Total Summer Precipitation Research Articles

Role of vegetation and soil in the Holocene megathermal climate over China

There was significant difference between vegetation cover in mid‐Holocene and that at present over China based on various evidences as concluded by Shi et al [1992]. These changes were introduced to the climate model to study the role of the changing vegetation and associated soil to the simulated climate of mid‐Holocene at 6000 years before present (BP) with bigger seasonal cycle of insolation than present (caused by the change of orbital parameters). Results show that the changes in vegetation and soil could further strengthen the monsoon rainfall over China. We found that replacing the today's seasonal cycle of insolation by that of mid‐Holocene increases the summer (June‐August) precipitation by 20% in eastern China (100°–120°E, 18°–42°N); while considering both the effect of changing orbital forcing and the vegetation and soil, the total summer precipitation increase is 29% in the same region. Compared with the reconstructed precipitation over China, the result of that including changing vegetation and soil is quantitatively better.

Assessment of the temperature and precipitation of 1990 during the Northern Wetlands Study (NOWES)

Temperature and precipitation statistics are reviewed to assess the climate during the field season of the Northern Wetlands Study (NOWES). Significant climatic events are highlighted using different temporal and spatial scales. Long‐term meteorological observing stations at Moosonee, Ontario, Schefferville, Quebec, and Churchill, Manitoba, were selected to reflect the climate of nearby NOWES research sites. Climate statistics for 1990 are compared to the 1951–1980 reference period or “normal.” The summer of 1990, on average, was warm and wet throughout most of the study area. Total summer precipitation was above the normal accumulation for Churchill and Moosonee, while precipitation was below normal in Schefferville. At all three sites the mean daily temperature for June to August was higher than the 1951–1980 normal but not significantly higher. Climatic conditions for individual months at selected stations deviated from normal. For example, at Moosonee, June 1990 was the second wettest month on record since 1932. The 163‐mm accumulation was 2 times greater than the 1951–1980 mean of 78 mm, although 63 mm fell on June 3 alone. In contrast, July precipitation, at Moosonee, was 69% of normal. In Schefferville, only 44 mm of precipitation fell in August, half the 98 mm normal. At Moosonee, the July mean daily temperature of 16.9°C was the warmest since 1981, although it was well below the record of 18.9°C set in 1959.

Invasion of Subalpine Meadows by Lodgepole Pine in Yellowstone National Park, Wyoming, U.S.A.

Many of the dry and mesic subalpine meadows in Yellowstone National Park are bordered by bands of small lodgepole pine trees. The authors asked whether these stands of small trees represent a directional process of meadow invasion, or alternatively, (1) small patches of postfire succession or; (2) more-or-less stable populations of trees having small stature because of adverse site conditions. Transect studies revealed that the bands of small trees were consistently younger than adjacent forest stands of obvious fire origin, that they lacked any evidence of fire, and that the trees were progressively younger as they approached the meadow. Soils under the young trees generally were more similar to meadow soils than to coniferous forest soils. The authors concluded, therefore, that meadow invasion has been occurring as a directional process since at least the mid- to late 1800s. Frequency of tree establishment in two dry meadows was positively correlated with mean June temperature and total summer precipitation (R[sup 2] = 0.49, P<0.0001, multiple stepwise regression). Thus, the major cause of tree invasion into dry meadows appears to be a regional climatic trend towards warmer and wetter growing seasons since the end of the Little Ice Age. Tree establishment in twomore » mesic meadows was more weakly and inconsistently correlated with weather variables. Thus, the mechanism of invasion of mesic meadows may involve interactions of episodic seed crops and microhabitat changes at the forest border, as well as regional climatic variability. 30 refs., 7 figs., 1 tab.« less

Influence of stand age and spatial location on throughfall chemistry beneath black spruce

