scholarly journals Time-to-Detect Trends in Precipitable Water Vapor with Varying Measurement Error

2014 ◽  
Vol 27 (21) ◽  
pp. 8259-8275 ◽  
Author(s):  
Jacola Roman ◽  
Robert Knuteson ◽  
Steve Ackerman
Keyword(s):  
Water Vapor ◽  
Measurement Error ◽  
Measurement Errors ◽  
Climate Model ◽  
Global Climate ◽  
Spatial Scales ◽  
Global Climate Model ◽  
Precipitable Water ◽  
Precipitable Water Vapor ◽  
Eastern United States

Abstract This study determined the theoretical time-to-detect (TTD) global climate model (GCM) precipitable water vapor (PWV) 100-yr trends when realistic measurement errors are considered. Global trends ranged from 0.055 to 0.072 mm yr−1 and varied minimally from season to season. Global TTDs with a 0% measurement error ranged from 3.0 to 4.8 yr, while a 5% measurement error increased the TTD by almost 6 times, ranging from 17.6 to 22.0 yr. Zonal trends were highest near the equator; however, zonal TTDs were nearly independent of latitude when 5% measurement error was included. Zonal TTDs are significantly reduced when the trends are analyzed by season. Regional trends (15° × 30°) show TTDs close to those in the 15° latitude zones (15° × 360°). Detailed case study analysis of four selected regions with high population density—eastern United States, Europe, China, and India—indicated that trend analysis on regional spatial scales may provide the most timely information regarding highly populated regions when comparing detection time scales to global and zonal analyses.

scholarly journals Assessment of Regional Global Climate Model Water Vapor Bias and Trends Using Precipitable Water Vapor (PWV) Observations from a Network of Global Positioning Satellite (GPS) Receivers in the U.S. Great Plains and Midwest

2012 ◽  
Vol 25 (16) ◽  
pp. 5471-5493 ◽  
Author(s):  
Jacola A. Roman ◽  
Robert O. Knuteson ◽  
Steven A. Ackerman ◽  
David C. Tobin ◽  
Henry E. Revercomb
Keyword(s):  
Water Vapor ◽  
Great Plains ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Precipitable Water ◽  
Specific Humidity ◽  
Model Output ◽  
Global Positioning ◽  
The U.S

Abstract Precipitable water vapor (PWV) observations from the National Center of Atmospheric Research (NCAR) SuomiNet networks of ground-based global positioning system (GPS) receivers and the National Oceanic and Atmospheric Administration (NOAA) Profiler Network (NPN) are used in the regional assessment of global climate models. Study regions in the U.S. Great Plains and Midwest highlight the differences among global climate model output from the Fourth Assessment Report (AR4) Special Report on Emissions Scenarios (SRES) A2 scenario in their seasonal representation of column water vapor and the vertical distribution of moisture. In particular, the Community Climate System model, version 3 (CCSM3) is shown to exhibit a dry bias of over 30% in the summertime water vapor column, while the Goddard Institute for Space Studies Model E20 (GISS E20) agrees well with PWV observations. A detailed assessment of vertical profiles of temperature, relative humidity, and specific humidity confirm that only GISS E20 was able to represent the summertime specific humidity profile in the atmospheric boundary layer (<3%) and thus the correct total column water vapor. All models show good agreement in the winter season for the region. Regional trends using station-elevation-corrected GPS PWV data from two complimentary networks are found to be consistent with null trends predicted in the AR4 A2 scenario model output for the period 2000–09. The time to detect (TTD) a 0.05 mm yr−1 PWV trend, as predicted in the A2 scenario for the period 2000–2100, is shown to be 25–30 yr with 95% confidence in the Oklahoma–Kansas region.

scholarly journals Predicted Changes in the Frequency of Extreme Precipitable Water Vapor Events

2015 ◽  
Vol 28 (18) ◽  
pp. 7057-7070 ◽  
Author(s):  
Jacola Roman ◽  
Robert Knuteson ◽  
Steve Ackerman ◽  
Hank Revercomb
Keyword(s):  
United States ◽  
Water Vapor ◽  
Climate Models ◽  
Global Climate ◽  
Precipitable Water ◽  
Heavy Precipitation ◽  
Precipitable Water Vapor ◽  
Global Climate Models ◽  
Eastern United States ◽  
Mean Trend

Abstract A high amount of precipitable water vapor (PWV) is a necessary requirement for heavy precipitation and extreme flooding events. This study determined the predicted shift in extreme PWV from a set of CMIP5 global climate models using the highest emission scenario over three different spatial resolutions (global, zonal, and regional) and four different case regions (India, China, Europe, and eastern United States). For the globe, the frequency of the extreme 1% of PWV events between 2006 and 2030 was predicted to increase by a median factor (herein called an X factor) of 9 by 2075–99. Areas of high PWV, like the tropics, tended toward higher factors. The annual median X factor for India, China, central Europe, and the eastern United States was 24, 17, 15, and 16, respectively. For India, the minimum median X factor was 10 during December–February (DJF) and the maximum was 48 during June–August (JJA). In China, the minimum median X factor (8) occurred during DJF, and the maximum was 42 in JJA. For Europe, DJF and September–November (SON) had the smallest median X factor of 15, whereas JJA had the largest median X factor of 30. The smallest median X factor for the eastern United States (11) occurred during March–May (MAM), whereas the largest median X factor (32) occurred in JJA. Regional X factors were significantly larger than global (1.5–2 times larger), illustrating the importance of regional assessments of extreme PWV. The mean trend in the extreme PWV was approximately linear for all regions with a slope of about 3% decade−1. Observations for 10 (20) years are needed for the extreme PWV to change by an amount that exceeds a 3% (5%) measurement error.

