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Knowledge about precipitation particles in clouds is a prerequisite for the study of precipitation and cloud electrification mechanisms. A videosonde that can inform in-cloud precipitation particle shape and charge has been designed and more than 200 videosondes have been launched into monsoon clouds from 13 different locations in east Asia during the past 12 years. Rain is divided into three different regions with respect to the precipitation mechanisms: 'cool' in inland China, 'mixed' over the Maritime Continent, and 'frozen' over the west Pacific. Low concentrations of both ice crystal and graupel were observed over the west Pacific where lightning activities are weak. Ice crystals grew primarily on frozen drops and varied highly with different drop-size distributions near the melting level. Large cloud drops over the open ocean due to low CCN are slow to form ice crystals and suggest inactive ice crystal production. Electric charge measurements helped to study the particle evolution in rain systems. In squall lines, extensive recirculation of precipitation particles and rapid growth of frozen drops through capturing of supercooled drops from forward cells correlate with intense rainfall. Information about precipitation particles in heavy rain areas is essential for the study of precipitation and cloud electrification mechanisms. The purpose of this article is to demonstrate that a videosonde that can fly into any area of a rain system is a powerful tool to study rain and cloud electrification. The videosonde provides images of in-cloud precipitation particles ranging from cloud drop and ice crystal to raindrop, graupel, and hail as well as charges of precipitation particles. This article shows how important results were derived from each function of videosondes launched in East Asia monsoon clouds. More than 200 videosondes ascended from 13 different locations during the past 12 years. Highlights of this project are presented. It is hoped that this videosonde system will be used by workers in many different research fields related to the study of rain and electricity; enabling the sharing of knowledge obtained on East Asian monsoon rain. DOI: 10.1175/2010BAMS2777.1

In two-moment bulk microphysics schemes, the practice of using different weighted fall velocities for the various moments is known to lead to artificial growth in reftectivity values for fast-falling particles, particularly at the downward leading edge of a precipitation column. Two simple correction schemes that prevent these artifacts while still allowing some effects of size sorting are presented. The corrections are obtained by comparing particle number concentrations that result from two or three different sedimentation calculations. The corrections do not conserve particle number concentrations but do prevent spurious reflectivity growth automatically without the need to place ad hoc limits on mean particle size. Multimoment bulk microphysics schemes often have used inconsistent variables in terms of the appropriate advection equation (e.g., mass mixing ratio and particle number concentration). A brief review of consistent advection and turbulent mixing for such variables is presented to provide clarification. DOI: 10.1175/2010JAS3341.1

In previous work, it was argued that a source of radar coherent scatter occurs in the direction perpendicular to the direction of wave propagation because of the presence of grids of enhanced particle concentrations with spatial periodicities in resonance with the radar wavelength. While convincing, the evidence thus far has been indirect. In this work the authors now present direct observations of radar coherent backscattered signals in precipitation in the direction of wave propagation. The theory is developed for the cross-correlation function of the complex amplitudes in the direction of propagation calculated for nearest neighbor range bins. Data are analyzed in snow and in rain. The results agree with the earlier conclusions in the previous work, namely that coherent scatter occurs in both rain and snow, that it is larger in snow than it is in rain, and that it can be significant at times. DOI: 10.1175/2010JAS3488.1

Classical radar theory only considers incoherent backscatter from precipitation. Can precipitation generate coherent scatter as well? Until now, the accepted answer has been no, because hydrometeors are distributed sparsely in space (relative to radar wavelength) so that the continuum assumption used to explain coherent scatter in clear air and clouds does not hold. In this work, a theory for a different mechanism is presented. The apparent existence of the proposed mechanism is then illustrated in both rain and snow. A new power spectrum Z(f), the Fourier transform of the time series of the radar backscattered reflectivities, reveals statistically significant frequencies f of periodic components that cannot be ascribed to incoherent scatter. It is shown that removing those significant fs from Z(f) at lower frequencies greatly reduces the temporal coherency. These lower frequencies, then, are associated with the increased temporal coherency. It is also shown that these fs are also directly linked to the Doppler spectral peaks through integer multiples of one-half the radar wavelength, characteristic of Bragg scatter. Thus, the enhanced temporal coherency is directly related to the presence of coherent scatter in agreement with theory. Moreover, the normalized backscattered power spectrum Z(f) permits the estimation of the fractional coherent power contribution to the total power, even for an incoherent radar. Analyses of approximately 26 000 one-second Z(f) in both rain and snow reveal that the coherent scatter is pervasive in these data. These findings present a challenge to the usual assumption that the scatter of radar waves from precipitation is always incoherent and to interpretations of backscattered power based on this assumption. DOI: 10.1175/2010JAS3336.1

This study focuses on the evaluation of 3-hourly, 0.25[degrees] x 0.25[degrees], satellite-based precipitation products: the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) 3B42RT, the NOAA/Climate Prediction Center morphing technique (CMORPH), and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN). CMORPH is primarily microwave based, 3B42RT is primarily microwave based when microwave data are available and infrared based when microwave data are not available, and PERSIANN is primarily infrared based. The results show that 1) 3B42RT and CMORPH give similar rainfall fields (in terms of bias, spatial structure, elevation-dependent trend, and distribution function), which are different from PERSIANN rainfall fields; 2) PERSIANN does not show the elevation-dependent trend observed in rain gauge values, 3B42RT, and CMORPH; and 3) PERSIANN considerably underestimates rainfall in high-elevation areas. DOI: 10.1175/2009JAMC2298.1

S-band radar surveillance scans of precipitating shallow convection are analyzed. The scans are complied from 52 days of near-continuous measurements in the winter trades of the North Atlantic during the Rain in Cumulus over the Ocean (RICO) field campaign. After being analyzed and filtered to exclude spurious returns, the scans are segmented to identify contiguous returns, or echoes. The echo size and reflectivity statistics are then analyzed. A new normalization method is developed to account for biases associated with the nonuniformity in the native radar grid. The echo area distribution robustly exhibits power-law scaling up until sizes of about 10 [km.sup.2], with a scaling exponent of about -1.1. At larger sizes the scaling behavior breaks down and varies more markedly across subsamples of the data. Conditional sampling suggests that the scaling behavior of the larger echoes does, however, approach that of the smaller echoes as echo coverage increases, which supports the idea of a limiting distribution. Departures from this limiting distribution are argued to reflect finite size effects, modulated by the presence of a capping inversion whose height and strength varies across the samples. DOI: 10.1175/2009JAS3178.1

Scientists have long believed that the turbulent air within clouds causes water droplets to link together in clusters that can then influence precipitation formation, but the complexities of cloud turbulence [...]

