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This dataset showcases the role of shortwave and longwave radiation in planetary boundary layer (PBL) development and winds. Radiation budget is part of the energy budget.
This dataset showcases the role of shortwave and longwave radiation in planetary boundary layer (PBL) development and winds. Radiation budget is part of the energy budget.
Abstract. An extreme warming event near the North Pole, with 2 m temperature rising above 0 °C, was observed in late December 2015. This specific event has been attributed to cyclones and their associated moisture intrusions. However, little is known about the characteristics and drivers of similar events in the historical record. Here, using data from European Centre for Medium-Range Weather Forecasts Reanalysis, version 5 (ERA5), we study these winter extreme warming events with 2 m temperature over a grid point above 0 °C over the high Arctic (poleward of 80° N) that occurred during 1980–2021. In ERA5, such wintertime extreme warming events can only be found over the Atlantic sector. They occur rarely over many grid points, with a total absence during some winters. Furthermore, even when occurring, they tend to be short-lived, with the majority of the events lasting for less than a day. By examining their surface energy budget, we found that these events transition with increasing latitude from a regime dominated by turbulent heat flux into the one dominated by downward longwave radiation. Positive sea level pressure anomalies which resemble blocking over northern Eurasia are identified as a key ingredient in driving these events, as they can effectively deflect the eastward propagating cyclones poleward, leading to intense moisture and heat intrusions into the high Arctic. Using an atmospheric river (AR) detection algorithm, the roles of ARs in contributing to the occurrence of these extreme warming events defined at the grid-point scale are explicitly quantified. The importance of ARs in inducing these events increases with latitude. Poleward of about 83° N, 100 % of these events occurred under AR conditions, corroborating that ARs were essential in contributing to the occurrence of these events. Over the past 4 decades, both the frequency, duration, and magnitude of these events have been increasing significantly. As the Arctic continues to warm, these events are likely to increase in both frequency, duration, and magnitude, with great implications for the local sea ice, hydrological cycle, and ecosystem.
Earth system models (ESMs) are progressively advancing towards the kilometer scale (“k-scale”). However, the surface parameters for land surface models (LSMs) within ESMs running at the k-scale are typically derived from coarse-resolution and outdated datasets. This study aims to develop a new set of global land surface parameters with a resolution of 1 km for multiple years from 2001 to 2020, utilizing the latest and most accurate available datasets. Specifically, the datasets consist of parameters related to land use and land cover, vegetation, soil, and topography. Differences between the newly developed 1 km land surface parameters and conventional parameters emphasize their potential for higher accuracy due to the incorporation of the most advanced and latest data sources. To demonstrate the capability of these new parameters, we conducted 1 km resolution simulations using the E3SM Land Model version 2 (ELM2) over the contiguous United States. Our results demonstrate that land surface parameters contribute to significant spatial heterogeneity in ELM2 simulations of soil moisture, latent heat, emitted longwave radiation, and absorbed shortwave radiation. On average, about 31 % to 54 % of spatial information is lost by upscaling the 1 km ELM2 simulations to a 12 km resolution. Using eXplainable Machine Learning (XML) methods, the influential factors driving the spatial variability and spatial information loss of ELM2 simulations were identified, highlighting the substantial impact of the spatial variability and information loss of various land surface parameters, as well as the mean climate conditions. The comparison against four benchmark datasets indicates that ELM generally performs well in simulating soil moisture and surface energy fluxes. The new land surface parameters are tailored to meet the emerging needs of k-scale LSM and ESM modeling with significant implications for advancing our understanding of water, carbon, and energy cycles under global change. The 1 km land surface parameters are publicly available at https://doi.org/10.5281/zenodo.10815170 (Li et al., 2024).