scholarly journals Composite Analysis of Winter Cyclones in a GCM: Influence on Climatological Humidity

2006 ◽  
Vol 19 (9) ◽  
pp. 1652-1672 ◽  
Author(s):  
Mike Bauer ◽  
Anthony D. Del Genio
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Cloud Properties ◽  
Frontal Zones ◽  
Goddard Institute ◽  
Ageostrophic Circulation

Abstract The role of midlatitude baroclinic cyclones in maintaining the extratropical winter distribution of water vapor in an operational global climate model is investigated. A cyclone identification and tracking algorithm is used to compare the frequency of occurrence, propagation characteristics, and composite structure of 10 winters of storms in the Goddard Institute for Space Studies general circulation model (GCM) and in two reanalysis products. Cyclones are the major dynamical source of water vapor over the extratropical oceans in the reanalyses. The GCM produces fewer, generally weaker, and slower-moving cyclones than the reanalyses and is especially deficient in storms associated with secondary cyclogenesis. Composite fields show that GCM cyclones are shallower and drier aloft than those in the reanalyses and that their vertical structure is less tilted in the frontal region because of the GCM’s weaker ageostrophic circulation. This is consistent with the GCM’s underprediction of midlatitude cirrus. The GCM deficiencies do not appear to be primarily due to parameterization errors; the model is too dry despite producing less storm precipitation than is present in the reanalyses and in an experimental satellite precipitation dataset, and the weakness and shallow structure of GCM cyclones is already present at storm onset. These shortcomings may be common to most climate GCMs that do not resolve the mesoscale structure of frontal zones, and this may account for some universal problems in climate GCM midlatitude cloud properties.

scholarly journals On the Seasonal Forecasting of Regional Tropical Cyclone Activity

2014 ◽  
Vol 27 (21) ◽  
pp. 7994-8016 ◽  
Author(s):  
G. A. Vecchi ◽  
T. Delworth ◽  
R. Gudgel ◽  
S. Kapnick ◽  
A. Rosati ◽  
...  
Keyword(s):  
High Resolution ◽  
Climate Model ◽  
Global Climate ◽  
Spatial Scales ◽  
Global Climate Model ◽  
Regional Climate ◽  
Weather Extremes ◽  
Moderate Resolution ◽  
Systematic Biases ◽  
Constrained Conditions

Abstract Tropical cyclones (TCs) are a hazard to life and property and a prominent element of the global climate system; therefore, understanding and predicting TC location, intensity, and frequency is of both societal and scientific significance. Methodologies exist to predict basinwide, seasonally aggregated TC activity months, seasons, and even years in advance. It is shown that a newly developed high-resolution global climate model can produce skillful forecasts of seasonal TC activity on spatial scales finer than basinwide, from months and seasons in advance of the TC season. The climate model used here is targeted at predicting regional climate and the statistics of weather extremes on seasonal to decadal time scales, and comprises high-resolution (50 km × 50 km) atmosphere and land components as well as more moderate-resolution (~100 km) sea ice and ocean components. The simulation of TC climatology and interannual variations in this climate model is substantially improved by correcting systematic ocean biases through “flux adjustment.” A suite of 12-month duration retrospective forecasts is performed over the 1981–2012 period, after initializing the climate model to observationally constrained conditions at the start of each forecast period, using both the standard and flux-adjusted versions of the model. The standard and flux-adjusted forecasts exhibit equivalent skill at predicting Northern Hemisphere TC season sea surface temperature, but the flux-adjusted model exhibits substantially improved basinwide and regional TC activity forecasts, highlighting the role of systematic biases in limiting the quality of TC forecasts. These results suggest that dynamical forecasts of seasonally aggregated regional TC activity months in advance are feasible.

scholarly journals Optimal Spectral Nudging for Global Dynamic Downscaling

2017 ◽  
Vol 145 (3) ◽  
pp. 909-927 ◽  
Author(s):  
Martina Schubert-Frisius ◽  
Frauke Feser ◽  
Hans von Storch ◽  
Sebastian Rast
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Spatial Scales ◽  
Global Climate Model ◽  
Circulation Model ◽  
Prognostic Variables ◽  
Reanalysis Dataset ◽  
Spectral Nudging ◽  
High Dependency

