Martin Setvák - Academia.edu (original) (raw)

Papers by Martin Setvák

Research paper thumbnail of MODIS OBSERVATIONS OF DEEP CONVECTIVE CLOUD TOPS

Past studies of the NOAA AVHRR/2 and GOES I-M imagery (e.g., Setvák et al., 1996) have shown that... more Past studies of the NOAA AVHRR/2 and GOES I-M imagery (e.g., Setvák et al., 1996) have shown that frozen tops of deep convective storms occasionally exhibit significant increase of cloud top reflectivity when observed in the 3.7 or 3.9 µm spectral bands. Similar storm top features have been documented in the NOAA-KLM AVHRR/3 1.6 µm spectral band (Setvák et al.,

Research paper thumbnail of SIMULTANEOUS BTD (WV6.2-IR10.8) ANOMALY AND ABOVE-ANVIL ICE PLUME OBSERVED ABOVE THE STORM OF 06 JULY 2010, NORTH ITALY

Research paper thumbnail of Deep convective cross-tropopause transport in the tropics and evidence by A-Train satellites

Cross-tropopause transport by deep convective clouds can be an (and perhaps the most) important s... more Cross-tropopause transport by deep convective clouds can be an (and perhaps the most) important source of water vapor in the stratosphere. Our previous studies have verified that deep convective cross-tropopause transport does occur rather regularly in midlatitudes. This transport is demonstrated by the presence of cloud top features of above anvil cirrus plumes and jumping cirrus phenomenon that have been observed by aircraft, satellite and ground-based observations. The present paper will demonstrate that the same mechanism occurs in the tropics. Because the tropics typically have weaker wind shear at the tropopause level, previous observation did not show clear evidence of the presence of such cross-tropopause features. But the recent NSAS A-Train satellites, especially CloudSat, CALIPSO and MODIS, provide both horizontal cloud top and vertical cross-sectional views of the cloud structure and making the identification of such features much less unambiguous. In this study, we will...

Research paper thumbnail of COLD-RING SHAPED STORMS IN CENTRAL EUROPE

This paper addresses satellite observations of Central European convective storms which exhibit a... more This paper addresses satellite observations of Central European convective storms which exhibit a cloud-top feature resembling a cold ring in the IR-window bands, surrounding a distinct central warm spot (CWS). The storms from 25 June 2006 above the Czech Republic and Austria (Figure 1), the prime topic of this paper, are extraordinary examples of storms with such features - not

Research paper thumbnail of The AVHRR Channel 3 Cloud Top Reflectivity of Convective Storms

Monthly Weather Review, 1991

Research paper thumbnail of Multispectral, High-Resolution Satellite Observations of Plumes on Top of Convective Storms

Journal of the Atmospheric Sciences, 1996

Multispectral, high-resolution imagery from the Advanced Very High Resolution Radiometer of NOAA ... more Multispectral, high-resolution imagery from the Advanced Very High Resolution Radiometer of NOAA polar orbiting satellites is used to analyze the cloud-top structure of convective storms that develop a cirrus feature above the anvil, referred to as a plume, whose origin remains unclear. Images from the radiometer's channels 2, 3, and 4 and a combination of any two of these suggest a relationship between the emergence of such plumes and a source of small ice particles (diameter around 3.7 mm, channel 3 wavelength) at the cloud top. Unique observations of deep convective storms over Europe are presented and discussed. The paper does not provide an exhaustive explanation of the phenomenon but contributes original material to the study of convective storm cloud-top structure, which is far from being completely described.

Research paper thumbnail of Satellite observations of convective storm tops in the 1.6, 3.7 and 3.9 μm spectral bands

Atmospheric Research, 2003

Spatial and temporal characteristics of convective storm tops observed in the 1.6, 3.7 or 3.9 Am ... more Spatial and temporal characteristics of convective storm tops observed in the 1.6, 3.7 or 3.9 Am and visible satellite spectral bands were examined. National Oceanic and Atmospheric Administration (NOAA)/Advanced Very High Resolution Radiometer (AVHRR) observations over Europe during the 1980s have shown that some storms exhibit a significant increase in the 3.7 Am cloud top reflectivity. Subsequent NOAA/AVHRR observations have shown that similar cloud top phenomena can be found as well for convective storms over the US Great Plains. The launch of the Geostationary Operational Environmental Satellite (GOES)-8, 9 and 10 has enabled the study of the evolution of storm cloud top structures in a similar band (3.9 Am) with high temporal resolution. This imagery shows that the smallest areas of increased 3.9 Am reflectivity (within or above storm tops) appear and fade on the scale of a few minutes, although larger ones can persist for tens of minutes to several hours. Occasionally, cloud top structures resembling plumes have been observed above some of the storms, apparently emanating from cores of these.

