Low-frequency Time Scale Research Articles

Modulation of East Asian atmospheric rivers by the Pacific-Japan teleconnection pattern

Despite growing recognition that atmospheric rivers (ARs) play an important role in summer monsoon rainfall in East Asia, the AR variability related to low-frequency (LF) climate modes remains largely unknown. This study reports the significant control of the Pacific-Japan (PJ) teleconnection pattern on East Asian summer ARs. While Korea and central to eastern Japan experience more frequent, intense, and persistent ARs during the positive PJ, ARs in eastern China become more active during the negative PJ. Such AR activity changes are closely related to the PJ modulation of the western North Pacific subtropical high along which anomalous moisture transport organizes on the LF time scale. This finding suggests that the PJ pattern is an important source of East Asian summer AR variability and needs to be considered in medium-range forecasts of AR-related hydrological extremes.

An Optimal Atmospheric Circulation Mode in the Arctic Favoring Strong Summertime Sea Ice Melting and Ice–Albedo Feedback

Abstract The rapid decline of summer Arctic sea ice over the past few decades has been driven by a combination of increasing greenhouse gases and internal variability of the climate system. However, uncertainties remain regarding spatial and temporal characteristics of the optimal internal atmospheric mode that most favors summer sea ice melting on low-frequency time scales. To pinpoint this mode, we conduct a suite of simulations in which atmospheric circulation is constrained by nudging tropospheric Arctic (60°–90°N) winds within the Community Earth System Model, version 1 (CESM1), to those from reanalysis. Each reanalysis year is repeated for over 10 model years using fixed greenhouse gas concentrations and the same initial conditions. Composites show the strongest September sea ice losses are closely preceded by a common June–August (JJA) barotropic anticyclonic circulation in the Arctic favoring shortwave absorption at the surface. Successive years of strong wind-driven melting also enhance declines in Arctic sea ice through enhancement of the ice–albedo feedback, reaching a quasi-equilibrium response after repeated wind forcing for over 5–6 years, as the effectiveness of the wind-driven ice–albedo feedback becomes saturated. Strong melting favored by a similar wind pattern as observations is detected in a long preindustrial simulation and 400-yr paleoclimate reanalysis, suggesting that a summer barotropic anticyclonic wind pattern represents the optimal internal atmospheric mode maximizing sea ice melting in both the model and natural world over a range of time scales. Considering strong contributions of this mode to changes in Arctic climate, a better understanding of its origin and maintenance is vital to improving future projections of Arctic sea ice.

Impact of filtering methods on ultrafine particles turbulent fluxes by eddy covariance

In the present work, a comparison between Linear Detrending (LDT) and a Recursive Digital Filter (RDF) in removing the low-frequency contribution to the vertical turbulent fluxes was performed. The two methods were applied in order to obtain a correct evaluation of ultrafine particles, sensible heat and momentum turbulent fluxes. Exchange velocity was also evaluated separating the positive cases (the so called deposition velocity Vd) from negative cases (named emission velocity Ve). The low-frequency time scales (τc) required by the RDF were obtained by means of an ogive analysis of turbulent fluxes for different atmospheric stability conditions (i.e. unstable, stable and neutral). RDF was applied also with a constant low-frequency time scale (RDF300, τc = 300s). The stationarity test proposed by Mahrt (1998 - MST98) has been applied to momentum, kinematic temperature and particle number fluxes before and after applying LDT and RDF methods, in order to investigate the impact of filtering criteria on stationarity of time series. Results emphasised that there were no significant differences in stationary cases for different filtering procedures. The comparison analysis on the main turbulent variables highlighted that wider discrepancies occurred between LDT and RDF300, showing on average an increase in turbulent number particles flux obtained through RDF methods, especially in unstable atmospheric conditions. On the other hand, a mean decrease for momentum and sensible heat fluxes was observed. Filtering procedures led to a slight increase of exchange velocity, although an underestimation occurred for emission and deposition velocities when considered separately.