This study analyzes a method of constructing a homogeneous, high-resolution global atmospheric hindcast. The method is the spectral nudging technique, which was applied to a state-of-the-art general circulation model (ECHAM6, T255L95). Large spatial scales of the global climate model prognostic variables were spectrally nudged toward a reanalysis dataset (NCEP-1, T62L28) for the past few decades. The main idea is the addition of dynamically consistent regional weather details to the coarse-grid NCEP-1 reanalysis. A large number of sensitivity experiments was performed, using different nudging e-folding times, vertical profiles, wavenumbers, and variables. Comparisons with observations and several reanalyses showed a high dependency on the variations of the nudging configuration. At the global scale, the accordance is very high for extratropical regions and lower in the tropics. A wavenumber truncation of 30, a relatively short e-folding time of 50 min, and a plateau-shaped nudging profile applied only to divergence and vorticity generally yielded the best results. This is one of the first global spectral nudging hindcast studies and the first applying an altitude-dependent profile to selected prognostic variables. The method can be applied to reconstructing the history of extreme events such as intense storms within the context of ongoing climate change.

scholarly journals Relationship Between the Ozone and Water Vapor Columns on Mars as Observed by SPICAM and Calculated by a Global Climate Model

2021 ◽  
Vol 126 (4) ◽  
Author(s):  
F. Lefèvre ◽  
A. Trokhimovskiy ◽  
A. Fedorova ◽  
L. Baggio ◽  
G. Lacombe ◽  
...  
Keyword(s):  
Water Vapor ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model

scholarly journals Estimating Minimum Detection Times for Satellite Remote Sensing of Trends in Mean and Extreme Precipitable Water Vapor

2016 ◽  
Vol 29 (22) ◽  
pp. 8211-8230 ◽  
Author(s):  
Jacola Roman ◽  
Robert Knuteson ◽  
Steve Ackerman ◽  
Hank Revercomb
Keyword(s):  
Water Vapor ◽  
Time Window ◽  
Spatial Scales ◽  
Precipitable Water ◽  
Precipitable Water Vapor ◽  
Trend Detection ◽  
Observation System ◽  
Climate Trends ◽  
Intergovernmental Panel ◽  
Uncertainty Estimates

Abstract The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report found that changes in extreme events have occurred and the frequency of such events is expected to increase. Precipitable water vapor (PWV) is a useful measure of the moisture content of the atmosphere. This paper combines the predicted GCM trends in PWV from 2000 to 2100 with uncertainty estimates from infrared spectrometers, NASA Atmospheric Infrared Sounder (AIRS) and EUMETSAT Infrared Atmospheric Sounding Interferometer (IASI), to estimate minimum trend detection times on regional and global spatial scales. The minimum detection time (MDT) is the number of years before the multimodel GCM trend exceeds a fractional change equal to the uncertainty in the observed product, plus the width of the time window used to smooth out natural variability. Results indicate that the median value of PWV has an MDT of 15 yr or less over all scales, while extreme dry (5th) and wet (95th) PWV conditions (percentiles) have higher measurement uncertainty and corresponding larger MDTs. Product providers have done a relatively good job tuning results to the mean atmospheric state but more attention should be given to improving the satellite estimates for extreme PWV. A fractional measurement error of 3% is desirable to detect predicted climate trends within 15 years or less for the entire PDF of PWV. This paper presents an important case study for the design of observing systems directly linking the estimated uncertainty of the PWV products to the detectability of long-term trends. If there is a need to decrease detection times over the existing weather observation system then necessary changes to the climate observational system design can be understood quantitatively.

scholarly journals The sensitivity of the energy budget and hydrological cycle to CO<sub>2</sub> and solar forcing

2013 ◽  
Vol 4 (1) ◽  
pp. 393-428
Author(s):  
N. Schaller ◽  
J. Cermak ◽  
M. Wild ◽  
R. Knutti
Keyword(s):  
Water Vapor ◽  
Energy Budget ◽  
Large Scale ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Strong Increase ◽  
Solar Forcing ◽  
Co2 Forcing

Abstract. The transient responses of the energy budget and the hydrological cycle to CO2 and solar forcings of the same magnitude in a global climate model are quantified in this study. Idealized simulations are designed to test the assumption that the responses to forcings are linearly additive, i.e. whether the response to individual forcings can be added to estimate the response to the combined forcing, and to understand the physical processes occurring as a response to a surface warming caused by CO2 or solar forcing increases of the same magnitude. For the global climate model considered, the responses of most variables of the energy budget and hydrological cycle, including surface temperature, do not add linearly. A separation of the response into a forcing and a feedback term shows that for precipitation, this non-linearity arises from the feedback term, i.e. from the non-linearity of the temperature response and the changes in the water cycle resulting from it. Further, changes in the energy budget show that less energy is available at the surface for global annual mean latent heat flux, and hence global annual mean precipitation, in simulations of transient CO2 concentration increase compared to simulations with an equivalent transient increase in the solar constant. On the other hand, lower tropospheric water vapor increases more in simulations with CO2 compared to solar forcing increase of the same magnitude. The response in precipitation is therefore more muted compared to the response in water vapor in CO2 forcing simulations, leading to a larger increase in residence time of water vapor in the atmosphere compared to solar forcing simulations. Finally, energy budget calculations show that poleward atmospheric energy transport increases more in solar forcing compared to equivalent CO2 forcing simulations, which is in line with the identified strong increase in large-scale precipitation in solar forcing scenarios.

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