Diurnal Cycle

Surface radiation data were collected at seven sites in the Riviera Valley in southern Switzerland during the special observing period of the Mesoscale Alpine Programme's Riviera project from August until October 1999. During the daytime on selected 'valley wind' days, strong site contrasts occurred with respect to solar and downward long-wave radiation fluxes. Site-to-site differences of incoming global radiation were caused by the different orientations of valley surfaces relative to the direct solar beam component and by shading from surrounding topography. Diurnal cycles of albedo, determined from horizontal and slope-parallel measurements of reflected and incoming global radiation at three eastern side-wall sites, show that reflection of the direct radiation component from the inclined surfaces is predominantly anisotropic diffuse radiation. Downward longwave radiation decreases with elevation in the valley because the higher sites have an increased angular exposure to the radiating sky (i.e. sky view factor). Contrasts between the valley-floor and ridge-top sites are largest on valley wind days but also occur on overcast days. Finally,strong site-to-site variations of the net all-wave radiation occur during daytime due to variations in the received direct beam component of incoming global radiation. During night-time, net outgoing all-wave radiation increases with elevation, again because sky view fraction increases with elevation. On valley wind days, significant contrasts are found in mean diurnal cycles and daily sums of available radiation energy between south-west and north-east facing slopes. When the direct beam component is absent, inter-site contrasts in radiation components are reduced, especially short-wave radiation components. A simple semi-empirical method is described to estimate the net all-wave radiation in a slope-parallel frame of reference from measurements with horizontally exposed net radiometers. This method employs the theoretical ratio of short-wave radiation on a slope to the horizontal equivalent. The method is tested successfully at one site where simultaneous measurements were made with inclined and horizontal sensors.

Continuous measurements of aerosol size distributions were made in El Paso, TX, for a 21 day period in winter 1999. Size distribution measurements were performed at two urban locations in El Paso using two pairs of the scanning mobility particle sizer and the aerodynamic particle sizer. Complementary measurements also were performed for gas phase pollutants (CO, NO, NO 2 , O 3) and meteorological conditions. Throughout the study, the mean ultrafine particle (those smaller than 0.1 mm in diameter) number concentration was 14,400 particles cm À3. There was a significant correlation between CO and both ultrafine and accumulation mode (those between 0.1 and 1 mm in diameter) particle count, with the Pearson correlation coefficient (r) values of 0.81 and 0.87, respectively. The correlation between NO and both ultrafine and accumulation mode particle count is also significant, but not as strong as the correlation of CO and the particle concentrations. Most pollutants were found to vary on diurnal cycles and to follow one of two different trends, either vehicular traffic schedules or sunlight intensity. Wind direction was found to have an influence not only on pollutant concentrations, but also on the correlation between pollutants. With southerly winds, CO, NO and NO 2 concentrations were 25-140% greater than when the wind was coming from the north. Likewise, ultrafine and accumulation mode particle concentrations were approximately 100% greater for southerly than for northerly winds.

The linkages between the space-time variability of observed clouds, rainfall, large-circulation patterns and topography in northern India and the Himalayas were investigated using remote sensing data. The research purpose was to test the hypothesis that cloudiness patterns are dynamic tracers of rainstorms, and therefore their temporal and spatial evolution can be used as a proxy of the spatial and temporal organization of precipitation and precipitation processes in the Himalayan range during the monsoon. The results suggest that the space-time distribution of precipitation, the spatial variability of the diurnal cycle of convective activity, and the terrain (landform and altitudinal gradients) are intertwined at spatial scales ranging from the order of a few kms (1-5 km) up to the continental-scale. Furthermore, this relationship is equally strong in the time domain with respect to the onset and intra-seasonal variability of the monsoon. Infrared and microwave imagery of cloud fields were analyzed to characterize the spatial and temporal evolution of mesoscale convective weather systems and short-lived convection in Northern India, the Himalayan range, and in the Tibetan Plateau during three monsoon seasons (1999, 2000 and 2001). The life cycle of convective systems suggests landform and orographic controls consistent with a convergence zone constrained to the valley of the Ganges and the Himalayan range, bounded in the west by the Aravalli range and the Garhwal mountains and in the East by the Khasi Hills and the Bay of Bengal, which we call the Northern India Convergence Zone (NICZ). The NICZ exhibits strong nighttime activity along the south-facing slopes of the Himalayan range, which is characterized by the development of shortlived convection (1-3 h) aligned with protruding ridges between 1:00 and 3:00 AM. The intra-annual and inter-annual variability of convective activity in the NICZ were assessed with respect to large-scale synoptic conditions, monsoon activity in the Bay of Bengal, and the modulating role of orography. Empirical orthogonal function (EOF) and canoni

