A5016343857- Meteorological Phenomena and Simulations
- Cryospheric studies and observations
- Precipitation Measurement and Analysis
- Atmospheric aerosols and clouds
- Climate variability and models
- Atmospheric chemistry and aerosols
- Arctic and Antarctic ice dynamics
- Landslides and related hazards
- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Tropical and Extratropical Cyclones Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Soil Moisture and Remote Sensing
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Flood Risk Assessment and Management
- Spacecraft and Cryogenic Technologies
- Climate change and permafrost
- Remote Sensing and LiDAR Applications
- Solar and Space Plasma Dynamics
- Urban Heat Island Mitigation
- Advanced Aircraft Design and Technologies
- Particle Accelerators and Free-Electron Lasers
- Time Series Analysis and Forecasting
GKN (United States)
2023-2024
University of Wisconsin–Madison
2014-2024
Cooperative Institute for Climate and Satellites
2016-2020
University of Aveiro
2018-2019
University of Utah
2019
Norwegian Meteorological Institute
2019
Colorado State University
1996-2011
Cooperative Institute for Research in Environmental Sciences
1999
University of Leicester
1983-1985
Many different techniques are used for the calculation of Rayleigh optical depth in atmosphere. In some cases differences among these can be important, especially UV region spectrum and under clean atmospheric conditions. The authors recommend that approached by going back to first principles scattering theory rather than variety curve-fitting currently use. A survey literature was conducted order determine latest values physical constants necessary review methods available depth....
A method for retrieving precipitation over the ocean using spaceborne W‐band (94 GHz) radar is introduced and applied to CloudSat Cloud Profiling Radar. The most applicable stratiform‐type precipitation. Measurements of backscatter from surface are combined with information about wind speed sea temperature derive path‐integrated attenuation through precipitating cloud systems. scattering extinction characteristics raindrops modeled a combination Mie theory (for raindrops) discrete dipole...
On average, the models in Fifth Climate Model Intercomparison Project archive predict an increase Antarctic precipitation from 5.5 to 24.5 % between 1986–2005 and 2080–2099, depending on greenhouse gas emissions scenarios. This translates into a moderation of future sea level rise ranging −19 −71 mm 2006 2099. However, comparison with CloudSat ERA-Interim data show that almost all overestimate current precipitation, some by more than 100 %. If only agree within 20 error are considered,...
Among the largest uncertainties in quantifying radiative impacts of clouds are those that arise from inherent difficulty precisely specifying vertical distribution cloud optical properties using passive satellite measurements. Motivated by need to address this problem, CloudSat was launched April 2006 carrying into orbit first millimeter wavelength radar be flown space. Retrieved profiles liquid and ice microphysical Cloud Profiling Radar form basis CloudSat's fluxes heating rates algorithm,...
Abstract The impacts of enhanced aerosol concentrations such as those associated with dust intrusions on the trimodal distribution tropical convection have been investigated through use large-domain (10 000 grid points), fine-resolution (1 km), long-duration (100 days), two-dimensional idealized cloud-resolving model simulations conducted under conditions radiative–convective equilibrium (RCE). focus this research is aerosols that serve primarily cloud condensation nuclei (CCN). results...
Abstract. Climate models predict Antarctic precipitation to increase during the 21st century, but their present day differs. A model-independent climatology of characteristics, such as snowfall rates and frequency, is needed assess models, it not yet available. Satellite observations by active sensors has been possible in polar regions since launch CloudSat 2006. Here, we use two products generate first multi-year, precipitation. The product used determine frequency phase precipitation,...
Abstract Retrievals of falling snow from space-based observations represent key inputs for understanding and linking Earth’s atmospheric, hydrological, energy cycles. This work quantifies investigates causes differences among the first stable retrieval products Global Precipitation Measurement (GPM) Core Observatory satellite CloudSat ’s Cloud Profiling Radar (CPR) product. An important part this analysis details challenges associated with comparing various GPM estimates arising different...
Abstract The first observationally based near-global shallow cumuliform snowfall census is undertaken using multiyear CloudSat Cloud Profiling Radar observations. observations and rate estimates from the 2C-Snow Water Content Snowfall Rate (2C-SNOW-PROFILE) product are partitioned between nimbostratus cloud structures by utilizing coincident category classifications 2B-Cloud Scenario Classification (2B-CLDCLASS) product. Shallow (nimbostratus) events comprise about 36% (59%) of in dataset....
Abstract The ability of ground‐based in situ and remote sensing observations to constrain microphysical properties for dry snow is examined using a Bayesian optimal estimation retrieval method. Power functions describing the variation mass horizontally projected area with particle size parameter related shape are retrieved from near‐Rayleigh radar reflectivity, distribution, snowfall rate, size‐resolved fall speeds. Algorithm performance explored context instruments deployed during Canadian...
The primary purpose of this study is to assess the performance 1D solar radiative transfer codes that are used currently both for research and in weather climate models. Emphasis on interpretation handling unresolved clouds. Answers sought following questions: (i) How well do interpret handle columns information pertaining partly cloudy atmospheres? (ii) Regardless adequacy their assumptions about clouds, perform as intended? One clear-sky two plane-parallel, homogeneous (PPH) overcast cloud...