The North Atlantic Oscillations: Lead–Lag Relations for the NAO, the AMO, and the AMOC—A High-Resolution Lead–lag Analysis

Several studies examine cycle periods and the interactions between the three major climate modes over the North Atlantic, namely the Atlantic meridional overturning circulation (AMOC), the Atlantic multidecadal oscillation (AMO), and the North Atlantic oscillation (NAO). Here, we use a relatively novel high-resolution Lead–lag (LL) method to identify short time windows with persistent LL relations in the three series during the period from 1947 to 2020. We find that there are roughly 20-year time windows where LL relations change direction at both interannual, high-frequency and multidecadal, low-frequency timescales. However, with varying LL strength, the AMO leads AMOC for the full period at the interannual timescale. During the period from 1980 to 2000, we had the sequence NAO→AMO→AMOC→NAO at the interannual timescale. For the full period in the decadal time scale, we obtain NAO→AMO→AMOC. The Ekman variability closely follows the NAO variability. Both single time series and the LL relation between pairs of series show pseudo-oscillating patterns with cycle periods of about 20 years. We list possible mechanisms that contribute to the cyclic behavior, but no conclusive evidence has yet been found.

Changes in the characteristics of North Pacific Jet as a Conduit for U. S. surface air temperature in boreal winter across the late 1990s

AbstractThe leading modes of the North Pacific Jet (NPJ) variability include intensity changes and meridional shifts in jet position on the low frequency timescales. These leading modes of NPJ variability are closely associated with weather and climate conditions spanning from Asia to the United States (US). In this study, we investigated changes in the NPJ’s role as a conduit for US surface air temperature (SAT) anomalies during the boreal winter across the late 1990s. We found that the leading mode of NPJ variability changed from the NPJ intensity changes to meridional shifts in NPJ position across the late 1990s. It leads to the change in the role of NPJ as a conduit for US SAT anomalies. Before the late 1990s, the variability of NPJ’s intensity significantly impacted western US SAT anomalies related to the anomalous surface cyclonic circulation over the North Pacific. After the late 1990s, however, the variability of NPJ’s meridional shift significantly influenced on the eastern US SAT anomalies in association with the anomalous surface cyclonic circulation over the northern North Pacific. Further analysis and model experiments revealed that the western to central North Pacific Ocean has been warming since the late 1990s and modulates atmospheric baroclinicity. This phenomenon mainly leads to a northward NPJ shift and implies that the eddy driven mechanism on the NPJ’s formation, which acts to enhance the meridional variability of NPJ position, becomes dominant. We conclude that this northward shift of NPJ could have contributed to enhancing the NPJ’s meridional shift variability, significantly influencing the eastern US SAT anomalies since the late 1990s.

Changes in the role of Pacific decadal oscillation on sea ice extent variability across the mid-1990s

Characteristics of sea ice extent (SIE) have been rapidly changing in the Pacific Arctic sector (PAS) in recent years. The SIE variability in PAS during the late spring and early summer (i.e., April–May–June, AMJ) plays a key role in determining the SIE during the following fall when SIE is at a minimum. We find that the Pacific Decadal Oscillation (PDO), which is the most dominant variability of sea surface temperature (SST) on the low-frequency timescales, differently influences the SIE in PAS during AMJ before and after the mid-1990s. While a positive phase of PDO during the previous winter acts to increases SIE during AMJ before the mid-1990s, it acts to decrease SIE during AMJ after the mid-1990s. Further analysis indicates that atmospheric circulation associated with PDO differently influences the variability of SIE in the PAS during AMJ by modulating poleward moisture transport across the Alaska or the Far East Asia peninsula. This results in the change in the relationship of PDO and SIE in the PAS before and after the mid-1990s.

Interannual variations of the influences of MJO on winter rainfall in southern China

The influences of Madden-Julian Oscillation (MJO) on the winter rainfall in southern China exhibit prominent interannual variations. In general, when MJO is active over the Indian Ocean (western Pacific), winter rainfall in southern China increases (decreases) substantially; however, it also decreases (increases) significantly in some winters. The anomalous atmospheric circulation, especially the intraseasonal and low-frequency circulation anomalies, like are responsible for these variations. Both the intraseasonal and low-frequency circulation anomalies are almost opposite between wetter and drier winters MJO is active over the Indian Ocean and the western Pacific, which leads to the different moisture convergences in southern China. As a result, the influences of MJO over the same region on winter rainfall in southern China are different. When MJO is active over the Indian Ocean, the moisture convergence (divergence) in wetter (drier) winters is dominated primarily by the meridional (zonal) moisture convergence (divergence) and advection. When MJO is active over the western Pacific, in both wetter and drier winters, the anomalous moisture divergence is controlled by the meridional moisture divergence and advection. Therefore, it is not only the location and intensity of MJO activity that are important; the anomalous circulation and moisture on different timescales (in particular the intraseasonal and low-frequency timescales) should be considered in the operational weather forecast when using MJO as a predictor.

