperature between 1961 and 2000. For precipitation, most regional indices of wet extremes show little change in this period as a result of low spatial trend coherence with mixed positive and negative station trends. Relative to the changes in the total amounts, there is a slight indication of disproportionate changes in the precipitation extremes. Stations with near‐complete data for the longer period of 1901–2000 suggest that the recent trends in extremes of minimum temperature are consistent with long‐term trends, whereas the recent trends in extremes of maximum temperature are part of multidecadal climate variability.

Impact of increasing CO2 on monthly-to-annual precipitation extremes: analysis of the CMIP2 experiments

The impact of increasing atmospheric CO2 on high and low extremes of monthly-to-annual precipitation is studied using 20 model experiments participating in the second phase of the coupled model intercomparison project (CMIP2). In marked contrast with previous research on daily precipitation extremes, the simulated changes in extremes on these longer time scales are well correlated with the changes in the long-term mean precipitation: wet extremes become more severe especially where the mean precipitation increases, and dry extremes where the mean precipitation decreases. Changes in relative variability play a smaller but discernible role. In an ensemble-mean sense, the variability increases slightly in most areas, so that the contrast between the high and low precipitation extremes grows larger with increasing CO2. The changes in the frequency of extremes (fraction of cases with precipitation above a high or below a low predefined threshold) are much larger than the changes in their magnitude. Most of the ensemble-averaged changes in the frequency of extremes can be reconstructed by using the changes in time mean precipitation alone, provided that the variation in time mean precipitation change between different models is taken into account. The nonlinear relationship between the mean precipitation and the frequency of extremes complicates the interpretation of the frequency changes, especially when averaging frequencies over different models.

Role of storm track activity in the interannual seesaw of summer precipitation over northern Eurasia

Oscillation between relatively dry and wet extremes is a noteworthy characteristic of the interannual variability in summer precipitation over Siberia. Recently, we identified an out‐of‐phase relationship in the temporal signature of basin‐scale precipitation between eastern and western Siberia (ES and WS). This east‐west seesaw has been especially pronounced during the past 30 years. The spatial structure of large‐scale precipitation and circulation anomalies associated with this east‐west seesaw is characterized by an east‐west dipole across northern Eurasia. We extended our work to investigate the important atmospheric processes involved in the dipole patterns of precipitation and large‐scale circulation anomalies for the northern summers (June–August) of 1972–2001. In particular, this work focuses on the role of storm track activities associated with synoptic‐scale (<10 days) eddies in producing the stationary waves that correspond to the precipitation anomaly dipoles. Linear regression and composite analyses of various eddy statistics are performed for two contrasting extremes in the Siberian summer precipitation seesaw. These two extreme phases are denoted ES‐wet‐WS‐dry and WS‐wet‐ES‐dry. The summer mean atmospheric anomalies related to the precipitation seesaw show stationary wavetrain patterns in conjunction with the precipitation dipole anomalies. The cold trough/warm ridge dipole corresponds to the relative wet and dry region. Analysis of storm track activity reveals similar east‐west contrasting structures, meaning that the displacements associated with the anomalous storm tracks are accompanied by a phase reversal between the two extreme phases. An anomalous stationary trough (ridge) corresponds to the anomalous high‐(low‐)synoptic‐scale‐eddy‐activity region in both ES and WS. The forcing by synoptic‐scale eddies is examined to confirm the storm track feedback on the Eurasian stationary waves. The results show that barotropic feedback induced by synoptic‐scale eddy vorticity fluxes is in phase with the Eurasian wave field. Cyclonic (anticyclonic) circulation forcing is collocated with the anomalous stationary trough (ridge). These spatially coherent relationships suggest that storm track feedback due to eddy vorticity fluxes helps to reinforce and maintain the Eurasian wave structure coupled with the precipitation dipole pattern of each phase. Consequently, the interannual variability of the Eurasian storm track intensity and location is a crucial factor in forcing the mean precipitation and circulation patterns between the two extreme phases.