The tidal migration, temporal and spatial patterns in feeding of the surface-swimming four-eyed fish Anableps anableps (Anablepidae) were studied in a macrotidal mangrove area in north Brazil to exemplify the ecology of a tropical intertidal fish. Visual censuses in the main channel showed that abundances were high at low water (LW) and low at high water (HW). Anableps anableps entered the intertidal creeks with the first flood rise. They fed in the inundated mangrove at HW and returned gradually after the ebb current maximum to concentrate again in the subtidal parts of the main channel at LW. This pattern occurred at neap, mid and spring tides throughout the year. The tidal migration was triggered by water level, not by time. In the study area the diet of A. anableps caught with block nets was dominated by intertidal red algae (Catanella sp.). Other important food items were Insecta and Grapsidae. The combination of high inundation and daylight (spring tide-day) provided the best foraging conditions, probably emphasizing the importance of the above-water eye. Darkness and low inundation was linked to poorest foraging conditions (neap tide-night). The quantity of food consumed by A. anableps was clearly influenced by the factors tide, time of day and creek location, but not by size and sex. The qualitative composition of the diet was not influenced by any of the factors, except for mud, which was only ingested at neap tides. The temporal and spatial variability in food consumption suggests that food web modelling in macrotidal areas may lead to misinterpretations of the overall systems dynamics if the spring and neap tide alternation and the diurnal cycle are not considered.

1] A performance assessment of the Worldwide Lightning Location Network (WWLLN) is presented using the National Lightning Detection Network (NLDN) as ground truth, over unprecedented time and spatial scales. The study spans 3 years, from 5 April 2006 to 31 March 2009, throughout the contiguous United States. The capabilities of the network are shown to improve greatly from the first to the third year of the study, with an overall detection efficiency of cloud-to-ground flashes increasing from 3.88% in 2006 −2007 to 10.30% in 2008−2009. The WWLLN cloud-to-ground detection efficiency is found to be strongly dependent on peak current and polarity, attaining values larger than 10% (35%) for currents stronger than ±35 kA (−130 kA) and values less than 2% for currents between 0 and −10 kA. The location accuracy is found to have a northward and westward bias, with average location errors of 4.03 km in the north-south and 4.98 km in the east-west directions, respectively. The WWLLN is shown to have strong limitations in capturing the diurnal cycle, missing both the timing of the maximum and minimum lightning activity (around 1600 and 0900 LT, respectively), and the amplitude of the cycle as well. It is found that in 3 h intervals, the number of flashes in the WWLLN has some proportionality to the number of flashes in the NLDN, suggesting that the WWLLN has strong potential for meteorological applications.

An intercomparison study for single column models (SCMs) of the diurnal cycle of shallow cumulus convection is reported. The case, based on measurements at the ARM Southern Great Plain site on 21 ¢ ¡ June 1997, has been used in an LES intercomparison study before. Results of the SCMs reveal the following general deficiencies: too large values of cloud cover and cloud liquid water, unrealistic thermodynamic profiles, and high amounts of noise. These results are analyzed in terms of the behavior of different parameterization schemes involved: the convection scheme, the turbulence scheme, and the cloud scheme. In general the behavior of the SCMs can be grouped in two different classes: one class with too strong mixing by the turbulence scheme, the other class with too strong activity by the convection scheme. In both classes high values of cloud cover and cloud liquid water content occur. Many of the SCMs suffer from a numerical instability in the cloud layer mainly due to the turbulence scheme. Results are also strongly dependent on vertical resolution, in particular caused by resolution dependencies in the mass flux scheme. The coupling between subcloud turbulence and the convection scheme plays a crucial role in determining the thermodynamic profiles. Finally, (in part) motivated by these results several models have been successfully updated with new parameterization schemes and/or their present schemes have been successfully modified. QJRMS 1

Aerosol optical depth (AOD) very often shows a distinct diurnal cycle pattern, which seems to be an artifact. This phenomenon is the result of a deficient calibration (or an equivalent effect, as filter degradation). The fictitious sinusoidal shape of the AOD diurnal cycle is a function of the cosine of the solar zenith angle (SZA) and its effect is more accentuated during midday. The observation of this effect is not easy at current field stations and only those stations with excellent weather conditions permit an easier detection and correction. By taking advantage of this diurnal cycle behavior because of its dependence on the cosine of the SZA, we propose an improved ''in situ'' calibration correction procedure. The method is named KCICLO because the determination of a constant K and the behavior of AOD as a cycle (ciclo, in Spanish). It can be seen as a modification of the classical Langley technique (CLT) with the same level of accuracy when CLT is applied at high-altitude stations, and results in an accuracy of 0.2-0.5% for the calibration ratio constant K (or 0.002-0.005 in AOD). The application of this correction method to current and old data series at sunny stations is a significant improvement over ''in situ'' methods, because no other information beyond the AOD data is necessary.