The two-way coupled Weather Research and Forecasting and Community Multiscale Air Quality (WRF-CMAQ) model has been developed to more realistically represent the atmosphere by accounting for complex chemistry–meteorology feedbacks. In this study, we present a comparative analysis of two-way (with consideration of both aerosol direct and indirect effects) and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous US. Long-term (5 years from 2008 to 2012) simulations using WRF-CMAQ with both offline and two-way coupling modes are carried out with anthropogenic emissions based on multiple years of the U.S. National Emission Inventory and chemical initial and boundary conditions derived from an advanced Earth system model (i.e., a modified version of the Community Earth System Model/Community Atmospheric Model). The comprehensive model evaluations show that both two-way WRF-CMAQ and WRF-only simulations perform well for major meteorological variables such as temperature at 2 m, relative humidity at 2 m, wind speed at 10 m, precipitation (except for against the National Climatic Data Center data), and shortwave and longwave radiation. Both two-way and offline CMAQ also show good performance for ozone (O3) and fine particulate matter (PM 2.5 ). Due to the consideration of aerosol direct and indirect effects, two-way WRF-CMAQ shows improved performance over offline coupled WRF and CMAQ in terms of spatiotemporal distributions and statistics, especially for radiation, cloud forcing, O 3 , sulfate, nitrate, ammonium, elemental carbon, tropospheric O 3 residual, and column nitrogen dioxide (NO 2 ). For example, the mean biases have been reduced by more than 10 W m –2 for shortwave radiation and cloud radiative forcing and by more than 2 ppb for max 8 h O 3 . However, relatively large biases still exist for cloud predictions, some PM 2.5 species, and PM 10 that warrant follow-up studies to better understand those issues. The impacts of chemistry–meteorological feedbacks are found to play important roles in affecting regional air quality in the US by reducing domain-average concentrations of carbon monoxide (CO), O 3 , nitrogen oxide (NO x ), volatile organic compounds (VOCs), and PM 2.5 by 3.1 % (up to 27.8 %), 4.2 % (up to 16.2 %), 6.6 % (up to 50.9 %), 5.8 % (up to 46.6 %), and 8.6 % (up to 49.1 %), respectively, mainly due to reduced radiation, temperature, and wind speed. The overall performance of the two-way coupled WRF-CMAQ model achieved in this work is generally good or satisfactory and the improved performance for two-way coupled WRF-CMAQ should be considered along with other factors in developing future model applications to inform policy making.
Nudging techniques are commonly employed to constrain atmospheric simulations toward observed states, facilitating model evaluation and sensitivity studies. However, if applied improperly – particularly to thermodynamic variables such as temperature and humidity – nudging can distort physical processes and introduce spurious biases, undermining the credibility of the simulations. This study presents an improved nudging implementation that applies vertically modulated tendencies to reduce adverse impacts on model physics. The framework is tested in version 2 of the Energy Exascale Earth System Model (EAMv2) using a suite of hindcast simulations nudged toward ERA5 reanalysis. We systematically evaluate the individual and combined effects of nudging wind, temperature, and humidity fields on the model's ability to represent large-scale atmospheric states and high-impact weather systems. Results show that the revised strategy – particularly when nudging temperature and humidity at selected levels – enhances hindcast skill by improving agreement with ERA5 without degrading the hydrological cycle or precipitation processes. Additional improvements in surface temperature, outgoing longwave radiation, and precipitation biases are achieved through targeted nudging of land-surface variables. The proposed approach strengthens the representation of large-scale conditions relevant to tropical cyclones, atmospheric rivers, and extratropical cyclones in the low-resolution EAMv2. These findings demonstrate that carefully designed thermodynamic nudging, especially of temperature and humidity, improves the realism of constrained simulations and broadens the utility of nudged EAMv2 for atmospheric modeling, machine learning, and high-impact weather research.
The effects of two different evaporation parameterizations on the sensitivity of simulated climate to solar constant variations are investigated by using a zonally averaged climate model. One parameterization is a nonlinear formulation in which the evaporation is nonlinearly proportional to the sensible heat flux, with the Bowen ratio determined by the predicted vertical temperature and humidity gradients near the earth's surface (model A). The other is the formulation of Saltzman (1968) with the evaporation linearly proportional to the sensible heat flux (model B). The computed climates of models A and B are in good agreement except for the energy partition between sensible and latent heat at the earth's surface. The difference in evaporation parameterizations causes a difference in the response of temperature lapse rate to solar constant variations and a difference in the sensitivity of longwave radiation to surface temperature which leads to a smaller sensitivity of surface temperature to solar constant variations in model A than in model B. The results of model A are qualitatively in agreement with those of the general circulation model calculations of Wetherald and Manabe (1975).