Seasonality in the impact of ENSO and the north atlantic high on caribbean rainfall

Caribbean rainfall is affected by climate variability of Pacific and Atlantic origin, e.g. the El Nino-Southern Oscillation (ENSO) phenomenon, and variability in the North Atlantic High sea level pressure (SLP) center, respectively. During the lifetime of an ENSO cycle, the basin experiences dry and wet extremes. In the case of a warm event, the dry extreme precedes the mature ENSO phase, and can be explained in terms of a direct response to the atmospheric anomaly generated by the warm sea surface temperatures (SST) in the eastern equatorial Pacific. The wet extreme follows the mature phase, and is consistent with the lagged warming effect of ENSO on tropical North Atlantic SSTs. The wintertime state of the North Atlantic High is hypothesized to affect Caribbean rainfall through its effect on tropical SST. A strong North Atlantic High SLP center during the early months of the calendar year strengthens the trade winds, hence cooling SSTs in the tropical latitudes of the North Atlantic. The effect lingers on most noticeably until the start of the Caribbean rainy season, in May–June, when cool SSTs are associated with deficient rainfall in the basin.

Wetland occurrence in relation to topography: a test of topographic indices as moisture indicators

Information about the spatial distributions of soil moisture or groundwater levels is needed for aggregation of soil–vegetation–atmosphere–transfer (SVAT) models. The possibility of predicting wetness distributions in catchments from topographic data was investigated using topographic indices, notably the TOPMODEL index. The indices were calculated from commercially available gridded data (50×50m2) over two areas with contrasting topography: a catchment (Nåsten) in the low-relief NOPEX region in southern Sweden and a group of catchments in a hilly area (Kassjöån) in central Sweden. The occurrence of mires, assumed to represent the extreme wetness end of the wetness spectrum, was used as field data.The frequency distributions of topographic indices for mire and non-mires were clearly different in Kassjöån, although there was a large overlapping, whereas the two distributions were very similar in Nåsten. Prediction of mires from topographic indices was meaningful only in Kassjöån. Although it gave poor results in terms of fractions of successfully predicted mire cells out of the observed mire cells, the general spatial patterns of mires were fairly well simulated. One important reason for the failure of the indices to predict mires in Nåsten, and probably also to predict other wetness classes, is that the spatial resolution in the index calculation was coarser than typical length scales of the topographic features in this catchment, being only a few tenths of meters.The importance of geologic conditions in modifying the topographic control over the wetness is exemplified from the obtained relationship between topographic indices and mire occurrence.

Minimisation of organic matter disruption during particle-size fractionation of grassland epipedons

In order to be able to avoid artefacts during fractionation of soil into primary particles, knowledge is required about the soil organic matter (SOM) behaviour when dispersing soil aggregates from different environments. This study was designed to investigate dispersion behaviour of macro- and microaggregates of native grassland epipedons from different climatic regions. Samples were collected from eight grassland epipedons to a depth of 10 cm along a climosequence in the prairie from Central Saskatchewan, Canada, to Southern Texas, USA. The samples were sieved to 2 mm and ultrasonically dispersed at 0, 1, 5, 15, 25, and 75 kJ, with partial dispersion also at 2 and 3 kJ. Carbon and nitrogen analysis was performed on the <20 μm, 20–250 μm and 250–2000 μm size separates of all dispersion treatments. Dispersion of macroaggregates (250–2000 μm) was achieved at 1 kJ ultrasonic energy for most of the sites whereas 3 kJ were needed for dispersing macroaggregates at wet extremes in the prairie. More ultrasonic energy (≥5 kJ) was required to disperse microaggregates (20–250 μm). Intense dispersion (>5 kJ), however, disrupted particulate organic matter. Ultrasonic dispersion at 75 kJ was different for different ultrasonic instruments, suggesting that the calorimetric calibration was not very suitable for standardisation of ultrasonic energy input. For minimisation of artefacts, it is suggested that particulate SOM should be removed after weak dispersion (≥3 kJ), and, prior to subsequent aggregate disruption at 22 kJ, input energy should be checked at intervals by ultrasonic pressure measurements to determine whether the tip of the probe has deteriorated.

