Monthly covariability of Amazonian convective cloud properties and radiative diurnal cycle

Abstract. Here, liquid water path (LWP), cloud fraction, cloud top height, and cloud base height retrieved by a suite of A-train satellite instruments (the CPR aboard CloudSat, CALIOP aboard CALIPSO, and MODIS aboard Aqua) are compared to ship observations from research cruises made in 2001 and 2003–2007 into the stratus/stratocumulus deck over the southeast Pacific Ocean. It is found that CloudSat radar-only LWP is generally too high over this region and the CloudSat/CALIPSO cloud bases are too low. This results in a relationship (LWP~h9) between CloudSat LWP and CALIPSO cloud thickness (h) that is very different from the adiabatic relationship (LWP~h2) from in situ observations. Such biases can be reduced if LWPs suspected to be contaminated by precipitation are eliminated, as determined by the maximum radar reflectivity Zmax>−15 dBZ in the apparent lower half of the cloud, and if cloud bases are determined based upon the adiabatically-determined cloud thickness (h~LWP1/2). Furthermore, comparing results from a global model (CAM3.1) to ship observations reveals that, while the simulated LWP is quite reasonable, the model cloud is too thick and too low, allowing the model to have LWPs that are almost independent of h. This model can also obtain a reasonable diurnal cycle in LWP and cloud fraction at a location roughly in the centre of this region (20° S, 85° W) but has an opposite diurnal cycle to those observed aboard ship at a location closer to the coast (20° S, 75° W). The diurnal cycle at the latter location is slightly improved in the newest version of the model (CAM4). However, the simulated clouds remain too thick and too low, as cloud bases are usually at or near the surface.

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An Observed Tropical Oceanic Radiative–Convective Cloud Feedback

Journal of Climate ◽

10.1175/2009jcli3091.1 ◽

2010 ◽

Vol 23 (8) ◽

pp. 2065-2078 ◽

Cited By ~ 12

Author(s):

Matthew D. Lebsock ◽

Christian Kummerow ◽

Graeme L. Stephens

Keyword(s):

Atmospheric Stability ◽

Convective Cloud ◽

Precipitation Anomaly ◽

Cloud Feedback ◽

Radiative Heating ◽

Large Spatial Scale ◽

Cloud Properties ◽

Tropical Oceans ◽

The Mean ◽

High Level

Abstract Anomalies of precipitation, cloud, thermodynamic, and radiation variables are analyzed on the large spatial scale defined by the tropical oceans. In particular, relationships between the mean tropical oceanic precipitation anomaly and radiative anomalies are examined. It is found that tropical mean precipitation is well correlated with cloud properties and radiative fields. In particular, the tropical mean precipitation anomaly is positively correlated with the top of the atmosphere reflected shortwave anomaly and negatively correlated with the emitted longwave anomaly. The tropical mean relationships are found to primarily result from a coherent oscillation of precipitation and the area of high-level cloudiness. The correlations manifest themselves radiatively as a modest decrease in net downwelling radiation at the top of the atmosphere, and a redistribution of energy from the surface to the atmosphere through reduced solar radiation to the surface and decreased longwave emission to space. Integrated over the tropical oceanic domain, the anomalous atmospheric column radiative heating is found to be about 10% of the magnitude of the anomalous latent heating. The temporal signature of the radiative heating is observed in the column mean temperature that indicates a coherent phase-lagged oscillation between atmospheric stability and convection. These relationships are identified as a radiative–convective cloud feedback that is observed on intraseasonal time scales in the tropical atmosphere.