Research paper thumbnail of Further evidences of deep convective vertical transport of water vapor through the tropopause

Atmospheric Research, 2009

A few years ago, we identified a deep convective transport mechanism, of water vapor through the ... more A few years ago, we identified a deep convective transport mechanism, of water vapor through the tropopause, namely, storm top gravity wave breaking, such that tropospheric water substance can be injected into the lower stratosphere via this pathway. The main evidence presented previously was taken from the lower resolution AVHRR images of the storm anvil top cirrus plumes obtained by polar orbiting satellites. Recent observations have provided further supporting evidence for this important cross-tropopause transport mechanism. There are now many higher resolution satellite images, mainly from MODIS instrument, that show more definitely the existence of these plumes, many of which would probably be unseen by lower resolution images. Furthermore, a thunderstorm movie taken in Denver (USA) area during STEPS2000 field campaign and another thunderstorm movie taken by a building top webcam in Zurich also demonstrate that the jumping cirrus phenomenon, first identified by T. Fujita in 1980s, may be quite common in active thunderstorm cells, quite contrary to previous belief that it is rare. We have used a cloud model to demonstrate that the jumping cirrus is exactly the gravity wave breaking phenomenon that transports water vapor through the tropopause. These additional evidences provide increasing support that deep convection contributes substantially to the troposphere-to-stratosphere transport of water substance. This corroborates well with recent studies of the stratospheric HDO/H 2 O ratio which is much highly than it would be if the transport is via slow ascent. The only explanation that can be used to interpret this observation at present is that water substance is transported through the tropopause via rapid vertical motion, i.e., deep convection.

Research paper thumbnail of Contribution of the MODIS instrument to observations of deep convective storms and stratospheric moisture detection in GOES and MSG imagery

Atmospheric Research, 2007

Past studies based on the NOAA/AVHRR and GOES I-M imager instruments have documented the link bet... more Past studies based on the NOAA/AVHRR and GOES I-M imager instruments have documented the link between certain storm top features referred to as the "cold-U/V" shape in the 10-12 μm IR band imagery and plumes of increased 3.7/3.9 μm band reflectivity. Later, similar features in the 3.7/3.9 μm band have been documented in the AVHRR/3 1.6 μm band imagery.

Research paper thumbnail of Indication of water vapor transport into the lower stratosphere above midlatitude convective storms: Meteosat Second Generation satellite observations and radiative transfer model simulations

Atmospheric Research, 2008

Past studies using a variety of satellite instruments have demonstrated the possibility of detect... more Past studies using a variety of satellite instruments have demonstrated the possibility of detecting lower stratospheric water vapor against a cold background of deep convective storm tops. The method is based on the brightness temperature difference (BTD) between the water vapor absorption and infrared window bands, assuming a thermal inversion above the cloud top level. This paper confirms the earlier studies, documenting positive BTD values between the 6.2 μm and 10.8 μm bands in Meteosat Second Generation (MSG) Spinning Enhanced Visible and InfraRed Imager (SEVIRI) imagery above tops of deep convective storms over Europe. The observed positive BTD values for a case from 28 June 2005 are compared to calculations from a radiative transfer model, and possible reasons for their existence are discussed. A localized increase in positive BTD is observed at the later stages of storm evolution, and this increase is likely a signal of water vapor being transported by this particular storm from the troposphere into the lower stratosphere.