Total summer precipitation and throughfall chemistry are investigated beneath black spruce (Piceamariana (Mill.) B.S.P.) in central Canada under the null hypothesis that no variation occurs with postfire stand age nor from one location on the feather moss dominated forest floor to another. Data from collectors at inner, mid, and edge radial positions beneath individual tree crowns and between neighbouring trees (gaps), within each of a 61-, 90-, and 120-year-old stand, were summed to yield a growing season total volume and the deposition of NO3−-N, NH4+-N, PO43−-P, K+, Ca2+, and Mg2+. Relative to incident precipitation, NO3−-N and NH4+-N showed highly significant net uptake by the canopy foliage. In contrast, K+, Ca2+, and Mg2+ showed net losses from the canopy throughfall. No appreciable difference in net throughfall (i.e., throughfall minus precipitation) volume and K+ deposition appeared among the stands. However, NH4+-N, NO3−-N, PO43−-P, Ca2+, and Mg2+ showed significant differences. NH4+-N and NO3−-N were less readily retained by foliage of the old stand than by that of the young stand, whereas Ca2+ and Mg2+ leached more readily from trees in the 120-year-old stand than in the other two. PO43−-P showed no net throughfall in the 61- and 120-year-old stands, whereas there were net losses from the canopy of the 90-year-old stand. This may reflect soil differences between the 90-year-old site and the other two. Significant differences in spatial location emerged for all variables measured. Net throughfall deposition of PO43−-P, K+, Ca2+, and Mg2+ declined from the inner to gap positions, whereas volume, NO3−-N, and NH4+-N increased. These effects were proportional to the canopy profile depth above each collector. The heterogeneity observed in nutrient deposition on the forest floor has important implications for the distribution and growth of forest floor plants, such as mosses and lichens, which seem to depend on precipitation and throughfall for their nutrient supply.

Relationship between number of human Japanese encephalitis cases and summer meteorological conditions in Nagasaki, Japan.

Analysis of epidemiological and meteorological data for Nagasaki Prefecture, southwest Japan, for the period 1950-1979, showed a correlation between size of epidemics of human Japanese encephalitis (JE) and weather factors. It was demonstrated that during the period 1950-1969 the epidemic size (ES) had two types of correlation: ES correlated inversely with total summer precipitation, and ES correlated directly with mean summer temperature. The fact that in the 1970s there were fewer cases of JE cannot be attributed to changes in the weather factors. Large epidemics occurred in summers with low precipitation and high temperatures, while the epidemic size was small when there was heavy precipitation and temperatures were low. The two weather factors jointly explain 0.53 of the observed variance in annual JE ES. Furthermore, they strongly correlate with each other, and total summer precipitation alone is sufficient to explain about one-half of the total variance. How these factors influence the number of JE cases is discussed in relation to the population dynamics of the vector mosquito, Culex tritaeniorhynchus.

Regional water balance on the Arctic Tundra in summer

The regional distributions of evaporation and precipitation were investigated on the arctic tundra on Axel Heiberg Island, Northwest Territory, Canada, during the summers of 1969 and 1970. The measurements were made using small weighing lysimeters and Canadian standard rain gauges installed at eight locations ranging in altitude from the sea level to 800 m above mean sea level. The mean evaporation rate for the snow‐free period increases slightly with altitude. The total evaporation for the snow‐free period at high altitudes, however, is cut short due to the longer duration of the snow cover. Consequently, the total summer evaporation shows a maximum value in the altitude zone between 100 and 600 m. Summer total precipitation increases steadily with altitude, exceeding evaporation at about 500 m. Below this altitude, most of the annual runoff takes place during and immediately after the melt of the winter snow cover. At higher altitudes, runoff is observed throughout summer.

Preliminary calculations of average storm duration and seasonal precipitation rates for the northeast sector of the united states

Regional and seasonal averages of storm duration and precipitation rates are needed as input variables in models aimed at describing precipitation processes relating to acid rain and other problems. Hourly precipitation data for 77 first order weather stations were used to calculate the summer and winter regional average storm duration and average precipitation rates over the northeastern United States. Average storm duration for summer (June–July–August), and winter (December–January–February) seasons considered periods of up to three dry hours in summer storms, and up to 6 dry hours in winter storms to be part of the same storm. Thus, each storm consisted of one or more precipitation periods. The average precipitation event rates for summer and winter storms were calculated. By considering storm duration on an hourly basis, the 3-h summer storm was found to contribute the greatest fraction to total summer precipitation. Similarly, the 26-h winter storm was found to contribute the greatest fraction to winter precipitation. The summer storms typically consisted of one rain event lasting about three hours with rain rates averaging ~ 2.5 mm h −1. The 25-h winter storm averaged about 3 precipitation periods (or rain bands). Each period lasted about seven hours and had an average precipitation rate of 1.0 mmh −1.