Ecologists increasingly suspect that climate change will directly impact species physiology, demography, and phenology, but also indirectly affect these measures via changes to the surrounding community. Unfortunately, few studies examine both the direct and indirect pathways of impact. Doing so is important because altered competitive pressures can reduce or magnify the direct responses of a focal species to climate change. Here, we examine the effects of changing rainfall on three rare annual plant species in the presence and absence of competition on the California Channel Islands. We used rain-out shelters and hand watering to exclude and augment early, late, and season-long rainfall, spanning the wide range of precipitation change forecast for the region. In the absence of competition, droughts reduced the population growth rates of two of three focal annuals, while increased rainfall was only sometimes beneficial. As compared to the focal species, the dominant competitors were more sensitive to the precipitation treatments, benefiting from increased season-long precipitation and harmed by droughts. Importantly, the response of two of three competitors to the precipitation treatments tended to be positively correlated with those of the focal annuals. Although this leads to the expectation that increased competition will counter the direct benefits of favorable conditions, such indirect effects of precipitation change proved weak to nonexistent in our experiment. Competitors had little influence on the precipitation response of two focal species, due to their low sensitivity to competition and highly variable precipitation responses. Competition did affect how our third focal species responded to precipitation change, but this effect only approached significance, and whether it truly resulted from competitor response to precipitation change was unclear. Our work suggests that even when competitors respond to climate change, these responses may have little effect on the focal species. Ultimately, the strength of the indirect effect depends on how strongly climate change alters competition, and how sensitive focal species are to changes in competition. Key words: annual plant population; Bromus diandrus; California Channel Islands; climate change; competition; Gilia tenuiflora ssp. hoffmannii; Lasthenia californica; Malacothrix indecora; Phacelia insularis vat. insularis; precipitation.

Partial-duration maximum precipitation series from Historical Climatology Network stations are used as a basis for assessing trends in extreme-precipitation recurrence-interval amounts. Two types of time series are analyzed: running series in which the generalized extreme-value (GEV) distribution is fit to separate overlapping 30-yr data series and lengthening series in which more recent years are iteratively added to a base series from the early part of the record. Resampling procedures are used to assess both trend and field significance. Across the United States, nearly two-thirds of the trends in the 2-, 5-, and 10-yr return-period rainfall amounts, as well as the GEV distribution location parameter, are positive. Significant positive trends in these values tend to cluster in the Northeast, western Great Lakes, and Pacific Northwest. Slopes are more pronounced in the 1960-2007 period when compared with the 1950-2007 interval. In the Northeast and western Great Lakes, the 2-yr return-period precipitation amount increases at a rate of approximately 2% per decade, whereas the change in the 100-yr storm amount is between 4% and 9% per decade. These changes result primarily from an increase in the location parameter of the fitted GEV distribution. Collectively, these increases result in a median 20% decrease in the expected recurrence interval, regardless of interval length. Thus, at stations across a large part of the eastern United States and Pacific Northwest, the 50-yr storm based on 1950-79 data can be expected to occur on average once every 40 yr, when data from the 1950-2007 period are considered. DOI: 10.1175/2009JAMC2179.1

Byline: Hemu Kharel Kafle (1), Hendrik J. Bruins (2) Abstract: Climatic trends in Israel during the period 1970--2002 were studied in detail on the basis of three parameters: average annual temperature, annual precipitation and the annual aridity (humidity) index P/PET (P = Precipitation PET = Potential Evapotranspiration). Significant warming is evident in all 12 evaluated meteorological stations, situated in different parts of Israel. Along the Mediterranean coast, the average annual precipitation and P/PET values remained more or less at the same level. However, more inland, both eastward and southward, precipitation and P/PET trends are declining, indicating increased aridity. Eilat, Beer Sheva and Sedom Pans, situated in the desert, showed the most significant increase in aridity among the 12 meteorological stations we investigated. The relationship between changes in temperature and precipitation showed a negative correlation in all cases except for Eilat, the southernmost and driest part of Israel. The negative correlations for Negba, Kefar Blum, Har Kena'an, Beer Sheva and Sedom Pans are statistically significant. In conclusion, the climate in Israel has become more arid in most regions, except for the coastal plain. Author Affiliation: (1) Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464--8601, Japan (2) Jacob Blaustein Institutes for Desert Research, Swiss Institute for Dryland Environmental Research, Ben-Gurion University of the Negev, Sede Boker Campus, 84990, Israel Article History: Registration Date: 13/02/2009 Received Date: 12/03/2007 Accepted Date: 10/12/2008 Online Date: 26/05/2009

Lake-water isotopes can be used to track moisture regimes and water sources at present and in the geologic record. However, the effects of seasonal drought and the seasonal distribution of precipitation on lake-water isotopes are not well documented. To improve our understanding of lake-water isotopes, we analyzed the [delta]D and [[delta].sup.18]O values of water from a hundred lakes in the western United States across a broad range of seasonal precipitation regimes. Our results show that the isotopic composition of lake-water inputs is correlated with the isotopic composition of annual precipitation. In areas associated with the summer monsoon in northern New Mexico and southern Colorado, lake-water inputs are skewed toward summer precipitation. These results contrast with published western U.S. river-water isotopic data, which are biased toward winter precipitation, and the paradigm that lakes represent the annual moisture surplus. From the lake-water input compositions, on plots of oxygen versus hydrogen isotopes, evaporative enrichment of individual lakes follows regionally coherent evaporation trends (0.96 < [r.sup.2] < 0.99). We found that the extent of evaporative enrichment in lakes is controlled by local hydrology and is not directly tied to climate or elevation. Our results suggest that paleoclimate reconstructions based on single isotope records could therefore be confounded by multiple factors (i.e., changes in air mass, seasonality of precipitation, temperature, or evaporation). A spatial network of lake-isotope records, however, could be used to separately assess the influences of these multiple factors.

The 'natural laboratory' of mountainous Dominica (15[degrees]N) in the trade wind belt is used to study the physics of tropical orographic precipitation in its purest form, unforced by weather disturbances or by the diurnal cycle of solar heating. A cross-island line of rain gauges and 5-min radar scans from Guadeloupe reveal a large annual precipitation at high elevation (7 m [yr.sup.-1]) and a large orographic enhancement factor (2 to 8) caused primarily by repetitive convective triggering over the windward slope. The triggering is caused by terrain-forced lifting of the conditionally unstable trade wind cloud layer. Ambient humidity fluctuations associated with open-ocean convection may play a key role. The convection transports moisture upward and causes frequent brief showers on the hilltops. The drying ratio of the full air column from precipitation is less than 1% whereas the surface air dries by about 17% from the east coast to the mountain top. On the lee side. a plunging trade wind inversion and reduced instability destroys convective clouds and creates an oceanic rain shadow.

