warming of global abyssal and deep southern ocean waters between the 1990s and 2000s contributions to global heat and sea level rise budgets abyssalglobalanddeepsouthern oceantemperature trendsarequantifiedbetweenthe1990sand2000sto assesstheroleofrecentwarmingoftheseregionsin globalheatandsealevelbudgets theauthors1 compute warming rates with uncertainties along 28 full depth high quality hydrographic sections that have been occupied two or more times between 1980 and 2010 2 divide the global ocean into 32 basins defined by the topography and climatological ocean bottom temperatures and then 3 estimate temperature trends in the 24 sampled basins the three southernmost basins show a strong statistically significant abyssal warming trend with that warming signal weakening to the north in the central pacific western atlantic and eastern indian oceans eastern atlantic and western indian ocean basins show statistically insignificant abyssal cooling trends excepting the arctic ocean and nordic seas the rate of abyssal below 4000 m global ocean heat content change in the 1990s and 2000s is equivalent to a heat flux of 0 027 60 009 w m 22 applied over the entire surface of the earth deep 1000 4000 m warming south of the subantarctic front of the antarctic circumpolar current adds 0 068 60 062 w m 22 the abyssal warming produces a 0 053 60 017 mm yr 21 increase in global average sea level and the deep warming south of the subantarctic front adds another 0 093 60 081 mm yr 21 thus warmingin theseregions ventilatedprimarilyby antarcticbottomwater accounts for a statistically significant fraction of the present global energy and sea level budgets

destabilization of glacial climate by the radiative impact of atlantic meridional overturning circulation disruptions during each of the dramatic global warmings that ended the pleistocene ice ages the atlantic meridional overturning circulation amoc was disrupted it is not clear whether this was a contributing cause or simply an effect of deglaciation here we show that in an ensemble of simulations with a global climate model amoc disruption causes a consistent and sustained positive radiative imbalance of 0 4wm2 the imbalance is accommodated by heat accumulation in the ocean interior representing an overall planetary warming subsequently released by deep convection in the north atlantic when the amoc resumes the results suggest a means by which amoc disruptions could have helped to tip the planet out of stable glaciated states however the fact that amoc disruptions occurred during prior heinrich stadials without causing deglaciation shows that other factors such as ice sheet dynamics or controls on co2 were also key for deglaciation

the mesoscale and microscale structure and organization of clouds and precipitation in midlatitude cyclones viii a model for the seeder feeder process in warm frontal rainbands abstract previous field studies have indicated that warm frontal rainbands form when ice particles from a seeder cloud grow as they fall through a lower level feeder cloud in this paper we present results from a parameterized numerical model of the growth processes that can lead to the enhancement of precipitation in a seeder feeder type situation the model is applied to two types of warm frontal rainbands in the first type 1 situation the vertical air motions are typical of those associated with slow widespread lifting in the vicinity of warm fronts in the second type 2 situation the vertical air motions are stronger and more characteristic of the mesoscale the model simulations show that in the type 1 situations the growth of the seed ice crystals within the feeder zone is due to vapor deposition the feeder zone in this case is slightly sub saturated with respect to water due to the presence of the seed crystals in regions where the feeder zone is not seeded from aloft snow cryst

dynamics of the cumulus cloud margin an observational study aircraft observations of shallow to moderately deep cumulus clouds are analyzed with the purpose of describing the typical horizontal structure of thermodynamic and kinematic parameters near the cumulus margin from the cloud center into the ambient clear air the cumuli were sampled in a broad range of environments in three regions the tropical atlantic ocean in winter the sonoran desert during the monsoon and the arid high plains of wyoming in summer the composite analysis of 1624 cumulus penetrations shows thattheverticalmassflux temperature buoyancy thebuoyancyflux andtheturbulentkineticenergyalltend toreachaminimumnearthecloudedge mostofthesevariables andalsotheliquidwatercontent thedroplet concentration and the mean droplet size generally decrease in value from within the cumulus toward the cloud edge slowly atfirst and rapidly close to the cloud edge thesefindingscorroborate recent observational and modeling studies and provide further evidence for significant evaporative cooling in laterally entraining and detraining eddies in the cloud margin a transition zone within 200 m or 10 of the cloud diameter ofthecloudedge thiscoolingexplainsthetendencyfordownwardaccelerating buoyantlydrivensubsidence in the cloud margin

vertical distributions of raindrops and z r relationships using microrain radar and 2 d video distrometer measurements during the integrative monsoon frontal rainfall experiment imfre

the role of mesoscale eddies in the rectification of the southern ocean response to climate change abstract simulations from a fine resolution global coupled model the geophysical fluid dynamics laboratory climate model version 2 4 cm2 4 are presented and the results are compared with a coarse version of the same coupled model cm2 1 under idealized climate change scenarios a particular focus is given to the dynamical response of the southern ocean and the role played by the eddies parameterized or permitted in setting the residual circulation and meridional density structure compared to the case in which eddies are parameterized and consistent with recent observational and idealized modeling studies the eddy permitting integrations of cm2 4 show that eddy activity is greatly energized with increasing mechanical and buoyancy forcings buffering the ocean to atmospheric changes and the magnitude of the residual oceanic circulation response is thus greatly reduced although compensation is far from being perfect changes in poleward eddy fluxes partially compensate for the enhanced equatorward

classification of sediments on exposed tidal flats in the german bight using multi frequency radar data we present a new method for the extraction of roughness parameters of sand ripples on exposed tidal flats from multi frequency synthetic aperture radar sar data the method is based on the integral equation model iem which predicts the normalized radar cross section nrcs of randomly rough dielectric surfaces the data used for this analysis were acquired in the german bight of the north sea by the spaceborne imaging radar c x band sar sir c x sar in 1994 in situ measurements of the root mean squared rms height and the correlation length of the sand ripples clearly demonstrate a relationship between these roughness parameters and the c band nrcs determined from an ers sar image using the iem we have calculated nrcs isolines for the three frequency bands deployed by sir c x sar l c and x band as a function of the rms height and the correlation length of the sand ripples for each sir c x sar image pixel these two roughness parameters were determined from the intersections of the nrcs isolines at different radar bands and they were used for a crude sediment classification for a small test area at the german north sea coast comparing our results with available sediment maps we conclude that the presented method is very promising for tidal flat classification by using data from presently existing airborne and future spaceborne multi frequency sar systems

properties of tropical convection observed by millimeter wave radar systems abstract this paper describes the results of analysis of over 825 000 profiles of millimeter wave radar mwr reflectivities primarily collected by zenith pointing surface radars observing tropical convection associated with various phases of activity of the large scale tropical circulation the data principally analyzed in this paper come from surface observations obtained at the atmospheric radiation measurement manus site during active and break episodes of the madden julian oscillation mjo and from observations collected from a shipborne radar during an active phase of the monsoon over the indian ocean during the joint air sea monsoon interaction experiment it was shown for example in a histogram regime analysis that the mwr data produce statistics on convection regimes similar in most respects to the analogous regime analysis of the tropical rainfall measuring mission radar radiometer observations attenuation of the surface mwrs by heavy precipitation however incorrectly shifts a small fracti

