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Buoy: IABP Daily Buoy Positions [Moritz, R.]

During SHEBA, the Polar Science Center at the University of Washington deployed a network of automatic buoys for monitoring synoptic-scale fields of pressure, temperature, and ice motion throughout the Arctic Basin. This dataset contains the daily buoy positions. For more information, please see the readme file. https://data.eol.ucar.edu/dataset/13.452

GCIP/EAOP-98 Surface: Daily Precipitation Composite

The Daily Precipitation Composite was formed from several data sources (i.e., National Centers for Environmental Prediction daily precipitation, National Weather Service Cooperative Observers daily precipitation data, W.K. Kellogg Biological Station daily precipitation, USDA Agricultural Research Service NAEW daily precipitation data (Coshocton), Tennessee Valley Authority daily precipitation data, and the daily precipitation data extracted from the GCIP LSA-E EAOP-98 Hourly Precipitation Composite). Data from these sources were quality controlled and merged to form this precipitation composite. https://doi.org/doi:10.5065/D6R49P2Q

Improvement of the temperature and moisture retrievals in the lower troposphere using AIRS and GPS radio occultation measurements

Accurate temperature and water vapor profiles in the middle and lower troposphere (LT) are crucial for understanding the water cycle, cloud systems, and energy balance. Global positioning system (GPS) radio occultation (RO) is the first technique that can provide a high-vertical-resolution all-weather refractivity profile, which is a function of pressure, temperature, and moisture. However, in the moist LT over the Tropics, the refractivity retrievals from GPS RO data are often significantly negatively biased because of tracking errors and propagation effects related to sharp vertical moisture gradients that may result in superrefraction (SR). The Atmospheric Infrared Sounder (AIRS) is a nadir-viewing sounder that can measure vertical temperature and moisture profiles with about 1 - 2-km vertical resolution. However, AIRS observations cannot usually obtain accurate temperature and water vapor profiles in the planetary boundary layer (PBL) because of the poor resolving power in the LT. This study uses simulations based on radiosonde profiles by combining the AIRS and the GPS RO measurements to obtain the best temperature and moisture retrievals in the LT. Different approaches are used for the drier LT and the moist LT. For the drier LT, where GPS RO data are not affected by SR errors, a multivariable regression algorithm for inverting the combined AIRS and GPS RO measurements is used. In the moist LT (e.g., SR on top of PBL), the combined AIRS and GPS RO regression inversion above the LT is used as the first guess for AIRS-only physical retrieval, which is extended into the LT. The results show that combining AIRS and GPS RO data effectively constrains the individual solutions, and therefore significantly improves inversion results. The algorithm is also applied for all available radiosonde profiles (19 profiles) over a 1-month period from the site characterized by strong SR on top of the PBL. Retrieved temperature and water vapor profiles yield unbiased... http://n2t.net/ark:/85065/d7zk5gt4

An analysis of the effect of global warming on the intensity of Atlantic hurricanes using a GCM with statistical refinement

A statistical intensity adjustment is utilized to extract information from tropical cyclone simulations in a 50 km resolution global model A simple adjustment based on the modeled and observed probability distribution of storm lifetime maximum wind speed allows the model to capture the differences between ob served intensity distributions in active/inactive year composites from the 1981-2008 period in the North Atlantic This intensity adjustment is then used to examine the atmospheric model s responses to different sea surface temperature anomalies generated by coupled models for the late twenty first century In the North Atlantic all simulations produce a reduction in the total number of cyclones but with large intermodel spread in the magnitude of the reduction The intensity response is positively correlated with changes in frequency across the ensemble However there is on average an increase in intensity in these simulations despite the mean reduction in frequency The authors argue that it is useful to decompose these intensity changes into two parts an increase in intensity that is intrinsic to the climate change experiments and a change in intensity positively correlated with frequency just as in the active/inactive historical composites By isolating the intrinsic component which is relatively independent of the details of the SST warming pattern an increase is found in storm lifetime maximum winds of 5-10 m s⁻¹ for storms with intensities of 30-60 m s⁻¹ by the end of the twenty first century The effects of change in frequency which are dependent on the details of the spatial structure of the warming must then be superimposed on this intrinsic change http://n2t.net/ark:/85065/d73r0tfd

Spatio-temporal models for large-scale indicators of extreme weather

Extreme weather events such as thunderstorms and tornadoes are of great concern as these events pose a significant threat to life, property, and economic stability. Because of the difficulty of gathering data on extreme events, this paper proposes modeling the conditions for extreme weather through large-scale indicators. The advantage of using large-scale indicators is that climate models can be used to generate data whereas climate models cannot generate data on extreme events themselves. This paper focuses on comparing spatio-temporal models for reanalysis data of large-scale indicators for extreme weather observed across the continental United States and Mexico. Results indicate that rigorous treatment of spatial and temporal dynamics is necessary. The models find that the intensity of conditions for extreme weather is particularly high for the central United States and the intensity of these conditions is increasing over time but the amount of increase may not be practically significant. http://n2t.net/ark:/85065/d7qr4zdq

