scholarly journals A mechanism for dust-induced destabilization of glacial climates

2012 ◽  
Vol 8 (6) ◽  
pp. 2061-2067 ◽  
Author(s):  
B. F. Farrell ◽  
D. S. Abbot
Keyword(s):  
Hydrological Cycle ◽  
Temporal Distribution ◽  
External Forcing ◽  
Feedback Process ◽  
Climate Record ◽  
Mountain Glaciers ◽  
Millennial Time Scale ◽  
Glacial Periods ◽  
Convective Model ◽  
Dust Precipitation

Abstract. Abrupt transitions between cold/dry stadial and warm/wet interstadial states occurred during glacial periods in the absence of any known external forcing. The climate record preserved in polar glaciers, mountain glaciers, and widespread cave deposits reveals that these events were global in extent with temporal distribution implying an underlying memoryless process with millennial time scale. Here a theory is advanced implicating feedback between atmospheric dust and the hydrological cycle in producing these abrupt transitions. Calculations are performed using a radiative-convective model that includes the interaction of aerosols with radiation to reveal the mechanism of this dust/precipitation interaction feedback process and a Langevin equation is used to illustrate glacial climate destabilization by this mechanism. This theory explains the observed abrupt, bimodal, and memoryless nature of these transitions as well as their intrinsic connection with the hydrological cycle.

scholarly journals A mechanism for dust-induced destabilization of glacial climates

2012 ◽  
Vol 8 (3) ◽  
pp. 1721-1735
Author(s):  
B. F. Farrell ◽  
D. S. Abbot
Keyword(s):  
Hydrological Cycle ◽  
Temporal Distribution ◽  
External Forcing ◽  
Feedback Process ◽  
Climate Record ◽  
Mountain Glaciers ◽  
Millennial Time Scale ◽  
Glacial Periods ◽  
Convective Model ◽  
Dust Precipitation

Abstract. Abrupt transitions between cold/dry stadial and warm/wet interstadial states occurred during glacial periods in the absence of any known external forcing. The climate record preserved in polar glaciers, mountain glaciers, and widespread cave deposits reveals that these events were global in extent with temporal distribution implying an underlying memoryless process with millennial time scale. Here a theory is advanced implicating feedback between atmospheric dust and the hydrological cycle in producing these abrupt transitions. Calculations are performed using a radiative-convective model that includes the interaction of aerosols with radiation to reveal the mechanism of this dust/precipitation interaction feedback process and a Langevin equation is used to illustrate qualitatively glacial climate destabilization by this mechanism. This theory explains the observed abrupt, bimodal, and memoryless nature of these transitions as well as their intrinsic connection with the hydrological cycle.

scholarly journals MODIS Collection 6 shortwave-derived cloud phase classification algorithm and comparisons with CALIOP

2015 ◽  
Vol 8 (11) ◽  
pp. 11893-11924 ◽  
Author(s):  
B. Marchant ◽  
S. Platnick ◽  
K. Meyer ◽  
G. T. Arnold ◽  
J. Riedi
Keyword(s):  
Hydrological Cycle ◽  
Temporal Distribution ◽  
Phase Discrimination ◽  
Ice Surface ◽  
Phase Classification ◽  
Microphysical Property ◽  
Moderate Resolution ◽  
Cloud Optical Thickness ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Thermodynamic Phase

Abstract. Cloud thermodynamic phase (ice, liquid, undetermined) classification is an important first step for cloud retrievals from passive sensors such as MODIS (Moderate-Resolution Imaging Spectroradiometer). Because ice and liquid phase clouds have very different scattering and absorbing properties, an incorrect cloud phase decision can lead to substantial errors in the cloud optical and microphysical property products such as cloud optical thickness or effective particle radius. Furthermore, it is well established that ice and liquid clouds have different impacts on the Earth's energy budget and hydrological cycle, thus accurately monitoring the spatial and temporal distribution of these clouds is of continued importance. For MODIS Collection 6 (C6), the shortwave-derived cloud thermodynamic phase algorithm used by the optical and microphysical property retrievals has been completely rewritten to improve the phase discrimination skill for a variety of cloudy scenes (e.g., thin/thick clouds, over ocean/land/desert/snow/ice surface, etc). To evaluate the performance of the C6 cloud phase algorithm, extensive granule-level and global comparisons have been conducted against the heritage C5 algorithm and CALIOP. A wholesale improvement is seen for C6 compared to C5.

scholarly journals Assessing urban groundwater table response to climate change and increased stormwater infiltration

1969 ◽  
Vol 28 ◽  
pp. 33-36 ◽  
Author(s):  
Mark T. Randall ◽  
Lars Troldborg ◽  
Jens Christian Refsgaard ◽  
Jacob B. Kidmose
Keyword(s):  
Climate Change ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Temporal Distribution ◽  
Urban Groundwater ◽  
Direct Consequence ◽  
Groundwater Table ◽  
Droughts And Floods ◽  
Recharge Rates ◽  
Stormwater Infiltration