A WATER BALANCE MODEL FOR A SUBARCTIC SEDGE FEN AND ITS APPLICATION TO CLIMATIC CHANGE

A model to calculate the water balance of a hummocky sedge fen in the northern Hudson Bay Lowland is presented. The model develops the potential latent heat flux (evaporation) as a function of net radiation and atmospheric temperature. It is about equally sensitive to a 2% change in net radiation and a 1°C change in temperature. The modelled potential evaporation agrees well with the Priestley–Taylor formulation of evaporation under conditions of a non-limiting water supply. The actual evaporative heat flux is modelled by expressing actual/potential evaporation as a function of potential accumulated water deficit. Model evaporation agrees well with energy balance calculations using 7 years of measured data including wet and dry extremes. Water deficit is defined as the depth of water below reservoir capacity. Modelled water table changes concur with measurements taken over a 4 year period. When net radiation, temperature and precipitation measurements are available the water balance can be projected to longer time periods. Over a 30 year interval (1965–1994) the water balance of the sedge fen showed the following. During the growing season, there was an increase in precipitation, no change in temperature and a decrease in net radiation, evapotranspiration and water deficit. There was also a decrease in winter snow depths. The fen was brought back to reservoir capacity during final snowmelt every year but one. Summer rainfall was the most important single factor affecting the water balance and the ratio actual/potential evaporation emerged as a linear function of rainfall amount. A 2 × CO2 climate warming scenario with an annual temperature increase of 4°C and no precipitation change indicates lesser snow amounts and a shorter snow cover period. A greater summer water deficit, triggered mainly by greater evaporation during the month of May, is partially alleviated by lesser evaporation magnitudes in July. The greater water deficit would be counterbalanced by a 23% increase in summer rainfall. On average, the fen's water reservoir would still be recharged after winter snowmelt but the ground would remain at reservoir capacity for a shorter time. The warming scenario with a 10% decline in summer rainfall would create a large increase in the longevity and severity of the water deficit and this would be particularly evident during drier years. The carbon budget and peat accumulation and breakdown rates are strongly affected by changes in the water balance. Some evidence implies that greater water deficits lead to an increase in net carbon emissions. This implies that the sedge peatland could lose biomass under such conditions. An example is given where increased water deficit results in large decreases in local wetland streamflow.

Monsoon Forests in Northwestern Australia I. Vegetation Classification and the Environmental Control of Tree Species

An indirect gradient analysis was performed on woody species basal area data collected from 144 monsoon forests situated throughout northewestern Australia. In order to eliminate edge effects each monsoon forest was differentiated from surrounding vegetation by inspection of sorted lists of tree species recorded from quadrats $(10 \times 20 m)$ placed on a transect that traversed each forest boundary. On each transect the monsoon forest quadrats were amalgamated to yield a single averaged sample of tree species basal area and environmental characteristics to represent each fo the 144 sampled forests. Surface soil physical and chemical characteristics were related to compositional patterns of tree species abundance data in one-, two-and three-dimensional Hybrid Multi-dimensional Scaling ordination solutions. The unidimensional ordination recovered a major environmental gradient where dry fertile soils, often on rocky slopes occur at one extreme and infertile waterlogged soils charcterize the other. Mean basal area of the fifty species with the highest importance values showed a continuously varying sequence of unimodal curves over the unidimensional ordination axis, although individual species distribution and abundance showed considerable variation on the gradient. Forest biomass, as measured by mean canopy height and mean total basal area, increased linearly over the gradient. With the exception of the dry extreme, stem density was relatively uniform across the gradient. Both the wet and dry extremes of the gradient have lower species richness per $200 m^2$ and fewer species with peaks of abundance. There appears to be a relatively sharp environmental and physiognomic discontinuity along the gradient as indicated by surface soil moisture content, and the cover of ferns and palm regeneration. This beak is consistent with a primary dichotomy of wet and dry forest formations as derived by other floristic and structural classifications of this vegetation. Of the common tree species (149), 53% of the dry forest species (125) only occurred in that community, while 29% of the wet forest species (83) were restricted to the wet forest.