Cloud cover usually denies the generation of land surface temperature (LST) time series over large areas from thermal infrared (TIR) data sensed by satellites. If cloud cover is brief ( < 4 h) and only partial on the scale of a METEOSAT pixel, the discontinuous time series of cloud-free measurements still approximates a cloud-free diurnal temperature cycle (DTC). In order to interpolate the missing values and to describe the thermal behaviour of the land surface as a whole, advantage is taken of METEOSAT's high temporal resolution of 30 min. A Levenberg ± Marquardt minimisation scheme is utilised to automatically fit a model of the DTC to the time series of cloud-screened brightness temperatures (BT). Out of physical considerations and in order to stabilise the fits, a priori knowledge from solar geometry is utilised and the model function is required to be smooth and continuous. A robust estimator of the error, which is based on the median rather than the arithmetic mean, is used to lessen the impact of outliers on the fits. The thermal behaviour of the land surface is then described by the determined model parameters, and the 48 METEOSAT BTs per pixel per day are reduced to five parameters per pixel per day. Monthly maximum and median composites of cloud-screened METEOSAT BTs yield synthetic DTCs, which are less influenced by synoptic effects. Fitting the model to monthly composites reduces the 17 520 METEOSAT BTs per pixel per year to 60 parameters per pixel per year. This data reduction is advantageous to climatological studies, which require the processing of long time series. The model parameters are shown to be related to physical properties of the land surface, particularly to the normalised difference vegetation index (NDVI) and thermal inertia. D

This study focuses on using remote sensing for comparative assessment of surface urban heat island (UHI) in 18 mega cities in both temperate and tropical climate regions. Least-clouded day-and night-scenes of TERRA/MODIS acquired between 2001 and 2003 were selected to generate land-surface temperature (LST) maps. Spatial patterns of UHIs for each city were examined over its diurnal cycle and seasonal variations. A Gaussian approximation was applied in order to quantify spatial extents and magnitude of individual UHIs for inter-city comparison. To reveal relationship of UHIs with surface properties, UHI patterns were analyzed in association with urban vegetation covers and surface energy fluxes derived from high-resolution Landsat ETM+ data. This study provides a generalized picture on the UHI phenomena in the Asian region and the findings can be used to guide further study integrating satellite high-resolution thermal data with land-surface modeling and meso-scale climatic modeling in order to understand impacts of urbanization on local climate in Asia. #

Rates of pelagic primary production, respiration, and bacterioplankton dynamics were measured in relation to water quality parameters in three extensive shrimp ponds in the Mekong delta, Vietnam. There were few consistent differences in pelagic characteristics among different locations within these ponds, among the three ponds, or between the ponds and adjacent river Ž 14 .

This second part of a two-paper series compares deterministic precipitation forecasts from the Storm-Scale Ensemble Forecast System (4-km grid) run during the 2008 NOAA Hazardous Weather Testbed (HWT) Spring Experiment, and from the Canadian Global Environmental Multiscale (GEM) model (15 km), in terms of their ability to reproduce the average diurnal cycle of precipitation during spring 2008. Moreover, radar-based nowcasts generated with the McGill Algorithm for Precipitation Nowcasting Using Semi-Lagrangian Extrapolation (MAPLE) are analyzed to quantify the portion of the diurnal cycle explained by the motion of precipitation systems, and to evaluate the potential of the NWP models for very short-term forecasting.

Multiple state-of-the-art instruments sampled ambient aerosol in Riverside, California during the 2005 Study of Organic Aerosols at Riverside (SOAR) to investigate sources and chemical composition of fine particles (PM f ) in the inland region of Southern California. This paper briefly summarizes the spatial, meteorological and gas-phase con-5 ditions during SOAR-1 (15 July-15 August) and provides detailed intercomparisons of complementary measurements and average PM f composition during this period. Daily meteorology and gas-phase species concentrations were highly repetitive with meteorological and gas-phase species concentrations displaying clear diurnal cycles and weekday/weekend contrast, with organic aerosol (OA) being the single largest com-10 ponent contributing approximately one-third of PM f mass. In contrast with historical characterizations of OA in the region, several independent source apportionment efforts attributed the vast majority (∼80%) of OA mass during SOAR-1 to secondary organic aerosol (SOA). Given the collocation of complementary aerosol measurements combined with a dominance of SOA during SOAR-1, this paper presents new results 15 on intercomparisons among several complementary measurements and on PM f composition during this period. Total non-refractory submicron (NR-PM 1 ) measurements from a high-resolution aerosol mass spectrometer (HR-AMS) are compared with measurements by tapered element oscillating microbalances (TEOM) including a filter dynamics measurement system (TEOM FDMS ). NR-PM 1 is highly correlated with PM 2.5 20 TEOM FDMS measurements and accounts for the bulk of PM 2.5 mass with the remainder contributed primarily by refractory material. In contrast, measurements from a heated TEOM show substantial losses of semi-volatile material, including ammonium nitrate and semi-volatile organic material. Speciated HR-AMS measurements are also consistent and highly correlated with several complementary measurements, includ-25

This research was performed to characterize the variability of weather behavior in the lower and upper atmosphere layers, particularly its dependence on conditions in the troposphere and ionosphere at six different stations over UKM Bangi, Selangor. The measurements are based on short-term monitoring of precipitable water vapour (PWV) in the troposphere and total electron content (TEC) in the ionosphere using