Changes in climate during the 20th century differ from region to region across the United States. We provide strong evidence that spatial variations in US temperature trends are linked to the hydrologic cycle, and we also present unique information on the seasonal and latitudinal structure of the linkage. We show that there is a statistically significant inverse relationship between trends in daily temperature and average daily precipitation across regions. This linkage is most pronounced in the southern United States (30-40[degrees]N) during the May-June time period and, to a lesser extent, in the northern United States (40-50[degrees]N) during the July-August time period. It is strongest in trends in maximum temperatures ([T.sub.max]) and 90th percentile exceedance trends (90PET), and less pronounced in the [T.sub.max] 10PET and the corresponding [T.sub.min] statistics, and it is robust to changes in analysis period. Although previous studies suggest that areas of increased precipitation may have reduced trends in temperature compared with drier regions, a change in sign from positive to negative trends suggests some additional cause. We show that trends in precipitation may account for some, but not likely all, of the cause point to evidence that shows that dynamical patterns (El Nino/Southern Oscillation, North Atlantic Oscillation, etc.) cannot account for the observed effects during May-June. We speculate that changing aerosols, perhaps related to vegetation changes, and increased strength of the aerosol direct and indirect effect may playa role in the observed linkages between these indices of temperature change and the hydrologic cycle. atmosphere | trends

Something utterly insubstantial is rising above the rim of the beaker on the table. It looks like a white mist; it feels like nothing. Run your hand through it and [...]

This study presents a climatological analysis of the frequency and characteristics of lake-effect precipitation events that were initiated or enhanced by lakes within the New York State (NYS) Finger Lakes region for the 11 winters (October-March) from 1995/96 through 2005/06. Weather Surveillance Radar-1988 Doppler (WSR-88D) data from Binghamton, New York, were used to identify 125 lake-effect events. Events occurred as 1) a well-defined, isolated precipitation band over and downwind of a lake, 2) an enhancement of mesoscale lake-effect precipitation originating from Lake Ontario and extending southward over an individual Finger Lake, 3) a quasi-stationary mesoscale precipitation band positioned over a lake embedded within extensive regional precipitation from a synoptic weather system, or 4) a transition from one type to another. Results show that lake-effect precipitation routinely develops over lakes that are considerably smaller than lakes previously discussed as being associated with lake-effect precipitation, such as the Great Lakes. Lake-effect events occurred during each month (October-March) across the 11 winters studied and were identified in association with each of the six easternmost Finger Lakes examined in this study. The frequency of NYS Finger Lakes lake-effect events determined in the current investigation paired with subsequent analyses of the environmental conditions leading to these events will allow for i) comparative analyses of necessary conditions for lake-effect development across a range of lake sizes (e.g., NYS Finger Lakes, Lake Champlain, Great Salt Lake, and Great Lakes) and 2) an informative examination of the connection between mesoscale processes and climate variability.

Lightning data from the Pacific Lightning Detection Network (PacNet) and Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite were compared with TRMM precipitation radar products and latent heating and hydrometeor data. Three years of data over the central North Pacific Ocean were analyzed. The data were divided into winter (October-April) and summer (June-September) seasons. During the winter, the thunderstorms were typically embedded in cold fronts associated with eastward-propagating extratropical cyclones. Summer thunderstorms were triggered by cold upper-level lows associated with the tropical upper-tropospheric trough (TUTT). Concurrent lightning and satellite data associated with the storms were averaged over 0.5[degrees] x 0.5[degrees] grid cells and a detection efficiency correction model was applied to quantify the lightning rates. The results of the data analysis show a consistent logarithmic increase in convective rainfall rate with increasing lightning rates. Moreover, other storm characteristics such as radar reflectivity, storm height, ice water path, and latent heat show a similar logarithmic increase. Specifically, the reflectivity in the mixed-phase region increased significantly with lightning rate and the lapse rate of Z decreased; both of these features are well-known indicators of the robustness of the cloud electrification process. In addition, the height of the echo tops showed a strong logarithmic correlation with lightning rate. These results have application over data-sparse ocean regions by allowing lightning-rate data to be used as a proxy for related storm properties, which can be assimilated into NWP models.

Data from the new two-dimensional stereo (2D-S) probe are used to evaluate drop size distributions in rain shafts observed during the Rain in Shallow Cumulus over the Ocean (RICO) experiment. The 2D-S takes images of both precipitation drops and cloud droplets with 10-[micro]m resolution. These are the first reported measurements of rain to include sizes smaller than 100 [micro]m. The primary result is that there are almost no hydrometeors smaller than about 100 [micro]m in these rain shafts. The measured low concentration of small hydrometeors implies that their rate of production is slow relative to their removal rate. Algorithms for removing the spurious effects of splashing precipitation and noisy photodiodes on 2D probes are also described.

The Fire Weather Index System has been in use across Canada for the past 30 years in the daily operations of fire management agencies. As part of this system, the Drought Code (DC) was developed to act as a daily index of water stored in the soil. A major obstacle to the completion of climate risk analyses on the DC is that lengthy series of daily temperature and precipitation are not available for large portions of the circumboreal forest. Here the authors present a methodological modification to the daily DC to allow its approximation using monthly data. This new Monthly Drought Code (MDC) still retains its ability to capture moisture trends in deep organic layers. On the basis of high-resolution temperature and precipitation data, an analysis of summer moisture availability across Canada over 1901-2002 is presented. The driest periods on record were from the 1920s to the early 1960s, with the driest years being 1955, 1958, and 1961. The wettest period was from the mid-1960s to the 1980s. For the century-long period, drying was statistically significant in northern Canada. Locations south of the Hudson Bay, in the eastern Maritimes, and in western Canada recorded a trend toward decreasing dryness. When analyzed over 1951-2002, trends could hardly be distinguished from the (multi) decadal variability. Annual values of a spatial average of all July MDC grid cells showed an excellent fit against fire statistics: 63% of the variance in the Canada-wide annual area burned from 1959 to 1999 was explained by summer moisture availability.