the passive and active nature of ocean heat uptake in idealized climate change experiments the influence of ocean circulation changes on heat uptake is explored using a simply configured primitive equation ocean model resembling a very idealized atlantic ocean we focus on the relative importance of the redistribution of the existing heat reservoir due to changes in the circulation and the contribution from anomalous surface heat flux in experiments in which the surface boundary conditions are changed we perform and analyze numerical experiments over a wide range of parameters including experiments that simulate global warming and others that explore the robustness of our results to more general changes in surface boundary conditions we find that over a wide range of values of diapycnal diffusivity and southern ocean winds and with a variety of changes in surface boundary conditions the spatial patterns of ocean temperature anomaly are nearly always determined as much or more by the existing heat reservoir redistribution than by the nearly passive uptake of temperature due to changes in the surface boundary conditions calculating heat uptake by neglecting the existing reservoir redistribution which is similar to treating temperature as a passive tracer leads to significant quantitative errors notably at high latitudes and secondarily in parts of the main thermocline experiments with larger circulation changes tend to produce a relatively larger magnitude of existing reservoir redistribution and a faster growing effective heat capacity of the system the effective heat capacity is found to be sensitive to both vertical diffusivity and southern ocean wind

the vertical structure of toga coare convection part i radar echo distributions radar data collected by the 5 cm mit radar which was deployed aboard the r v vickers during the intensive observing period of the tropical ocean global atmosphere coupled ocean atmosphere response experiment are partitioned into convective and stratiform cartesian grid columns the vertical structure of convective echo is examined through the use of two variables echo top height and the height of the 30 dbz reflectivity contour the first of these variables has traditionally been used to describe the vertical structure characteristics of convection and the second has recently been linked to internal microphysical properties and lightning histograms of the relative frequency of convective only echo top heights and 30 dbz contour heights were constructed for the three cruises of the vickers with each cruise experiencing different phases of the intraseasonal oscillation iso cruise 1 which was dominated by the convectively inactive phase of the iso was characterized by the highest frequency of shallow convection based on echo top heights whereas cruise 2 which was dominated by a particularly well defined passage of the convective phase of the iso exhibited the tallest echo top heights cruise 3 convection was influenced by moderate westerly surface winds characteristic of postwesterly wind burst conditions and convection was of intermediate height when viewed as a function of internal vertical structure i e 30 db z contour height the frequency distributions vary less from cruise to cruise with cruises 1 and 2 having nearly identical distributions of convective 30 dbz contour heights furthermore when the contribution to convective rainfall is examined as a function of 30 dbz contour height it is seen that relatively more rain fell from vertically intense convection i e convection with tall 30 dbz contours during cruises 1 and 3 than during cruise 2 instantaneous correlations between rainfall rate and radar echo height were highly scattered about a mean value of about 0 55 whereas rainfall rate and 30 dbz contour height correlations peaked at about 0 8 and exhibited much less scatter

creating a more realistic idealized supercell thunderstorm evolution via incorporation of base state environmental variability abstractconvective environments are known to be heterogeneous in both time and space yet idealized models use fixed base state environments to simulate storm evolution recently the base state su

evolution of the total lightning structure in a leading line trailing stratiform mesoscale convective system over houston texas 1 line normal vertical cross sections of houston lightning detection and ranging ldar vhf radiation sources and radar reflectivity provide new insights into the three dimensional total lightning structure and evolution of a leading line trailing stratiform llts mesoscale convective system mcs over houston texas on 31 october 2005 previous research examining only the mature stage of an mcs showed that the overwhelming majority of vhf lightning sources occurred in the convective region with a lightning pathway extending rearward and descending in altitude into the stratiform region this descending pathway was most likely associated with small charged ice particles advected from the convective line unlike previous research the lightning pathway observed during the evolution of the mcs on 31 october 2005 initially extended rearward 40 km at a nearly constant height of 9 10 km in less than an hour the lightning pathway evolved into a sloped pathway similar to that found by previous research with a horizontal extent between 50 to 60 km and downward descent of 4 to 5 km during the lightning pathway evolution radar analysis showed an increase of reflectivity in the midlevels of the stratiform region consistent with increased depositional and aggregational growth above the melting layer broadening increased range of values of radar reflectivity above the melting layer was most likely an indication of a strengthening mesoscale updraft in the stratiform region this strengthening updraft may have contributed to an increase in the growth of the small charge carrying ice crystals giving them a greater fall speed in addition the mesoscale updraft may have promoted an environment conducive to local stratiform region charge generation in the mixed phase region just above the melting layer

investigation of microphysical processes occurring in isolated convection during name abstracta major objective of the north american monsoon experiment name was to quantify microphysical processes within convection occurring near the steep topography of northwestern mexico a previous study compared examples of isolated convection using polarimetric radar data and noted a dependence on mixed phase processes via drop freezing and subsequent riming growth along the coastal plain and western slopes with an even greater role of melting ice in rainfall production over the highest terrain despite the higher frequency of these isolated cells compared to organized convective systems the latter were responsible for 75 of rainfall therefore this study seeks to evaluate the role of mesoscale organization on microphysical processes and describes the evolution of these systems as a function of topography similar to isolated convection both warm rain and ice based processes played important roles in producing intense rainfall in organized convection although similarities existed between cell

dynamics of the stratiform sector of a tropical cyclone rainband abstractairborne doppler radar documented the stratiform sector of a rainband within the stationary rainband complex of hurricane rita the stratiform rainband sector is a mesoscale feature consisting of nearly uniform precipitation and weak vertical velocities from collapsing convective cells upward transport and associated latent heating occur within the stratiform cloud layer in the form of rising radial outflow beneath downward transport is organized into descending radial inflow in response to two regions of latent cooling in the outer upper regions of the rainband sublimational cooling introduces horizontal buoyancy gradients which produce horizontal vorticity and descending inflow similar to that of the trailing stratiform region of a mesoscale convective system within the zone of heavier stratiform precipitation melting cooling along the outer rainband edge creates a midlevel horizontal buoyancy gradient across the rainband that drives air farther inward beneath the brightband the organi

the interaction of clouds and dry air in the eastern tropical pacific cloud radar observations of eastern pacific intertropical convergence zone cloud vertical structure are interpreted in light of soundings 100 km scale divergence profiles calculated from precipitation radar doppler velocities and surface rain gauge data from a ship at 10 n 95 w during the 2001 east pacific investigation of climate epic experiment the transition from convective to stratiform rain is clear in all four datasets indicating a coherence from local to 100 km scale a novel finding is dry air intrusions at altitudes of 6 8 km often undercutting upper level ice clouds two distinct dry air source regions are identified one is a relatively dry area overlying the cooler waters of the costa rica oceanic thermocline dome centered approximately 400 km east northeast of the ship site the other is the even drier nearequatorial subsidence zone south of 6 7 n the former source is somewhat peculiar to this specific ship location so that the ship sample is not entirely representative of the region the 20 25 september period is studied in detail as it depicts two influences of the dry air on cloud vertical structure one is the modulation of small scale surface based convection evident as a weakening and narrowing of cloud radar reflectivity features the other springs from intense sublimation cooling as differential advection brought snowing anvil clouds over the dry layers during one half day period of strong sublimation the cooling rate is inferred to be several tens of degrees per day over a 100 hpa layer based on a heat budget estimate at 100 km scale involving the horizontal wind divergence data this is consistent with fluxing ice water contents of 0 05 0 10 g m 3 derived from the cloud radar reflectivities the temperature profile shows the dynamically expected response to this cooling a positive negative positive temperature anomaly pattern centered on the sublimating layer a buoyancy sorting diagnostic model of convection indicates that these upper troposphere temperature anomalies can cause premature detrainment of updrafts into the lower part of the cloudy layer a feedback that may actively maintain these long lasting dense anvils middle troposphere southerly dry air inflow is also evident in large scale analysis given the proximity of the dry equatorial subsidence zone to the eastern tropical pacific the differential advection of dry and cloudy air the ensuing sublimation and its dynamical aftereffects may play a role in establishing the region s climate although the extent of their significance needs to be further established