Submicron aerosol was analyzed during the MI-LAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Aerosol Mass Spectrometer (AMS) and complementary instrumentation. Positive Matrix Factorization (PMF) of high resolution AMS spectra identified a biomass burning organic aerosol (BBOA) component, which includes several large plumes that appear to be from forest fires within the region. Here, we show Correspondence to: J. L. Jimenez ([email protected]) that the AMS BBOA concentration at T0 correlates with fire counts in the vicinity of Mexico City and that most of the BBOA variability is captured when the FLEXPART model is used for the dispersion of fire emissions as estimated from satellite fire counts. The resulting FLEXPART fire impact factor (FIF) correlates well with the observed BBOA, acetonitrile (CH 3 CN), levoglucosan, and potassium, indicating that wildfires in the region surrounding Mexico City are the dominant source of BBOA at T0 during MILAGRO. The impact of distant BB sources such as the Yucatan is small during this period. All fire tracers are correlated, with BBOA and levoglucosan showing little background, acetonitrile having Published by Copernicus Publications on behalf of the European Geosciences Union. www.atmos-chem-phys.net/10/5315/2010/ Atmos. Chem. Phys., 10, 5315-5341, 2010

Peach shoots collected prior to onset of chilling in early November from mid Georgia, were exposed to short days or cold temperature to induce dormancy. A gradual increase in bound water under both conditions was found in comparison to control left under warm long days condition. To release dormancy, buds were exposed to 0 or 48C, temperature that break dormancy, and to a 6-248C, diurnally cycled treatment that prevents chilling accumulation, and is inefficient in Ž . breaking dormancy. Chilling temperatures 0 and 48C induced somewhat freer water after 39 days than the 6-248C treatment. The proportion of free water increased until 55 days. When shoots were transferred to forcing conditions, a further rapid increase in free water was noted especially with shoots that were exposed to chilling previously. The conversion of bound to free water on exposure to forcing conditions was also verified with orchard-chilled peach buds. Buds on branches that were not exposed to effective chilling were also showing the appearance of free water after exposure to high temperatures for a long duration. Evaluating these data raises the possibility that bound water in buds of temperate fruit trees is correlated with the level of cold resistance rather than with the level of endo-dormancy. This may explain the much higher levels of freer water during dormancy in the less cold-resistant peach than in the more cold-resistant apple. q 1998 Elsevier Science B.V.

One of the possible ways to check the adequacy of the physical description of meteorological elements in global climate models (GCMs) is to compare the statistical structure of these elements reproduced by models with empirical data from the world climate observational system. The success in GCM development warranted a further step in this assessment. The description of the meteorological element in the model can be considered adequate if, with a proper reproduction of the mean and variability of this element (as shown by the observational system), the model properly reproduces the internal relationships between this element and other climatic variables (as observed during the past several decades). Therefore, to distinguish more reliable models, the authors suggest first analyzing these relationships, ''the behavior of the climatic system,'' using observational data and then testing the GCMs' output against this behavior.

'Biotic and abiotic factors affecting the δ 13 C of soil respired CO 2 in a Mediterranean oak woodland', Isotopes in Environmental and Health Studies, 45: 4,[343][344][345][346][347][348][349][350][351][352][353][354][355][356][357][358][359] To link to this Article:

Infant crying, and parental concern about unexplained crying, peak when infants are around 6 weeks of age. Diary measures of amounts of time infants spent crying, sleeping, wakingsettled and feeding at 6 weeks were obtained in three samples: a group of moderate criers (N 5 45), a group with an evening crying peak (N 5 33) and a group whose fuss / crying exceeded 3 h per day (persistent criers, N 5 54). Substantial negative correlations between amounts of fuss / crying and sleeping, but few associations between fuss / crying and waking or feeding, were found. The persistent criers slept an average of 77 min per 24 h less than the moderate criers. The clearest group differences were in the daytime and all three groups showed evidence of a diurnal organisation in their behaviour. Persistent crying at 6 weeks is associated with a sleeping deficit.

Surface spectral reflectance (albedo) is a fundamental variable affecting the transfer of solar radiation and the Earths climate. It determines the proportion of solar energy absorbed by the surface and reflected back to the atmosphere. The International Panel on Climate Change (IPCC) identified surface albedo among key factors influencing climate radiative forcing. Accurate knowledge of surface reflective properties is important for advancing weather forecasting and climate change impact studies. It is also important for determining radiative impact and acceptable levels of greenhouse gases in the atmosphere, which makes this work strongly linked to major scientific objectives of the Climate Change Research Division (CCRD) and Atmospheric Radiation Measurement (ARM) Program.; Most significant accomplishments of eth project are listed below. ; I) Surface albedo/BRDF datasets from 1995 to the end of 2004 have been produced. They were made available to the ARM community and other inte...

Submicron aerosol was analyzed during the MI-LAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and complementary instrumentation. Mass concentrations, diurnal cycles, and size distributions of inorganic and organic species are similar to results from the CENICA supersite in April 2003 with organic aerosol (OA) comprising about half of the Correspondence to: J. L. Jimenez ([email protected])

