Solving Global Cirrus Cloud Top-of-the-Atmosphere Radiative Forcing from Satellite Lidar

Abstract. Trends in cirrus cloud cover have been estimated based on 16 years of data from ISCCP (International Satellite Cloud Climatology Project). The results have been spatially correlated with aircraft density data to determine the changes in cirrus cloud cover due to aircraft traffic. The correlations are only moderate, as many other factors have also contributed to changes in cirrus. Still we regard the results to be indicative of an impact of aircraft on cirrus amount. The main emphasis of our study is on the area covered by the METEOSAT satellite to avoid trends in the ISCCP data resulting from changing satellite viewing geometry. In Europe, which is within the METEOSAT region, we find indications of a trend of about 1-2% cloud cover per decade due to aircraft, in reasonable agreement with previous studies. The positive trend in cirrus in areas of high aircraft traffic contrasts with a general negative trend in cirrus. Extrapolation in time to cover the entire period of aircraft operations and in space to cover the global scale yields a mean estimate of 0.03 Wm-2 (lower limit 0.01, upper limit 0.08 Wm-2) for the radiative forcing due to aircraft induced cirrus. The mean is close to the value given by IPCC (1999) as an upper limit.

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Long-term trend analysis and climatology of tropical cirrus clouds using 16 years of lidar data set over Southern India

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-13833-2015 ◽

2015 ◽

Vol 15 (24) ◽

pp. 13833-13848 ◽

Cited By ~ 16

Author(s):

A. K. Pandit ◽

H. S. Gadhavi ◽

M. Venkat Ratnam ◽

K. Raghunath ◽

S. V. B. Rao ◽

...

Keyword(s):

Optical Thickness ◽

Radiative Forcing ◽

Climate Model ◽

Cirrus Clouds ◽

Orthogonal Polarization ◽

Cirrus Cloud ◽

Data Set ◽

Tropical Tropopause ◽

Recent Climate ◽

Ground Based Lidar

Abstract. Sixteen-year (1998–2013) climatology of cirrus clouds and their macrophysical (base height, top height and geometrical thickness) and optical properties (cloud optical thickness) observed using a ground-based lidar over Gadanki (13.5° N, 79.2° E), India, is presented. The climatology obtained from the ground-based lidar is compared with the climatology obtained from 7 and a half years (June 2006–December 2013) of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations. A very good agreement is found between the two climatologies in spite of their opposite viewing geometries and the differences in sampling frequencies. Nearly 50–55 % of cirrus clouds were found to possess geometrical thickness less than 2 km. Ground-based lidar is found to detect a higher number of sub-visible clouds than CALIOP which has implications for global warming studies as sub-visible cirrus clouds have significant positive radiative forcing. Cirrus clouds with mid-cloud temperatures between −50 to −70 °C have a mean geometrical thickness greater than 2 km in contrast to the earlier reported value of 1.7 km. Trend analyses reveal a statistically significant increase in the altitude of sub-visible cirrus clouds which is consistent with the recent climate model simulations. The mid-cloud altitude of sub-visible cirrus clouds is found to be increasing at the rate of 41 ± 21 m year−1. Statistically significant decrease in optical thickness of sub-visible and thick cirrus clouds is observed. Also, the fraction of sub-visible cirrus cloud is found to have increased by 9 % in the last 16 years (1998 to 2013). This increase is mainly compensated by a 7 % decrease in thin cirrus cloud fraction. This has implications for the temperature and water vapour budget in the tropical tropopause layer.

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Influence of cirrus cloud radiative forcing on climate and climate sensitivity in a general circulation model

Journal of Geophysical Research Atmospheres ◽

10.1029/95jd01383 ◽

1995 ◽

Vol 100 (D8) ◽

pp. 16305 ◽

Cited By ~ 57

Author(s):

Ulrike Lohmann ◽

Erich Roeckner

Keyword(s):

General Circulation Model ◽

Climate Sensitivity ◽

Radiative Forcing ◽

General Circulation ◽

Circulation Model ◽

Cirrus Cloud ◽

Cloud Radiative Forcing

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Cirrus cloud radiative forcing at the top of atmosphere using the nighttime global distribution with the microphysical parameters derived from AVHRR