the deep ocean buoyancy budget and its temporal variability abstractdespite slow rates of ocean mixing observational and modeling studies suggest that buoyancy is redistributed to all depths of the ocean on surprisingly short interannual to decadal time scales the mechanisms responsible for this redistribution remain poorly understood this work uses an earth system model to evaluate the global steady state ocean buoyancy and related steric sea level budget its interannual variability and its transient response to a doubling of co2 over 70 years with a focus on the deep ocean at steady state the simple view of vertical advective diffusive balance for the deep ocean holds at low to midlatitudes at higher latitudes the balance depends on a myriad of additional terms namely mesoscale and submesoscale advection convection and overflows from marginal seas and terms related to the nonlinear equation of state these high latitude processes rapidly communicate anomalies in surface buoyancy forcing to the deep ocean locally the deep high latitude changes th

organization and structure of clouds and precipitation on the mid atlantic coast of the united states part ii the mesoscale and microscale structures of some frontal rainbands abstract the mesoscale and microscale structures of the clouds and precipitation associated with a frontal system on the mid atlantic coast of the united states are investigated using radar reflectivity and doppler velocity data surface mesonet conventional surface upper air and microphysical data the frontal structure showed similarities to a warm occlusion with code air advection aloft preceding cold air advection at lower levels six rainbands were observed in association with the frontal system all of these rainbands developed within the region of coverage of the nws wsr 57 radar at cape hatteras north carolina two were upper level features associated with a prefrontal surge of cold air and the main push of cold dry air aloft these rainbands were similar in structure to prefrontal surge and wide cold frontal rainbands respectively observed on the pacific northwest coast the microphysical and small mesoscale structures of the wide cold frontal rainband are examined three of the rainbands

latitudinal dependence of atlantic meridional overturning circulation amoc variations 1 amoc variations are often thought to propagate with the kelvin wave speed resulting in a short time lead between high and low latitudes amoc variations however as shown in this paper using a coupled climate model gfdl cm2 1 with the existence of interior pathways of north atlantic deep water nadw from flemish cap to cape hatteras as that observed recently amoc variations estimated in density space propagate with the advection speed in this region resulting in a much longer time lead several years between subpolar and subtropical amoc variations and providing a more useful predictability the results suggest that amoc variations have significant meridional coherence in density space and monitoring amoc variations in density space at higher latitudes might reveal a stronger signal with a several year time lead

joint use of multiple synthetic aperture radar imagery for the detection of bivalve beds and morphological changes on intertidal flats abstract we analyzed a large amount of high resolution synthetic aperture radar sar data of dry fallen intertidal flats on the german north sea coast with respect to the imaging of sediments macrophytes and mussels terrasar x and radarsat 2 images of four test areas acquired from 2008 to 2013 form the basis for the present investigation and are used to demonstrate that pairs of sar images if combined through basic algebraic operations can already provide indicators for morphological changes and for bivalve oyster and mussel beds multi temporal analyses of series of sar images allow detecting bivalve beds since the radar backscattering from those beds is generally high whereas that from sediments may vary with imaging geometry and environmental conditions our results further show evidence that also single acquisition dual polarization sar imagery can be used in this respect the polarization coefficient i e the ratio of the difference and the sum of both co polarizations can be used to infer indicators for oyster and blue mussel beds

numerical modeling of precipitation cores on cold fronts abstract a nonhydrostatic three dimensional mesoscale model including cloud physics is used to simulate the structure of a narrow cold frontal rainband ncfr the model simulations reproduce the observed core gap structure of the ncfr trapped gravity waves triggered by regions of stronger convection on the cold front induce subsidence and regions of warming aloft in these regions precipitation is suppressed thereby creating precipitation gaps along the front separated by precipitation cores the advection of hydrometeors is responsible for the parallel orientation and the elliptical shapes of the precipitation cores gravity waves produce pressure perturbations just behind the cold front which modify the wind and thermal structure parts of the front behave locally like a gravity current traveling at the theoretical gravity current speed in a direction perpendicular to the local orientation of the front but the motion of the front as a whole is not well described by the gravity current spe

multiscale mountain waves influencing a major orographic precipitation event abstract 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 20 km horizontal wavelength undulations over the windward foothills triggered by interaction

vertical velocity and physical structure of generating cells and convection in the comma head region of continental winter cyclones abstractthe vertical motion and physical structure of elevated convection and generating cells within the comma heads of three continental winter cyclones are investigated using the wyoming w band cloud radar mounted on the national science foundation national center for atmospheric research nsf ncar c 130 supplemented by analyses from the rapid update cycle model and weather surveillance radar 1988 doppler wsr 88d data the cyclones followed three distinct archetypical tracks and were typical of those producing winter weather in the midwestern united states in two of the cyclones dry air in the middle and upper troposphere behind the pacific cold front intruded over moist gulf of mexico air at lower altitudes within the comma head separating the comma head into two zones elevated convection in the southern zone extended from the cold frontal surface to the tropopause the stronger convective updrafts ranged from 2 to 7 m s 1 and downdrafts ranged from 2 to 6 m s 1 the horizontal scale of the

lake effect mode and precipitation enhancement over the tug hill plateau during owles iop2b abstractimproved understanding of the influence of orography on lake effect storms is crucial for weather forecasting in many lake effect regions the tug hill plateau of northern new york hereafter tug hill rising 500 m above eastern lake ontario experiences some of the most intense snowstorms in the world herein the authors investigate the enhancement of lake effect snowfall over tug hill during iop2b of the ontario winter lake effect systems owles field campaign during the 24 h study period total liquid precipitation equivalent along the axis of maximum precipitation increased from 33 5 mm at a lowland 145 m msl site to 62 5 mm at an upland 385 m msl site the latter yielding 101 5 cm of snow however the ratio of upland to lowland precipitation or orographic ratio varied with the mode of lake effect precipitation strongly organized long lake axis parallel bands some of which formed in association with the approach or passage of upper level short wave troughs produced the highest pre