Research paper thumbnail of Tornadoes within the Czech Republic: from early medieval chronicles to the “internet society”

Atmospheric Research, 2003

This paper addresses the historical documentation of tornadoes and the awareness of tornadic even... more This paper addresses the historical documentation of tornadoes and the awareness of tornadic events in the area of the present Czech Republic throughout the last nine centuries. The oldest records of tornado occurrence in the region can be found in chronicles from the first half of the 12th century—the two most interesting of these are presented here in translation from

Research paper thumbnail of Ship wave signature at the cloud top of deep convective storms

Atmospheric Research, 2010

We identify certain features atop some thunderstorms observed by meteorological satellites as shi... more We identify certain features atop some thunderstorms observed by meteorological satellites as ship wave-like. A few examples of satellite visible images are shown and the ship wave signature patterns in them are identified and discussed. The presence of ship wave signatures implies the existence of a dynamical mechanism in the storm that behaves like an obstacle to the ambient flow. We use a numerical storm model simulation to show that this mechanism is due to the strong updraft and divergence in the upper part of the storm.

Research paper thumbnail of Satellite-observed cold-ring-shaped features atop deep convective clouds

This paper focuses on deep convective storms which exhibit a distinct long-lived cold ring at the... more This paper focuses on deep convective storms which exhibit a distinct long-lived cold ring at their cloud top, as observed in enhanced infrared (IR) window satellite imagery. The feature seems to be closely linked to a similar phenomenon, cold-U/V (enhanced-V) shape, or in general to storms which exhibit an enclosed warm spot or larger warm area downwind of the overshooting tops, surrounded by colder parts of the storm anvil. While storms exhibiting some form of warm spots seem to be quite common, storms exhibiting distinct cold rings or cold-U/ Vs are significantly less frequent. The cold-ring feature is described here for storms which occurred above the Czech Republic and Austria on 25 June 2006. Compared to other cold-ringshaped storms, this case was extraordinary not only by the magnitude and duration of the cold ring and its central warm spot, but also by storm cloud-top heights, reaching 16-17 km, as determined from ground-based C-band radar observations. The paper also addresses a possible link between cold-ring-shaped storms with those exhibiting a cold-U/V (enhanced-V) feature, indicating (based on model results) that the stratification and wind shear just above the tropopause are key conditions for the cold-ring to exist. The case from 25 June 2006 also shows that the cloud top height, derived from satellite radiances, has significant error when applied to this particular type of storm. Finally, we discuss the potential of the satellite-observed cold-ring feature as an indicator of storm severity.

Research paper thumbnail of MODIS OBSERVATIONS OF DEEP CONVECTIVE CLOUD TOPS

Past studies of the NOAA AVHRR/2 and GOES I-M imagery (e.g., Setvák et al., 1996) have shown that... more Past studies of the NOAA AVHRR/2 and GOES I-M imagery (e.g., Setvák et al., 1996) have shown that frozen tops of deep convective storms occasionally exhibit significant increase of cloud top reflectivity when observed in the 3.7 or 3.9 µm spectral bands. Similar storm top features have been documented in the NOAA-KLM AVHRR/3 1.6 µm spectral band (Setvák et al.,

Research paper thumbnail of SIMULTANEOUS BTD (WV6.2-IR10.8) ANOMALY AND ABOVE-ANVIL ICE PLUME OBSERVED ABOVE THE STORM OF 06 JULY 2010, NORTH ITALY

Research paper thumbnail of Deep convective cross-tropopause transport in the tropics and evidence by A-Train satellites

Cross-tropopause transport by deep convective clouds can be an (and perhaps the most) important s... more Cross-tropopause transport by deep convective clouds can be an (and perhaps the most) important source of water vapor in the stratosphere. Our previous studies have verified that deep convective cross-tropopause transport does occur rather regularly in midlatitudes. This transport is demonstrated by the presence of cloud top features of above anvil cirrus plumes and jumping cirrus phenomenon that have been observed by aircraft, satellite and ground-based observations. The present paper will demonstrate that the same mechanism occurs in the tropics. Because the tropics typically have weaker wind shear at the tropopause level, previous observation did not show clear evidence of the presence of such cross-tropopause features. But the recent NSAS A-Train satellites, especially CloudSat, CALIPSO and MODIS, provide both horizontal cloud top and vertical cross-sectional views of the cloud structure and making the identification of such features much less unambiguous. In this study, we will...