An investigation of the dynamic and thermodynamic influences of the Tibetian Plateau on the monsoon circulation in southeastern Asia and China is reported. A five-day primitive equation numerical model was used to simulate the influences of the high mountains in the 0-180 deg E and 25-55 deg N region on a typical July day. The equations predicted horizontal motion, heat, the water vapor mixing ratio, and surface pressure. Consideration was given to solar and longwave radiation and the release of latent heat by deep cumulus clouds. A net warming over the Plateau as opposed to the surrounding areas was found to lead to vertical air ascent and the establishment of strong summer monsoon circulation to the south. It is noted that the grid was too coarse to adequately describe the distribution of precipitation on the steep mountains.
At present, space-borne sensors cannot give accurate measurements of net longwave radiation and sensible heat flux at ocean surface. The variability of ocean surface net insolation was successfully estimated from observations using geostationary satellites. Global coverages of the low frequency variation of major atmosphere-ocean exchanges, momentum, latent heat, and insolation are within reach. Data from research and defense satellites should be made available in useful form to the user community. High quality in-situ measurements are required to calibrate space-borne sensors and numerical models are needed to integrate satellite and in-situ data as well as interpolate both in space and time. Techniques that can resolve boundary layer parameters should be developed.
A simplified linear two-level zonally averaged atmospheric model is used to determine the minimum zonal kinetic energy (ZKE) plus the zonal available potential energy (ZAPE) of equilibrium states for any distribution of horizontal eddy momentum fluxes. The model assumes fixed thermal forcing except for coefficients of the longwave radiative response to temperature. Some distinctive features of the model solutions are described. It is found that: the states of minimum ZKE or minimum ZKE + ZAPE contain a jet stream; the structure of the zonal winds is dependent on thermal forcing; the horizontal eddy momentum fluxes which minimize ZKE or ZKE + ZAPE can be up-gradient everywhere with respect to the upper level zonal mean zonal winds, or down-gradient depending on the thermal forcing; ZKE minimization results in a jet stream at 54 deg latitude independent of external parameters. The minimization of ZKE + ZAPE results in a jet stream at 35 deg latitude for a planet of the earth's radius and similar static stability.
The effect of strong amplitude and high frequency oscillations of divergent circulations in the Southern Hemisphere on estimates of tropical geopotential during the summer is quantified. FGGE data are analyzed in order to determine the mass-flow balance in the upper troposphere, and outgoing longwave radiation averaged over two periods, January and February 1979, is given. It is found that the divergence terms for balance equations may represent geopotential perturbations on the order of 20 to 30 m, and that the influence of strong latent heat releases and divergent circulations in the Southern Hemisphere can invalidate analysis schemes based on quasi-nondivergent solutions.
Progress in the development of a multi-reservoir, time dependent energy balance climate model for Mars driven by prescribed insolation at the top of the atmosphere is reported. The first approximately half-year of the program was devoted to assembling and testing components of the full model. Specific accomplishments were made on a longwave radiation code, coupling seasonal solar input to a ground temperature simulation, and conceptualizing an approach to modeling the seasonal pressure waves that develop in the Martian atmosphere as a result of sublimation and condensation of CO2 in polar regions.
Atmospheric teleconnections in the medium to long (10-90 days) time scales focusing on the interactions between extratropical circulation and tropical convection are studied. In a continuing effort to study short-term climate variability and atmospheric teleconnection as inferred from satellite observed outgoing longwave radiation, the low frequency variability (LFB) of tropical and extratropical cloud fluctuation over the Pacific was studied. It was found that during the Northern winter, the LFV of tropical cloud fluctuation is dominated by a 40-50 day dipole-like oscillation linking convection over Indonesia and the equatorial central Pacific. Eastward propagating signals appearing as outbursts of convective cloud clusters originating from the Indian Ocean appear to periodically feed energy into this dipole oscillation. It was also found that there are cloud features appearing over East Asia and subsequently over the eastern North Pacific which vary coherently with the tropical dipole anomaly. Based on analysis and an a priori phenomenological model, it is believed that the cloud fluctuations are associated with two space/time extended normal modes of tropical-extratropical interactions over the Pacific involving a coupling between the tropical dipole convective heating anomaly with cold surges over East Asia, and blocking over the eastern North Pacific respectively.