comparison of simulated and observed continental tropical anvil clouds and their radiative heating profiles abstractvertically pointing millimeter wavelength radar observations of anvil clouds extending from mesoscale convective systems mcss that pass over an atmospheric radiation measurement program arm field site in niamey niger are compared to anvil structures generated by the weather research and forecasting wrf mesoscale model using six different microphysical schemes the radar data provide the statistical distribution of the radar reflectivity values as a function of height and anvil thickness these statistics are compared to the statistics of the modeled anvil cloud reflectivity at all altitudes requiring the model to be statistically accurate at all altitudes is a stringent test of the model performance the typical vertical profile of radiative heating in the anvil clouds is computed from the radar observations variability of anvil structures from the different microphysical schemes provides an estimate of the inherent uncertainty in anvil radiative heating profiles all schemes underestima

three dimensional kinematic and microphysical evolution of florida cumulonimbus part ii frequency distributions of vertical velocity reflectivity and differential reflectivity abstract high resolution radar data collected in florida during the convection and precipitation electrification experiment are used to elucidate the microphysical and kinematic processes occurring during the transition of a multicellular storm from convective to stratiform stages a statistical technique is employed to examine the evolving properties of the ensemble small scale variability of radar reflectivity vertical velocity and differential reflectivity over the entire storm differential radar reflectivity data indicate that the precipitation at upper levels was nearly glaciated early in the storm s lifetime dual doppler radar data show that throughout the storm s lifetime both updrafts and down drafts were present at all altitudes and that most of the volume of the radar echo contained vertical velocities incapable of supporting precipitation size particles thus the ensemble microphysical properties of the storm were increasingly dominated by particles falling in an environment of weak vertic

comparing the convective structure and microphysics in two sahelian mesoscale convective systems radar observations and crm simulations two mesoscale convective systems mcss observed during the african monsoon multidisciplinary analyses amma experimentaresimulatedusingthethree dimensional 3d goddardcumulusensemble model this studywasundertaken todeterminethe performance ofthe cloud resolving modelin representing distinct convective and microphysical differences between the two mcss over a tropical continental location simulations are performed using 1 km horizontal grid spacing a lower limit on current embedded cloudresolving models within a global multiscale modeling framework simulated system convective structure and microphysics are compared to radar observations using contoured frequency by altitude diagrams cfads calculated ice and water mass and identified hydrometeor variables vertical distributions of ice hydrometeors indicate underestimation at the mid and upper levels partially due to the inability of the model to produce adequate system heights the abundance of high reflectivity values below and near the melting level in the simulation led to a broadening of the cfad distributions observed vertical reflectivity profiles show thathighreflectivityis presentat greaterheights thanthe simulations produced thoughtto bea resultof using a single moment microphysics scheme relative trends in the population of simulated hydrometeors are in agreement with observations though a secondary convective burst is not well represented despite these biases the radar observed differences between the two cases are noticeable in the simulations as well suggesting that the model has some skill in capturing observed differences between the two mcss

the occurrence of irregular ice particles in stratiform clouds abstract recent studies that have classified ice particles from airborne imaging probe data have concluded that the vast majority of ice particles in stratiform precipitation systems are of an irregular shape this conclusion stands in contrast to the findings from microscope observations of snow particles at the ground during the improvement of microphysical parameterization through observational verification experiment from november to december 2001 in the oregon cascade mountains improve 2 which show that most snow crystals either single crystals or the component crystals of snow aggregates are readily identified as regular types within established crystal classification systems this apparent contradiction is rectified by examining the definition of the term irregular as applied to ice particles and by considering limitations of different methods for observing ice particles it is concluded that the finding of the airborne probe based studies is a consequence of both limitations of the observin

two types of precipitation particle distribution in convective cells accompanying a baiu frontal rainband around okinawa island japan 1 polarimetric radar variables and ground based raindrop size distributions dsds of two convective cells in a baiu frontal rainband over the okinawa region were analyzed to clarify the precipitation particle distributions in convective cells with low echo top heights one cell existed in the stratiform rain zone and the other was in the convective rain zone of the rainband both cells had echo top 30 dbz heights of approximately 5 5 km above sea level with large radar reflectivity z h greater than 50 dbz in each core for the cell in the stratiform rain zone polarimetric variables indicated that small raindrops predominated differential reflectivity z dr was smaller than 1 5 db and the correlation coefficient hv was greater than 0 98 with large z h 40 dbz the dsd showed high number densities of small raindrops with diameters of 1 2 mm for the other cell polarimetric variables indicated the presence of large raindrops z dr greater than 1 5 db and hv smaller than 0 98 predominated in large z h 40 dbz the dsd for this cell showed lower number densities of raindrops with diameters of 1 2 mm and higher number densities of raindrops exceeding 3 mm the significance of these distributions was confirmed by the z dr and hv for 25 cells in the stratiform rain zone and for 28 cells in the convective rain zone it is notable that different precipitation particle distributions in convective cells were found in the stratiform and convective rain zones of a baiu frontal rainband with common characteristics of low echo top heights and large z h

kinematic structure of convective scale elements in the rainbands of hurricanes katrina and rita 2005 1 airborne doppler radar data collected during the hurricane rainband and intensity change experiment rainex show the convective scale air motions embedded in the principal rainbands of hurricanes katrina and rita these embedded convective cells have overturning updrafts and low level downdrafts originating at 2 4 km that enter the rainband on its radially outward side and cross over each other within the rainband as well as a strong downdraft emanating from upper levels 6 km on the radially inward side these vertical motion structures repeat from one convective cell to another along each rainband the resulting net vertical mass transport is upward in the upwind portion of the band and greatest in the middle sector of the principal rainband where the updraft motions contribute generally to an increase of potential vorticity below the 3 4 km level because the convective cells in the middle sector are systematically located radially just inside the secondary horizontal wind maximum shwm the local increase in vorticity implied by the convective mass transport is manifest locally as an increase in the strength of the shwm at midlevels 4 km the overturning updrafts of the convective cells tilt stretch and vertically transport vorticity such that the convergence of the vertical flux of vorticity strengthens the vorticity anomaly associated with the shwm this process could strengthen the shwm by several meters per second per hour and may explain how high wave number convective scale features can influence a low wave number feature such as the principal rainband and subsequently influence the primary vortex

the climatology of the north atlantic abstract data from approximately 144 000 hydrographic stations in the north atlantic have been retrieved from the national oceanic data centre and analysed to produce maps of mean pressure temperature salinity and oxygen on selected potential density surfaces for the domain bounded by 0 85 w and 0 65 n the data span the period from 1904 to 1990 with the majority of the data from the last four decades the data set for this region is 60 larger than that used in the production of levitus climatological world atlas this increase in stations coupled with smoothing scales specific to the north atlantic rather than the global ocean considerably improves the resolution of the basin s features the mean property fields and their associated standard deviations are resolved on a one degree grid with little smoothing contrasting with the levitus atlas where properties although presented on a one degree grid have been smoothed on the order of 1000km another important feature of this database is the process by which irregularly spaced data are averaged onto a regular grid in a significant departure from the levitus analysis which averaged on depth surfaces these data were averaged on potential density surfaces thus eliminating an artificial mixing of water mass properties the database is used to describe the baroclinicity of well known features such as the gulf stream the north atlantic current and the deep western boundary current and to elucidate the recirculations associated with these currents it additionally resolves several new features in the intermediate and deep north atlantic these features include the signature of a large scale deep recirculation that extends southwestward from the eastward extension of the north atlantic current to the separation point of the gulf stream near cape hatteras this recirculation which spans approximately 2000m of the water column encompasses more local recirculations and potentially mixes subpolar and subtropical waters furthermore in the upper thermocline this database reveals a coherent azores current that stretches from the gulf stream system south of the tail of the grand banks to madeira this flow is marked by divergences to the south and convergences from the north such that its downstream transport is not much changed