Nitrate and several organic compounds such as dicarboxylic acids (e.g. succinic acid, glutaric acid), Polycyclic Aromatic Hydrocarbons (PAHs) or n-alkanes form the group of the most volatile compounds in atmospheric aerosol particles. The transition of these compounds between gas and particulate phase may significantly change the aerosol 5 particles radiative properties, the heterogeneous chemical properties, and, naturally, the total particulate mass concentration. To better assess these time-dependent effects, three intensive field experiments were conducted in 2008-2009 at the Central European EMEP research station Melpitz (Germany) using an Aerodyne Aerosol Mass Spectrometer (AMS). Data coverage from all seasons highlighted organic matter as be-10 ing the most important particulate fraction during summertime, while the nitrate fraction was more prevalent in winter. The variation in particulate nitrate was inherently linked to the gas-to-particle-phase equilibrium of ammonium nitrate, which depends on ambient temperature and relative humidity. During short episodes immediately after dawn, the particulate nitrate seems to disobey this dependency so that additional local nitrate 15 formation, such as from HONO photolysis is needed as an explanation. During the summer 2008's experiment, a remarkable diurnal evolution in the oxidation state of the organic matter became evident, which could be correlated to hydroxyl radical (OH) and ozone concentrations indicating photochemical transformation process. In summer, the organic particulate matter seems to be heavily influenced by regional secondary 20 formation and transformation processes, facilitated by photochemical production processes as well as a diurnal cycling of the substances between the gas and particulate phase. In winter, these processes were obviously much weaker, so that organic matter apparently originated mainly from aged particles and long range transport. and relative humidity. This underlines the fact that particle mass concentration is linked to both semi-volatile precursor's concentrations and meteorological conditions. Moreover, the ammonium nitrate formation is not solely depending on its gas-to-particle equilibrium, it is also directly depending on the available ammonia which competes with HNO 3 and H 2 SO 4 to lead to the formation of AN and ammonium sulphate respec-5 25 range transmissions of air pollutants in Europe) and the UBA (Umweltbundesamt, the German federal environment agency) providing for the first time, at Melpitz, high time resolved aerosol chemical composition. These measurements covered different seasonsAbstract 20 Aerosol measurements were performed using both on-line and off-line instruments. All on-line instruments were set up in the same container laboratory and utilized to the same air inlet. This inlet line consisted of a PM 10 Anderson impactor located approximately 6 m above ground level. It was followed directly by an automatic aerosol diffusion dryer that maintained the relative humidity (RH) in the sampling line below 30% 25 all the time (Tuch et al., 2009). After entering the container laboratory, the sampling 11615 ACPD Abstract of the mass fraction of ammonium and chloride was also observed from summer to 11620 ACPD .: O/C and OM/OC ratios of primary, secondary, and ambient organic aerosols with high-resolution time-of-flight aerosol mass spectrometry, Environ. Sci. Technol., 42,[4478][4479][4480][4481][4482][4483][4484][4485]

1] A simulation of a diurnal cycle of atmospheric boundary layer (ABL) flow over a homogeneous terrain is performed using large-eddy simulation (LES) with the Lagrangian scale-dependent dynamic subgrid-scale model. The surface boundary condition is derived from the field observations of surface heat flux from the HATS experiment . The simulation results display good general agreement with previous modeling and experimental studies with regard to characteristic features such as growth of the convective boundary layer by entrainment, nocturnal jet, and multilayered flow structure of the nocturnal regime. To gain a better understanding of the physical parameters affecting the statistics of the flow, we study the dependence of a subgrid parameter (dynamic Smagorinsky coefficient), resolved turbulent kinetic energy, and resolved vertical velocity variance upon atmospheric stability. The profiles of these turbulent variables plotted as a function of Obukhov length show ''hysteretic'' behavior that implies nonunique dependence. The subsequent use of local Richardson number as the scaling parameter shows a decrease in this ''hysteresis,'' but there is an increased scatter in the profiles with increasing height. Conversely, profiles plotted as a function of local Obukhov length (based on the fluxes at the local vertical level) show almost no hysteresis, confirming the validity of Nieuwstadt's local scaling hypothesis. Although the local scaling hypothesis was formulated for the stable boundary layer, we find that it applies to the entire stability range of the diurnal cycle. Citation: Kumar, V., J. Kleissl, C. Meneveau, and M. B. Parlange (2006), Large-eddy simulation of a diurnal cycle of the atmospheric boundary layer: Atmospheric stability and scaling issues, Water Resour. Res., 42, W06D09,

The cloud-top brightness temperature data from 2001 to 2010 are used to derive a climatology of deep convection duration, span, and propagation speed over the Indonesian Maritime Continent (10°S-10°N, 80°E-160°E). The full domain of study is divided into northern (0°-10°N) and southern (0°-10°S) regions to investigate the seasonal and latitudinal variabilities of cloud streaks. The ratio of westward-to eastward-propagating cloud streaks is found to be approximately 3:1. Westward-moving streaks generally have longer spans and faster speeds than eastward-moving systems. Coherent episodes of westward-(eastward-) propagating systems have 9.5 (7.5) h durations and 519 (378) km spans on average; most episodes have zonal phase speeds of 6-30 m s −1 . Median zonal phase speeds of 14.2 (westward) and 13.5 m s −1 (eastward) are found for events with >1000 km spans and >20 h durations. The recurrence frequency, which is categorized from 1 event per day to 1 event per month, is also discussed. The latitudinal and seasonal dependences of statistical properties are strongly influenced by the Inter-Tropical Convergence Zone annual cycle. The number of westward-migrating systems is significant every month, while eastward-migrating systems strongly vary by season and latitude. Eastward migration is less frequent in the southern region during June, July and August (JJA) and in the northern region during December, January and February (DJF). In the northern region, the westward-propagating events' mean span is much longer during JJA, September, October, and November (SON) than the other periods; this effect is partially due to the favorable environmental shear conditions necessary to sustain a long-lived system. Eastward-and westward-propagating events are found during the shortwave heating and dissipation modes of diurnal cycle phase. Thus, thermal forcing, which is associated with the elevated terrain found over the islands and the landsea interface, is dominant on a daily basis. Several possible reasons behind the present results besides the environmental conditions are discussed. It is found that low-level wind may support the precipitation propagation speed, and its support may depend on the Madden-Julian Oscillation (MJO) phase. However, advection by wind alone is likely insufficient to propagate the precipitation as quickly, as our results show. The speed of precipitation migration particularly around Sumatra is similar to the values reported in the framework of propagating gravity waves and moist Kelvin waves.

