Yoko Naito

Selfing and inbreeding depression in seeds and seedlings of Neobalanocarpus heimii (Dipterocarpaceae).

We evaluated the degree of selfing and inbreeding depression at the seed and seedling stages of a threatened tropical canopy tree, Neobalanocarpus heimii, using microsatellite markers. Selection resulted in an overall decrease in the level of surviving selfed progeny from seeds to established seedlings, indicating inbreeding depression during seedling establishment. Mean seed mass of selfed progeny was lower than that of outcrossed progeny. Since the smaller seeds suffered a fitness disadvantage at germination in N. heimii, the reduced seed mass of selfed progeny would be one of the determinants of the observed inbreeding depression during seedling establishment. High selfing rates in some mother trees could be attributed to low local densities of reproductive individuals, thus maintenance of a sufficiently high density of mature N. heimii should facilitate regeneration and conservation of the species.

Behavior of Planetary Waves before and after Stratospheric Sudden Warming Events in Several Phases of the Equatorial QBO

Almost a thousand stratospheric sudden warming (SSW) events are obtained through long time integrations with a simple global circulation model, and a statistical analysis based on such a large number of samples is made to investigate behavior of planetary waves before and after SSW events depending on the phase of the equatorial quasi-biennial oscillation (QBO). An idealized zonal momentum forcing to mimic a phase of the QBO is imposed under a perpetual winter condition, and eight phases of the QBO-wind forcing are examined for 8 10 800-day datasets. Some systematic dependence on the phase of the QBO-wind forcing is seen in the anomaly of the Eliassen–Palm (EP) flux in the winter hemisphere, both in the 10 800-day average and in the composites for SSW events. The composite analysis shows that before SSW events, the upward EP flux in the troposphere and midlatitude lower stratosphere as well as the equatorward flux above the tropopause is larger in the westerly forcing runs than in the easterly forcing runs. After SSW events, the upward EP flux in the troposphere is still larger in the westerly forcing runs. Correlation associated with the differences among SSW events that occurred in each run is significantly positive between the magnitude of the warming and the planetary wave activity flux before all the events in QBO-wind forcing in the stratosphere, but only in the easterly forcing runs in the troposphere.

A parameter sweep experiment on the effects of the equatorial QBO on stratospheric sudden warming events

The effects of the equatorial quasi-biennial oscillation (QBO) on stratospheric sudden warming (SSW) events are investigated by performing long time integrations with a simple global circulation model under a perpetual winter condition. Zonal momentum forcing is imposed to produce a westerly or easterly phase of the QBO in the equatorial stratosphere, and a parameter that determines strength and direction of the forcing is swept for nine values as an experimental parameter. The polar night jet is weaker and polar stratosphere is warmer in the runs with easterly ‘‘QBO wind’’ forcing, in qualitative agreement with the observational result. The polar night jet is strongest for a moderate westerly forcing, while it becomes weaker for too strong westerly forcing. Occurrence of SSW events is irregular, intermittent, and least frequent in the run with the moderate westerly forcing. As a result, frequency distribution of the polar stratospheric temperature shows the largest skewness. The frequency distribution of polar temperature is systematically dependent on the QBO wind forcing not only in the stratosphere but in the troposphere. The dependence is statistically significant even in the troposphere in spite of heavy overlap of the frequency distributions. Composite analysis for a large number of SSW events shows downward influence of the upper-stratospheric warming to the lower levels in two characteristic timescales. Short-time cooling response within several days is extended to the summer hemisphere, while long-time response persisting a couple of weeks is confined within the winter hemisphere and extends down to the level near the tropopause. The response of polar temperature in the lower stratosphere shows systematic dependence on the QBO wind forcing; mean warming rate is smallest for the moderate westerly forcing, and warming is more rapid for the easterly forcings.

Current status of level 2 product of Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)

New level 2 products v2.0 of JEM/SMILES are scheduled to be released in Sep., 2011. This will be the first publicreleased version. In pre-released product v1.3, positive bias of retrieved temperature in the stratosphere was the largest issue since temperature is basic parameter which characterizes the atmospheric structure. The new product use latest L1B 007 which includes gain nonlinearity effect of receivers, bias of temperature in upper stratosphere is suppressed. In addition, we stopped temperature retrieval above 40km and refer MLS temperature product with applying migrating tidal model. HCl profiles in mesosphere become constant, which supports this temperature processing.

