scholarly journals Spectroscopic Imaging of Sub-Kilometer Spatial Structure in Lower Tropospheric Water Vapor

2020 ◽  
Author(s):  
David R. Thompson ◽  
Brian H. Kahn ◽  
Philip G. Brodrick ◽  
Matthew D. Lebsock ◽  
Mark Richardson ◽  
...  
Keyword(s):  
Water Vapor ◽  
Spatial Variability ◽  
General Circulation ◽  
Imaging Spectroscopy ◽  
General Circulation Models ◽  
Order Structure ◽  
Scaling Properties ◽  
Observation Network ◽  
Airborne Imaging ◽  
Shortwave Infrared

Abstract. Understanding the subgrid spatial variability of water vapor is important for parameterizing and simulating cloud processes in General Circulation Models (GCMs). This study maps sub-kilometer spatial structures in total atmospheric column water vapor with Visible to Shortwave Infrared (VSWIR) imaging spectroscopy. We describe our inversion approach and validate its accuracy with coincident measurements by airborne imaging spectrometers and the AERONET ground-based observation network. Next, data from NASA’s AVIRIS-NG spectrometer enables the highest resolution measurement to date of water vapor’s spatial variability and scaling properties. We find second order structure function scaling exponents consistent with prior studies of convective atmospheres. Finally, we conclude by discussing the implications of these measurements and paths toward future campaigns to build upon these results.

scholarly journals Spectroscopic imaging of sub-kilometer spatial structure in lower-tropospheric water vapor

2021 ◽  
Vol 14 (4) ◽  
pp. 2827-2840
Author(s):  
David R. Thompson ◽  
Brian H. Kahn ◽  
Philip G. Brodrick ◽  
Matthew D. Lebsock ◽  
Mark Richardson ◽  
...  
Keyword(s):  
Water Vapor ◽  
Spatial Variability ◽  
Imaging Spectroscopy ◽  
Lower Troposphere ◽  
Airborne Lidar ◽  
Order Structure ◽  
Scaling Properties ◽  
Airborne Imaging ◽  
Shortwave Infrared ◽  
Airborne Lidar Data

Abstract. The subgrid spatial variability of water vapor is an important geophysical parameter for modeling tropical convention and cloud processes in atmospheric models. This study maps sub-kilometer spatial structures in total atmospheric column water vapor with visible to shortwave infrared (VSWIR) imaging spectroscopy. We describe our inversion approach and validate its accuracy with coincident measurements by airborne imaging spectrometers and the AERONET ground-based observation network. Next, data from NASA's AVIRIS-NG spectrometer enable the highest-resolution measurement to date of water vapor's spatial variability and scaling properties. We find second-order structure function scaling exponents consistent with prior studies of convective atmospheres. Airborne lidar data show that this total column measurement provides information about variability in the lower troposphere. We conclude by discussing the implications of these measurements and paths toward future campaigns to build upon these results.

scholarly journals Review on Applications of 17O in Hydrological Cycle

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4468
Author(s):  
Yalalt Nyamgerel ◽  
Yeongcheol Han ◽  
Minji Kim ◽  
Dongchan Koh ◽  
Jeonghoon Lee
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Hydrological Cycle ◽  
General Circulation Models ◽  
Convective Precipitation ◽  
Subsurface Water ◽  
Polar Regions ◽  
Sea Ice Concentration ◽  
Moisture Source ◽  
Depositional Processes

The triple oxygen isotopes (16O, 17O, and 18O) are very useful in hydrological and climatological studies because of their sensitivity to environmental conditions. This review presents an overview of the published literature on the potential applications of 17O in hydrological studies. Dual-inlet isotope ratio mass spectrometry and laser absorption spectroscopy have been used to measure 17O, which provides information on atmospheric conditions at the moisture source and isotopic fractionations during transport and deposition processes. The variations of δ17O from the developed global meteoric water line, with a slope of 0.528, indicate the importance of regional or local effects on the 17O distribution. In polar regions, factors such as the supersaturation effect, intrusion of stratospheric vapor, post-depositional processes (local moisture recycling through sublimation), regional circulation patterns, sea ice concentration and local meteorological conditions determine the distribution of 17O-excess. Numerous studies have used these isotopes to detect the changes in the moisture source, mixing of different water vapor, evaporative loss in dry regions, re-evaporation of rain drops during warm precipitation and convective storms in low and mid-latitude waters. Owing to the large variation of the spatial scale of hydrological processes with their extent (i.e., whether the processes are local or regional), more studies based on isotopic composition of surface and subsurface water, convective precipitation, and water vapor, are required. In particular, in situ measurements are important for accurate simulations of atmospheric hydrological cycles by isotope-enabled general circulation models.