Recent precipitation observations provided by CloudSat are used to evaluate the ability of various meteorological analyses and reanalyses reproduce Antarctic snowfall. The performance ECMWF Interim Re-Analysis (ERA Interim), Climate Forecast System Reanalysis (CFSR), Japanese 55-year (JRA55), Modern Era Retrospective-Analysis for Research Application (MERRA), 2 (MERRA-2), as well operational compared over 2007–2010 period. mean snowfall rate Antarctica north 82 °S simulated between 2007 2010...
Because atmospheric longwave radiation is one of the most fundamental elements an expected climate change, there has been a strong interest in improving measurements and model calculations recent years. Important questions are how reliable consistent what uncertainties? The First International Pyrgeometer Absolute Sky‐scanning Radiometer Comparison, which was held at Atmospheric Radiation Measurement program's Southern Great Plains site Oklahoma, answers these least for midlatitude summer...
Abstract. Accurate snowfall estimates are important for both weather and climate applications. Ground-based radars space-based satellite sensors often used as viable alternatives to rain gauges estimate precipitation in this context. In particular, the Cloud Profiling Radar (CPR) on board CloudSat is proving be a useful tool map globally, part due its high sensitivity light ability provide near-global vertical structure. play particularly role high-latitude regions other ground-based...
CORRESPONDING AUTHOR: M. W. Christensen, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom, E-mail: matt.christensen@jpl.nasa.gov
CloudSat has provided the first spaceborne snowfall observations in polar regions. Nevertheless, retrievals may be affected by ground clutter even if rate at surface is estimated from reflectivity measured about 1200 m above land/ice surface. In this study, impact of contamination on over Antarctic and Greenland ice sheets investigated. Our results suggest that affects some areas, particularly complex terrain such as mountain ranges fjords. Over these rates deduced can be, therefore,...
Remote-sensing observations are needed to estimate the regional and global impacts of snow. However, retrieve accurate estimates snow mass rate, these require augmentation through additional information assumptions about hydrometeor properties. The Precipitation Imaging Package (PIP) provides precipitation characteristics can be utilized improve snowfall rate accumulation. Here, goal is demonstrate quality utility two higher-order PIP-derived products: liquid water equivalent an...
Abstract. Estimates of snow microphysical properties obtained by analyzing collections individual particles are often limited to short timescales and coarse time resolution. Retrievals using disdrometer observations coincident with bulk measurements such as radar reflectivity snowfall amounts may overcome these limitations; however, retrieval techniques require uncertainty estimates not only for the themselves, but also simulated modeled from observations. Disdrometer uncertainties arise due...
Abstract The detailed microphysical processes and properties within the melting layer (ML)—the continued growth of aggregates by collection small particles, breakup these aggregates, effects relative humidity on particle melting—are largely unresolved. This study focuses addressing questions for in-cloud heights from just above to below ML. Observations four field programs employing in situ measurements ML are used characterize microphysics through this region. With increasing temperatures...
Abstract A Bayesian optimal estimation retrieval is used to determine probability density functions of snow microphysical parameters from ground-based observations taken during four snowfall events in southern Ontario, Canada. The retrieved variables include the power laws describing particle mass and horizontally projected area. results reveal nontrivial correlations between area that were not apparent prior studies. provide information mainly about coefficient , somewhat less exponent...
Abstract Two methods for deriving relationships between the equivalent radar reflectivity factor Z e and snowfall rate S at three wavelengths are described. The first method uses collocations of in situ aircraft (microphysical observations) overflying (radar from two field programs to develop – relationships. In second method, measurements top melting layer (ML), radars on Tropical Rainfall Measuring Mission (TRMM), Global Precipitation Measurement (GPM), CloudSat satellites, related...
Abstract While snowfall makes a major contribution to the hydrological cycle in Arctic, state-of-the-art climatologies still significantly disagree. We present satellite-based characterization of Arctic using CloudSat observations, and compare it with various other climatologies. First, we examine frequency phase precipitation as well rates from over 2007–10. Frequency solid is higher than 70% Ocean 95% Greenland, while mixed occurs mainly North Atlantic (50%) liquid land south 70°N (40%)....
Different approaches for parameterizing the effects of vertical variability cloudiness on radiative transfer are assessed using a database constructed from observations derived lidar and millimeter cloud radar data collected three different locations. Five methods dealing with overlap clouds were incorporated into single radiation model that was applied to lidar/radar averaged in time. The calculated fluxes heating rates this compared broadband independent column approximation time-resolved...
Abstract Many Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) intercomparisons of boundary layer clouds have used a convenient but idealized longwave radiation formula for in their large-eddy simulations (LESs). Under what conditions is this justified? Can it be extended to midlevel clouds? This note first derives the GCSS using an alternative method effective emissivity. A key simplifying assumption that cloud isothermal vertical (and horizontal). However, does...
Abstract Microphysical data and radar reflectivities ( Z e , −15 < 10 dB) measured from flights during the NASA Tropical Clouds, Convection, Chemistry Climate field program are used to relate at X W band ice water content (IWC). Because nearly collocated IWC were each directly measured, – relationships could be developed directly. Using particle size distributions masses evaluated based on direct measurements, reflectivity–snowfall rate S ) also derived. For dB, herein yield larger than...