Extracting the Buoyancy-Driven Atlantic Meridional Overturning Circulation

AbstractVariations in the Atlantic meridional overturning circulation (AMOC) driven by buoyancy forcing are typically characterized as having a low-frequency time scale, interhemispheric structure, cross-equatorial heat transport, and linkages to the strength of Northern Hemisphere gyre circulations and the Gulf Stream. This study first tests whether these attributes ascribed to the AMOC are reproduced in a coupled model that is mechanically decoupled and, hence, is only buoyancy coupled. Overall, the mechanically decoupled model reproduces these attributes, with the exception that in the subpolar gyre, buoyancy drives AMOC variations on interannual to multidecadal time scales, yet only the multidecadal variations penetrate into the subtropics. A stronger AMOC is associated with a strengthening of the Northern Hemisphere gyre circulations, Gulf Stream, and northward oceanic heat transport throughout the basin. We then determine whether the characteristics in the mechanically decoupled model can be recovered by low-pass filtering the AMOC in a fully coupled version of the same model, a common approach used to isolate the buoyancy-driven AMOC. A major conclusion is that low-pass filtering the AMOC in the fully coupled model reproduces the buoyancy-driven AMOC pattern and most of the associated attributes, but not the statistics of the temporal variability. The strength of the AMOC–Gulf Stream connection is also not reproduced. The analyses reveal caveats that must be considered when choosing indexes and filtering techniques to estimate the buoyancy-driven AMOC. Results also provide insight on the latitudinal dependence of time scales and drivers of ocean circulation variability in coupled models, with potential implications for measurement and detection of the buoyancy-driven AMOC in the real world.

Subtidal circulation in a microtidal Mediterranean bay

We examine the role of different forcings on the subtidal circulation in a microtidal bay with freshwater inputs in the NW Mediterranean Sea: Alfacs Bay. Observations of subtidal flow in summer 2013 and winter 2014 reveal a two-layered, vertically sheared circulation. During the summer, there is a significant positive correlation between surface currents and winds along the main axis of the bay, while a negative correlation is observed between wind and the bottom layers. During the winter, the cross-shore response is correlated with the most energetic winds, showing a two-layered vertical structure inside the bay and a nearly depth-independent water motion caused by high wind speeds at the bay mouth. The vertical structure of the velocities, as determined through empirical orthogonal function analysis, confirms that surface layers are affected by winds and bottom currents correlated negatively with winds as a response of the wind set-up. Seasonal mean circulation reveals gravitational exchange at the bay mouth during the summer. However, mean circulation is unclear in the inner bay and close to the drainage channels. Observed flow patterns are supported by modelling results that confirm the persistence of averaged current in the low-frequency dynamics. Re-circulation areas in the inner bay indicate the rich spatial variability in flow at low-frequency time scales.

From Synoptic to Interdecadal Variability in Southern African Rainfall: Toward a Unified View across Time Scales

AbstractDuring the austral summer season (November–February), southern African rainfall, south of 20°S, has been shown to vary over a range of time scales, from synoptic variability (3–7 days, mostly tropical temperate troughs) to interannual variability (2–8 years, reflecting the regional effects of El Niño–Southern Oscillation). There is also evidence for variability at quasi-decadal (8–13 years) and interdecadal (15–28 years) time scales, linked to the interdecadal Pacific oscillation and the Pacific decadal oscillation, respectively. This study aims to provide an overview of these ranges of variability and their influence on regional climate and large-scale atmospheric convection and quantify uncertainties associated with each time scale. We do this by applying k-means clustering onto long-term (1901–2011) daily outgoing longwave radiation anomalies derived from the 56 individual members of the Twentieth Century Reanalysis. Eight large-scale convective regimes are identified. Results show that 1) the seasonal occurrence of the regimes significantly varies at the low-frequency time scales mentioned above; 2) these modulations account for a significant fraction of seasonal rainfall variability over the region; 3) significant associations are found between some of the regimes and the aforementioned modes of climate variability; and 4) associated uncertainties in the regime occurrence and convection anomalies strongly decrease with time, especially the phasing of transient variability. The short-lived synoptic anomalies and the low-frequency anomalies are shown to be approximately additive, but even if they combine their respective influence at both scales, the magnitude of short-lived perturbations remains much larger.