Precipitation characteristics of trade wind clouds over the Atlantic Ocean near Barbuda are derived from radar and aircraft data and are compared with satellite-observed cloud fields collected during the Rain in Cumulus over the Ocean (RICO) field campaign. S-band reflectivity measurements Z were converted to rainfall rates R using a Z-R relationship derived from aircraft measurements. Daily rainfall rates varied from 0 to 22 mm [day.sup.-1]. The area-averaged rainfall rate for the 62-day period was 2.37 mm [day.sup.-1]. If corrected for evaporation below cloud base, this value is reduced to 2.23 mm [day.sup.-1], which translates to a latent heat flux to the atmosphere of 63 W [m.sup.-2]. When compared with the wintertime ocean-surface latent heat flux from this region, the average return of water to the ocean through precipitation processes within the trade wind layer during RICO was 31%-39%. A weak diurnal cycle was observed in the area-averaged rainfall rate. The magnitude of the rainfall and the frequency of its occurrence had a maximum in the predawn hours and a minimum in the midmorning to early afternoon on 64% of the days. Radar data were collocated with data from the Multiangle Imaging Spectroradiometer (MISR) to develop relationships between cloud-top height, cloud fraction, 866-nm bidirectional reflectance factor (BRF), and radar-derived precipitation. The collocation took place at the overpass time of ~1045 local time. These relationships revealed that between 5.5% and 10.5% of the cloudy area had rainfall rates that were > 0.1 mm [h.sup.-1], and between 1.5% and 3.5% of the cloudy area had rainfall rates that were >1 mm [h.sup.-1]. Cloud-top heights between ~3 and 4 km and BRFs between 0.4 and 1.0 contributed ~50% of the total rainfall. For cloudy pixels having detectable rain, average rainfall rates increased from ~1 to 4 mm [h.sup.-1] as cloud-top heights increased from ~1 to 4 km. Rainfall rates were closely tied to the type of mesoscale organization, with much of the rainfall originating from shallow (

Results from a 20-yr simulation of a high-resolution AGCM forced with climatological SST, along with simplified model experiments and supplementary data diagnostics, are used to investigate internal feedbacks arising from monsoon-midlatitude interactions during droughts in the Indian summer monsoon. The AGCM simulation not only shows a fairly realistic mean monsoon rainfall distribution and large-scale circulation features but also exhibits remarkable interannual variations of precipitation over the subcontinent, with the 20-yr run showing incidence of four 'monsoon droughts.' The present findings indicate that the internally forced droughts in the AGCM emanate largely from prolonged 'monsoon breaks' that occur on subseasonal time scales and involve dynamical feedbacks between monsoon convection and extratropical circulation anomalies. In this feedback, the suppressed monsoon convection is shown to induce Rossby wave dispersion in the summertime subtropical westerlies and to set up ah anomalous quasi-stationary circulation pattern extending across continental Eurasia in the middle and upper troposphere. This pattern is composed of a cyclonic anomaly over west central Asia and the IndoPakistan region, a meridionally deep anticyclonic anomaly over East Asia (~100 [degrees]E). and a cyclonic anomaly over the Far East. The results suggest that the anchoring of the west central Asia cyclonic anomaly by the stagnant ridge located downstream over East Asia induces anomalous cooling in the middle and upper troposphere through cold-air advection, which reduces the meridional thermal contrast over the subcontinent. Additionally, the intrusion of the dry extratropical winds into northwest India can decrease the convective instability, so that the suppressed convection can in turn weaken the monsoon flow. The sustenance of monsoon breaks through such monsoon-midlatitude feedbacks can generate droughtlike conditions over India.

Soil morphology is often used as a predictor of water table levels in hydric soil determinations or other on-site evaluations. These predictions are based on the assumption that the relationships between water table levels and morphologic properties were established during typical weather patterns. Because climatic factors such as precipitation and evapotranspiration vary widely from year to year, there are often concerns about the validity of using short-term hydrologic data to predict longer term relationships. In this study, we monitored water table levels in three soils formed in glacial fluvial and till parent materials for 18 mo. Using these data, we developed a simple model that applies archived precipitation data and established hydrologic patterns to predict water table levels and cumulative saturation. The model was calibrated for each site through an iterative process. The minimal average differences between actual and predicted water table levels (

A new approach to simulating the urban environment with a mesocale model has been developed to identify efficient strategies for mitigating increases in surface air temperatures associated with the urban heat island (UHI). A key step in this process is to define a ''global' roughness for the cityscape and to use this roughness to diagnose 10-m temperature, moisture, and winds within an atmospheric model. This information is used to calculate local exchange coefficients for different city surface types (each with their own 'local roughness' lengths); each surface's energy balances, including surface air temperatures, humidity, and wind, are then readily obtained. The model was run for several summer days in 2001 for the New York City five-county area. The most effective strategy to reduce the surface radiometric and 2-m surface air temperatures was to increase the albedo of the city (impervious) surfaces. However, this caused increased thermal stress at street level, especially noontime thermal stress. As an alternative, the planting of trees reduced the UHI's adverse effects of high temperatures and also reduced noontime thermal stress on city residents (and would also have reduced cooling energy requirements of small structures). Taking these results together, the analysis suggests that the best mitigation strategy is planting trees at street level and increasing the reflectivity of roofs.