Combined effects of QBO and 11‐year solar cycle on the winter hemisphere in a stratosphere‐troposphere coupled system

[1] Combined effects of the quasi-biennial oscillation (QBO) and the 11-year solar cycle (SC) on the winter hemisphere are investigated with an idealized mechanistic circulation model of a stratosphere-troposphere coupled system. A zonal momentum forcing is imposed to mimic a westerly or easterly phase of the QBO and a heating anomaly associated with the SC is introduced around the stratopause. A series of long time integrations of 39,600 days are performed to obtain statistically significant results for forty-six combinations of these experimental parameters. The obtained dependence of the temperature response in the polar stratosphere on the combination of QBO and SC are qualitatively consistent with the observed responses. The difference in the winter polar stratosphere between the solar maximum and minimum phase is highly significant at above the 95% confidence level in many cases of the QBO westerly runs. The SC effect is, however, relatively small compared to the QBO effect. Citation: Ito, K., Y. Naito, and S. Yoden (2009), Combined effects of QBO and 11-year solar cycle on the winter hemisphere in a stratosphere-troposphere coupled system, Geophys. Res. Lett., 36, L11804, doi:10.1029/2008GL037117.

Can Tiny Thrips Provide Sufficient Pollination Service During a General Flowering Period in Tropical Rainforest

One of the most crucial and interesting topics in tropical rainforest research is the pollination systems adapted to mast species, which flower massively at multiyear intervals. Highly fecund flower thrips are the primary pollinators and can respond rapidly to such an abrupt increase of flowers. Because thrips are minute and rather weak flyers, however, it had remained unclear to what extent they could contribute to cross-pollination of mast species growing at low population densities. However, microsatellite DNA analyses of single pollen grains adhering to pollinators, combined with the direct observation of flower visitors with the aid of canopy observation systems, revealed the pollination efficiency of flower thrips during the masting period. In this study of Shorea acuminata, the principal flower visitors were flower thrips, accounting for more than 60% of the collected insects during the flowering time. The thrips visitation pattern was clearly synchronous with the flowering phenology of S. acuminata. However, the genetic analysis of pollen grains suggested geitonogamous self-pollination by flower thrips. Thus, flower thrips made a small contribution to the outcrossing of S. acuminata, although their high visitation frequency on S. acuminata synchronous with the flowering phenology of the trees brought about vast production of self-pollinated seeds. On the other hand, the greater genetic diversity of seeds than that of their adherent pollen load implied the existence of other pollinators that provide sufficient pollination service for S. acuminata. In this study, lygaeid and plant bugs (Hemiptera) were collected frequently (12.2%), placing them third after flower and stipule thrips. Lygaeid bugs typified by big-eyed bugs (Geocoris and Piocoris) are known to prey on thrips, and their visitations to S. acuminata trees increased with increasing numbers of flower thrips. Thus, it was considered that outbreaks of flower thrips may attract the visitation of lygaeid bugs to flowering S. acuminata trees as edible resources during the general flowering period, and such an ecological food chain would provide high levels of genetic diversity of seeds and promote sufficient pollination service for S. acuminata.

Fruiting behavior of dipterocarps in two consecutive episodes of general flowering in a Malaysian lowland rain forest

We examined fruiting behaviors of 24 dipterocarp species in a lowland rain forest of Peninsular Malaysia during two consecutive episodes of general flowering (GF). The first GF episode (GF2001) occurred from August 2001 to February 2002, and the second GF episode (GF2002) followed immediately, from March to September 2002. The magnitude of GF2002 was greater than that of GF2001 at the community level. Significant positive size dependence of fruiting behavior at the community level was found in both GF2001 and GF2002, but there was no significant association between the fruiting behaviors in GF2001 and GF2002 except for one species. These results imply that tree size was one of the explanatory factors for fruiting behavior of dipterocarp species, but there was no evidence that adjacent reproduction caused the absence of reproduction and decreased fecundity in the subsequent fruiting event. In contrast, strong spatial aggregation of fruiting trees was found in GF2001, suggesting that external factors may affect fruiting behavior of dipterocarps in a minor GF episode. Among the 12 study species, there were large variations in fruiting behavior, but growth type (e.g., fast-growing or slow-growing) did not simply explain the inter-specific pattern of fruiting behavior. Thus, tree size may account for fruiting behavior of dipterocarps during the consecutive GF episodes through species-specific differences in phonological responses to internal and external conditions.

Sub-MM limb observation of stratosphere and mesosphere using ISS/JEM/SMILES

Performance of Superconducting Submillimeter-Wave Limb Emission Sounder (SMILES) onboard International Space Station was discussed from the analysis of random errors of Chlorine monoxide (ClO) in the stratosphere and mesosphere. Some lessons learned from the SMILES operation in space are discussed.