Comparison of Low-Frequency Internal Climate Variability in CMIP5 Models and Observations

Low-frequency internal climate variability (ICV) plays an important role in modulating global surface temperature, regional climate, and climate extremes. However, it has not been completely characterized in the instrumental record and in the Coupled Model Intercomparison Project phase 5 (CMIP5) model ensemble. In this study, the surface temperature ICV of the North Pacific (NP), North Atlantic (NA), and Northern Hemisphere (NH) in the instrumental record and historical CMIP5 all-forcing simulations is isolated using a semiempirical method wherein the CMIP5 ensemble mean is applied as the external forcing signal and removed from each time series. Comparison of ICV signals derived from this semiempirical method as well as from analysis of ICV in CMIP5 preindustrial control runs reveals disagreement in the spatial pattern and amplitude between models and instrumental data on multidecadal time scales (>20 yr). Analysis of the amplitude of total variability and the ICV in the models and instrumental data indicates that the models underestimate ICV amplitude on low-frequency time scales (>20 yr in the NA; >40 yr in the NP), while agreement is found in the NH variability. A multiple linear regression analysis of ICV in the instrumental record shows that variability in the NP drives decadal-to-interdecadal variability in the NH, whereas the NA drives multidecadal variability in the NH. Analysis of the CMIP5 historical simulations does not reveal such a relationship, indicating model limitations in simulating ICV. These findings demonstrate the need to better characterize low-frequency ICV, which may help improve attribution and decadal prediction.

Multi-year climate variability in the Southwestern United States within a context of a dynamically downscaled twentieth century reanalysis

This investigation evaluates whether there is coherency in warm and cool season precipitation at the low-frequency scale that may be responsible for multi-year droughts in the US Southwest. This low-frequency climate variability at the decadal scale and longer is studied within the context of a twentieth-century reanalysis (20CR) and its dynamically-downscaled version (DD-20CR). A spectral domain matrix methods technique (Multiple-Taper-Method Singular Value Decomposition) is applied to these datasets to identify statistically significant spatiotemporal precipitation patterns for the cool (November–April) and warm (July–August) seasons. The low-frequency variability in the 20CR is evaluated by exploring global to continental-scale spatiotemporal variability in moisture flux convergence (MFC) to the occurrence of multiyear droughts and pluvials in Central America, as this region has a demonstrated anti-phase relationship in low-frequency climate variability with northern Mexico and the southwestern US By using the MFC in lieu of precipitation, this study reveals that the 20CR is able to resolve well the low-frequency, multiyear climate variability. In the context of the DD-20CR, multiyear droughts and pluvials in the southwestern US (in the early twentieth century) are significantly related to this low-frequency climate variability. The precipitation anomalies at these low-frequency timescales are in phase between the cool and warm seasons, consistent with the concept of dual-season drought as has been suggested in tree ring studies.

Evidencing decadal and interdecadal hydroclimatic variability over the Central Andes

In this study we identified a significant low frequency variability (8 to 20 years) that characterizes the hydroclimatology over the Central Andes. Decadal–interdecadal variability is related to the central-western Pacific Ocean (R2 = 0.50) and the zonal wind at 200 hPa above the Central Andes (R2 = 0.66). These two oceanic–atmospheric variables have a dominant decadal–interdecadal variability, and there is a strong relationship between them at a low frequency time scale (R2 = 0.66). During warming decades in the central-western Pacific Ocean, westerlies are intensified at 200 hPa above the Central Andes, which produce decadal periods of hydrological deficit over this region. In contrast, when the central-western Pacific Ocean is cooler than usual, easterly anomalies prevail over the Central Andes, which are associated with decades of positive hydrological anomalies over this region. Our results indicate that impacts of El Niño on hydrology over the Central Andes could be influenced by the low frequency variability documented in this study.