We review twentieth century and projected twenty-first century changes in climatic and hydrologic conditions in the northeastern United States and the implications of these changes for forest ecosystems. Climate warming and increases in precipitation and associated changes in snow and hydrologic regimes have been observed over the last century, with the most pronounced changes occurring since 1970. Trends in specific climatic and hydrologic variables differ in their responses spatially (e.g., coastal vs. inland) and temporally (e.g., spring vs. summer). Trends can differ depending on the period of record analyzed, hinting at the role of detach)-scale climatic variation that is superimposed over the longer-term trend. Model predictions indicate that continued increases in temperature and precipitation across the northeastern United States can be expected over the next century. Ongoing increases in growing season length (earlier spring and later autumn) will most likely increase evapotranspiration and frequency of drought. In turn, an increase in the frequency of drought will likely increase the risk of fire and negatively impact forest productivity, maple syrup production, and the intensity of autumn foliage coloration. Climate and hydrologic changes could have profound effects on forest structure, composition, and ecological functioning in response to the changes discussed here and as described in related articles in this issue of the Journal. Nous avons passe en revue les changements dans les conditions climatiques et hydrologiques survenues pendant le 20e siecle et projetees au cours du 21e siecle dans le nord-est des Etats-Unis ainsi que les repercussions de ces changements sur les ecosystemes forestiers. Un rechauffement du climat et une augmentation des precipitations ainsi que des changements dans les regimes nivologique et hydrologique ont ete observes pendant le dernier siecle et les changements les plus prononces sont survenus depuis 1970. Les tendances de variables climatiques et hydrologiques specifiques different dans f espace (p. ex. zone cotiere vs interieur des terres) et dans le temps (p. ex. printemps vs ete) dans leur reponse. Les tendances different selon la periode couverte par les donnees qui sont analysees, un indice du role de la variation du climat a une echelle decennale qui se superpose a la tendance a long terme. Les predictions du modele indiquent qu'on peut s'attendre a des augmentations continues de la temperature et des precipitations partout dans la region au cours du prochain siecle. L'allongement en cours de la saison de croissance (printemps qui arrive plus tot et automne qui arrive plus tard) augmentera l'evapotranspiration et la frequence des secheresses. Des secheresses plus frequentes vont probablement augmenter les risques d'incendie et avoir un impact negatif sur la productivite de la foret, la production de sirop d'erable et l'intensite de la coloration automnale du feuillage. Les changements climatiques et hydrologiques pourraient avoir de serieux effets sur la structure, la composition et le fonctionnement ecologique de la foret en reaction aux hangements discutes dans cet article et decrits dans d'autres articles relies au meme sujet et publies dans ce numero. [Traduit par la Redaction], Introduction and overview of climate and hydrology in the region Introduction At a regional scale, interpretations of the effects of recent climate change and predictions of the potential effects of [...]

When a climatological station is relocated or is closing, it is often possible to join the climate observations of a nearby site to create a longer time series. However, joining climate observations can sometimes introduce artificial discontinuity that affects the trend. A procedure to detect discontinuities at the joining dates for precipitation station observations is described. It is based on standardized ratios between a tested station and a neighbor, and the t test is used to determine whether the means before and after the joining dates are statistically significantly different. The procedure is applied to 234 climalological stations across Canada to identify steps in rainfall and snowfall. The results indicate that joining precipitation station observations creates steps of different magnitude for rain and snow. It is concluded that about 35% of the stations need adjustment for rain whereas 58% of the stations need adjustment for snow. The magnitude of the adjustments varies from 0.75 to 1.25 for rain and from 0.65 to 1.60 for snow. The annual and seasonal trends before and after adjustments are also examined for 1930-2007. The results show that the trends computed from the adjusted data present a more consistent regional pattern than do trends computed from the unadjusted observations.

Summer convective systems (CSs) initiated over the Tibetan Plateau identified by the International Satellite Cloud Climatology Project (ISCCP) deep convection database and associated Tropical Rainfall Measuring Mission (TRMM) precipitation for 1998-2001 have been analyzed for their basic characteristics in terms of initiation, distribution, trajectory, development, life cycle, convective intensity, and precipitation. Summer convective systems have a dominant center over the Hengduan Mountain and a secondary center over the Yaluzangbu River Valley. Precipitation associated with these CSs contributes more than 60% of total precipitation over the central-eastern area of the Tibetan Plateau and 30%-40% over the adjacent region to its southeast. The average CS life cycle is about 36 h; 85% of CSs disappear within 60 h of their initiation. About 50% of CSs do not move out of the Tibetan region, with the remainder split into eastward-and southward-moving components. These CSs moving out the Tibetan Plateau are generally larger, have longer life spans, and produce more rainfall than those staying inside the region. Convective system occurrences and associated rainfall present robust diurnal variations. The midafternoon maximum of CS initiation and associated rainfall over the plateau is mainly induced by solar heating linked to the unique Tibetan geography. The delayed afternoon--late night peak of rainfall from CSs propagating out of this region is a combined outcome of multiple mechanisms working together. Results suggest that interactions of summer Tibetan CSs with the orientation of the unique Tibetan geography and the surrounding atmospheric circulations are important for the development, intensification, propagation, and life span of these CSs.

Understanding how the aboveground net primary production (ANPP) of arid and semiarid ecosystems of the world responds to variations in precipitation is crucial for assessing the impacts of climate change on terrestrial ecosystems. Rain-use efficiency (RUE) is an important measure for acquiring this understanding. However, little is known about the response pattern of RUE for the largest contiguous natural grassland region of the world, the Eurasian Steppe. Here we investigated the spatial and temporal patterns of ANPP and RUE and their key driving factors based on a long-term data set from 21 natural arid and semiarid ecosystem sites across the Inner Mongolia steppe region in northern China. Our results showed that, with increasing mean annual precipitation (MAP), (1) ANPP increased while the interannual variability of ANPP declined, (2) plant species richness increased and the relative abundance of key functional groups shifted predictably, and (3) RUE increased in space across different ecosystems but decreased with increasing annual precipitation within a given ecosystem. These results clearly indicate that the patterns of both ANPP and RUE are scale dependent, and the seemingly conflicting patterns of RUE in space vs. time suggest distinctive underlying mechanisms, involving interactions among precipitation, soil N, and biotic factors. Also, while our results supported the existence of a common maximum RUE, they also indicated that its value could be substantially increased by altering resource availability, such as adding nitrogen. Our findings have important implications for understanding and predicting ecological impacts of global climate change and for management practices in arid and semiarid ecosystems in the Inner Mongolia steppe region and beyond. Key words: ANPP; arid and semiarid land; ecosystem management; Eurasian Steppe; Inner Mongolia grassland; mean annual precipitation; nitrogen addition; plant functional group composition; rain-use efficiency.

Atmospheric aerosol particles serve as condensation nuclei for the formation of both, cloud droplets and atmospheric ice particles. As a result, they exert a substantial influence on the microphysical properties of water and ice clouds, which in turn affect the processes that lead to the formation of rain, snow, hail, and other forms of precipitation. In recent years, considerable progress has been made in understanding the chemical composition of aerosols, their microphysical properties, and the factors that enable them to act as cloud condensation nuclei (CCN) and ice nuclei (IN). The first part of this review article will focus on the nature and sources of CCN and IN. We discuss the fundamentals of the cloud droplet and ice nucleation processes, and the role that the chemical composition and particle size play in this process. We show that, in many instances, the influence of chemical composition can be represented by a simple parameterization, which leaves particle size as the main variable controlling CCN efficiency. Aerosol particles are produced either directly by anthropogenic and natural sources (dust, sea salt. soot. biological particles, etc.), or they are formed in the atmosphere by condensation of low-volatility compounds (e.g., sulfuric acid or oxidized organic compounds). We discuss the magnitude of these sources, and the CCN and IN characteristics of the particles they produce. In contrast to previous assessments, which focused on the aerosol mass, we are emphasizing the number of particles being produced, as this is the key variable in cloud microphysics. Large uncertainties still exist for many aerosol sources, e.g., the submicron part of the seaspray aerosol, the particles produced by the biosphere, and the secondary organic aerosol. We conclude with a discussion on what particle concentrations may have been in the pristine atmosphere, before the onset on anthropogenic pollution. Model calculations and observations in remote continental regions consistently suggest that CCN concentrations over the pristine continents were similar to those now prevailing over the remote oceans, suggesting that human activities have modified cloud microphysics more than what is reflected in conventional wisdom. The second part of this review will address the effects of changing CCN and IN abundances on precipitation processes, the water cycle, and climate.