Climate impacts of parameterized Nordic Sea overflows

A new overflow parameterization (OFP) of density-driven flows through ocean ridges via narrow, unresolved channels has been developed and implemented in the ocean component of the Community Climate System Model version 4. It represents exchanges from the Nordic Seas and the Antarctic shelves, associated entrainment, and subsequent injection of overflow product waters into the abyssal basins. We investigate the effects of the parameterized Denmark Strait (DS) and Faroe Bank Channel (FBC) overflows on the ocean circulation, showing their impacts on the Atlantic Meridional Overturning Circulation and the North Atlantic climate. The OFP is based on the Marginal Sea Boundary Condition scheme of Price and Yang (1998), but there are significant differences that are described in detail. Two uncoupled (ocean-only) and two fully coupled simulations are analyzed. Each pair consists of one case with the OFP and a control case without this parameterization. In both uncoupled and coupled experiments, the parameterized DS and FBC source volume transports are within the range of observed estimates. The entrainment volume transports remain lower than observational estimates, leading to lower than observed product volume transports. Due to low entrainment, the product and source water properties are too similar. The DS and FBC overflow temperature and salinity properties are in better agreement with observations in the uncoupled case than in the coupled simulation, likely reflecting surface flux differences. The most significant impact of the OFP is the improved North Atlantic Deep Water penetration depth, leading to a much better comparison with the observational data and significantly reducing the chronic, shallow penetration depth bias in level coordinate models. This improvement is due to the deeper penetration of the southward flowing Deep Western Boundary Current. In comparison with control experiments without the OFP, the abyssal ventilation rates increase in the North... http://n2t.net/ark:/85065/d78k79pt

Radar observation of precipitation asymmetries in tropical cyclones making landfall on East China Coast

This study explores, for the first time, the asymmetric distribution of precipitation in tropical cyclones (TCs) making landfall along east China coast using reflectivity data collected from coastal Doppler radars at mainland China and Taiwan. Six TCs (Saomai, Khanun, Wipha, Matsa, Rananim and Krosa) from 2004 to 2007 are examined. The temporal and spatial evolution of these TCs’ inner and outer core asymmetric precipitation patterns before and after landfall is investigated. The radius of inner-core region is a function of the size of a TC apart from a fixed radius (100 km) adopted in previous studies. All six TCs possessed distinct asymmetric precipitation patterns between the inner- and outer- core regions. The amplitude of asymmetry decreases with the increasing TC intensity and it displays an ascending (descending) trend in the inner (outer) core. In the inner-core region, the heavy rainfall with reflectivity factor above 40 dBZ tends to locate at the downshear side before landfall. Four cases have precipitation maxima on the downshear left side, in agreement with previous studies. As TCs approaching land (~ 2 hr before landfall), their precipitation maxima generally shift to the front quadrant of the motion partly due to the interaction of TC with the land surface. In the outer-core region, the precipitation maxima occur in the front quadrant of the motion in five of the six cases before landfall. After landfall, the precipitation maxima shift from the right-front quadrant clockwisely to the right-rear quadrant of the motion collocated well with the mountainous areas along the coast, which indicates the impact of topography forcing on the precipitation distribution. This study illustrated how the precipitation asymmetry in the inner- and outer-core at different stages of TC landfall is affected by storm motion, vertical wind shear and topography. http://n2t.net/ark:/85065/d7rr207f

Acoustic Ice Nucleus Counter Data

This dataset contains acoustic ice nuclei data for the Seeded and Natural Orographic Wintertime clouds – the Idaho Experiment (SNOWIE). The Acoustic Ice Nucleus Counter (AINC) was developed at the National Center for Atmospheric Research (NCAR). The location for the AINC deployment, along Idaho State Highway 21 approximately 80 km (line-of-sight) from Boise, was determined by Idaho Power Company (IPC). Equipment was deployed on 26 January, and data collection began late in the day. These data are in Excel spreadsheets with the extension .xlsx, and there are 2 sets of data included in this dataset. There are 1 minute and 15 minute data. The frequency of the data in any file is indicated in the file name. Please see the readme file for more information. https://doi.org/doi:10.5065/D6MK6BN9

Simulations of the West African monsoon with a superparameterized climate model. Part II: African easterly waves

The relationship between African easterly waves and convection is examined in two coupled general circulation models: the Community Climate System Model (CCSM) and the “superparameterized” CCSM (SP-CCSM). In the CCSM, the easterly waves are much weaker than observed. In the SP-CCSM, a two-dimensional cloud-resolving model replaces the conventional cloud parameterizations of CCSM. Results show that this allows for the simulation of easterly waves with realistic horizontal and vertical structures, although the model exaggerates the intensity of easterly wave activity over West Africa. The simulated waves of SP-CCSM are generated in East Africa and propagate westward at similar (although slightly slower) phase speeds to observations. The vertical structure of the waves resembles the first baroclinic mode. The coupling of the waves with convection is realistic. Evidence is provided herein that the diabatic heating associated with deep convection provides energy to the waves simulated in SP-CCSM. In contrast, horizontal and vertical structures of the weak waves in CCSM are unrealistic, and the simulated convection is decoupled from the circulation. http://n2t.net/ark:/85065/d75h7h89

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