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Improvements to the Geostationary Visible Imager Ray-Matching Calibration Algorithm for CERES Edition 4

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-16-0113.1 ◽

2016 ◽

Vol 33 (12) ◽

pp. 2679-2698 ◽

Cited By ~ 26

Author(s):

David R. Doelling ◽

Conor O. Haney ◽

Benjamin R. Scarino ◽

Arun Gopalan ◽

Rajendra Bhatt

Keyword(s):

Dynamic Range ◽

Spectral Band ◽

Radiant Energy ◽

Convective Cloud ◽

Energy System ◽

Processing Scheme ◽

Matching Algorithm ◽

Cloud Properties ◽

Calibration Algorithm ◽

The Difference

AbstractThe Clouds and the Earth’s Radiant Energy System (CERES) project relies on geostationary imager–derived TOA broadband fluxes and cloud properties to account for the regional diurnal fluctuations between the Terra and Aqua CERES and MODIS measurements. The CERES project employs a ray-matching calibration algorithm in order to transfer the Aqua MODIS calibration to the geostationary (GEO) imagers, thereby allowing the derivation of consistent fluxes and cloud retrievals across the 16 GEO imagers utilized in the CERES record. The CERES Edition 4 processing scheme grants the opportunity to recalibrate the GEO record using an improved GEO/MODIS all-sky ocean ray-matching algorithm. Using a graduated angle matching method, which is most restrictive for anisotropic clear-sky ocean radiances and least restrictive for isotropic bright cloud radiances, reduces the bidirectional bias while preserving the dynamic range. Furthermore, SCIAMACHY hyperspectral radiances are used to account for both the solar incoming and Earth-reflected spectra in order to correct spectral band differences. As a result, the difference between the linear regression offset and the maintained GEO space count was reduced, and the calibration slopes computed from the linear fit and the regression through the space count agreed to within 0.4%. A deep convective cloud (DCC) ray-matching algorithm is also presented. The all-sky ocean and DCC ray-matching timeline gains are within 0.7% of one another. Because DCC are isotropic and the brightest, Earth targets with near-uniform visible spectra, the temporal standard error of GEO imager gains, are reduced by up to 60% from that of all-sky ocean targets.

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Diurnal variation of high-level clouds from the synergy of AIRS and IASI space-borne infrared sounders

10.5194/acp-2019-166 ◽

2019 ◽

Author(s):

Artem G. Feofilov ◽

Claudia J. Stubenrauch

Keyword(s):

Diurnal Variation ◽

Diurnal Cycle ◽

Cloud Amount ◽

Convective Cloud ◽

Cirrus Clouds ◽

Local Times ◽

Cloud Type ◽

Cloud Data ◽

High Level ◽

The Tropics

Abstract. Among the processes governing the energy balance of our planet, high-level clouds, due to their coverage of about 30 %, play an important role. The net radiative effect (cooling or warming of the planet) of these clouds strongly depends on their emissivity. The combination of cloud data retrieved from two space-borne infrared sounders, the Atmospheric InfraRed Sounder, AIRS, and the Infrared Atmospheric Sounding Interferometer, IASI, which observe the Earth at four local times per day, allows to investigate the diurnal variation of these high-level clouds, distinguishing between high opaque, cirrus, and thin cirrus clouds. We demonstrate that the diurnal phase and amplitude of high-level clouds can be estimated from these measurements with an uncertainty of 1.5 h and 20 %, respectively. We have applied the developed methodology to AIRS and IASI observations and obtained monthly distributions of diurnal phase and amplitude for the period 0f 2008–2015. In agreement with other studies, the diurnal cycle is the largest over land in the tropics. At higher latitudes, the diurnal cycle is the largest during the summer. For the regions of high diurnal activity over land, the diurnal amplitudes of cloud amount are about 7 % for high opaque clouds, 9 % for cirrus, and 7 % for thin cirrus clouds. Over ocean, these values are 2 to 3 times smaller. The diurnal cycle of tropical thin cirrus seems to be similar over land and over ocean, with a minimum in the morning (9 h LT) and a maximum during night (1 h LT). Tropical high opaque clouds have a maximum in the evening (21 h LT over land), a few hours after the peak of convective rain. This lag is explained by the fact that this cloud type not only includes the convective cores, but also part of the thicker anvils. Tropical cirrus (with an emissivity > 0.5 or visible optical depth > 1.4) show a maximum amount during night (1 h LT over land). This lag indicates that they may be a part of the deep convective cloud systems. However, the peak local times also vary regionally. We are providing a global monthly database of detected diurnal cycle amplitude and phase for each cloud type.

