Hampton, VA, United States
Hampton, VA, United States

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Lin B.,NASA | Chambers L.,NASA | Stackhouse Jr. P.,NASA | Wielicki B.,NASA | And 7 more authors.
Atmospheric Chemistry and Physics | Year: 2010

Large climate feedback uncertainties limit the accuracy in predicting the response of the Earth's climate to the increase of CO2 concentration within the atmosphere. This study explores a potential to reduce uncertainties in climate sensitivity estimations using energy balance analysis, especially top-of-atmosphere (TOA) radiation imbalance. The time-scales studied generally cover from decade to century, that is, middle-range climate sensitivity is considered, which is directly related to the climate issue caused by atmospheric CO2 change. The significant difference between current analysis and previous energy balance models is that the current study targets at the boundary condition problem instead of solving the initial condition problem. Additionally, climate system memory and deep ocean heat transport are considered. The climate feedbacks are obtained based on the constraints of the TOA radiation imbalance and surface temperature measurements of the present climate. In this study, the TOA imbalance value of 0.85 W/m2 is used. Note that this imbalance value has large uncertainties. Based on this value, a positive climate feedback with a feedback coefficient ranging from-1.3 to-1.0 W/m2/K is found. The range of feedback coefficient is determined by climate system memory. The longer the memory, the stronger the positive feedback. The estimated time constant of the climate is large (70∼120 years) mainly owing to the deep ocean heat transport, implying that the system may be not in an equilibrium state under the external forcing during the industrial era. For the doubled-CO2 climate (or 3.7 W/m2 forcing), the estimated global warming would be 3.1 K if the current estimate of 0.85 W/m2 TOA net radiative heating could be confirmed. With accurate long-term measurements of TOA radiation, the analysis method suggested by this study provides a great potential in the estimations of middle-range climate sensitivity.


Singh U.N.,NASA | Yu J.,NASA | Petros M.,Science and Technology Corporation | Chen S.,NASA | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Sustained research efforts at NASA Langley Research Center (LaRC) during last fifteen years have resulted in a significant advancement in 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurement from ground, air and space-borne platform. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2- micron solid-state laser technology development and discuss results from recent ground-based field measurements. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Lin B.,NASA | Minnis P.,NASA | Fan T.-F.,One Enterprise Parkway | Hu Y.,NASA | Sun W.,One Enterprise Parkway
International Journal of Remote Sensing | Year: 2010

Radiative properties measured by the Clouds and the Earth's Radiant Energy System (CERES) and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua spacecraft are evaluated for the same types of clouds in selected areas. Individual measurements are analysed statistically to take advantage of both gridded and individual cloud characteristics. The seasonal variations of radiative fluxes for the same types of clouds from different areas are remarkably similar. Although cloud liquid water paths (LWPs) or ice water paths (IWPs) vary considerably for the same types of clouds, their statistical distributions are very stable for different periods and areas, suggesting that the regional differences in dynamics and thermodynamics primarily cause changes in the cloud frequency or coverage and only secondarily in the cloud macrophysical characteristics such as IWPs or LWPs. These results establish a systematic approach of observations for testing modelled cloud statistics and for improving cloud model parameterizations. © 2010 Taylor & Francis.


Lin B.,NASA | Stackhouse P.,NASA | Sun W.,One Enterprise Parkway | Hu Y.,NASA | And 2 more authors.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2013

Land surface hydrology is important to regional climate, ecosystem, agriculture, and even human activities. Changes in soil moisture can produce considerable impacts on socioeconomics. Analysis of assimilation model results, especially those from the Community Land Model, shows that soil moisture over Oklahoma region is continuously reduced from 1980 to 2009. The potential drying trend in the Oklahoma region is evaluated by observations taken during last three decades in this study. Satellite data from Global Precipitation Climatology Project exhibit a clear precipitation decrease in the Oklahoma region during the last decade or so compared with those of two or three decades ago. Accompanying with the precipitation variation, land surface net radiation and temperature over the region are found increases by satellite and/or in-situ measurements. These changes in regional climate conditions also likely result in reduction of regional evaporation and enhancement of sensible heat transport from land surface into the atmosphere as indicated in assimilated data. These observed and modeled evidences of the changes in regional water and energy cycles lead us to conclude that the soil moisture over the Oklahoma region was reduced during the last decade. This soil moisture drop could increase a risk in water shortage for agriculture in the Oklahoma state if the dry period continues. Further investigations on the drying in the Oklahoma State or even entire Southern Great Plains are needed to mitigate potential droughts, reductions in vegetation products, and other socioeconomic impacts. © 2012.


Lin B.,NASA | Min Q.,Albany State University | Sun W.,One Enterprise Parkway | Hu Y.,NASA | Fan T.-F.,One Enterprise Parkway
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2011

Increasing the knowledge in climate radiative feedbacks is critical for current climate studies. This work focuses on short-term relationships between global mean surface temperature and top-of-atmosphere (TOA) net radiation. The relationships may be used to characterize the climate feedback as suggested by some recent studies. As those recent studies, an energy balance model with ocean mixed layer and both radiative and non-radiative heat sources is used here. The significant improvement of current model is that climate system memories are considered. Based on model simulations, short-term relationship between global mean surface temperature and TOA net radiation (or the linear striation feature as suggested by previous studies) might represent climate feedbacks when the system had no memories. However, climate systems with the same short-term feedbacks but different memories would have a similar linear striation feature. This linear striation feature reflects only fast components of climate feedbacks and may not represent the total climate feedback even when the memory length of climate systems is minimal. The potential errors in the use of short-term relationships in estimations of climate sensitivity could be big. In short time scales, fast climate processes may overwhelm long-term climate feedbacks. Thus, the climate radiative feedback parameter obtained from short-term data may not provide a reliable estimate of climate sensitivity. This result also suggests that long-term observations of global surface temperature and TOA radiation are critical in the understanding of climate feedbacks and sensitivities. © 2010.

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