Real permittivity of snow at 1 MHz and 0°C

The real permittivity of 200 snow samples with wide range of density and wetness was measured in a capacitive cell at 1 MHz and at 0°C. Measurements fit three empirical functions. A good fit for the full density and wetness range is: ϵ=Σν jϵ j−0.43ν Aν I−50ν Iν w−100ν Aν w where ϵ is the relative real permittivity; j=A, I and W (air, ice and water); v j is the volume proportion of each phase; and ϵ j is the dielectric constant of each phase. For low v W, the measurements fit closely a polynomial proposed earlier for ∼ 10 MHz measurements, namely: ϵ=1+1.92ρ+0.44ρ 2+18.7ν w+45ν 2 w where ϱ is snow density (g/cm 3). Measurements also fit a third function ϵ q =∑ v j ϵ q j which was used in an earlier microwav study. In agreement with microwave measurements, the empirical constant q was found to be 0.4 for wet snow in the range 0.02< v w≤0.4. The value of q was found to be higher at both the dry and very wet extremes: q=0.7 for dry snow ( v w≈0); and q=0.6 for slush (0.4< v w≤1). These q values are consistent with a qualitative model of snow microstructure as a sintered ice skeleton with water inclusions that are disconnected at low v w and connect at high v w.

Diets of Black-stripped wallabies in New South Wales

In both the wet and dry extremes of its remnant range in northern New South Wales, the black-striped wallaby, Macropus dorsalis, eats predominantly monocotyledonous plants, selecting leaves and, in some seasons, seedheads. The wallabies eat a wide range of monocot species, taking these from the habitat in which they shelter in the daytime as well as from that in which they forage at night. This study suggests that reserves for the conservation of the species need to include nocturnal foraging as well as diurnal sheltering habitats.

Books

Based on the ERA-40 reanalysis data, dryness and wetness over the Tibetan Plateau are categorized according to the monthly standardized precipitation index. The atmospheric features associated with severe and extreme dryness and wetness reveal two cross-Eurasia wave trains: the Scandinavia-East Asia wave train and the Mediterranean-East Asia wave train. Severe and extreme dryness is associated with an anomalous cyclone over south and southeast Asia, which directs the moisture supply from the Arabian Sea, the Bay of Bengal, and the South China Sea directly eastward towards the western Pacific, thus bypassing the Tibetan Plateau. This cyclone anomaly constitutes part of the Scandinavia-East Asia wave train, which is sustained by the divergence and convergence of the anomalous transient eddy heat transport associated with a more southwest-northeast oriented North Atlantic storm track and a northward shift of the polar front jet in the North Atlantic.In contrast, severe and extreme wetness over the Tibetan Plateau is associated with a more zonally elongated North Atlantic storm track; wave trains excited from there have a high probability to reach the Mediterranean region and to propagate eastward following the subtropical westerly jet. This Mediterranean-East Asia wave train generates anticyclonic anomalies around the Tibetan Plateau and East China, which bring more moisture supply from the Arabian Sea, the South China Sea, and the western Pacific towards the Tibetan Plateau and enhance the moisture convergence there. This paper demonstrates how atmospheric bridging processes affect regional climate variability under present day climatic conditions, which are also relevant for understanding past climates.

HYDROLOGY OF TWO SMALL WETLAND BASINS IN EASTERN MASSACHUSETTS1

ABSTRACT: A hydrologic budget was prepared for two geologically different wetland basins in eastern Massachusetts for the 1971 water‐year. Water table conditions prevailed at one wetland underlain by peat while an artesian system functioned at the other wetland which was underlain by muck. Hydrologic responses were generally similar at both wetlands, although each functioned differently in detail. Both wetlands exhibited high spring discharges and depressions of low flow. Ground water accounted for an estimated 93% of the total annual discharge from both wetlands; in late summer the peat deposit recharged the regional ground water body. Evapotranspiration in the spring was retarded in probable consequence of the extreme wetness of the wetland soils.