The global climate is expected to show continued warming throughout the coming century. As a direct consequence of higher temperatures, the hydrological cycle will undergo significant changes in the spatial and temporal distribution of precipitation and evapotranspiration. In addition to more frequent and severe droughts and floods, climate change can affect groundwater recharge rates and groundwater table elevation (Bates et al. 2008).

scholarly journals Water Storage Variations in Tibet from GRACE, ICESat, and Hydrological Data

2019 ◽  
Vol 11 (9) ◽  
pp. 1103 ◽  
Author(s):  
Fang Zou ◽  
Robert Tenzer ◽  
Shuanggen Jin
Keyword(s):  
Tibetan Plateau ◽  
Water Budget ◽  
Hydrological Cycle ◽  
Water Storage ◽  
The Tibetan Plateau ◽  
Total Water ◽  
Satellite Mission ◽  
Mountain Glaciers ◽  
Grace Data ◽  
The Impact

The monitoring of water storage variations is essential not only for the management of water resources, but also for a better understanding of the impact of climate change on hydrological cycle, particularly in Tibet. In this study, we estimated and analyzed changes of the total water budget on the Tibetan Plateau from the Gravity Recovery And Climate Experiment (GRACE) satellite mission over 15 years prior to 2017. To suppress overall leakage effect of GRACE monthly solutions in Tibet, we applied a forward modeling technique to reconstruct hydrological signals from GRACE data. The results reveal a considerable decrease in the total water budget at an average annual rate of −6.22 ± 1.74 Gt during the period from August 2002 to December 2016. In addition to the secular trend, seasonal variations controlled mainly by annual changes in precipitation were detected, with maxima in September and minima in December. A rising temperature on the plateau is likely a principal factor causing a continuous decline of the total water budget attributed to increase melting of mountain glaciers, permafrost, and snow cover. We also demonstrate that a substantial decrease in the total water budget due to melting of mountain glaciers was partially moderated by the increasing water storage of lakes. This is evident from results of ICESat data for selected major lakes and glaciers. The ICESat results confirm a substantial retreat of mountain glaciers and an increasing trend of major lakes. An increasing volume of lakes is mainly due to an inflow of the meltwater from glaciers and precipitation. Our estimates of the total water budget on the Tibetan Plateau are affected by a hydrological signal from neighboring regions. Probably the most significant are aliasing signals due to ground water depletion in Northwest India and decreasing precipitation in the Eastern Himalayas. Nevertheless, an integral downtrend in the total water budget on the Tibetan Plateau caused by melting of glaciers prevails over the investigated period.

A simple radiative-convective model with a hydrological cycle and interactive clouds

1999 ◽  
Vol 125 (555) ◽  
pp. 837-869 ◽  
Author(s):  
Michael A. Kelly ◽  
David A. Randall ◽  
Graeme L. Stephens
Keyword(s):  
Hydrological Cycle ◽  
Convective Model

scholarly journals Changes in mountain glaciers and ice caps during the 20th century

2006 ◽  
Vol 43 ◽  
pp. 361-368 ◽  
Author(s):  
Atsumu Ohmura
Keyword(s):  
Mass Balance ◽  
20Th Century ◽  
Hydrological Cycle ◽  
Dominant Role ◽  
Climatic Conditions ◽  
Melt Temperature ◽  
Average Mass ◽  
Mountain Glaciers ◽  
The Mean

AbstractThe global mass balance of the glaciers outside Greenland and Antarctica is evaluated based on long-term mass-balance observations on 75 glaciers. The cause of the mass-balance change is investigated by examining winter and summer balances from 34 glaciers. The main finding is a common development in mass-balance changes shared by a number of glaciers separated by large distances and climatic conditions. The average mass balance for the second half of the 20th century was negative at –270 to –280 mma−1. The negative mass balance was found to be intensified at –10mm a−2. Increasing summer melt plays a dominant role in determining the long-term trend in mass balance. During the same period the mean winter mass balance increased slightly, indicating an acceleration (3 mma−2) of the hydrological cycle. On some Scandinavian glaciers the mean mass balance was not only positive but its tendency was accelerating. This trend is due to the strong precipitation increase in the last four decades. The melt/temperature relationships for the two warmer periods in the 20th century, one centred around the 1940s and the other ongoing, are different. Reduced melt in the modern warm period, in comparison with the earlier warm phase of the 1940s, is caused by the global dimming which reduced the solar radiation at the Earth’s surface during the second half of the 20th century.

scholarly journals Using GRACE Data to Estimate Climate Change Impacts on the Earth’s Moment of Inertia

2021 ◽  
Vol 9 ◽  
Author(s):  
Diandong Ren ◽  
Aixue Hu
Keyword(s):  
Hydrological Cycle ◽  
Center Of Mass ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Climate Change Impacts ◽  
Moment Of Inertia ◽  
Mountain Glaciers ◽  
Grace Data ◽  
Continuous Mass ◽  
Gravity Recovery