Research paper thumbnail of COLD-RING SHAPED STORMS IN CENTRAL EUROPE

This paper addresses satellite observations of Central European convective storms which exhibit a... more This paper addresses satellite observations of Central European convective storms which exhibit a cloud-top feature resembling a cold ring in the IR-window bands, surrounding a distinct central warm spot (CWS). The storms from 25 June 2006 above the Czech Republic and Austria (Figure 1), the prime topic of this paper, are extraordinary examples of storms with such features - not

Research paper thumbnail of The AVHRR Channel 3 Cloud Top Reflectivity of Convective Storms

Monthly Weather Review, 1991

Research paper thumbnail of Multispectral, High-Resolution Satellite Observations of Plumes on Top of Convective Storms

Journal of the Atmospheric Sciences, 1996

Multispectral, high-resolution imagery from the Advanced Very High Resolution Radiometer of NOAA ... more Multispectral, high-resolution imagery from the Advanced Very High Resolution Radiometer of NOAA polar orbiting satellites is used to analyze the cloud-top structure of convective storms that develop a cirrus feature above the anvil, referred to as a plume, whose origin remains unclear. Images from the radiometer's channels 2, 3, and 4 and a combination of any two of these suggest a relationship between the emergence of such plumes and a source of small ice particles (diameter around 3.7 mm, channel 3 wavelength) at the cloud top. Unique observations of deep convective storms over Europe are presented and discussed. The paper does not provide an exhaustive explanation of the phenomenon but contributes original material to the study of convective storm cloud-top structure, which is far from being completely described.

Research paper thumbnail of Satellite observations of convective storm tops in the 1.6, 3.7 and 3.9 μm spectral bands

Atmospheric Research, 2003

Spatial and temporal characteristics of convective storm tops observed in the 1.6, 3.7 or 3.9 Am ... more Spatial and temporal characteristics of convective storm tops observed in the 1.6, 3.7 or 3.9 Am and visible satellite spectral bands were examined. National Oceanic and Atmospheric Administration (NOAA)/Advanced Very High Resolution Radiometer (AVHRR) observations over Europe during the 1980s have shown that some storms exhibit a significant increase in the 3.7 Am cloud top reflectivity. Subsequent NOAA/AVHRR observations have shown that similar cloud top phenomena can be found as well for convective storms over the US Great Plains. The launch of the Geostationary Operational Environmental Satellite (GOES)-8, 9 and 10 has enabled the study of the evolution of storm cloud top structures in a similar band (3.9 Am) with high temporal resolution. This imagery shows that the smallest areas of increased 3.9 Am reflectivity (within or above storm tops) appear and fade on the scale of a few minutes, although larger ones can persist for tens of minutes to several hours. Occasionally, cloud top structures resembling plumes have been observed above some of the storms, apparently emanating from cores of these.

Research paper thumbnail of Further evidences of deep convective vertical transport of water vapor through the tropopause

Atmospheric Research, 2009

A few years ago, we identified a deep convective transport mechanism, of water vapor through the ... more A few years ago, we identified a deep convective transport mechanism, of water vapor through the tropopause, namely, storm top gravity wave breaking, such that tropospheric water substance can be injected into the lower stratosphere via this pathway. The main evidence presented previously was taken from the lower resolution AVHRR images of the storm anvil top cirrus plumes obtained by polar orbiting satellites. Recent observations have provided further supporting evidence for this important cross-tropopause transport mechanism. There are now many higher resolution satellite images, mainly from MODIS instrument, that show more definitely the existence of these plumes, many of which would probably be unseen by lower resolution images. Furthermore, a thunderstorm movie taken in Denver (USA) area during STEPS2000 field campaign and another thunderstorm movie taken by a building top webcam in Zurich also demonstrate that the jumping cirrus phenomenon, first identified by T. Fujita in 1980s, may be quite common in active thunderstorm cells, quite contrary to previous belief that it is rare. We have used a cloud model to demonstrate that the jumping cirrus is exactly the gravity wave breaking phenomenon that transports water vapor through the tropopause. These additional evidences provide increasing support that deep convection contributes substantially to the troposphere-to-stratosphere transport of water substance. This corroborates well with recent studies of the stratospheric HDO/H 2 O ratio which is much highly than it would be if the transport is via slow ascent. The only explanation that can be used to interpret this observation at present is that water substance is transported through the tropopause via rapid vertical motion, i.e., deep convection.