Some soils of the British Solomon Islands Protectorate

Soils were studied on the islands of Guadalcanal, Kolombangara, Santa Isabel, San Jorge, and San Cristobal, mainly under tropical rain forest in mountainous inland regions. The climate of the Solomon Islands is characterized by high temperatures and humidity, copious rain and a high proportion of cloudy days, with little seasonal variation except in the rainfall of the central coastal region of northern Gaudalcanal. In the areas studied soils on stable sites are deep, and intensely weathered and leached. On steep slopes soils are shallow and unstable, with much colluvial rock debris. Most soils are strongly acid to acid (pH 3 to 5) clays and have very low plant nutrient contents. On soils from basic igneous and ultrabasic metamorphic rocks weathering and leaching have resulted in loss of virtually all of the more readily weatherable constituents and extreme relative accumulation of oxides, principally of aluminium, iron and titanium. Rendzinas are found on recently exposed coral limestone, but older limestone areas have strongly leached soils similar to those on basic igneous rocks. The Solomons soils are related to similar soils in Hawaii, Western Samoa, New Caledonia, New Zealand, Australia, the West Indies and south-east Asia. In general the most strongly leached Solomons soils have reached a stage of degradation beyond that of similar soils described from other regions. There is apparently an almost closed organic cycle of nutrient turn-over under rain forest, with most of the available plant nutrients concentrated in organic-matter-enriched surface soil horizons and with little contribution to plant growth from underlying mineral horizons. There is little evidence of close relationships between soils and vegetation, except in soils derived from serpentine which have a forest dominated by Casuarina papuana. Large-scale destruction by fire of Casuarina forest on soils from serpentine has resulted in loss of surface horizons by erosion, failure of the forest to regenerate, and formation of laterite on the bare soil surface. Small-scale destruction of forest for native gardens appears to have little long-term effect on soils or vegetation. ‘ Soil ’ animals are usually confined to logs and other above-ground habitats and are rare in the soil, apparently due to the extreme wetness and probably partial anaerobiosis of below-ground habitats.

Agro-climatic Studies on the Difference of the Climate in Each Year

In order to research the relationship between the yields of rice plants and soybeans and the climate, the writer studied the variations of climate among years and of growth of rice plants and soybeans, which had been observed at Morioka (from 1926 to 1955).The results are summarized as follows1) The Variation of climate was different in each year and time. The variation of the mean air temperature with year was the smallest of the measured meteorological elements, and that of the amount of precipitation was the largest. Seasonally, the variations of elements were the largest in the first 20 days in July (Table 1).2) Owing to Tables 3 and 4, there were close relationships between the yield of rice plant and air temperature and number of hour with sunshine. Especially, it was rational consideration to show the limits of the Mean value of climate.3) The yield of soybeans had the delicate relationship with not only air temperature and sunshine but also amount of precipitation. It was larger than the standard deviation of yield of rice plant.4) There were close relationships between the dates of first appearance of mean air temperature of more than 20°C and dates of head sprout of rice plants, and also between number of days of the mean air temperature of more than 20°C and the yield of rice plants. (Fig. 1, Fig. 2)5) Generally the yield of soybeans was similar to rice plant excepting the fact that the bad harvest of soybeans was due to the extreme drying or wetness of flowering day which did not exist for the case of rice plant (Fig. 2).

Compensation in Weather

As our climate does not, in a long series of years, undergo permanent change, we are accustomed, in a time of extreme cold, wetness, or other quality of weather, to expect, in a vague way, that we shall have, ere long, a variation in the opposite direction, equalising matters. Is it possible to attain greater definiteness in such expectation, and, utilising the principle of compensation, to forecast, in a measure, the character of an approaching season?