The widely used 15-year Gravity Recovery and Climate Experiment (GRACE) measured mass redistribution shows an increasing trend in the nontidal Earth’s moment of inertia (MOI). Various contributing components are independently evaluated using five high-quality atmospheric reanalysis datasets and a novelty numerical modeling system. We found a steady, statistically robust (passed a two-tailed t-test at p = 0.04 for dof = 15) rate of MOI increase reaching ∼11.0 × 1027 kg m2/yr, equivalent to a 11.45 sμ/yr increase in the length of day, during 2002–2017. Further analysis suggests that the Antarctic ice sheet contributes the most, followed by the Greenland ice sheet, the precipitation-driven land hydrological cycle, mountain glaciers, and the fluctuation of atmosphere, in this order. Short-term MOI spikes from the GRACE measurements are mostly associated with major low/mid-latitude earthquakes, fitting closely with the MOI variations from the hydrological cycle. Atmospheric fluctuation contributes the least but has a steady trend of 0.5 sμ/yr, with horizontal mass distribution contributing twice as much as the vertical expansion and associated lift of the atmosphere’s center of mass. The latter is a previously overlooked term affecting MOI fluctuation. The contribution to the observed MOI trend from a warming climate likely will persist in the future, largely due to the continuous mass loss from the Earth’s ice sheets.

scholarly journals MODIS Collection 6 shortwave-derived cloud phase classification algorithm and comparisons with CALIOP

2016 ◽  
Vol 9 (4) ◽  
pp. 1587-1599 ◽  
Author(s):  
Benjamin Marchant ◽  
Steven Platnick ◽  
Kerry Meyer ◽  
G. Thomas Arnold ◽  
Jérôme Riedi
Keyword(s):  
Hydrological Cycle ◽  
Temporal Distribution ◽  
Phase Discrimination ◽  
Ice Surface ◽  
Phase Classification ◽  
Microphysical Property ◽  
Moderate Resolution ◽  
Cloud Optical Thickness ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Thermodynamic Phase

Abstract. Cloud thermodynamic phase (ice, liquid, undetermined) classification is an important first step for cloud retrievals from passive sensors such as MODIS (Moderate Resolution Imaging Spectroradiometer). Because ice and liquid phase clouds have very different scattering and absorbing properties, an incorrect cloud phase decision can lead to substantial errors in the cloud optical and microphysical property products such as cloud optical thickness or effective particle radius. Furthermore, it is well established that ice and liquid clouds have different impacts on the Earth's energy budget and hydrological cycle, thus accurately monitoring the spatial and temporal distribution of these clouds is of continued importance. For MODIS Collection 6 (C6), the shortwave-derived cloud thermodynamic phase algorithm used by the optical and microphysical property retrievals has been completely rewritten to improve the phase discrimination skill for a variety of cloudy scenes (e.g., thin/thick clouds, over ocean/land/desert/snow/ice surface, etc). To evaluate the performance of the C6 cloud phase algorithm, extensive granule-level and global comparisons have been conducted against the heritage C5 algorithm and CALIOP. A wholesale improvement is seen for C6 compared to C5.

scholarly journals Overview towards improved understanding of the mechanisms leading to heavy precipitation in the Western Mediterranean: lessons learned from HyMeX

2021 ◽  
Author(s):  
Samira Khodayar ◽  
Silvio Davolio ◽  
Paolo Di Girolamo ◽  
Cindy Lebeaupin Brossier ◽  
Emmanouil Flaounas ◽  
...  
Keyword(s):  
Recurrent Events ◽  
Hydrological Cycle ◽  
Deep Convection ◽  
Temporal Distribution ◽  
Heavy Precipitation ◽  
Western Mediterranean ◽  
Lessons Learned ◽  
Coupled Models ◽  
The Mediterranean ◽  
Spatio Temporal

Abstract. Heavy precipitation (HP) constitutes a major meteorological threat in the western Mediterranean (WMed). Every year, recurrent events affect the area with fatal consequences on infrastructure and personal losses. Despite this being a well-known issue, widely investigated in the past, still open questions remain. Particularly, the understanding of the underlying mechanisms and the modelling representation of the events must be improved. One of the major goals of the Hydrological cYcle in the Mediterranean eXperiment (HyMeX; 2010–2020) has been to advance knowledge on this topic. In this article we present an overview of the most recent lessons learned from HyMeX towards improved understanding of the mechanisms leading to HP in the WMed. The unique network of instruments deployed, the use of finer model resolutions and of coupled models, provided an unprecedented opportunity to validate numerical model simulations, to develop improved parameterizations, designing high-resolution ensemble modelling approaches and sophisticated assimilation techniques across scales. All in all, HyMeX and particularly the science team heavy precipitation favoured the evidencing of theoretical results, the enrichment of our knowledge on the genesis and evolution of convection in a complex topography environment, and the improvement of precipitation forecasts. Illustratively, the intervention of cyclones and warm conveyor belts in the occurrence of heavy precipitation has been pointed out, the crucial role of the spatio-temporal distribution of the atmospheric water vapor for the understanding and accurate forecast of the timing and location of deep convection has been evidenced, as well as the complex interaction among processes across scales. The importance of soil and ocean conditions and the interactions among systems were highlighted and such systems were specifically developed in the framework of HyMeX to improve the realism of weather forecasts. Furthermore, the benefits of cross-disciplinary efforts within HyMeX have been a key asset in bringing a step forward our knowledge about heavy precipitation in the Mediterranean region.

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