Distribution of Rrecipitation during the Short Dry Period of Mid-Summer in Fukushima Prefecture and Northern Kanto Area

It is said that Japan has a short dry period in mid-summer. However even in such a period, the local rainfall is frequent in some regions. The author clarifies the distribution of such a local rainfall during the short dry period, using data for precipitation in Fukushima Prefecture and Northern Kanto area (Fig. 1).The results are summarized as follows;1) The local rainfall in mid-summer is often observed along the north borders of Tochigi Prefecture. This area does not always coincide with the region abundant in total summer precipitation (Fig. 3).2) As a whole, the local rainfall in mid-summer occurs during 1600-1800 JST, and it tends to stop within two hours (Table 1), but each station has a different characteristic in hourly occurrence (Fig. 4). In the northwestern Tochigi Prefecture, the local rainfall in mid-summer inclines to occur in the earliest time (Fig. 5 and Fig. 7).3) The ratio (%) of amount of precipitation in the dry period of mid-summer to that of total summer precipitation is highest, about 20%, in Yamizo Mountains, Tadami area, and around Kiryu (Fig. 9). The ratios fluctuate considerably year-to-year, and in some case, they exceed 50%.

Highest telescope

Determination of carbon isotope (δ13C) values of tree-ring tissue is a well-established method to reconstruct past climate variability at annual resolution, but such records are limited in tropical latitudes due to the lack of well-defined annual growth bands. Recent work has demonstrated the potential for high-resolution, intra-ring δ13C records to help define ring boundaries in tropical environments and provide additional climate information at sub-annual resolution. Here we present a high-resolution, intra-ring carbon isotope (δ13C) record of the Hawaiian endemic species Sophora chrysophylla (also known as “māmane”) in order to assess the ability to extract seasonal climate information from these drought tolerant trees. Tree cores were sampled from high-elevation māmane trees growing on the west side of Mauna Kea, Big Island. Across our entire dataset (1986–2008), we identified a notable decreasing linear trend in the δ13C record of 0.061‰/year that can be attributed to changes in the δ13C value of atmospheric CO2 and pCO2 concentration associated with fossil fuel burning. Correcting for these affects yields a nearly flat δ13C record with a slope of − 0.0075‰/year, suggesting no long-term trends in climate across the study period. We observe a quasi-periodic change in the δ13C values [Δ(δ13C)] measured within each ring that averages 1.09 ± 0.50‰ (± 1σ, n = 23) in amplitude. These variations are interpreted as the intra-annual isotopic signal in tree photosynthesis. The δ13C variability correlates with the visible ring structure of the sample, suggesting the presence of annual growth rings at this tropical high elevation site.We applied these data to a model that relates the Δ(δ13C) value to seasonal changes in precipitation in order to reconstruct annual changes in total summer (May through October) and winter (November through April) precipitation at the site. Across the 23-year record (1986–2008; n = 579 δ13C measurements), reconstructed values for the ratio of summer to winter precipitation, total summer precipitation, and total winter precipitation correlate well with rainfall data collected from a nearby weather station (r = 0.65, 0.36, and 0.70, respectively). These results support application of this model to reconstruct inter-annual changes in seasonal precipitation from long-term tree-ring chronologies. They also demonstrate the potential of using māmane δ13C for future long-term climate reconstructions.

Light-traps in the control of insects

The influence of climate on winter wheat yields were examined in two important global breadbaskets—the Picardy Region of northern France and the Rostov Oblast of southern Russia. Thirty-year climatologies were established for each region and the magnitude of change between 1973 and 2010 was quantified for a variety of climate variables important to crop development. Using a “first differences” analysis, the aspects of climate that winter wheat yields have been most sensitive to were identified and the impact of changes in these variables on winter wheat yield trends was quantified. A number of aspects of climate have changed at unprecedented rates in the two regions. Between 1973 and 2010, summer precipitation totals decreased by 61% and maximum summer temperatures increased by 4 °C in Rostov, while fall precipitation totals decreased by 9% and maximum spring temperatures increased by 2.4 °C in Picardy. In addition, winter wheat yields were strongly correlated with a number of climate variables, although the most important drivers of yield variability differed between the two regions. May and June average temperatures explained 49% (p < 0.0001) and 16% (p < 0.05) of interannual yield variability in Rostov, while in Picardy, November precipitation and minimum summer temperatures explained 26% (p ≤ 0.001) and 23% (p < 0.01). The climate variables that exhibited significant historical trends were often not the climate drivers that winter wheat yields were strongly correlated with in Rostov. Therefore, it appears that recent climate change has not significantly impacted winter wheat yield trends thus far in the region. However, in Picardy, there was partial overlap in the climate variables that winter wheat yields were most responsive to and those that have already exhibited significant changes over time. Consequently, climate change has likely caused an 11% decrease in winter wheat yield trends in the region.