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Ozone in the Tropical Troposphere from Sentinel-5P TROPOMI data: CCD and CSL results

10.5194/egusphere-egu2020-9116 ◽

2020 ◽

Author(s):

Kai-Uwe Eichmann ◽

Mark Weber ◽

Klaus-Peter Heue ◽

John P. Burrows

Keyword(s):

Tropospheric Ozone ◽

Stratospheric Ozone ◽

Convective Cloud ◽

Mean Value ◽

Differential Method ◽

Mixing Ratios ◽

Temporal Sampling ◽

Cloud Properties ◽

Tropical Troposphere ◽

Column Ozone

The TROPOspheric Monitoring Instrument (TROPOMI), on board the Sentinel 5 precursor (S5p) satellite, was launched in October 2017. The TROPOMI instrument has high spatial resolution and daily coverage of the Earth. About two years of level 2 data (version 1.1.5/1.1.7) of ozone and cloud properties (fraction and height) are available. Using the OFFL GODFIT ozone and OCRA/ROCINN CRB cloud dataset, we derived tropical tropospheric ozone using the convective cloud differential method for tropical tropospheric column ozone (TTCO) [DU] and the cloud slicing method for upper tropospheric ozone volume mixing ratios (TUTO) [ppbv].The CCD algorithm was optimized for TROPOMI with respect to the reference sector Above Cloud Column Ozone field (ACCO). It was adjusted in time and latitude space in order to reduce data gaps in the daily ACCO vectors. Also, daily total ozone maps were used to minimize the error in stratospheric ozone differences.The CHOVA algorithm (Cloud Height induced Ozone Variation Analysis) was developed to fully exploit with the S5p instruments characteristics. A temporal sampling of cloud/ozone data is not necessary for the high amount of S5p measurements. The spatial sampling is 2&#176; latitude/longitude grid boxes. CHOVA results are quality checked based on the statistical properties of cloud, ozone and retrieval parameters to exclude unreliable TUTO values.Comparisons with ozone sondes show a good agreement for both methods taking into account the principal differences between a sonde point measurement and a satellite sampled mean value.&#160;The work on TROPOMI/S5P geophysical products is funded by ESA and national contributions from the Netherlands, Germany, Belgium, and Finland.

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Evaluation of the diurnal cycle of model predicted cloud properties using MSG‐SEVIRI observations

10.1063/1.3117010 ◽

2009 ◽

Author(s):

R. A. Roebeling ◽

A. Feijt ◽

E. van Meijgaard

Keyword(s):

Diurnal Cycle ◽

Cloud Properties

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Cloud Properties and Their Seasonal and Diurnal Variability from TOVS Path-B

Journal of Climate ◽

10.1175/jcli3929.1 ◽

2006 ◽

Vol 19 (21) ◽

pp. 5531-5553 ◽

Cited By ~ 93

Author(s):

C. J. Stubenrauch ◽

A. Chédin ◽

G. Rädel ◽

N. A. Scott ◽

S. Serrar

Keyword(s):