10.1063/1.4804867 ◽

2013 ◽

Cited By ~ 1

Author(s):

Shuichiro Katagiri ◽

Miho Sekiguchi ◽

Tadahiro Hayasaka ◽

Teruyuki Nakajima

Keyword(s):

Radiative Forcing ◽

Global Distribution ◽

Cirrus Cloud ◽

Cloud Radiative Forcing ◽

Microphysical Parameters

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The effect of optically thin cirrus clouds on solar radiation in Camagüey, Cuba

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-8625-2011 ◽

2011 ◽

Vol 11 (16) ◽

pp. 8625-8634 ◽

Cited By ~ 11

Author(s):

B. Barja ◽

J. C. Antuña

Keyword(s):

Solar Radiation ◽

Radiative Forcing ◽

Near Infrared ◽

Local Heating ◽

Spectral Band ◽

Solar Spectrum ◽

Cirrus Clouds ◽

Cloud Base ◽

Cirrus Cloud ◽

Heating Rates

Abstract. The effect of optically thin cirrus clouds on solar radiation is analyzed by numerical simulation, using lidar measurements of cirrus conducted at Camagüey, Cuba. Sign and amplitude of the cirrus clouds effect on solar radiation is evaluated. There is a relation between the solar zenith angle and solar cirrus cloud radiative forcing (SCRF) present in the diurnal cycle of the SCRF. Maximums of SCRF out of noon located at the cirrus cloud base height are found for the thin and opaque cirrus clouds. The cirrus clouds optical depth (COD) threshold for having double SCRF maximum out of noon instead of a single one at noon was 0.083. In contrast, the heating rate shows a maximum at noon in the location of cirrus clouds maximum extinction values. Cirrus clouds have a cooling effect in the solar spectrum at the Top of the Atmosphere (TOA) and at the surface (SFC). The daily mean value of SCRF has an average value of −9.1 W m−2 at TOA and −5.6 W m−2 at SFC. The cirrus clouds also have a local heating effect on the atmospheric layer where they are located. Cirrus clouds have mean daily values of heating rates of 0.63 K day−1 with a range between 0.35 K day−1 and 1.24 K day−1. The principal effect is in the near-infrared spectral band of the solar spectrum. There is a linear relation between SCRF and COD, with −30 W m−2 COD−1 and −26 W m−2 COD−1, values for the slopes of the fits at the TOA and SFC, respectively, in the broadband solar spectrum.

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Revisiting global satellite observations of stratospheric cirrus clouds

10.5194/acp-2020-304 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ling Zou ◽

Sabine Griessbach ◽

Lars Hoffmann ◽

Bing Gong ◽

Lunche Wang

Keyword(s):

Radiative Forcing ◽

Lower Stratosphere ◽

Deep Convection ◽

Michelson Interferometer ◽

Satellite Observations ◽

Cirrus Clouds ◽

Detection Sensitivity ◽

Lapse Rate ◽

Cirrus Cloud ◽

The Tropics

Abstract. As knowledge about the cirrus clouds in the lower stratosphere is limited, reliable long-term measurements are needed to assess their characteristics, radiative impact and important role in upper troposphere and lower stratosphere (UTLS) chemistry. To investigate the global and seasonal distribution of stratospheric cirrus clouds, we used the latest version (V4.x) of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) data. For the identification of stratospheric cirrus clouds, precise information on both, the cloud top height (CTH) and the tropopause height is crucial. Here, we used lapse rate tropopause heights estimated from the ERA-Interim global reanalysis. Considering the uncertainties of the tropopause heights and the vertical sampling grid of the CALIPSO data, we considered cirrus clouds with CTHs more than 0.5 km above the tropopause as being stratospheric. We focused on nighttime CALIPSO measurements, because of their higher detection sensitivity. A six-year mean (2006–2012) global distribution of stratospheric cirrus cloud from CALIPSO showed that higher CTH occurrence frequencies are observed in the tropics than in the extra-tropics. Tropical hotspots of stratospheric cirrus clouds associated with deep convection are located over Equatorial Africa, South and Southeast Asia, the western Pacific and South America. Stratospheric cirrus clouds were more often detected in December–February (15 %) than June–August (8 %) in the tropics (± 20°). At middle (40–60°) and higher latitudes (> 60°), CALIPSO observed on average about 2 % stratospheric cirrus clouds. Observations of stratospheric cirrus cloud with MIPAS are presented here for the first time. Taking into account the MIPAS vertical sampling and broad field of view, we considered cirrus CTHs detected not less than 0.75 km above the tropopause as being stratospheric. Compared to CALIPSO, MIPAS observed twice as many stratospheric cirrus clouds at northern and southern middle latitudes (occurrence frequencies of 4–5 % for MIPAS rather than about 2 % for CALIPSO). We attribute more frequent observations of stratospheric cirrus clouds with MIPAS to higher detection sensitivity of the instrument to optically thin clouds. Sensitivity tests on MIPAS stratospheric cloud detections have been conducted to rule out sampling artefacts. Future work should focus on better understanding the origin of the stratospheric cirrus clouds and their impact on radiative forcing and climate.