Large-eddy simulations are used to explore the structure and mesoscale organization of precipitating stratocumulus. The simulations incorporate a simple, two-moment, bulk representation of microphysical processes, which by varying specified droplet concentrations allows for comparisons of simulations that do and do not develop precipitation. The boundary layer is represented over a large (25.6 km x 25.6 km) horizontal domain using a relatively fine mesh, thereby allowing for the development of mesoscale circulations while retaining an explicit representation of cloud radiative, dynamical and microphysical interactions on scales much smaller than the dominant eddy scale. Initial conditions are based on measurements made as part of the Second Dynamics and Chemistry of the Marine Stratocumulus field study (DYCOMSII). The simulations show that precipitation is accompanied by sharp reductions in cloudiness and changes in flow topology. Mesoscale features emerge in all of the simulations but are amplified in the presence of drizzle. A cloud albedo of near 75% in the nonprecipitating simulation is reduced to less than 35% in the precipitating case. The circulation transitions from a well-mixed, stationary stratocumulus layer with closed-cellular cloud planforms to a stationary cumulus-coupled layer, with incipient open-cellular cloud planforms and sustained domain-averaged surface precipitation rates near 1 mm [day.sup.-1]. The drizzling simulations embody many other features of observed precipitating stratocumulus, including elevated cloud tops in regions of precipitation and locally higher values of subcloud equivalent potential temperature. The latter is shown to result from the tendency for precipitating simulations to develop greater thermodynamic gradients in the subcloud layer as well as mesoscale circulations that locate regions of upward motion in the vicinity of precipitating cells.

This study investigates the effects of aerosol on clouds, precipitation, and the organization of trade wind cumuli using large eddy simulations (LES). Results show that for this shallow-cumulus-under-stratocumulus case, cloud fraction increases with increasing aerosol as the aerosol number mixing ratio increases from 25 (domain-averaged surface precipitation rate ~0.65 mm [day.sup.-1]) to 100 [mg.sup.-1] (negligible surface precipitation). Further increases in aerosol result in a reduction in cloud fraction. It is suggested that opposing influences of aerosol-induced suppression of precipitation and aerosol-induced enhancement of evaporation are responsible for this nonmonotonic behavior. Under clean conditions (25 [mg.sup.-1]), drizzle is shown to initiate and maintain mesoscale organization of cumulus convection. Precipitation induces downdrafts and cold pool outflow as the cumulus cell develops. At the surface, the center of the cell is characterized by a divergence field, while the edges of the cell are zones of convergence. Convergence drives the formation and development of new cloud cells, leading to a mesoscale open cellular structure. These zones of new cloud formation generate new precipitation zones that continue to reinforce the cellular structure. For simulations with an aerosol concentration of 100 mg the cloud fields do not show any cellular organization. On average, no evidence is found for aerosol effects on the lifetime of these clouds, suggesting that cloud fraction response to changes in aerosol is tied to the frequency of convection and/or cloud size.

To explore the role of cloud microphysics in a large dataset of precipitating clouds, a 6-month dataset of satellite-derived cloud-top brightness temperatures from the longwave infrared band (channel 4) on the Geostationary Operational Environmental Satellite (GOES) is constructed over precipitation-reporting surface observation stations, producing 144 738 observations of snow, rain, freezing rain, and sleet. The distributions of cloud-top brightness temperatures were constructed for each precipitation type, as well as light, moderate, and heavy snow and rain. The light-snow distribution has a maximum at -16[degrees]C, whereas the moderate- and heavy-snow distributions have a bimodal distribution with a primary maximum around -16[degrees] to -23[degrees]C and a secondary maximum at -35[degrees] to -45[degrees]C. The light, moderate, and heavy rain, as well as the freezing rain and sleet, distributions are also bimodal with roughly the same temperature maxima, although the colder mode dominates when compared with the snow distributions. The colder of the bimodal peaks trends to lower temperatures with increasing rainfall intensity: -45[degrees]C for light rain, -47[degrees]C for moderate rain, and -50[degrees]C for heavy rain. Like the distributions for snow, the colder peak increases in amplitude relative to the warmer peak at heavier rainfall intensities. The steep slope in the snow distribution for cloud-tops warmer than -15[degrees]C is likely due to the combined effects of above-freezing cloud-top temperatures not producing snow, the activation of ice nuclei, the maximum growth rate for ice crystals at temperatures near -15[degrees]C, and ice multiplication processes from -3[degrees] to -8[degrees]C. In contrast, the rain distributions have a gentle slope toward higher cloud-top brightness temperatures (-5[degrees] to 0[degrees]C), likely due to the warm-rain process. Last, satellite-derived cloud-top brightness temperatures are compared with coincident radiosonde-derived cloud-top temperatures. Although most differences between these two are small, some are as large as [+ or -] 60[degrees]C. The cause of these differences remains unclear, and several hypotheses are offered.

Cloud droplet effective radius (DER) and liquid water path (LWP) are two key parameters for the quantitative assessment of cloud effects on the exchange of energy and water. Chang and Li presented an algorithm using multichannel measurements made at 3.7, 2.1, and 1.6 [micro]m to retrieve a cloud DER vertical profile for improved cloud LWP estimation. This study applies the multichannel algorithm to the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) data on the Aqua satellite, which also carries the Advanced Microwave Scanning Radiometer (AMSR-E) for measuring cloud LWP and precipitation. By analyzing one day of coincident MODIS and AMSR-E observations over the tropical oceans between 40[degrees]S and 40[degrees]N for overcast warm clouds (>273 K) having optical depths between 3.6 and 23, the effects of DER vertical variation on the MODIS-derived LWP are reported. It is shown that the LWP tends to be overestimated if the DER increases with height within the cloud and underestimated if the DER decreases with height within the cloud. Despite the uncertainties in both MODIS and AMSR-E retrievals, the result shows that accounting for the DER vertical variation reduces the mean biases and root-mean-square errors between the MODIS- and AMSR-E-derived LWPs. Besides, the manner in which the DER changes with height has the potential for differentiating precipitative and nonprecipitative warm clouds. For precipitating clouds, the DER at the cloud top is substantially smaller than the DER at the cloud base. For nonprecipitating clouds, however, the DER differences between the cloud top and the cloud base are much less.