South America ◽

Diurnal Cycle ◽

Cloud Amount ◽

Early Morning ◽

Infrared Observation ◽

Relevant Variable ◽

Diurnal Variability ◽

Cloud Properties ◽

Early Afternoon ◽

The Tropics

Abstract Eight years of cloud properties retrieved from Television Infrared Observation Satellite-N (TIROS-N) Observational Vertical Sounder (TOVS) observations aboard the NOAA polar orbiting satellites are presented. The relatively high spectral resolution of these instruments in the infrared allows especially reliable cirrus identification day and night. This dataset therefore provides complementary information to the International Satellite Cloud Climatology Project (ISCCP). According to this dataset, cirrus clouds cover about 27% of the earth and 45% of the Tropics, whereas ISCCP reports 19% and 25%, respectively. Both global datasets agree within 5% on the amount of single-layer low clouds, at 30%. From 1987 to 1995, global cloud amounts remained stable to within 2%. The seasonal cycle of cloud amount is in general stronger than its diurnal cycle and it is stronger than the one of effective cloud amount, the latter the relevant variable for radiative transfer. Maximum effective low cloud amount over ocean occurs in winter in SH subtropics in the early morning hours and in NH midlatitudes without diurnal cycle. Over land in winter the maximum is in the early afternoon, accompanied in the midlatitudes by thin cirrus. Over tropical land and in the other regions in summer, the maximum of mesoscale high opaque clouds occurs in the evening. Cirrus also increases during the afternoon and persists during night and early morning. The maximum of thin cirrus is in the early afternoon, then decreases slowly while cirrus and high opaque clouds increase. TOVS extends information of ISCCP during night, indicating that high cloudiness, increasing during the afternoon, persists longer during night in the Tropics and subtropics than in midlatitudes. A comparison of seasonal and diurnal cycle of high cloud amount between South America, Africa, and Indonesia during boreal winter has shown strong similarities between the two land regions, whereas the Indonesian islands show a seasonal and diurnal behavior strongly influenced by the surrounding ocean. Deeper precipitation systems over Africa than over South America do not seem to be directly reflected in the horizontal coverage and mesoscale effective emissivity of high clouds.

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Correcting orbital drift signal in the time series of AVHRR derived convective cloud fraction using rotated empirical orthogonal function

Atmospheric Measurement Techniques ◽

10.5194/amt-5-267-2012 ◽

2012 ◽

Vol 5 (2) ◽

pp. 267-273 ◽

Cited By ~ 8

Author(s):

A. Devasthale ◽

K.-G. Karlsson ◽

J. Quaas ◽

H. Grassl

Keyword(s):

Time Series ◽

Empirical Orthogonal Function ◽

Diurnal Cycle ◽

Function Analysis ◽

Cloud Amount ◽

Convective Cloud ◽

Orthogonal Function ◽

Orbital Drift ◽

The Impact ◽

Rotated Empirical Orthogonal Function

Abstract. The Advanced Very High Resolution Radiometer (AVHRR) instruments onboard the series of National Oceanic and Atmospheric Administration (NOAA) satellites offer the longest available meteorological data records from space. These satellites have drifted in orbit resulting in shifts in the local time sampling during the life span of the sensors onboard. Depending upon the amplitude of the diurnal cycle of the geophysical parameters derived, orbital drift may cause spurious trends in their time series. We investigate tropical deep convective clouds, which show pronounced diurnal cycle amplitude, to estimate an upper bound of the impact of orbital drift on their time series. We carry out a rotated empirical orthogonal function analysis (REOF) and show that the REOFs are useful in delineating orbital drift signal and, more importantly, in subtracting this signal in the time series of convective cloud amount. These results will help facilitate the derivation of homogenized data series of cloud amount from NOAA satellite sensors and ultimately analyzing trends from them. However, we suggest detailed comparison of various methods and rigorous testing thereof applying final orbital drift corrections.

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Potential impact of aerosols on convective clouds revealed by Himawari-8 observations over different terrain types in eastern China

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-6199-2021 ◽

2021 ◽

Vol 21 (8) ◽

pp. 6199-6220

Author(s):

Tianmeng Chen ◽

Zhanqing Li ◽

Ralph A. Kahn ◽

Chuanfeng Zhao ◽

Daniel Rosenfeld ◽

...

