Low‐frequency variations in surface atmospheric humidity, temperature, and precipitation: Inferences from reanalyses and monthly gridded observational data sets

[1] Evidence is presented of a reduction in relative humidity over low-latitude and midlatitude land areas over a period of about 10 years leading up to 2008, based on monthly anomalies in surface air temperature and humidity from comprehensive European Centre for Medium-Range Weather Forecasts reanalyses (ERA-40 and ERA-Interim) and from Climatic Research Unit and Hadley Centre analyses of monthly station temperature data (CRUTEM3) and synoptic humidity observations (HadCRUH). The data sets agree well for both temperature and humidity variations for periods and places of overlap, although the average warming over land is larger for the fully sampled ERA data than for the spatially and temporally incomplete CRUTEM3 data. Near-surface specific humidity varies similarly over land and sea, suggesting that the recent reduction in relative humidity over land may be due to limited moisture supply from the oceans, where evaporation has been limited by sea surface temperatures that have not risen in concert with temperatures over land. Continental precipitation from the reanalyses is compared with a new gauge-based Global Precipitation Climatology Centre (GPCC) data set, with the combined gauge and satellite products of the Global Precipitation Climatology Project (GPCP) and the Climate Prediction Center (CPC), Merged Analysis of Precipitation (CMAP), and with CPC's independent gauge analysis of precipitation over land (PREC/L). The reanalyses agree best with the new GPCC and latest GPCP data sets, with ERA-Interim significantly better than ERA-40 at capturing monthly variability. Shifts over time in the differences among the precipitation data sets make it difficult to assess their longer-term variations and any link with longer-term variations in humidity.

[1]  D. Randall,et al.  Climate models and their evaluation , 2007 .

[2]  David Carlson,et al.  Corrections of Humidity Measurement Errors from the Vaisala RS80 Radiosonde—Application to TOGA COARE Data , 2002 .

[3]  Nils Wedi,et al.  Comparison of trends and low-frequency variability in CRU, ERA-40, and NCEP//NCAR analyses of surface air temperature , 2004 .

[4]  K. Trenberth,et al.  Observational needs for climate prediction and adaptation , 2008 .

[5]  Jean-Noël Thépaut,et al.  Analysis and forecast impact of the main humidity observing systems , 2007 .

[6]  J. Chiang,et al.  Supplementary information for "Control of land-ocean temperature contrast by ocean heat uptake" , 2007 .

[7]  S. Clough,et al.  Dry Bias and Variability in Vaisala RS80-H Radiosondes: The ARM Experience , 2003 .

[8]  A. Sterl,et al.  The ERA‐40 re‐analysis , 2005 .

[9]  Vincent R. Gray.  Climate Change 2007: The Physical Science Basis Summary for Policymakers , 2007 .

[10]  Thomas M. Smith,et al.  An Improved In Situ and Satellite SST Analysis for Climate , 2002 .

[11]  J. Thepaut,et al.  Assimilation and modeling of the hydrological cycle in the ECMWF forecasting system: Future observational requirements , 2011 .

[12]  Peter W. Thorne,et al.  Attribution of observed surface humidity changes to human influence , 2007, Nature.

[13]  D. P. DEE,et al.  Bias and data assimilation , 2005 .

[14]  Elizabeth C. Kent,et al.  Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century , 2003 .

[15]  W. Collins,et al.  Global climate projections , 2007 .

[16]  S. Solomon.  The Physical Science Basis : Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[17]  D. Dee,et al.  Variational bias correction of satellite radiance data in the ERA‐Interim reanalysis , 2009 .

[18]  J. Gregory,et al.  Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations , 2007 .

[19]  Steven J. Worley,et al.  ICOADS release 2.1 data and products , 2005 .

[20]  Kevin E. Trenberth,et al.  Trends and variability in column-integrated atmospheric water vapor , 2005 .

[21]  J. Thepaut,et al.  Assimilation and Modeling of the Atmospheric Hydrological Cycle in the ECMWF Forecasting System , 2005 .

[22]  Xungang Yin,et al.  Comparison of the GPCP and CMAP Merged Gauge-Satellite Monthly Precipitation Products for the Period 1979-2001 , 2004 .

[23]  J. Kennedy,et al.  Improved Analyses of Changes and Uncertainties in Sea Surface Temperature Measured In Situ since the Mid-Nineteenth Century: The HadSST2 Dataset , 2006 .

[24]  J. Janowiak,et al.  The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present) , 2003 .

[25]  N. Lott,et al.  The FCC integrated surface hourly database : a new resource of global climate data , 2001 .

[26]  J. Janowiak,et al.  Global Land Precipitation: A 50-yr Monthly Analysis Based on Gauge Observations , 2002 .

[27]  Jean-François Mahfouf,et al.  Evaluation of the Optimum Interpolation and Nudging Techniques for Soil Moisture Analysis Using FIFE Data , 2000 .

[28]  P. Jones,et al.  Hemispheric and Large-Scale Surface Air Temperature Variations: An Extensive Revision and an Update to 2001. , 2003 .

[29]  K. Trenberth,et al.  Observations: Surface and Atmospheric Climate Change , 2007 .

[30]  P. Xie,et al.  Global Precipitation: A 17-Year Monthly Analysis Based on Gauge Observations, Satellite Estimates, and Numerical Model Outputs , 1997 .

[31]  O. Edenhofer,et al.  Mitigation from a cross-sectoral perspective , 2007 .

[32]  S. Kobayashi,et al.  The JRA-25 Reanalysis , 2007 .

[33]  Jonathan M. Gregory,et al.  Mechanisms for the land/sea warming contrast exhibited by simulations of climate change , 2008 .

[34]  Peter W. Thorne,et al.  Recent Changes in Surface Humidity: Development of the HadCRUH Dataset , 2008 .

[35]  P. Jones,et al.  Uncertainty estimates in regional and global observed temperature changes: A new data set from 1850 , 2006 .

[36]  A. Dai.  Recent climatology, variability, and trends in global surface humidity , 2006 .