Atmospheric System Research

Recent Content

Recent Highlights

Lawrence Livermore National Laboratory scientists together with scientists from Colorado State University and State University of New York – Albany analyzed multiple ground-based retrievals of cloud properties to quantify how low cloud reflectivity responds to changes in temperature. They also...
Atmospheric secondary organic aerosols (SOA) particles affect air quality, visibility, human health, clouds, and radiation. Unseen by the naked eye, large quantities of carbon-containing vapors enter the atmosphere as they escape from trees, fossil-fuel burning, and forest fires. The atmosphere...
In the tropics, the upper troposphere is cloudier, on average, than either the middle or lower troposphere. The conventional paradigm for these clouds attributes their existence to the rapidly-declining convective mass flux below the tropopause, which implies a large source of detraining cloudy air...
We developed a process-based El Niño-Southern Oscillation (ENSO) index that, for the first time, accounts for the nonlinear relationship between sea surface temperature and deep convection by tracking the average longitude of tropical Pacific deep convection. 
Methane also heats the climate system by absorbing sunlight, and the absorption is maximized over bright clouds and deserts.  
Trends in maximum summertime temperature, moisture, and heat index are tracked over three time periods: 1900–2011, 1950–2011, and 1979–2011; these trends differ notably from annual temperature trends. A warming hole in the Midwest generally decreases in size and magnitude when heat stress trends...
Mesoscale convective systems (MCSs) are a form of massive organized thunderstorms that can last up to 24 hours, and are projected to increase in both frequency and rainfall amount across the US by the end of this century. While climate models with spatial resolution comparable to regional weather...
Due to a scarcity of useful observations to guide model development, Earth system models often miss the mark in predicting tropical clouds and their effects on incoming and outgoing energy in the atmosphere. For most of the past two decades, the U.S. Department of Energy (DOE) Atmospheric Radiation...
Wind gusts beneath rain storms over the ocean increase surface evaporation, but how this process influences tropical circulations—a key component of the global climate system—and precipitation remains unclear. A research team led by scientists at the U.S. Department of Energy’s Pacific Northwest...
Scientists at the Met Office in the UK, along with colleagues at the Lawrence Livermore National Laboratory, have organized an international multi-model inter-comparison project, called CAUSES (Clouds Above the United States and Errors at the Surface). The project aims to identify the physical...

Recent Publications

Ground‐based observations from three middle‐ and high‐latitude sites managed by the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program are used to determine the sensitivity of the low‐cloud optical depth to temperature and to test whether observations support mechanisms...
We developed a parametrizable box model to empirically derive the yields of semivolatile products from VOC oxidation using chamber measurements, while explicitly accounting for the multigenerational chemical aging processes (such as the gas-phase fragmentation and functionalization and aerosol-...
Tropical anvil clouds play a large role in Earth’s radiation balance, but their effect on global warming is uncertain. The conventional paradigm for these clouds attributes their existence to the rapidly-declining convective mass flux below the tropopause, which implies a large source of detraining...
We show that the well‐known failure of any single index to capture the diversity and extremes of El Niño‐Southern Oscillation (ENSO) results from the inability of existing indices to uniquely characterize the average longitude of deep convection in the Walker Circulation. We present a simple sea...
Recently, it was recognized that widely used calculations of methane radiative forcing systematically underestimated its global value by 15% by omitting its shortwave effects. We show that shortwave forcing by methane can be accurately calculated despite considerable uncertainty and large gaps in...
Warming is a major climate change concern, but the impact of high maximum temperatures depends upon the air’s moisture content. Trends in maximum summertime temperature, moisture, and heat index are tracked over three time periods: 1900–2011, 1950–2011, and 1979–2011; these trends differ notably...
Regional climate simulations over the continental United States were conducted for the 2011 warm season using the Weather Research and Forecasting model at convection‐permitting resolution (4 km) with two commonly used microphysics parameterizations (Thompson and Morrison). Sensitivities of the...
Long-term Atmospheric Radiation Measurement (ARM) datasets collected at the three tropical western Pacific (TWP) sites are used to evaluate the ability of the Community Atmosphere Model (CAM5) to simulate the various types of clouds, their seasonal and diurnal variations, and their impact on...
Precipitation is an important climate quantity that is critically relevant to society. In spite of intense efforts, significant precipitation biases remain in most climate models. One pervasive and persistent bias found in many general circulation models occurs in the Tropical West Pacific where...
We introduce the Clouds Above the United States and Errors at the Surface (CAUSES) project with its aim of better understanding the physical processes leading to warm screen temperature biases over the American Midwest in many numerical models. In this first of four companion papers, 11 different...

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