Keyword(s):

Water Cycle ◽

Eastern China ◽

Convective Cloud ◽

Northern China ◽

Cloud Data ◽

Convective Clouds ◽

Cloud Properties ◽

Cloud Development ◽

Potential Impact ◽

The Impact

Abstract. Convective clouds are common and play a major role in Earth's water cycle and energy balance; they may even develop into storms and cause severe rainfall events. To understand the convective cloud development process, this study investigates the impact of aerosols on convective clouds by considering the influence of both topography and diurnal variation in radiation. By combining texture analysis, clustering, and thresholding methods, we identify all convective clouds in two warm seasons (May–September, 2016/17) in eastern China based on Himawari-8 Level 1 data. Having large diurnally resolved cloud data together with surface meteorological and environmental measurements, we investigate convective cloud properties and their variation, stratified by elevation and diurnal change. We then analyze the potential impact of aerosol on convective clouds under different meteorological conditions and topographies. In general, convective clouds tend to occur preferentially under polluted conditions in the morning, which reverses in the afternoon. Convective cloud fraction first increases then decreases with aerosol loading, which may contribute to this phenomenon. Topography and diurnal meteorological variations may affect the strength of aerosol microphysical and radiative effects. Updraft is always stronger along the windward slopes of mountains and plateaus, especially in northern China. The prevailing southerly wind near the foothills of mountains and plateaus is likely to contribute to this windward strengthening of updraft and to bring more pollutant into the mountains, thereby strengthening the microphysical effect, invigorating convective clouds. By comparison, over plain, aerosols decrease surface heating and suppress convection by blocking solar radiation reaching the surface.

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Sensitivity of a Large Ensemble of Tropical Convective Systems to Changes in the Thermodynamic and Dynamic Forcings

Journal of the Atmospheric Sciences ◽

10.1175/2007jas2446.1 ◽

2008 ◽

Vol 65 (6) ◽

pp. 1773-1794 ◽

Cited By ~ 7

Author(s):

Zachary A. Eitzen ◽

Kuan-Man Xu

Keyword(s):

Radiative Forcing ◽

Large Scale ◽

Radiant Energy ◽

Convective Cloud ◽

Energy System ◽

Scale Model ◽

Convective Clouds ◽

Cloud Properties ◽

Deep Convective Clouds ◽

Deep Convective Cloud

Abstract A two-dimensional cloud-resolving model (CRM) is used to perform five sets of simulations of 68 deep convective cloud objects identified with Clouds and the Earth’s Radiant Energy System (CERES) data to examine their sensitivity to changes in thermodynamic and dynamic forcings. The control set of simulations uses observed sea surface temperatures (SSTs) and is forced by advective cooling and moistening tendencies derived from a large-scale model analysis matched to the time and location of each cloud object. Cloud properties, such as albedo, effective cloud height, cloud ice and snow path, and cloud radiative forcing (CRF), are analyzed in terms of their frequency distributions rather than their mean values. Two sets of simulations, F+50% and F−50%, use advective tendencies that are 50% greater and 50% smaller than the control tendencies, respectively. The increased cooling and moistening tendencies cause more widespread convection in the F+50% set of simulations, resulting in clouds that are optically thicker and higher than those produced by the control and F−50% sets of simulations. The magnitudes of both longwave and shortwave CRF are skewed toward higher values with the increase in advective forcing. These significant changes in overall cloud properties are associated with a substantial increase in deep convective cloud fraction (from 0.13 for the F−50% simulations to 0.34 for the F+50% simulations) and changes in the properties of non–deep convective clouds, rather than with changes in the properties of deep convective clouds. Two other sets of simulations, SST+2K and SST−2K, use SSTs that are 2 K higher and 2 K lower than those observed, respectively. The updrafts in the SST+2K simulations tend to be slightly stronger than those of the control and SST−2K simulations, which may cause the SST+2K cloud tops to be higher. The changes in cloud properties, though smaller than those due to changes in the dynamic forcings, occur in both deep convective and non–deep convective cloud categories. The overall changes in some cloud properties are moderately significant when the SST is changed by 4 K. The changes in the domain-averaged shortwave and longwave CRFs are larger in the dynamic forcing sensitivity sets than in the SST sensitivity sets. The cloud feedback effects estimated from the SST−2K and SST+2K sets are comparable to prior studies.

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