This study focuses on using remote sensing for comparative assessment of surface urban heat island (UHI) in 18 mega cities in both temperate and tropical climate regions. Least-clouded day-and night-scenes of TERRA/MODIS acquired between 2001 and 2003 were selected to generate land-surface temperature (LST) maps. Spatial patterns of UHIs for each city were examined over its diurnal cycle and seasonal variations. A Gaussian approximation was applied in order to quantify spatial extents and magnitude of individual UHIs for inter-city comparison. To reveal relationship of UHIs with surface properties, UHI patterns were analyzed in association with urban vegetation covers and surface energy fluxes derived from high-resolution Landsat ETM+ data. This study provides a generalized picture on the UHI phenomena in the Asian region and the findings can be used to guide further study integrating satellite high-resolution thermal data with land-surface modeling and meso-scale climatic modeling in order to understand impacts of urbanization on local climate in Asia. #

Dry-bulb temperature, dew-point, wind speed, and wind direction were measured in and around an isolated vegetative canopy in Davis CA from 12 to 25 October 1986. These meteorological variables were measured 1.5 m above ground along a transect of 7 weather stations set up across the canopy and the upwind/downwind open fields. These variables were averaged every 15 minutes for a period of two weeks so we could analyze their diurnal cycles as well as their spatial variability. The results indicate significant nocturnal heat islands and daytime oases within the vegetation stand, especially in clear weather. Inside the canopy within 5 m of its upwind edge, daytime temperature fell by as much as 4.5 °C, whereas the nighttime temperature rose by 1 °C. Deeper into the canopy and downwind, the daytime drop in temperature reached 6 °C, and the nighttime increase reached 2 °C. Wind speed was reduced by ~ 2 m s-1 in mild conditions and by as much as 6.7 m s-1 during cyclonic weather when openfield wind speed was in the neighborhood of 8 m s-1. Data from this project were used to construct correlations between temperature and wind speed within the canopy and their corresponding ambient, open-field values.

... mean square error of 2.5 K. The obtained results make possible to analyse the diurnal ... This procedure has an advantage to the common nearest neighbour resampling as it retains a ... Visualanalysis of data shows that water bodies also have an influence on LST — eg rivers can ...

Availability of high-resolution satellite rainfall products provides a great opportunity to monitor precipitation frequently over large and remote areas. However, the accuracies of these products need thorough assessment before they can be widely used. The objective of this study is to evaluate the accuracies of Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis 3B42 products (TMPA V6 and TMPA V7) using a network of 75 rain gauges over Southwestern China. The study region has a complex terrain, which makes it challenging for TMPA rainfall products to give reliable estimates. The results show that the TMPA products tend to underestimate the occurrences of rainfall events. Furthermore, TMPA V6 always underestimates the precipitation, while V7 generally overestimates rainfall in wet season and underestimates it in dry season. Under-and overestimation of rainfall by the two products can be mainly attributed to false alarm events. The overall accuracies of the two products depend heavily on the time scale. At the daily scale, these products may not be reliable; however, the overall accuracies are improved substantially when the time scale is extended from daily to monthly and seasonal scales. Reliability of the TMPA precipitation estimates is also dependent on the climate zones and elevation to some extent and shows clear seasonal variations. In the wet months from May to September, the estimates for TMPA 3B42 V6 and V7 tend to be more accurate. In comparison, the accuracy of V7 is improved slightly over V6. However, V7 still has some major limitations in reproducing precipitation in dry seasons and in high-elevation regions with complex terrains, suggesting that further improvements in TMPA precipitation retrieval algorithms are still needed for this type of regions.

In this work we present a climatology of the west coast of subtropical South America, with particular emphasis on those variables that determine the occurrence of marine clouds and coastal fog. Specifically, we document the mean structure of the marine boundary layer (MBL) and its capping inversion, their regular (diurnal and annual) cycles and non-regular (synoptic and interannual) variability. The comparison of the lifting condensation level and the inversion base height gives a useful framework to understand the fluctuations in cloud frequency at several time scales. Both variables are in turn modulated by a variety of atmospheric phenomena, some of them documented here. The correspondence between large-scale atmospheric variables and coastal fog is further complicated because of the effect of local phenomena, particularly the diurnal cycle of the inland winds and the geometry of the coast line. We also present an exploratory analysis of the interannual variability of the coastal fog based on qualitative records from the Fray Jorge National Park at 30º38'S 1. MEAN FEATURES OF THE LOWER TROPOSPHERIC CIRCULATION.