Oscillatory Darcy Flow in Porous Media

We investigate the flow in a porous medium subjected to an oscillatory (sinusoidal) pressure gradient. Direct numerical simulation (DNS) has been performed to benchmark the analytical solutions of the unsteady Darcy equation with two different expressions of the time scale: one given by a consistent volume averaging of the Navier–Stokes equation with a steady-state closure for the flow-resistance term, another given by volume averaging of the kinetic energy equation with a closure for the dissipation rate. For small and medium frequencies, the analytical solutions with the time scale obtained by the energy approach compare well with the DNS results in terms of amplitude and phase lag. For large dimensionless frequencies (\(\omega \tau \gtrsim 10\)), we observe a slightly smaller damping of the amplitude than predicted by the unsteady Darcy equation with the low-frequency time scale. This can be explained by a change in the velocity fields towards a potential flow solution. Note that at those high frequencies, the flow amplitudes remain below 1 % of those of the steady-state flows. Our DNSs, however, indicate that the time scale predicted by the steady-state closure for the flow-resistance term is too small. In general, this study supports the use of the unsteady form of Darcy’s equation with constant coefficients to solve time-periodic Darcy flow, provided the proper time scale has been found.

Relative Contributions of Synoptic and Low-Frequency Eddies to Time-Mean Atmospheric Moisture Transport, Including the Role of Atmospheric Rivers

The relative contributions to mean global atmospheric moisture transport by both the time-mean circulation and by synoptic and low-frequency (periods greater than 10 days) anomalies are evaluated from the vertically integrated atmospheric moisture budget based on 40 yr of “chi corrected” NCEP–NCAR reanalysis data. In the extratropics, while the time-mean circulation primarily moves moisture zonally within ocean basins, low-frequency and synoptic anomalies drive much of the mean moisture transport both from ocean to land and toward the poles. In particular, during the cool-season low-frequency variability is the largest contributor to mean moisture transport into southwestern North America, Europe, and Australia. While some low-frequency transport originates in low latitudes, much is of extratropical origin due to large-scale atmospheric anomalies that extract moisture from the northeast Pacific and Atlantic Oceans. Low-frequency variability is also integral to the Arctic (latitudes > 70°N) mean moisture budget, especially during summer, when it drives mean poleward transport from relatively wet high-latitude continental regions. Synoptic variability drives about half of the mean poleward moisture transport in the midlatitudes of both hemispheres, consistent with simple “lateral mixing” arguments. Extratropical atmospheric transport is also particularly focused within “atmospheric rivers” (ARs), relatively narrow poleward-moving moisture plumes associated with frontal dynamics. AR moisture transport, defined by compositing fluxes over those locations and times where column-integrated water vapor and poleward low-level wind anomalies are both positive, represents most of the total extratropical meridional moisture transport. These results suggest that understanding potential anthropogenic changes in the earth ’s hydrological cycle may require understanding corresponding changes in atmospheric variability, especially on low-frequency time scales.

The effect of ventricular assist devices on cerebral blood flow and blood pressure fractality

Biological signals often exhibit self-similar or fractal scaling characteristics which may reflect intrinsic adaptability to their underlying physiological system. This study analysed fractal dynamics of cerebral blood flow in patients supported with ventricular assist devices (VAD) to ascertain if sustained modifications of blood pressure waveform affect cerebral blood flow fractality. Simultaneous recordings of arterial blood pressure and cerebral blood flow velocity using transcranial Doppler were obtained from five cardiogenic shock patients supported by VAD, five matched control patients and five healthy subjects. Computation of a fractal scaling exponent (α) at the low-frequency time scale by detrended fluctuation analysis showed that cerebral blood flow velocity exhibited 1/f fractal scaling in both patient groups (α = 0.95 ± 0.09 and 0.97 ± 0.12, respectively) as well as in the healthy subjects (α = 0.86 ± 0.07). In contrast, fluctuation in blood pressure was similar to non-fractal white noise in both patient groups (α = 0.53 ± 0.11 and 0.52 ± 0.09, respectively) but exhibited 1/f scaling in the healthy subjects (α = 0.87 ± 0.04, P < 0.05 compared with the patient groups). The preservation of fractality in cerebral blood flow of VAD patients suggests that normal cardiac pulsation and central perfusion pressure changes are not the integral sources of cerebral blood flow fractality and that intrinsic vascular properties such as cerebral autoregulation may be involved. However, there is a clear difference in the fractal scaling properties of arterial blood pressure between the cardiogenic shock patients and the healthy subjects.

Dynamics and decoherence in the central spin model using exact methods

The dynamics and decoherence of an electronic spin-1/2 qubit coupled to a bath of nuclear spins via hyperfine interactions in a quantum dot is studied. We show how exact results from the integrable solution can be used to understand the dynamic behavior of the qubit. It is possible to predict the main frequency contributions and their broadening for relatively general initial states analytically, leading to an estimate of the corresponding decay times, which are related to ${T}_{1}$ of the electron. Furthermore, for a small bath polarization, a distinct low-frequency time scale is observed.