microphysical properties of cold frontal rainbands observations have been obtained within an intense precipitation rates 50 mm h 1 narrow cold frontal rainband ncfr embedded within a broader region of stratiform precipitation in situ data were obtained from an aircraft which flew near a steerable dual polarisation doppler radar the observations were obtained to characterise the microphysical properties of cold frontal clouds with an emphasis on ice and precipitation formation and development primary ice nucleation near cloud top 55 degrees c appeared to be enhanced by convective features however ice multiplication led to the largest ice particle number concentrations being observed at relativelyhigh temperatures 10 degrees c the multiplication process most likely rime splintering occurs when stratiform precipitation interacts with supercooled water generated in the ncfr graupel was notably absent in the data obtained ice multiplication processes are known to have a strong impact in glaciating isolated convective clouds but have rarely been studied within larger organised convective systems such as ncfrs secondary ice particles will impact on precipitation formation and cloud dynamics due to their relatively small size and high number density further modelling studies are required to quantify the effects of rime splintering on precipitation and dynamics in frontal rainbands available parametrizations used to diagnose the particle size distributions do not account for the influence of ice multiplication this deficiency in parametrizations is likely to be important in some cases for modelling the evolution of cloud systems and the precipitation formation ice multiplication has significant impact on artefact removal from in situ particle imaging probes

clouds in tropical cyclones abstract clouds within the inner regions of tropical cyclones are unlike those anywhere else in the atmosphere convective clouds contributing to cyclogenesis have rotational and deep intense updrafts but tend to have relatively weak downdrafts within the eyes of mature tropical cyclones stratus clouds top a boundary layer capped by subsidence an outward sloping eyewall cloud is controlled by adjustment of the vortex toward gradient wind balance which is maintained by a slantwise current transporting boundary layer air upward in a nearly conditionally symmetric neutral state this balance is intermittently upset by buoyancy arising from high moist static energy air entering the base of the eyewall because of the radial influx of low level air from the far environment supergradient wind in the eyewall zone and or small scale intense subvortices the latter contain strong erect updrafts graupel particles and large raindrops produced in the eyewall fall out relatively quickly while ice splinters left

detection of oyster habitat in tidal flats using multi frequency polarimetric sar data abstract exposed oyster reefs in tidal flats have complex and rough surfaces because of their unique surface texture which are quite distinct from the surrounding mud or sand flats here we investigate the microwave signatures backscattered from naturally distributed oyster reefs in tidal flats utilizing the polarimetric analysis techniques to fully polarimetric radarsat 2 c band and alos palsar l band data the study areas include the tidal flats around jebu island and hampyung bay on the west coast of the korean peninsula we analyzed the microwave scattering mechanisms associated with oyster reefs and surrounding areas using the polarimetric target decomposition theorem and quantitatively measu hhvv red target depolarization effects the cross polarized ratio hv vv the co polarized correlation coefficient hhvv and the co polarized phase difference between hh and vv on the basis of a large increase in the cross polarized backscattering hv in the c band sar data one can observe strong volume or multiple scattering and depolarization effects over oyster reefs areas whereas only surface scattering was dominant in most parts of the background tidal areas in oyster reefs the proportion of volume scattering and the cross polarized ratio were greater than 0 7 and 8 db respectively these scattering characteristics were also verified from in situ measurements in the field using a ground based polarimetric scatterometer system however almost no difference was observed between the scattering signatures of oyster reefs and background mudflat areas from l band data which have a considerably longer wavelength than c band the study clearly suggests that multi frequency c and l band polarimetric sar systems can be used to detect the naturally distributed oyster reefs in tidal flats

the role of the geothermal heat flux in driving the abyssal ocean circulation 1 the results presented in this paper demonstrate that the geothermal heat flux ghf from the solid earth into the ocean plays a non negligible role in determining both abyssal stratification and circulation strength based upon an ocean data set we show that the map of upward heat flux at the ocean floor is consistent within a factor of 2 with the ocean floor age dependent map of ghf the observed buoyancy flux above the ocean floor is consistent with previous suggestions that the ghf acts to erode the abyssal stratification and thereby enhances the strength of the abyssal circulation idealized numerical simulations are performed using a zonally averaged single basin model which enables us to address the ghf impact as a function of the depth dependence of diapycnal diffusivity we show that ignoring this vertical variation leads to an under prediction of the influence of the ghf on the abyssal circulation independent of the diffusivity profile introduction of the ghf in the model leads to steepening of the southern ocean isopycnals and to strengthening of the eddy induced circulation and the antarctic bottom water cell the enhanced circulation ventilates the ghf derived heating to shallow depths primarily in the southern ocean

propagation pathways of classical labrador sea water from its source region to 26 n 1 more than two decades of hydrography on the abaco line east of the bahamas at 26 n reveals decadal variability in the salinity of classical labrador sea water clsw despite the long distance from its source region in the north atlantic ocean hydrographic time series from the labrador sea and from the abaco line show a pronounced step like decrease in salinity between 1985 and 1995 in the labrador sea and between 1995 and 2010 at the abaco line suggesting a time lag between the two locations of approximately 9 years the amplitude of the anomaly at the abaco line is 50 of the amplitude in the labrador sea a similar time lag and reduction of amplitude is found in the high resolution ofes model in which salinity anomalies can be observed propagating through the deep western boundary current as well as through a broad interior pathway on its way south to the abaco line the clsw becomes 8 standard deviations saltier due to isopycnal mixing with mediterranean outflow water mow climatological data in the north atlantic suggests that the mixing ratio of mow to clsw at the abaco line is 1 4 and that no variability in mow is required to explain the observed variability at the abaco line the data studied here suggest that decadal clsw anomalies stay relatively coherent while getting advected despite the important role of interior pathways

insights into the evolving microphysical and kinematic structure of northeastern u s winter storms from dual polarization doppler radar abstractthe recent weather surveillance radar 1988 doppler wsr 88d network upgrade to dual polarization capabilities allows for bulk characterization of microphysical processes in northeastern u s winter storms for the first time in this study the quasi vertical profile qvp technique wherein data from a given elevation angle scan are azimuthally averaged and the range coordinate is converted to height is extended and applied to polarimetric wsr 88d observations of six northeast winter storms to survey their evolving bulk vertical microphysical and kinematic structures these analyses are supplemented using hourly analyses from the rapid refresh rap model regions of ascent inferred from qvps were consistently associated with notable polarimetric signatures implying planar crystal growth when near 15 c and riming and secondary ice production at higher temperatures the heaviest snowfall occurred most often when ascent and enhanced propagation differential phase shift occurred near 15 c