Boundary layer measurements in Nangatchori, Benin were performed over the period of one full year (2006) using a novel ground-based microwave profiler and additional remote-sensing instruments. In this paper, the diurnal cycle of the ITD (Inter-Tropical Discontinuity) in the transition period between dry and wet season during the month of April is described in detail. Dry air masses from the north (Sahel) and moist air from the south (tropical Atlantic Ocean) cause very sharp temperature and humidity gradients in the low troposphere over West Africa.

Daily NO 2 vertical column density (VCD) has been routinely measured by zenith sky spectroscopy at the subtropical station of Izaña (28 • N, 16 • W) since 1993 in the framework of the Network for the Detection of Atmospheric Composition Change (NDACC). Based on 14 years of data the first low latitude NO 2 VCD climatology has been established and the main characteristics from short timescales of one day to interannual variability are presented. Instrumental descriptions and different sources of errors are described in detail. The observed diurnal cycle follows that expected by gas-phase NO x chemistry, as can be shown by the good agreement with a vertically integrated chemical box model, and is modulated by solar radiation. The seasonal evolution departs from the phase of the hours of daylight, indicating the signature of upper stratospheric temperature changes. From the data record (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) no significant long-term trends in NO 2 VCD can be inferred. Comparison of the groundbased data sets with nadir-viewing satellite spectrometers shows excellent agreement for SCIAMACHY with differences between both datasets of 1.1%. GOME displays unrealistic features with the largest discrepancies during summer. The ground-based data are compared with long-term output of the SLIMCAT 3-D chemical transport model (CTM). The basic model, forced by ECMWF (ERA-40) analyses, captures the observed NO 2 annual cycle but significantly underestimates the spring/summer maximum (by 12% at sunset and up to 25% at sunrise). In a model run which uses assimilation of satellite CH 4 profiles to constrain the model long-lived tracers the agreement is significantly improved. This improvement in modelled column NO 2 is due to better Correspondence to: M. Gil ([email protected]) modelled NO y profiles and points to transport errors in the ECMWF ERA-40 reanalyses.

The Tropical Rainfall Measuring Mission (TRMM) satellite was launched on 27 November 1997, and data from all the instruments first became available approximately 30 days after the launch. Since then, much progress has been made in the calibration of the sensors, the improvement of the rainfall algorithms, and applications of these results to areas such as data assimilation and model

Hourly rainfall estimates from integrated satellite data are used to build a dynamically based climatology of convectively generated rainfall across South America, including tropical, sub-tropical and oceanic regions. Herein, we focus on 0S to 15S, including greater Amazon and NE Brazil leeward of the South Atlantic Ocean. Emphasis is placed on rainfall resulting from organized convective regimes, which are known to produce the majority of seasonal rainfall in various parts of South America and other continents. The statistical characteristics of individual events are quantified and examined with respect to regional atmospheric conditions. Among the factors considered are steering winds and wind shear, convective available potential energy (CAPE), sea and land breezes, and the occurrence of transient disturbances such as Kelvin Waves and Easterly Waves. Forcing and convective triggering mechanisms are inferred from the diagnosis of systematic patterns as evidenced in the continental diurnal cycle and longer periods of natural variability. The episodes of organized convection are analyzed in terms of their duration, span, phase speed, starting and ending time, starting and ending longitude, month and year through frequency distribution analysis. Most episodes of organized convection tend to move westward across the Amazon Basin. Descriptive statistics indicate average phase speed of westward and eastward episodes of convection in the Amazon basin at −11.8 m•s −1 and 13.0 m•s −1 , respectively. Eastward propagating systems are influenced by northeastward moving cold fronts in Southern South America and tend to trigger and to organize convection across the Amazon Basin. Hourly rainfall analyses indicate that convection over the Amazon region is often organized.

Observation due to its relation with the global CO 2 cycle. Chlorophyll fluorescence (ChF) emitted by the vegetation is an accurate indicator of the plant status and their photosynthetic activity. This work analyses the diurnal evolution of the ChF emission spectrum and the fluorescence yield in order to determine the best conditions for remote sensing of ChF from a satellite platform. The ChF evolution is studied at leaf level during several diurnal cycles, in simulated conditions, for two species under different stress conditions. The analysis of the signal levels gives an estimation of the values of ChF emission which could be observed from a remote sensing platform, and determines the best overpass time for this observation.