A pulsed system frequency analysis for device characterization and experimental design: Application to porous silicon sensors and extension

Methods of acoustic theory have been applied to signal analysis for improving device characterization on low-frequency timescales. The benefits of this approach include improved measurement sensitivity, isolation of periodic noise sources, and the ability to evaluate the trade-off between the precision and the duration of a measurement to aid the design of an experimental system. A defined gas pulsing technique is combined with FFT signal analysis to allow a sensor gas response to be measured, without saturation, and filtered on a drifting baseline, so as to eliminate false positives and the effects of external noise (as might be associated with pressure, temperature, and humidity variation). Significant advantages can be provided over traditional test-and-measure evaluation schemes, especially near the detection limit of a device, or in the presence of high amplitude noise. The technique, which has been implemented for a porous silicon sensor, shows the potential to improve a number of sensor and experimental systems. The range of applications is discussed.

Variability of surface heat flux over the Indian Ocean

The variability of surface heat flux over the Indian Ocean is investigated using in situ observational data. First, the Indian Ocean is divided into eight regions and the power spectra of surface heat fluxes are calculated for each region. Consequently it is shown that the surface heat flux over the Indian Ocean has three characteristic timescales: (1) the high frequency timescale (periods shorter than 20 months), (2) the middle frequency timescale (periods between 20 and 60 months), and (3) the low frequency timescale (periods longer than 60 months). Seasonal variation is dominant for the high frequency timescale, with shortwave radiation and the latent heat flux being the principal components of the variability at this timescale. Furthermore, the seasonal variation can be divided into three patterns depending on the region. The variation of shortwave radiation and the latent heat flux are also dominant in the middle‐frequency timescale. In some regions, heat flux variation for this timescale appears to be associated with El Niño. For the low‐frequency timescale, the latent heat flux is dominant. It should be noted that the heat flux from the ocean to the atmosphere has clearly increased since the late 1970s as a result of increases in wind speeds and the specific humidity difference.

Reply to comment by N. D. Marsh and H. Svensmark on “Solar influences on cosmic rays and cloud formation: A reassessment”

[1] Svensmark and Friis-Christensen [1997] (hereinafter referred to as SFC97) proposed a ‘‘galactic cosmic ray (GCR), clouds, and climate’’ hypothesis that cosmic ray flux, modulated by solar activity, may modify global total cloud cover (TCC) and thus global surface temperature by changing the number of ions in the atmosphere and thus the cloud droplet formation. This GCR-TCC hypothesis has been questioned by many authors who examined correlations of GCR with various satellite cloud properties and over different time intervals. We note that the SFC97 hypothesis differs from the one proposed by Marsh and Svensmark [2000] (hereinafter referred to as MS00), who postulated that the GCR influence on cloudiness is restricted to low cloud cover (LCC). [2] All the articles in this debate were based on satellite data and limited to the ocean. By contrast, Sun and Bradley [2002] (hereinafter SB02) combined short-period satellite data (from the International Satellite Cloud Climatology Project, ISCCP) with long-term visual total cloud observations to reassess the GCR-TCC relationship over the ocean and the land as well. The SB02 study was initialized in early 2000, focusing on the GCR-TCC hypothesis. In the early spring of 2001 we added to our revision several comments regarding the GCR-LCC hypothesis. We concluded in our analysis that there is no solid evidence for the existence of a GCR-cloud correlation (either total cloud or low cloud cover). [3] Marsh and Svensmark [2004] (hereinafter referred to as MS04) raised five comments about our analysis and finally claimed that ‘‘On the basis of satellite observations, there continue to be strong indications of a globally distributed correlation between cosmic rays and low-cloud cover.’’ We will demonstrate in this reply that their comments are either unfounded or illogical. All of their comments are dealt with in section 2, but issues relevant to the GCR-LCC hypothesis will be separately addressed in section 3. New evidence will be present in section 3 to indicate that the quality of the ISCCP infrared (IR) LCC data set, which MS00 and Marsh and Svensmark [2003] (hereinafter referred to as MS03) used to create the GCR-LCC hypothesis, is highly questionable. This reply confirms the view we expressed on the work of SB02 that there is no solid GCR-cloud relationship.