During the past 20 yr there has been substantial progress on the development and application of millimeter-wavelength (3.2 and 8.6 mm, corresponding to frequencies of 94 and 35 GHz) radars in atmospheric cloud research, boosted by continuous advancements in radar technology and the need to better understand clouds and their role in the Earth's climate. Applications of millimeter-wavelength radars range from detailed cloud and precipitation process studies to long-term monitoring activities that strive to improve our understanding of cloud processes over a wide range of spatial and temporal scales. These activities are the result of a long period of successful research, starting from the 1980s, in which research tools and sophisticated retrieval techniques were developed, tested, and evaluated in field experiments. This paper presents a cohesive, chronological overview of millimeter-wavelength radar advancements during this period and describes the potential of new applications of millimeter-wavelength radars on sophisticated platforms and the benefits of both lower- and higher-frequency radars for cloud and precipitation research.

A method of analyzing radar data is developed and applied to determine whether the X-band radar reflectivity evolution of clouds observed during summertime on the northeast Florida coast during the Small Cumulus Microphysics Study (SCMS) shows distinct differences in precipitation development that can be associated with the clouds' maritime or continental characteristics. For this study, the entire National Center for Atmospheric Research CP2 radar dataset from SCMS was examined, and 38 clouds were used. For these clouds the evolution in X-band radar reflectivity, from the clouds' earliest detection through precipitation, was clearly documented and met specific requirements concerning the clouds' location relative to the coastline and direction of movement. Since cloud condensation nuclei (CCN) and giant and ultragiant nuclei (GN) measurements were not available for the specific clouds used in this study, proxies were used to partition the clouds into four groups based on the cloud location and direction of movement. Specifically, it was assumed that clouds forming over the ocean during onshore flow had maritime characteristics (group 1: low CCN, high GN), clouds forming over land during onshore flow would have modified maritime characteristics (group 2: high CCN, high GN), clouds forming over land during offshore flow would have continental characteristics (group 3: high CCN, low GN), and clouds forming over the ocean during offshore flow would have modified continental characteristics (group 4: high CCN, high GN). These assumptions are based on past measurements presented by Sax and Hudson. Then, these populations were statistically compared using the nonparametric multiresponse permutation procedure developed by Mielke et al. A comparison of groups 1 and 2 provided a test of the role of CCN concentrations in precipitation development in these cloud populations. A comparison of groups 3 and 4 provided a test of the role of GN concentrations in precipitation development in these cloud populations. The two cloud populations that were disjoint at a statistically significant level were groups 1 and 2. For these groups, the analysis showed that the median characteristic total water content of the truly maritime clouds (group 1) was about half that of the modified maritime clouds (group 2) at the time of precipitation formation. The characteristic time to precipitation formation was about 60% smaller for the truly maritime clouds. Thus, the characteristic reflectivity threshold for precipitation development was reached at a much lower altitude above cloud base in a much faster time in the truly maritime clouds. This result supports the conclusions of Hudson and Yum that precipitation development in the SCMS clouds was primarily controlled by CCN concentrations rather than GN concentrations.

Ground-based vertically pointing and airborne/spaceborne nadir-pointing millimeter-wavelength radars are being increasingly used worldwide. Though such radars are primarily designed for cloud remote sensing, they can also be used for precipitation measurements including snowfall estimates. In this study, modeling of snowfall radar properties is performed for the common frequencies of millimeter-wavelength radars such as those used by the U.S. Department of Energy's Atmospheric Radiation Measurement Program ([K.sub.a] and W bands) and the CloudSat mission (W band). Realistic snowflake models including aggregates and single dendrite crystals were used. The model input included appropriate mass--size and terminal fall velocity--size relations and snowflake orientation and shape assumptions. It was shown that unlike in the Rayleigh scattering regime, which is often applicable for longer radar wavelengths, the spherical model does not generally satisfactorily describe scattering of larger snowflakes at millimeter wavelengths. This is especially true when, due to aerodynamic forcing, these snowflakes are oriented primarily with their major dimensions in the horizontal plane and the zenith/nadir radar pointing geometry is used. As a result of modeling using the experimental snowflake size distributions, radar reflectivity--liquid equivalent snowfall rates ([Z.sub.e]-S) relations are suggested for 'dry' snowfalls that consist of mostly unrimed snowflakes containing negligible amounts of liquid water. Owing to uncertainties in the model assumptions, these relations, which are derived for the common [K.sub.a]- and W-band radar frequencies, have significant variability in their coefficients that can exceed a factor of 2 or so. Modeling snowfall attenuation suggests that the attenuation effects in 'dry' snowfall can be neglected at the [K.sub.a] band for most practical cases, while at the W band attenuation may need to be accounted for in heavier snowfalls observed at longer ranges.

The triggering of convective orographic rainbands by small-scale topographic features is investigated through observations of a banded precipitation event over the Oregon Coastal Range and simulations using a cloud-resolving numerical model. A quasi-idealized simulation of the observed event reproduces the bands in the radar observations, indicating the model's ability to capture the physics of the band-formation process. Additional idealized simulations reinforce that the bands are triggered by lee waves past small-scale topographic obstacles just upstream of the nominal leading edge of the orographic cloud. Whether a topographic obstacle in this region is able to trigger a strong rainband depends on the phase of its lee wave at cloud entry. Convective growth only occurs downstream of obstacles that give rise to lee-wave-induced displacements that create positive vertical velocity anomalies [w.sub.c] and nearly zero buoyancy anomalies be as air parcels undergo saturation. This relationship is quantified through a simple analytic condition involving [w.sub.c], [b.sub.c], and the static stability [N.sup.2.sub.m] of the cloud mass. Once convection is triggered, horizontal buoyancy gradients in the cross-flow direction generate circulations that align the bands parallel to the flow direction.