To investigate the low-frequency variability of the large-scale circulation over the tropics and its relationship with different regions of the globe, statistics of cloud fluctuations, as inferred from outgoing longwave radiation (OLR) are used. The data consists of seven years of global OLR in a 2.5 x 2.5-deg grid derived from NOAA polar orbiting satellite observations. The time series of area-averaged monthly deviation from the seven-year mean of OLR over an equatorial Central Pacific region is presented. It is shown that positive and negative deviations reflect local drier and wetter than normal conditions, respectively. Consideration is given to teleconnection based on the Central Pacific variations and to southern oscillation contributions.
It was found that during the northern winter, fluctuation in tropical convection is dominated by eastware propagating cloud clusters from the Indian Ocean. Most of these clusters reach as far as the central Pacific. Longitude time sections of outgoing longwave radiation (OLR) anomaly along the equator show that there are about 3 to 4 such episodes each winter. Also, simultaneous OLR anomalies over the equatorial central Pacific (ECP) and the maritime continent (MC) are negatively correlated and their variations are dominated by a 40 to 60 day period, suggesting the presence of a standing wave phenomenon. Such combination of propagating and standing phenomena can be captured by the extended empirical orthogonal function (EEOF) analysis. The EEOF method combines the temporal as well as the spatial correlation information to produce eigenmodes which have space time dependence. A 5 day and a 10 day lag in addition to the simultaneous spatial correlation is used.
The tropical ocean-atmosphere exhibits two prominent modes of low-frequency oscillations, i.e., the '40-50' day oscillation and the El Nino/Southern Oscillation (ENSO). The two phenomena are viewed in the same perspective from 10 years of satellite-derived out-going-longwave-radiation data. Results reveal some interesting features that may lead to new insights into the understanding of the two phenomena.
Northern-Hemisphere twice-daily 500-mb-geopotential-height data for November-March 1975-1980 and November-December 1981 and NOAA satellite measurements of outgoing longwave radiation for the same period are processed to remove seasonal cycles and Fourier-decomposition bandpassed to study variations with 20-70-d periods. The results of analysis using correlation, complex EOF, and composite techniques are presented in extensive maps and graphs and characterized. Extratropical wavetrains are found to evolve systematically from Eurasia eastward to North America and the North Atlantic on 5-6-d time scales, while the intraseasonal variation in tropical convection is dominated by a dipolelike east-west feature propagating from the western Indian Ocean to the dateline with a quasi-period of 40-50 d. The possibility that normal modes coupled between the tropics and midlatitudes may be responsible for these phenomena is considered.
The major research objectives are to diagnose the physical processes responsible for the maintenance of the South Pacific Convergence Zone (SPCZ) and to examine the role of the SPCZ in the large-scale circulation patterns of the Southern Hemisphere. To accomplish these objectives researchers used several data sources which include: a modified set of Level III-b upper air analyses, originally produced by ECMWF (Vincent, 1982); subjectively analyzed surface analyses for the South Pacific based on island station reports (Vincent, 1985); outgoing longwave radiation values supplied to us by NOAA/NESDIS; and equivalent black body temperatures and precipitation rates derived by Robertson. In the past year researchers found that wave number four plays an inportant role in the Southern Hemisphere tropics during the 15-day period when the sPCZ was a dominant feature, particularly with regard to the baroclinic conversion of potential to kinetic energy (Huang and Vincent, 1985). The convectively-active SPCZ area was found to make a significant contribution to this conversion process; thus, it appears that baroclinic effects and latent heating are important in maintaining the SPCZ. Recently efforts concentrated on two research tasks, an examination of cyclone activity within the SPCZ (Kann, 1985; Vincent, 1985; Vincent and Kann, 1985) and a study of the heat and moisture budgets in the South Pacific (Miller, et al., 1985). It was found that cyclonic disturbances occurred with regularity in the Zone from 10 to 17 January.