Research paper thumbnail of Contribution of the MODIS instrument to observations of deep convective storms and stratospheric moisture detection in GOES and MSG imagery

Atmospheric Research, 2007

Past studies based on the NOAA/AVHRR and GOES I-M imager instruments have documented the link bet... more Past studies based on the NOAA/AVHRR and GOES I-M imager instruments have documented the link between certain storm top features referred to as the "cold-U/V" shape in the 10-12 μm IR band imagery and plumes of increased 3.7/3.9 μm band reflectivity. Later, similar features in the 3.7/3.9 μm band have been documented in the AVHRR/3 1.6 μm band imagery.

Research paper thumbnail of Indication of water vapor transport into the lower stratosphere above midlatitude convective storms: Meteosat Second Generation satellite observations and radiative transfer model simulations

Atmospheric Research, 2008

Past studies using a variety of satellite instruments have demonstrated the possibility of detect... more Past studies using a variety of satellite instruments have demonstrated the possibility of detecting lower stratospheric water vapor against a cold background of deep convective storm tops. The method is based on the brightness temperature difference (BTD) between the water vapor absorption and infrared window bands, assuming a thermal inversion above the cloud top level. This paper confirms the earlier studies, documenting positive BTD values between the 6.2 μm and 10.8 μm bands in Meteosat Second Generation (MSG) Spinning Enhanced Visible and InfraRed Imager (SEVIRI) imagery above tops of deep convective storms over Europe. The observed positive BTD values for a case from 28 June 2005 are compared to calculations from a radiative transfer model, and possible reasons for their existence are discussed. A localized increase in positive BTD is observed at the later stages of storm evolution, and this increase is likely a signal of water vapor being transported by this particular storm from the troposphere into the lower stratosphere.

Research paper thumbnail of Tornadoes within the Czech Republic: from early medieval chronicles to the “internet society”

Atmospheric Research, 2003

This paper addresses the historical documentation of tornadoes and the awareness of tornadic even... more This paper addresses the historical documentation of tornadoes and the awareness of tornadic events in the area of the present Czech Republic throughout the last nine centuries. The oldest records of tornado occurrence in the region can be found in chronicles from the first half of the 12th century—the two most interesting of these are presented here in translation from

Research paper thumbnail of Ship wave signature at the cloud top of deep convective storms

Atmospheric Research, 2010

We identify certain features atop some thunderstorms observed by meteorological satellites as shi... more We identify certain features atop some thunderstorms observed by meteorological satellites as ship wave-like. A few examples of satellite visible images are shown and the ship wave signature patterns in them are identified and discussed. The presence of ship wave signatures implies the existence of a dynamical mechanism in the storm that behaves like an obstacle to the ambient flow. We use a numerical storm model simulation to show that this mechanism is due to the strong updraft and divergence in the upper part of the storm.

Research paper thumbnail of Satellite-observed cold-ring-shaped features atop deep convective clouds

This paper focuses on deep convective storms which exhibit a distinct long-lived cold ring at the... more This paper focuses on deep convective storms which exhibit a distinct long-lived cold ring at their cloud top, as observed in enhanced infrared (IR) window satellite imagery. The feature seems to be closely linked to a similar phenomenon, cold-U/V (enhanced-V) shape, or in general to storms which exhibit an enclosed warm spot or larger warm area downwind of the overshooting tops, surrounded by colder parts of the storm anvil. While storms exhibiting some form of warm spots seem to be quite common, storms exhibiting distinct cold rings or cold-U/ Vs are significantly less frequent. The cold-ring feature is described here for storms which occurred above the Czech Republic and Austria on 25 June 2006. Compared to other cold-ringshaped storms, this case was extraordinary not only by the magnitude and duration of the cold ring and its central warm spot, but also by storm cloud-top heights, reaching 16-17 km, as determined from ground-based C-band radar observations. The paper also addresses a possible link between cold-ring-shaped storms with those exhibiting a cold-U/V (enhanced-V) feature, indicating (based on model results) that the stratification and wind shear just above the tropopause are key conditions for the cold-ring to exist. The case from 25 June 2006 also shows that the cloud top height, derived from satellite radiances, has significant error when applied to this particular type of storm. Finally, we discuss the potential of the satellite-observed cold-ring feature as an indicator of storm severity.