This study combines high-resolution mesoscale model simulations and comprehensive airborne Doppler radar observations to identify kinematic structures influencing the production and mesoscale distribution of precipitation and microphysical processes during a period of heavy prefrontal orographic rainfall over the Cascade Mountains of Oregon on 13-14 December 2001 during the second phase of the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2) field program. Airborne-based radar detection of precipitation from well upstream of the Cascades to the lee allows a depiction of terrain-induced wave motions in unprecedented detail. Two distinct scales of mesoscale wave-like air motions are identified: 1) a vertically propagating mountain wave anchored to the Cascade crest associated with strong midlevel zonal (i.e., cross barrier) flow, and 2) smaller-scale ( Errors in the model representation of a low-level shear layer and the vertically propagating mountain waves are analyzed through a variety of sensitivity tests, which indicated that the mountain wave's amplitude and placement are extremely sensitive to the planetary boundary layer (PBL) parameterization being employed. The effects of 1) using unsmoothed versus smoothed terrain and 2) the removal of upstream coastal terrain on the flow and precipitation over the Cascades are evaluated through a series of sensitivity experiments. Inclusion of unsmoothed terrain resulted in net surface precipitation increases of ~4%-14% over the windward slopes relative to the smoothed-terrain simulation. Small-scale waves (

A prominent increase in atmospheric C[O.sub.2] at the Paleocene-Eocene boundary, ca. 55 Ma, led to the warmest Earth of the Cenozoic for ~100 k.y. High-resolution studies of continental flood-plain sediment records across this boundary can provide crucial information on how the hydrological cycle responds to rapidly changing C[O.sub.2]. Here we show from continental records across the Paleocene-Eocene boundary in the Spanish Pyrenees, a subtropical paleosetting, that during the early, most intense phase of C[O.sub.2] rise, normal, semiarid coastal plains with few river channels of 10-200 m width were abruptly replaced by a vast conglomeratic braid plain, covering at least 500 [km.sup.2] and most likely more than 2000 [km.sup.2]. This braid plain is interpreted as the proximal parts of a megafan. Carbonate nodules in the megafan deposits attest to seasonally dry periods and together with megafan development imply a dramatic increase in seasonal rain and an increased intra-annual humidity gradient. The megafan formed over a few thousand years to ~10 k.y. directly after the Paleocene-Eocene boundary. Only repeated severe floods and rainstorms could have contributed the water energy required to transport the enormous amounts of large boulders and gravel of the megafan during this short time span. The findings represent evidence for considerable changes in regional hydrological cycles following greenhouse gas emissions. Keywords: Paleocene-Eocene boundary, fluvial megafan, greenhouse warming, hydrological cycle, carbon isotope excursion.

Simulations of one maritime and four continental observed cases of deep convection are performed with the Hebrew University Cloud Model that has spectral bin microphysics. The maritime case is from observations made on 18 September 1974 during the Global Atmospheric Research Program's Atlantic Tropical Experiment (GATE). The continental storm cases are those of summertime Texas clouds observed on 13 August 1999, and green-ocean, smoky, and pyro-clouds observed during the Large-Scale Biosphere-Atmosphere Experiment in Amazonia-Smoke, Aerosols, Clouds, Rainfall, and Climate (LBA-SMOCC) campaign on 1-4 October 2002. Simulations have been performed for these cases with a detailed melting scheme. This scheme allows calculation of liquid water fraction within each mass bin for the melting of graupel, hail, snowflakes, and crystals, as well as alteration of the sedimentation velocity of ice particles in the course of their melting. The results obtained with the detailed melting scheme are compared with corresponding results from simulations involving instantaneous melting at the freezing (0[degrees]C) level. The detailed melting scheme allows penetration of ice from the freezing level down into the boundary layer by distances ranging from a few hundred meters for the numerous, smaller particles to ~1.5 km for the largest particles, which are much scarcer. In these simulations, most of the mass of ice falling out melts over this short distance of a few hundred meters. The deepening and intensification of the layer of latent cooling enhances the convective destabilization of the troposphere. This effect is especially pronounced under continental conditions, causing significant changes in the accumulated rain amount.

This article is the second of two describing convective lines with parallel stratiform (PS) precipitation. The PS mode appears to be the preferred organizational structure in environments with line-parallel vertical wind shear. This paper presents a detailed analysis of the processes that lead to the development of the PS structure within line-parallel shear, and the positive and negative feedbacks associated with the mature PS structure. As well, the particular importance of line-perpendicular and line-parallel wind shear, line-end effects, inertial stability, and patterns of convective initiation are investigated through a battery of sensitivity tests. Convective lines with PS precipitation develop in environments with both significant line-perpendicular and line-parallel vertical wind shear. Although the studied environments are initially supportive of supercells, the merging of outflows soon renders a predominant linear forcing and the characteristic PS structure. The systems' linearity in the presence of along-line wind shear makes the local wind field more dependent upon the mesoscale structure of the convective system. For example, the along-line transport of hydrometeors is required for the development of a line-parallel precipitation region, and yet this transport does not occur immediately down the convective line's axis because it is interrupted by the pressure maxima associated with other convective cells that are farther down the line. However, the along-line flow within the line's leading and trailing anvils is able to contribute substantially because there are along-line pressure gradient accelerations associated with the tilted mesoscale structure of the system's buoyancy field. This paper concludes the study by synthesizing its dynamical and sensitivity analyses with the overarching structures described in the companion article, yielding perhaps the first consolidated view of these little-studied systems.

Because the flowering and fruiting phenology of plants is sensitive to environmental cues such as temperature and moisture, climate change is likely to alter community-level patterns of reproductive phenology. Here we report a previously unreported phenomenon: experimental warming advanced flowering and fruiting phenology for species that began to flower before the peak of summer heat but delayed reproduction in species that started flowering after the peak temperature in a tallgrass prairie in North America. The warming-induced divergence of flowering and fruiting toward the two ends of the growing season resulted in a gap in the staggered progression of flowering and fruiting in the community during the middle of the season. A double precipitation treatment did not significantly affect flowering and fruiting phenology. Variation among species in the direction and magnitude of their response to warming caused compression and expansion of the reproductive periods of different species, changed the amount of overlap between the reproductive phases, and created possibilities for an altered selective environment to reshape communities in a future warmed world. climate change | global warming | precipitation

Abstract: This study documents the discovery of calcite crusts on the upper surface of clasts within morainic complexes in Akshayuk Pass, southern Cumberland Peninsula (Baffin Island), a region underlain by [...]