the role of cloud top generating cells and boundary layer circulations in the finescale radar structure of a winter cyclone over the great lakes abstractdata from airborne w band radar are used in conjunction with thermodynamic fields from the weather research and forecasting model and air parcel back trajectories from the hysplit model to investigate the finescale reflectivity vertical motion and airmass structure of the comma head of a winter cyclone in the vicinity of the great lakes cloud top generating cells formed along an upper level frontal boundary vertically separating dry air which 48 h earlier was located in the upper troposphere over south central canada from moist air which was located in the lower troposphere over the southeast united states the stronger updrafts within the generating cells had vertical velocities ranging from 1 to 3 m s 1 the generating cells were important to precipitation production within the comma head precipitation trails formed within the generating cells could sometimes be followed to the boundary layer before merging boundary layer air beneath the cyclone s comma head exhibited convective circulati

polarimetric radar and aircraft observations of saggy bright bands during mc3e polarimetric radar observations increasingly are used to understand cloud microphysical processes which is critical for improving their representation in cloud and climate models in particular there has been recent focus on improving representations of ice collection processes e g aggregation and riming as these influence precipitation rate heating profiles and ultimately cloud life cycles however distinguishing these processes using conventional polarimetric radar observations is difficult as they produce similar fingerprints this necessitates improved analysis techniques and integration of complementary data sources the midlatitude continental convective clouds experiment mc3e provided such an opportunity quasi vertical profiles of polarimetric radar variables in two mc3e stratiform precipitation events reveal episodic melting layer sagging integrated analyses using scanning and vertically pointing radar and aircraft measurements reveal that saggy bright band signatures are produced when denser faster falling more isometric hydrometeors relative to adjacent times descend into the melting layer in one case strong circumstantial evidence for riming is found during bright band sagging times a bin microphysical melting layer model successfully reproduces many aspects of the signature supporting the observational analysis if found to be a reliable indicator of riming saggy bright bands could be a proxy for the presence of supercooled liquid water in stratiform precipitation which may provide important information for mitigating aircraft icing risks and for constraining microphysical models

deep ocean warming assessed from altimeters gravity recovery and climate experiment in situ measurements and a non boussinesq ocean general circulation model 1 observational surveys have shown significant oceanic bottom water warming but they are too spatially and temporally sporadic to quantify the deep ocean contribution to the present day sea level rise slr in this study altimetry sea surface height ssh gravity recovery and climate experiment grace ocean mass and in situ upper ocean 0 700 m steric height have been assessed for their seasonal variability and trend maps it is shown that neither the global mean nor the regional trends of altimetry slr can be explained by the upper ocean steric height plus the grace ocean mass a non boussinesq ocean general circulation model ogcm allowing the sea level to rise as a direct response to the heat added into the ocean is then used to diagnose the deep ocean steric height constrained by sea surface temperature data and the top of atmosphere toa radiation measurements the model reproduces the observed upper ocean heat content well combining the modeled deep ocean steric height with observational upper ocean data gives the full depth steric height adding a grace estimated mass trend the data model combination explains not only the altimetry global mean slr but also its regional trends fairly well the deep ocean warming is mostly prevalent in the atlantic and indian oceans and along the antarctic circumpolar current suggesting a strong relation to the oceanic circulation and dynamics its comparison with available bottom water measurements shows reasonably good agreement indicating that deep ocean warming below 700 m might have contributed 1 1 mm yr to the global mean slr or one third of the altimeter observed rate of 3 11 0 6 mm yr over 1993 2008

improving simulations of convective systems from trmm lba easterly and westerly regimes abstract the 3d goddard cumulus ensemble model is used to simulate two convective events observed during the tropical rainfall measuring mission large scale biosphere atmosphere trmm lba experiment in brazil these two events epitomized the type of convective systems that formed in two distinctly different environments observed during trmm lba the 26 january 1999 squall line formed within a sheared low level easterly wind flow on 23 february 1999 convection developed in weak low level westerly flow resulting in weakly organized less intense convection initial simulations captured the basic organization and intensity of each event however improvements to the model resolution and microphysics produced better simulations as compared to observations more realistic diurnal convective growth was achieved by lowering the horizontal grid spacing from 1000 to 250 m this produced a gradual transition from shallow to deep convection that occurred over a span of hours as opposed to an abrupt appearance of

anvil clouds of tropical mesoscale convective systems in monsoon regions the anvil clouds of tropical mesoscale convective systems mcss in west africa the maritime continent and the bay of bengal have been examined with trmm and cloudsat satellite data and arm ground based radar observations the anvils spreading out from the precipitating cores of mcss are subdivided into thick medium and thin portions the thick portions of anvils show distinct differences from one climatological regime to another in their upper portions the thick anvils of west africa mcss have a broad flat histogram of reflectivity and a maximum of reflectivity in their lower portions the reflectivity histogram of the bay of bengal thick anvils has a sharply peaked distribution of reflectivity at all altitudes with modal values that increase monotonically downward the reflectivity histogram of the maritime continent thick anvils is intermediate between that of the west africa and bay of bengal anvils consistent with the fact this region comprises a mix of land and ocean influences it is suggested that the difference between the statistics of the continental and oceanic anvils is related to some combination of two factors 1 the west african anvils tend to be closely tied to the convective regions of mcss while the oceanic anvils are more likely to be extending outward from large stratiform precipitation areas of mcss and 2 the west african mcss result from greater buoyancy so that the convective cells are more likely to produce graupel particles and detrain them into anvils copyright 2009 royal meteorological society

isopycnal mixing in ocean circulation models abstract a subgrid scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non eddy resolving ocean circulation models the mixing is applied in isopycnal coordinates to isopycnal layer thickness or inverse density gradient as well as to passive scalars temperature and salinity the transformation of these mixing forms to physical coordinates is also presented

a numerical model of the circulation in knight inlet british columbia canada abstract during spring 1988 a period of low freshwater runoff and summer 1989 a period of high freshwater runoff month long observations of velocity temperature and salinity were made throughout the water column in knight inlet both up inlet and down inlet of the sill measurements were made at depths of 2 4 6 9 and 12 m using s4 current meters at depths down to about 200 m using profiling current meters and at depths deeper than 200 m using aanderaa current meters anemometers were deployed at two locations along the inlet a laterally integrated two dimensional numerical model of the inlet that uses the mellor and yamada level 2 5 turbulence closure scheme and that accounts for the combined influence of the winds tides and freshwater runoff has been used to produce 30 day simulations of the velocity and density field in the inlet the vertical coordinate is transformed in the model so that very fine vertical resolution can be attained near the surface even though the tidal range is larg