PAM (Pulse Amplitude Modulation) fluorometer techniques directly measure the light reactions of photosynthesis that are otherwise difficult to estimate in CAM (Crassulacean Acid metabolism) plants such as pineapple (Ananas comosus comosus cv. Phuket). PAM machines calculate photosynthesis as the Electron Transport Rate (ETR) through PSII (4 electrons per O 2 produced) as mol m −2 s −1 . P vs. E curves fitted the waiting-in-line function (an equation of the form ETR ¼ ETR max  ð E=E opt Þ:e 1ÀE=Eopt ) allowing half-saturating and optimal irradiances (E opt ) to be estimated. Effective Quantum Yield (Y max ), Electron Transport Rate (ETR max ) and the Non-Photochemical Quenching parameter, NPQ max all vary on a diurnal cycle but the parameter qN max does not show a systematic variation over a diurnal period. Phuket pineapple is a "sun plant" with Optimum Irradiance (E opt ) from 755 to 1,130 μmol m −2 s −1 (

The biomass of a High Rate Algal Pond was separated into individual components of algae, bacteria and detritus. The two stage technique involved mechanical and chemical disaggregation of concentrated pond samples, followed by separation on preformed PercollR/sucrose density gradients. Throughout a diurnal cycle, monitored in September 1990, between 85 and 90% of the total chlorophyll a was recovered in the algal fraction. The greatest loss of chlorophyll from the sample occurred during the concentration stage; no further losses were encountered during physical and chemical disaggregation. The technique enabled the direct gravimetric determination of the separated algal biomass. The potential applications of the technique are discussed.

A new land surface parameterization scheme ALSIS , with emphasis on soil moisture prediction, is described and validated with observations from HAPEX-MOBILHY and Cabauw. An important feature of the scheme is the inclusion of vertical heterogeneity of soil hydraulic parameters is modelling unsaturated flow. The simulated soil moisture for HAPEX site using a vertically homogeneous soil has a positive bias in the upper soil layers and a negative bias in the deep soil layers. Taking into account the soil vertical heterogeneity greatly eliminates this discrepancy and results in an excellent agreement between annual cycles of modelled and observed soil moisture profiles. The mean annual soil moisture in the top 1.6 m of soil increased from 394 mm for homogeneous case to 433 mm for the heterogeneous case, consistent with 435 mm observed. The improvement in soil moisture simulation resulted in an improved skill in predicting the mean and the diurnal Ž . cycles of surface fluxes for the intensive observational period 28 May-3 July . The simulated monthly averages of surface temperature and fluxes follow observations over the year, except for January when the model overestimates the latent heat flux due to its failure in simulating high rates of dew fall. The deviation of modelled monthly mean surface fluxes from observations are well within the estimated observational errors. The simulated mean daily surface temperature, and surface fluxes are generally consistent with observations, except for some times in the winter period. The modelled diurnal cycles of temperature and fluxes are in agreement with those observed. However, the model overestimates the night-time latent heat flux, especially during January. q

The All-Sky interferometric meteor (SKYiMET) radar (MR) derived winds in the vicinity of the equatorial electrojet (EEJ) are discussed. As Thumba (8.5° N, 77° E; dip lat. 0.5° N) is under the EEJ belt, there has been some debate on the reliability of the meteor radar derived winds near the EEJ height region. In this regard, the composite diurnal variations of zonal wind profiles in the mesosphere-lower thermosphere (MLT) region derived from TIMED Doppler Interferometer (TIDI) and ground based meteor radar at Thumba are compared. In this study, emphasis is given to verify the meteor radar observations at 98 km height region, especially during the EEJ peaking time (11:00 to 14:00 LT). The composite diurnal cycles of zonal winds over Thumba are constructed during four seasons of the year 2006 using TIDI and meteor radar observations, which showed good agreement especially during the peak EEJ hours, thus assuring the reliability of meteor radar measurements of neutral winds close to the EEJ height region. It is evident from the present study that on seasonal scales, the radar measurements are not biased by the EEJ. The day-time variations of HF radar measured E-region drifts at the EEJ region are also compared with MR measurements to show there are large differences between ionospheric drifts and MR measurements. The significance of the present study lies in validating the meteor radar technique over Thumba located at magnetic equator by comparing with other than the radio technique for the first time.

 Bioclimatic conditions have been assessed for a large urban area located in the tropical highlands of central Mexico using the indices (in °C) of resultant temperature (RT) and effective temperature (ET). The well-developed heat island effect the city generates, reduces the number of nights categorized as cold (ET between 5 and 15° C) to cool (ET from 15 to 18.5° C). Most days fall in the cold to cool range and during the warm season (April to June) the bioclimate of Mexico City is mostly within the neutral (comfort) range. The effect of the nocturnal (to the west) and daytime (to the east of the town) heat island is noticeable in the central and northern sectors. The daytime heat island located in these regions, albeit small (urban air temperature 2–3° C greater than rural), compared with the nocturnal heat island intensity (9–10° C) still adds energy to the already heated afternoon urban air. ET values in the north and central sectors approach the threshold for comfort (ET of 25° C) during the warm months around noon. It is not surprising to find that as the nocturnal heat island has increased over the years (1921–1985) as the city grew, so has the ET for the central district and indicating the dominating role of temperature in the ET index. Assessment of the diurnal cycle of bioclimatic conditions in downtown Mexico City by means of two empirical indices (effective temperature and thermopreferendum) throughout the years gave similar results to those obtained from the application of Fanger’s predicted mean vote (PMV) model. An attempt has been made to characterize four bioclimatic zones in the capital city.