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Study of cirrus cloud properties and occurrence over Europe during the COVID-19 based on the lidar measurements of CALIPSO

10.5194/egusphere-egu21-5533 ◽

2021 ◽

Author(s):

Qiang Li ◽

Silke Groß

Keyword(s):

United States ◽

Radiative Forcing ◽

The United States ◽

Air Traffic ◽

Cirrus Clouds ◽

Cirrus Cloud ◽

Good Opportunity ◽

Mean Values ◽

Significance Level ◽

Cloud Properties

<p>Cirrus clouds have a wide global coverage providing considerable radiative forcing on the Earth&#8217;s climate system. Due to their inadequate representation in the global models, cirrus clouds can lead to large uncertainties in the climate prediction. To date, experimental and theoretical efforts have been widely carried out to study the anthropogenic effects such as aviation that may change the formation and microphysic and optical properties of cirrus clouds. Unfortunately, however, solid observational studies are still rare for us to draw any robust conclusion on anthropogenic influence on cirrus. During the COVID-19 pandemic the civil air traffic over Europe was significantly reduced. This unique situation provides a good opportunity to study the effect of air traffic on cirrus. In this work, based on the analysis of the CALIPSO measurements we present the changes of cirrus cloud properties and occurrence over Europe in March and April 2020 compared with the reference results in the previous years under normal conditions. The comparison shows that the cirrus cloud occurrence was reduced by about 30% with smaller cloud thicknesses found in April 2020. The average thickness of cirrus clouds was reduced to 1.18 km in April 2020 compared to a value of 1.40 km under normal conditions. In addition, the cirrus clouds measured in April 2020 possess smaller mean values of the particle linear depolarization ratio (PLDR) than the previous years at a high significance level, especially at colder temperatures (T<-50<sup>o</sup>C). The same exercises are extended to the observations over China and the United States. Besides the regional discrimination of cirrus clouds, we reach the final summary that cirrus clouds show significant changes in both March and April over Europe, no changes in both months over China, and significant changes only in April over the United States.</p>

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Field experiments on solar geoengineering: report of a workshop exploring a representative research portfolio

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2014.0175 ◽

2014 ◽

Vol 372 (2031) ◽

pp. 20140175 ◽

Cited By ~ 33

Author(s):

David W. Keith ◽

Riley Duren ◽

Douglas G. MacMartin

Keyword(s):

Solar Radiation ◽

Radiative Forcing ◽

Field Experiments ◽

Field Research ◽

Research Programme ◽

Solar Radiation Management ◽

Systematic Research ◽

Cirrus Cloud ◽

Solar Geoengineering ◽

Radiation Management

We summarize a portfolio of possible field experiments on solar radiation management (SRM) and related technologies. The portfolio is intended to support analysis of potential field research related to SRM including discussions about the overall merit and risk of such research as well as mechanisms for governing such research and assessments of observational needs. The proposals were generated with contributions from leading researchers at a workshop held in March 2014 at which the proposals were critically reviewed. The proposed research dealt with three major classes of SRM proposals: marine cloud brightening, stratospheric aerosols and cirrus cloud manipulation. The proposals are summarized here along with an analysis exploring variables such as space and time scale, risk and radiative forcing. Possible gaps, biases and cross-cutting considerations are discussed. Finally, suggestions for plausible next steps in the development of a systematic research programme are presented.

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