scholarly journals Wet scavenging limits the detection of aerosol–cloud–precipitation interactions

2015 ◽  
Vol 15 (5) ◽  
pp. 6851-6886 ◽  
Author(s):  
E. Gryspeerdt ◽  
P. Stier ◽  
B. A. White ◽  
Z. Kipling
Keyword(s):  
Spatial Variability ◽  
General Circulation ◽  
Regional Scale ◽  
General Circulation Models ◽  
Satellite Observations ◽  
Scale Model ◽  
Convective Clouds ◽  
Aerosol Cloud ◽  
Wet Scavenging ◽  
Aerosol Properties

Abstract. Satellite studies of aerosol–cloud interactions usually make use of retrievals of both aerosol and cloud properties, but these retrievals are rarely spatially co-located. While it is possible to retrieve aerosol properties above clouds under certain circumstances, aerosol properties are usually only retrieved in cloud free scenes. Generally, the smaller spatial variability of aerosols compared to clouds reduces the importance of this sampling difference. However, as precipitation generates an increase in spatial variability, the imperfect co-location of aerosol and cloud property retrievals may lead to changes in observed aerosol–cloud–precipitation relationships in precipitating environments. In this work, we use a regional-scale model, satellite observations and reanalysis data to investigate how the non-coincidence of aerosol, cloud and precipitation retrievals affects correlations between them. We show that the difference in the aerosol optical depth (AOD)-precipitation relationship between general circulation models (GCMs) and satellite observations can be explained by the wet scavenging of aerosol. Using observations of the development of precipitation from cloud regimes, we show how the influence of wet scavenging can obscure possible aerosol influences on precipitation from convective clouds. This obscuring of aerosol–cloud–precipitation interactions by wet scavenging suggests that even if GCMs contained a perfect representation of aerosol influences on convective clouds, the difficulty of separating the "clear-sky" aerosol from the "all-sky" aerosol in GCMs may prevent them from reproducing the correlations seen in satellite data.

Mapping methane point emissions with imaging spectroscopy satellite missions

2021 ◽  
Author(s):  
Luis Guanter ◽  
Itziar Irakulis-Loitxate ◽  
Elena Sánchez-García ◽  
Javier Gorroño ◽  
Yongguang Zhang ◽  
...  
Keyword(s):  
Imaging Spectroscopy ◽  
Electromagnetic Spectrum ◽  
Spectral Window ◽  
Remote Sensing Technique ◽  
The Earth ◽  
Spatial Coverage ◽  
Airborne Imaging ◽  
Emission Detection ◽  
Shortwave Infrared ◽  
Spectral Channels

<p>Imaging spectroscopy, also known as hyperspectral imaging, is a remote sensing technique in which images of the solar radiation reflected by the Earth are produced in hundreds of spectral channels between the visible and the shortwave infrared part of the electromagnetic spectrum (roughly 400–2500 nm). The 2100-2450 nm spectral window can be used for methane retrievals, as it has been demonstrated over the last years with airborne imaging  spectrometers, and very recently also with space-based instruments. Satellite-based hyperspectral images are acquired with a typical spatial sampling for satellite data of 30 m, a spatial coverage between 30x30 and 60x60 km per scene, and a spectral sampling of 10 nm. In this work, we will present an overview of the state-of-the-art of methane mapping with imaging spectroscopy missions. We will review the characteristics of the available missions, the main retrieval approaches, and will present examples of methane emission detection from a number of missions and locations around the Earth.</p><p> </p>

scholarly journals The MJO Transition from Shallow to Deep Convection in CloudSat/CALIPSO Data and GISS GCM Simulations

2012 ◽  
Vol 25 (11) ◽  
pp. 3755-3770 ◽  
Author(s):  
Anthony D. Del Genio ◽  
Yonghua Chen ◽  
Daehyun Kim ◽  
Mao-Sung Yao
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Deep Convection ◽  
General Circulation Models ◽  
Lapse Rate ◽  
Shallow Convection ◽  
Large Variability ◽  
Earth Observing System ◽  
Upper Level ◽  
Goddard Institute

