Performance of the ECMWF Operational Analyses over the Tropical Indian Ocean

Abstract The quality of the ECMWF operational analyses is evaluated against independent upper-air sounding data collected during the Joint Air–Sea Monsoon Interaction Experiment (JASMINE; April–May 1999) and the Indian Ocean Experiment (INDOEX; February–March 1999). Statistics of the difference between observations and analyses are compiled for temperature, humidity, and wind speed. The results show that the analyzed temperature has a cold bias between 1000 and 750 hPa. However, in the upper troposphere, a warm bias occurs between 350 and 150 hPa, while a cold bias is seen above 150 hPa. Compared to the observations, the analyzed humidity is lower between 1000 and 950 hPa and higher between 950 and 750 hPa. The analyzed wind speeds are close to observations over much of the troposphere, except near the tropopause, where they are overestimated by 1–2 m s−1 in the analyses. The low-level (1000– 750 hPa) biases in moisture and temperature in the ECMWF analyses over the Indian Ocean are similar to those repor...

[1]  Wojciech W. Grabowski,et al.  Cloud-Resolving Modeling of Tropical Cloud Systems during Phase III of GATE. Part I: Two-Dimensional Experiments. , 1996 .

[2]  Edward J. Zipser,et al.  Environmental Variability during TOGA COARE , 2000 .

[3]  P. Courtier,et al.  The ECMWF implementation of three‐dimensional variational assimilation (3D‐Var). I: Formulation , 1998 .

[4]  Richard H. Johnson,et al.  Kinematic and Thermodynamic Characteristics of the Flow over the Western Pacific Warm Pool during TOGA COARE , 1996 .

[5]  Shuyi S. Chen,et al.  Three-Dimensional Week-Long Simulations of TOGA COARE Convective Systems Using the MM5 Mesoscale Model , 1999 .

[6]  Heikki Järvinen,et al.  Variational quality control , 1999 .

[7]  Glenn E. Shaw,et al.  Indian Ocean Experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze , 2001 .

[8]  J. Mahfouf,et al.  The ecmwf operational implementation of four‐dimensional variational assimilation. III: Experimental results and diagnostics with operational configuration , 2000 .

[9]  T. N. Krishnamurti,et al.  A high resolution global reanalysis highlighting the winter monsoon. Part I, reanalysis fields , 1997 .

[10]  Badrinath Nagarajan,et al.  A Numerical Study of a Mesoscale Convective System during TOGA COARE. Part I: Model Description and Verification , 2001 .

[11]  David J. Stensrud,et al.  Behaviors of Variational and Nudging Assimilation Techniques with a Chaotic Low-Order Model , 1992 .

[12]  S. M. Loehrer,et al.  TOGA COARE Upper-Air Sounding Data Archive: Development and Quality Control Procedures , 1996 .

[13]  P. Webster,et al.  TOGA COARE: The Coupled Ocean-Atmosphere Response Experiment. , 1992 .

[14]  J. Michael Fritsch,et al.  Numerical Simulation of the Meso-β Scale Structure and Evolution of the 1977 Johnstown Flood. Part I: Model Description and Verification , 1986 .

[15]  Michèle Vesperini,et al.  Humidity in the ECMWF model: Monitoring of operational analyses and forecasts using SSM/I observations , 1998 .

[16]  David B. Parsons,et al.  Thermodynamic and Radiative Impact of the Correction of Sounding Humidity Bias in the Tropics , 2000 .

[17]  M. Tiedtke,et al.  Representation of Clouds in Large-Scale Models , 1993 .

[18]  Michel Chong,et al.  Monitoring the Performance of the ECMWF Operational Analysis Using the Enhanced TOGA COARE Observational Network , 1996 .