asynchronous warming and δ18o evolution of deep atlantic water masses during the last deglaciation the large scale reorganization of deep ocean circulation in the atlantic involving changes in north atlantic deep water nadw and antarctic bottom water aabw played a critical role in regulating hemispheric and global climate during the last deglaciation however changes in the relative contributions of nadw and aabw and their properties are poorly constrained by marine records including 18o of benthic foraminiferal calcite 18oc here we use an isotope enabled ocean general circulation model with realistic geometry and forcing conditions to simulate the deglacial water mass and 18o evolution model results suggest that in response to north atlantic freshwater forcing during the early phase of the last deglaciation nadw nearly collapses while aabw mildly weakens rather than reflecting changes in nadw or aabw properties caused by freshwater input as suggested previously the observed phasing difference of deep 18oc likely reflects early warming of the deep northern north atlantic by 1 4 c while deep southern ocean temperature remains largely unchanged we propose a thermodynamic mechanism to explain the early warming in the north atlantic featuring a strong middepth warming and enhanced downward heat flux via vertical mixing our results emphasize that the way that ocean circulation affects heat a dynamic tracer is considerably different from how it affects passive tracers like 18o and call for caution when inferring water mass changes from 18oc records while assuming uniform changes in deep temperatures

mesoscale convective systems 1 mesoscale convective systems mcss have regions of both convective and stratiform precipitation and they develop mesoscale circulations as they mature the upward motion takes the form of a deep layer ascent drawn into the mcs in response to the latent heating and cooling in the convective region the ascending layer overturns as it rises but overall retains a coherent layer structure a middle level layer of inflow enters the stratiform region of the mcs from a direction determined by the large scale flow and descends in response to diabatic cooling at middle to low levels a middle level mesoscale convective vortex mcv develops in the stratiform region prolongs the mcs and may contribute to tropical cyclone development the propagation of an mcs may have a discrete component but may further be influenced by waves and disturbances generated both in response to the mcs and external to the mcs waves of a larger scale may affect the propagation velocity by phase locking with the mcs in a cooperative mode the horizontal scale of an mcs may be limited either by a balance between the formation rate of convective precipitation and dissipation of stratiform precipitation or by the rossby radius of the mcv the vertical redistribution of momentum by an mcs depends on the size of the stratiform region while the net vertical profile of heating of the large scale environment depends on the amount of stratiform rain regional variability of the stratiform rain from mcss affects the large scale circulation s response to mcs heating

surface microphysical observations within east coast winter storms on long island new york abstractsurface observations of ice habit and degree of riming were measured for 12 cyclone events over 3 winter seasons at stony brook new york on the northeast coast of the united states a total of 205 6 cm of snow accumulated during these storms with an average degree of riming of 1 25 out of 5 and snow to liquid ratio ranging from 3 1 to 17 1 there were consistent spatial patterns of habit and riming intensity relative to the cyclone structure cold type habits side planes and bullets commonly occurred within the outer comma head to the north and northeast of the cyclone center in the middle of the comma head moderately rimed dendrites plates and needles were observed close to the cyclone center heavy riming was observed with needles and graupel the western quadrant of the comma head had primarily plates and dendrites with little to no riming periods of light riming and high snow liquid ratios 13 1 are dominated by cold type habits dendrites and plates and have similar vertical m

observed microphysical evolution for two east coast winter storms and the associated snow bands abstractthis paper presents the observed microphysical evolution of two coastal extratropical cyclones 19 20 december 2009 and 12 january 2011 and the associated passage of heavy snowbands in the cyclone comma head the observations were made approximately 93 km east of new york city at stony brook new york surface microphysical measurements of snow habit and degree of riming were taken every 15 30 min using a stereo microscope and camera and snow depth and snow density were also recorded a vertically pointing ku band radar observed the vertical evolution of reflectivity and doppler vertical velocities there were rapid variations in the snow habits and densities related to the changes in vertical motion and depth of saturation at any one time a mixture of different ice habits was observed certain ice habits were dominant at the surface when the maximum vertical motion aloft occurred at their favored temperature for depositional growth convective seeder cells above 4 km msl resulted in relativel

vertical heat transport in eddying ocean models 1 the effect of mesoscale eddies on the vertical heat transport of the ocean is examined using two eddy resolving numerical models the global heat transport by the mean flow and diffusion are both downwards and are balanced by an upward eddy heat flux mean and eddy advective heat fluxes dominate the subpolar regions while diffusive flux is important primarily in the subtropics in the subtropical abyss the mean advective heat flux is balanced by a combination of eddy and diffusive fluxes and the classical munk type advective diffusive heat balance must be modified the munk and wunsch 1998 expression for the vertical turbulent diffusivity over estimates the diffusivity by as much as a factor of four near the base of the main thermocline this implies that the mixing required to close the meridional overturning circulation determined by munk and wunsch 1998 may be an over estimate due to the neglect of mesoscale eddies

on the driving processes of the atlantic meridional overturning circulation because of its relevance for the global climate the atlantic meridional overturning circulation amoc has been a major research focus for many years yet the question of which physical mechanisms ultimately drive the amoc in the sense of providing its energy supply remains a matter of controversy here we review both observational data and model results concerning the two main candidates vertical mixing processes in the ocean s interior and wind induced ekman upwelling in the southern ocean in distinction to the energy source we also discuss the role of surface heat and freshwater fluxes which influence the volume transport of the meridional overturning circulation and shape its spatial circulation pattern without actually supplying energy to the overturning itself in steady state we conclude that both wind driven upwelling and vertical mixing are likely contributing to driving the observed circulation to quantify their respective contributions future research needs to address some open questions which we outline

multi frequency sar data help improving the monitoring of intertidal flats on the german north sea coast abstract we demonstrate that synthetic apertur radar sar data have great potential to improve an existing monitoring system based on optical data for intertidal flats and to complement the classification of sediments macrophytes and mussels in the german wadden sea multi satellite sar data acquired at different radar bands l c and x band from alos palsar from ers sar radarsat 2 and envisat asar and from terrasar x respectively were used to investigate whether they can be jointly used for crude sediment classification on dry fallen intertidal flats and for detecting benthic fauna such as blue mussel or oyster beds in this respect we show that both multi satellite and multi temporal analyses provide valuable input for the routine monitoring of exposed intertidal flats on the german north sea coast the latter already improving the identification of the spatial extent of mussel oyster beds in addition we demonstrate that high resolution sar is capable of detecting residuals of historical land use in areas that were lost to the sea during major storm surges in the 14th and 17th centuries

on the imaging of exposed intertidal flats by single and dual co polarization synthetic aperture radar abstract we used 26 radarsat 2 and terrasar x single and dual co polarization synthetic aperture radar sar images of a test site on the german north sea coast to investigate the influence of imaging geometry and environmental conditions wind speed water level and vegetation period on the radar return from exposed intertidal flats multi temporal analyses of single vv polarization sar imagery indicate that the surface roughness is more variable at shorter scales responsible for the x band backscatter than at longer scales c band less variation at both radar bands was found in sea grass meadows terrasar x dual co polarization data were used for polarimetric analyses based on a decomposition of the kennaugh matrix whose elements provide information on the total intensity at both co polarizations and on the relative strength of even and odd bounce backscattering at steep incidence angles around 30 the radar backscatter from bare sand flats is similarly strong at both co polarizations while the vertically polarized radar return dominates at higher incidence angles above 40 at low water levels resulting in lower moisture of the sandy sediments strong single bounce radar backscattering was observed while higher water levels and moisture caused weak mixed single and double bounce backscattering apart from the absolute water level its history e g the time and level of the closest low tide must be considered during the vegetation period sea grass meadows cause a stronger increase in horizontally hh polarized radar backscatter along with an increased double bounce backscattering we conclude that the kennaugh element framework has potential to be used for classification purposes in intertidal areas but also that for a full interpretation of the sar imagery the exact topography and the surface roughness have to be known