The relationship between convective penetration depth and tropospheric humidity is central to recent theories of the Madden–Julian oscillation (MJO). It has been suggested that general circulation models (GCMs) poorly simulate the MJO because they fail to gradually moisten the troposphere by shallow convection and simulate a slow transition to deep convection. CloudSat and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are analyzed to document the variability of convection depth and its relation to water vapor during the MJO transition from shallow to deep convection and to constrain GCM cumulus parameterizations. Composites of cloud occurrence for 10 MJO events show the following anticipated MJO cloud structure: shallow and congestus clouds in advance of the peak, deep clouds near the peak, and upper-level anvils after the peak. Cirrus clouds are also frequent in advance of the peak. The Advanced Microwave Scanning Radiometer for Earth Observing System (EOS) (AMSR-E) column water vapor (CWV) increases by ~5 mm during the shallow–deep transition phase, consistent with the idea of moisture preconditioning. Echo-top height of clouds rooted in the boundary layer increases sharply with CWV, with large variability in depth when CWV is between ~46 and 68 mm. International Satellite Cloud Climatology Project cloud classifications reproduce these climatological relationships but correctly identify congestus-dominated scenes only about half the time. A version of the Goddard Institute for Space Studies Model E2 (GISS-E2) GCM with strengthened entrainment and rain evaporation that produces MJO-like variability also reproduces the shallow–deep convection transition, including the large variability of cloud-top height at intermediate CWV values. The variability is due to small grid-scale relative humidity and lapse rate anomalies for similar values of CWV.

scholarly journals Theoretical comparison of subgrid turbulence in the atmosphere and ocean

2015 ◽  
Vol 2 (6) ◽  
pp. 1675-1704
Author(s):  
V. Kitsios ◽  
J. S. Frederiksen ◽  
M. J. Zidikheri
Keyword(s):  
General Circulation ◽  
Scaling Laws ◽  
General Circulation Models ◽  
Computational Effort ◽  
Geophysical Research ◽  
Scaling Properties ◽  
Transport Studies ◽  
Subgrid Model ◽  
Operational Activities ◽  
Physical Phenomena

Abstract. Due to the massive disparity between the largest and smallest eddies in the atmosphere and ocean, it is not possible to simulate these flows by explicitly resolving all scales on a computational grid. Instead the large scales are explicitly resolved, and the interactions between the unresolved subgrid turbulence and large resolved scales are parameterised. If these interactions are not properly represented then an increase in resolution will not necessarily improve the accuracy of the large scales. This has been a significant and long standing problem since the earliest climate simulations. Historically subgrid models for the atmosphere and ocean have been developed in isolation, with the structure of each motivated by different physical phenomena. Here we solve the turbulence closure problem by determining the parameterisation coefficients (eddy viscosities) from the subgrid statistics of high resolution quasi-geostrophic atmospheric and oceanic simulations. These subgrid coefficients are characterised into a set of simple unifying scaling laws, for truncations made within the enstrophy cascading inertial range. The ocean additionally has an inverse energy cascading range, within which the subgrid model coefficients have alternative scaling properties. Simulations adopting these scaling laws are shown to reproduce the statistics of the reference benchmark simulations across resolved scales, with orders of magnitude improvement in computational efficiency. This reduction in both resolution dependence and computational effort will improve the efficiency and accuracy of geophysical research and operational activities that require data generated by general circulation models, including: weather, seasonal and climate prediction; transport studies; and understanding natural variability and extreme events.

scholarly journals The global impact of supersaturation in a coupled chemistry-climate model

2007 ◽  
Vol 7 (6) ◽  
pp. 1629-1643 ◽  
Author(s):  
A. Gettelman ◽  
D. E. Kinnison
Keyword(s):  
Water Vapor ◽  
Radiative Forcing ◽  
General Circulation ◽  
Climate Model ◽  
General Circulation Models ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Strong Impact ◽  
Small Component ◽  
Enhanced Production

Abstract. Ice supersaturation is important for understanding condensation in the upper troposphere. Many general circulation models however do not permit supersaturation. In this study, a coupled chemistry climate model, the Whole Atmosphere Community Climate Model (WACCM), is modified to include supersaturation for the ice phase. Rather than a study of a detailed parameterization of supersaturation, the study is intended as a sensitivity experiment, to understand the potential impact of supersaturation, and of expected changes to stratospheric water vapor, on climate and chemistry. High clouds decrease and water vapor in the stratosphere increases at a similar rate to the prescribed supersaturation (20% supersaturation increases water vapor by nearly 20%). The stratospheric Brewer-Dobson circulation slows at high southern latitudes, consistent with slight changes in temperature likely induced by changes to cloud radiative forcing. The cloud changes also cause an increase in the seasonal cycle of near tropopause temperatures, increasing them in boreal summer over boreal winter. There are also impacts on chemistry, with small increases in ozone in the tropical lower stratosphere driven by enhanced production. The radiative impact of changing water vapor is dominated by the reduction in cloud forcing associated with fewer clouds (~+0.6 Wm−2) with a small component likely from the radiative effect (greenhouse trapping) of the extra water vapor (~+0.2 Wm−2), consistent with previous work. Representing supersaturation is thus important, and changes to supersaturation resulting from changes in aerosol loading for example, might have a modest impact on global radiative forcing, mostly through changes to clouds. There is no evidence of a strong impact of water vapor on tropical tropopause temperatures.

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