the evolution of lake effect convection during landfall and orographic uplift as observed by profiling radars abstracta pronounced snowfall maximum occurs about 30 km downwind of lake ontario over the 600 m high tug hill plateau hereafter tug hill a region where lake effect convection is affected by mesoscale forcing associated with landfall and orographic uplift profiling radar data from the ontario winter lake effect systems field campaign are used to characterize the inland evolution of lake effect convection that produces the tug hill snowfall maximum four k band profiling micro rain radars mrrs were aligned in a transect from the ontario coast onto tug hill additional observations were provided by an x band profiling radar xpr analysis is presented of a major lake effect storm that produced 6 4 cm liquid precipitation equivalent lpe snowfall over tug hill this event exhibited strong inland enhancement with lpe increasing by a factor of 1 9 over 15 km horizontal distance mrr profiles reveal that this enhancement was not due to increases in the depth or intensity of lake effect convection with

estimation of surface roughness parameter in intertidal mudflat using airborne polarimetric sar data the coastal zones of the korean peninsula are well known for their large tide ranges and vast expanse of intertidal flats in this paper methods of extracting the roughness of the scattering surface of intertidal mudflats from polarimetric synthetic aperture radar sar data have been investigated the l band nasa jet propulsion laboratories airborne sar data which were acquired in the intertidal zone during pacrim ii korea campaign were used to estimate the roughness of intertidal mudflats surface roughness can be utilized as a useful parameter to monitor the fishery activities in intertidal flats as well as the changes in textural characteristics of surface sediments in order to retrieve roughness parameters such as the rms height and the correlation length of intertidal mudflats three types of roughness inversion algorithms based on the integral equation method iem semiempirical and extended bragg models have been investigated and developed the inversion algorithms based on the iem and semiempirical models can be applied to the dual polarized sar while the extended bragg model based inversion approach is also applicable to the fully polarimetric sar observations results indicate the fully polarimetric approach is more pertinent to monitor geophysical parameters from space than the dual polarimetric approach even if it is possible to reduce the number of unknown surface variables in the specific case of inversion problems

a comprehensive habit diagram for atmospheric ice crystals confirmation from the laboratory airs ii and other field studies abstract recent laboratory experiments and in situ observations have produced results in broad agreement with respect to ice crystal habits in the atmosphere these studies reveal that the ice crystal habit at 20 c is platelike extending to 40 c and not columnar as indicated in many habit diagrams found in atmospheric science journals and texts these diagrams were typically derived decades ago from laboratory studies some with inherent habit bias or from combinations of laboratory and in situ observations at the ground observations that often did not account for habit modification by precipitation from overlying clouds of varying temperatures habit predictions from these diagrams often disagreed with in situ observations at temperatures below 20 c more recent laboratory and in situ studies have achieved a consensus on atmospheric ice crystal habits that differs from the traditional habit diagrams these newer results can now be combined to give a comprehensive description of ice crystal habits

study of the polarimetric characteristics of mud flats in an intertidal zone using c and x band spaceborne sar data abstract the polarimetric characteristics of a mud flat area in the intertidal zone near jiangsu china are analyzed under different environmental conditions using x band and c band spaceborne synthetic aperture radar sar data from the terrasar x tsx and radarsat 2 r2 satellites the dominant scattering mechanisms of different objects including mud flats and aquaculture facilities in the intertidal zone are studied based on the polarimetric target decomposition of fully polarimetric r2 data the polarimetric characteristics of different objects in the intertidal zone are quantitatively compared using the depolarization parameters derived from the r2 data which indicate that tides have different effects on the dominant scattering mechanisms of the mud flats and aquaculture farms furthermore comparisons of the c band and x band polarimetric characteristics of the mud flats and aquaculture farms in the intertidal zone are analyzed by combining the tsx and r2 data the results show that surface scattering is the dominant mechanism of the mud flats whereas different dominant mechanisms occur in the aquaculture areas present during different tides interestingly strikingly similar polarimetric characteristics of mud flats and aquaculture in x band and c band sar are observed and these novel results were achieved through a depolarization analysis based on the tsx and r2 data in synergy

evolution of microphysical structure of a subtropical squall line observed by a polarimetric radar and a disdrometer during opacc in eastern china the evolution of the microphysical structures of a subtropical squall line observed during the observation prediction and analysis of severe convection of china opacc field campaign in eastern china is documented in this paper the data collected from a c band polarimetric doppler radar reflectivity z differential reflectivity zdr and specific differential phase kdp and a disdrometer are used to investigate the variations of microphysical characteristics within the convective region during the formative intensifying and mature stages of the squall line the microphysical characteristics of the squall line are noticeably different among these three stages when the squall line develops from the formative stage to the mature stage its radar derived drop size distribution dsd in the convective region evolves from continental like convection to more maritime like convection contrary to previous studies the dsd characteristics of a convective line may not be simply locked to a geographical location but varied extensively throughout its life cycle the polarimetric radar derived liquid water content below the freezing level in the convective region is three times higher than the ice water content above the freezing level this in conjunction with a low cloud base 0 68 km and a high freezing level 5 km indicates a deep warm cloud layer and the dominance of the warm rain process within this squall line

the three dimensional morphology of simulated and observed convective storms over southern england abstracta set of high resolution radar observations of convective storms has been collected to evaluate such storms in the met office unified model during the dynamical and microphysical evolution of convective storms dymecs project the 3 ghz chilbolton advanced meteorological radar was set up with a scan scheduling algorithm to automatically track convective storms identified in real time from the operational rainfall radar network more than 1000 storm observations gathered over 15 days in 2011 and 2012 are used to evaluate the model under various synoptic conditions supporting convection in terms of the detailed three dimensional morphology storms in the 1500 m grid length simulations are shown to produce horizontal structures a factor of 1 5 2 wider compared to radar observations a set of nested model runs at grid lengths down to 100 m show that the models converge in terms of storm width but the storm structures in the simulations with the smallest grid lengths are too narrow and too intense c

airborne doppler observations of the inner core structural differences between intensifying and steady state tropical cyclones abstractdifferences in the inner core structure of intensifying in intensity increase of at least 20 kt 24 h 1 where 1 kt 0 51 m s 1 and steady state ss intensity remaining between 10 kt 24 h 1 tropical cyclones tcs are examined using composites of airborne doppler observations collected from noaa p 3 aircraft missions the in dataset contains 40 eyewall passes from 14 separate missions while the ss dataset contains 53 eyewall passes from 14 separate missions intensifying tcs have a ringlike vorticity structure inside the radius of maximum wind rmw lower vorticity in the outer core a deeper stronger inflow layer and stronger axisymmetric eyewall upward motion compared with steady state tcs there is little difference in the vortex tilt between 2 and 7 km and both in and ss tcs show an eyewall precipitation and updraft asymmetry whose maxima are located in the downshear and downshear left region the azimuthal coverage of eyewall and outer core precipitation is greater for in tcs